title: Logic programming

text: Although it was based on the proof methods of logic, Planner, developed at MIT, was the first language to emerge within this proceduralist paradigm. Planner featured pattern-directed invocation of procedural plans from goals (i.e. goal-reduction or backward chaining) and from assertions (i.e. forward chaining). The most influential implementation of Planner was the subset of Planner, called Micro-Planner, implemented by Gerry Sussman, Eugene Charniak and Terry Winograd. It was used to implement Winograd's natural-language understanding program SHRDLU, which was a landmark at that time. To cope with the very limited memory systems at the time, Planner used a backtracking control structure so that only one possible computation path had to be stored at a time. Planner gave rise to the programming languages QA-4, Popler, Conniver, QLISP, and the concurrent language Ether.


title: Logic programming

text: Hayes and Kowalski in Edinburgh tried to reconcile the logic-based declarative approach to knowledge representation with Planner's procedural approach. Hayes (1973) developed an equational language, Golux, in which different procedures could be obtained by altering the behavior of the theorem prover. Kowalski, on the other hand, developed SLD resolution, a variant of SL-resolution, and showed how it treats implications as goal-reduction procedures. Kowalski collaborated with Colmerauer in Marseille, who developed these ideas in the design and implementation of the programming language Prolog.


title: Logic programming

text: Prolog gave rise to the programming languages ALF, Fril, Gödel, Mercury, Oz, Ciao, Visual Prolog, XSB, and λProlog, as well as a variety of concurrent logic programming languages, constraint logic programming languages and Datalog.


title: Logic programming

text: Maarten van Emden and Robert Kowalski defined three semantics for Horn clause logic programs, model-theoretic, fixed-point, and proof-theoretic, and showed that they are equivalent.


title: Logic programming

text: Logic programming can be viewed as controlled deduction. An important concept in logic programming is the separation of programs into their logic component and their control component. With pure logic programming languages, the logic component alone determines the solutions produced. The control component can be varied to provide alternative ways of executing a logic program. This notion is captured by the slogan


title: Logic programming

text: where "Logic" represents a logic program and "Control" represents different theorem-proving strategies.


title: Logic programming

text: In the simplified, propositional case in which a logic program and a top-level atomic goal contain no variables, backward reasoning determines an and-or tree, which constitutes the search space for solving the goal. The top-level goal is the root of the tree. Given any node in the tree and any clause whose head matches the node, there exists a set of child nodes corresponding to the sub-goals in the body of the clause. These child nodes are grouped together by an "and". The alternative sets of children corresponding to alternative ways of solving the node are grouped together by an "or".


title: Logic programming

text: Any search strategy can be used to search this space. Prolog uses a sequential, last-in-first-out, backtracking strategy, in which only one alternative and one sub-goal is considered at a time. Other search strategies, such as parallel search, intelligent backtracking, or best-first search to find an optimal solution, are also possible.


title: Logic programming

text: In the more general case, where sub-goals share variables, other strategies can be used, such as choosing the subgoal that is most highly instantiated or that is sufficiently instantiated so that only one procedure applies. Such strategies are used, for example, in concurrent logic programming.


title: Logic programming

text: For most practical applications, as well as for applications that require non-monotonic reasoning in artificial intelligence, Horn clause logic programs need to be extended to normal logic programs with negative conditions. A "clause" in a normal logic program has the form:


title: Logic programming

text: where H and all the A and B are atomic formulas. The negation in the negative literals not B is commonly referred to as "negation as failure", because in most implementations, a negative condition not B is shown to hold by showing that the positive condition B fails to hold. For example:


title: Logic programming

text: there are two candidate solutions, which solve the first subgoal bird(X), namely X = john and X = mary. The second subgoal not abnormal(john) of the first candidate solution fails, because wounded(john) succeeds and therefore abnormal(john) succeeds. However, the second subgoal not abnormal(mary) of the second candidate solution succeeds, because wounded(mary) fails and therefore abnormal(mary) fails. Therefore, X = mary is the only solution of the goal.


title: Logic programming

text: Micro-Planner had a construct, called "thnot", which when applied to an expression returns the value true if (and only if) the evaluation of the expression fails. An equivalent operator typically exists in modern Prolog's implementations. It is typically written as codice_1 or codice_2, where codice_3 is some goal (proposition) to be proved by the program. This operator differs from negation in first-order logic: a negation such as codice_4 fails when the variable codice_5 has been bound to the atom codice_6, but it succeeds in all other cases, including when codice_5 is unbound. This makes Prolog's reasoning non-monotonic: codice_8 always fails, while codice_9 can succeed, binding codice_5 to codice_6, depending on whether codice_5 was initially bound (note that standard Prolog executes goals in left-to-right order).


title: Logic programming

text: The logical status of negation as failure was unresolved until Keith Clark [1978] showed that, under certain natural conditions, it is a correct (and sometimes complete) implementation of classical negation with respect to the completion of the program. Completion amounts roughly to regarding the set of all the program clauses with the same predicate on the left hand side, say


title: Logic programming

text: where "iff" means "if and only if". Writing the completion also requires explicit use of the equality predicate and the inclusion of a set of appropriate axioms for equality. However, the implementation of negation as failure needs only the if-halves of the definitions without the axioms of equality.


title: Logic programming

text: The notion of completion is closely related to McCarthy's circumscription semantics for default reasoning, and to the closed world assumption.


title: Logic programming

text: As an alternative to the completion semantics, negation as failure can also be interpreted epistemically, as in the stable model semantics of answer set programming. In this interpretation not(B) means literally that B is not known or not believed. The epistemic interpretation has the advantage that it can be combined very simply with classical negation, as in "extended logic programming", to formalise such phrases as "the contrary can not be shown", where "contrary" is classical negation and "can not be shown" is the epistemic interpretation of negation as failure.


title: Logic programming

text: The fact that Horn clauses can be given a procedural interpretation and, vice versa, that goal-reduction procedures can be understood as Horn clauses + backward reasoning means that logic programs combine declarative and procedural representations of knowledge. The inclusion of negation as failure means that logic programming is a kind of non-monotonic logic.


title: Logic programming

text: Despite its simplicity compared with classical logic, this combination of Horn clauses and negation as failure has proved to be surprisingly expressive. For example, it provides a natural representation for the common-sense laws of cause and effect, as formalised by both the situation calculus and event calculus. It has also been shown to correspond quite naturally to the semi-formal language of legislation. In particular, Prakken and Sartor credit the representation of the British Nationality Act as a logic program with being "hugely influential for the development of computational representations of legislation, showing how logic programming enables intuitively appealing representations that can be directly deployed to generate automatic inferences".


title: Logic programming

text: The programming language Prolog was developed in 1972 by Alain Colmerauer. It emerged from a collaboration between Colmerauer in Marseille and Robert Kowalski in Edinburgh. Colmerauer was working on natural-language understanding, using logic to represent semantics and using resolution for question-answering. During the summer of 1971, Colmerauer and Kowalski discovered that the clausal form of logic could be used to represent formal grammars and that resolution theorem provers could be used for parsing. They observed that some theorem provers, like hyper-resolution, behave as bottom-up parsers and others, like SL-resolution (1971), behave as top-down parsers.


title: Logic programming

text: It was in the following summer of 1972, that Kowalski, again working with Colmerauer, developed the procedural interpretation of implications. This dual declarative/procedural interpretation later became formalised in the Prolog notation


title: Logic programming

text: which can be read (and used) both declaratively and procedurally. It also became clear that such clauses could be restricted to definite clauses or Horn clauses, where H, B, ..., B are all atomic predicate logic formulae, and that SL-resolution could be restricted (and generalised) to LUSH or SLD-resolution. Kowalski's procedural interpretation and LUSH were described in a 1973 memo, published in 1974.


title: Logic programming

text: Colmerauer, with Philippe Roussel, used this dual interpretation of clauses as the basis of Prolog, which was implemented in the summer and autumn of 1972. The first Prolog program, also written in 1972 and implemented in Marseille, was a French question-answering system. The use of Prolog as a practical programming language was given great momentum by the development of a compiler by David Warren in Edinburgh in 1977. Experiments demonstrated that Edinburgh Prolog could compete with the processing speed of other symbolic programming languages such as Lisp. Edinburgh Prolog became the "de facto" standard and strongly influenced the definition of ISO standard Prolog.


title: Logic programming

text: Abductive logic programming is an extension of normal Logic Programming that allows some predicates, declared as abducible predicates, to be "open" or undefined. A clause in an abductive logic program has the form:


title: Logic programming

text: where H is an atomic formula that is not abducible, all the B are literals whose predicates are not abducible, and the A are atomic formulas whose predicates are abducible. The abducible predicates can be constrained by integrity constraints, which can have the form:


title: Logic programming

text: Problem-solving is achieved by deriving hypotheses expressed in terms of the abducible predicates as solutions to problems to be solved. These problems can be either observations that need to be explained (as in classical abductive reasoning) or goals to be solved (as in normal logic programming). For example, the hypothesis normal(mary) explains the observation canfly(mary). Moreover, the same hypothesis entails the only solution X = mary of the goal of finding something which can fly:


title: Logic programming

text: Abductive logic programming has been used for fault diagnosis, planning, natural language processing and machine learning. It has also been used to interpret Negation as Failure as a form of abductive reasoning.


title: Logic programming

text: Because mathematical logic has a long tradition of distinguishing between object language and metalanguage, logic programming also allows metalevel programming. The simplest metalogic program is the so-called "vanilla" meta-interpreter:


title: Logic programming

text: where true represents an empty conjunction, and clause(A,B) means that there is an object-level clause of the form A :- B.


title: Logic programming

text: Metalogic programming allows object-level and metalevel representations to be combined, as in natural language. It can also be used to implement any logic which is specified as inference rules. Metalogic is used in logic programming to implement metaprograms, which manipulate other programs, databases, knowledge bases or axiomatic theories as data.


title: Logic programming

text: Constraint logic programming combines Horn clause logic programming with constraint solving. It extends Horn clauses by allowing some predicates, declared as constraint predicates, to occur as literals in the body of clauses. A constraint logic program is a set of clauses of the form:


title: Logic programming

text: where H and all the B are atomic formulas, and the C are constraints. Declaratively, such clauses are read as ordinary logical implications:


title: Logic programming

text: However, whereas the predicates in the heads of clauses are defined by the constraint logic program, the predicates in the constraints are predefined by some domain-specific model-theoretic structure or theory.


title: Logic programming

text: Procedurally, subgoals whose predicates are defined by the program are solved by goal-reduction, as in ordinary logic programming, but constraints are checked for satisfiability by a domain-specific constraint-solver, which implements the semantics of the constraint predicates. An initial problem is solved by reducing it to a satisfiable conjunction of constraints.


title: Logic programming

text: The following constraint logic program represents a toy temporal database of john's history as a teacher:


title: Logic programming

text: Here ≤ and < are constraint predicates, with their usual intended semantics. The following goal clause queries the database to find out when john both taught logic and was a professor:


title: Logic programming

text: Constraint logic programming has been used to solve problems in such fields as civil engineering, mechanical engineering, digital circuit verification, automated timetabling, air traffic control, and finance. It is closely related to abductive logic programming.


title: Logic programming

text: Concurrent logic programming integrates concepts of logic programming with concurrent programming. Its development was given a big impetus in the 1980s by its choice for the systems programming language of the Japanese Fifth Generation Project (FGCS).


title: Logic programming

text: The conjunction G, ... , G is called the guard of the clause, and | is the commitment operator. Declaratively, guarded Horn clauses are read as ordinary logical implications:


title: Logic programming

text: However, procedurally, when there are several clauses whose heads H match a given goal, then all of the clauses are executed in parallel, checking whether their guards G, ... , G hold. If the guards of more than one clause hold, then a committed choice is made to one of the clauses, and execution proceeds with the subgoals B, ..., B of the chosen clause. These subgoals can also be executed in parallel. Thus concurrent logic programming implements a form of "don't care nondeterminism", rather than "don't know nondeterminism".


title: Logic programming

text: For example, the following concurrent logic program defines a predicate shuffle(Left, Right, Merge) , which can be used to shuffle two lists Left and Right, combining them into a single list Merge that preserves the ordering of the two lists Left and Right:


title: Logic programming

text: Here, [] represents the empty list, and [Head | Tail] represents a list with first element Head followed by list Tail, as in Prolog. (Notice that the first occurrence of | in the second and third clauses is the list constructor, whereas the second occurrence of | is the commitment operator.) The program can be used, for example, to shuffle the lists [ace, queen, king] and [1, 4, 2] by invoking the goal clause:


title: Logic programming

text: The program will non-deterministically generate a single solution, for example Merge = [ace, queen, 1, king, 4, 2].


title: Logic programming

text: Arguably, concurrent logic programming is based on message passing, so it is subject to the same indeterminacy as other concurrent message-passing systems, such as Actors (see Indeterminacy in concurrent computation). Carl Hewitt has argued that concurrent logic programming is not based on logic in his sense that computational steps cannot be logically deduced. However, in concurrent logic programming, any result of a terminating computation is a logical consequence of the program, and any partial result of a partial computation is a logical consequence of the program and the residual goal (process network). Thus the indeterminacy of computations implies that not all logical consequences of the program can be deduced.


title: Logic programming

text: Concurrent constraint logic programming combines concurrent logic programming and constraint logic programming, using constraints to control concurrency. A clause can contain a guard, which is a set of constraints that may block the applicability of the clause. When the guards of several clauses are satisfied, concurrent constraint logic programming makes a committed choice to use only one.


title: Logic programming

text: Inductive logic programming is concerned with generalizing positive and negative examples in the context of background knowledge: machine learning of logic programs. Recent work in this area, combining logic programming, learning and probability, has given rise to the new field of statistical relational learning and probabilistic inductive logic programming.


title: Logic programming

text: Several researchers have extended logic programming with higher-order programming features derived from higher-order logic, such as predicate variables. Such languages include the Prolog extensions HiLog and λProlog.


title: Logic programming

text: Basing logic programming within linear logic has resulted in the design of logic programming languages that are considerably more expressive than those based on classical logic. Horn clause programs can only represent state change by the change in arguments to predicates. In linear logic programming, one can use the ambient linear logic to support state change. Some early designs of logic programming languages based on linear logic include LO, Lolli, ACL, and Forum. Forum provides a goal-directed interpretation of all linear logic.


title: Logic programming

text: Logtalk extends the Prolog programming language with support for objects, protocols, and other OOP concepts. It supports most standard-compliant Prolog systems as backend compilers.


title: Logic programming

text: Transaction logic is an extension of logic programming with a logical theory of state-modifying updates. It has both a model-theoretic semantics and a procedural one. An implementation of a subset of Transaction logic is available in the Flora-2 system. Other prototypes are also available.


title: Leslie Ash

text: She is best known for her roles in "C.A.T.S. Eyes" (1985–1987), the BBC sitcom "Men Behaving Badly" (1992–1997), ITV drama "Where the Heart Is" (2000–2003), and BBC medical drama "Holby City" (2009–2010). Her book "My Life Behaving Badly: The Autobiography" was published in 2007.


title: Leslie Ash

text: Ash was born in Henley-on-Thames, Oxfordshire, and first appeared on British television in 1964 at the age of four asking "Mummy, why are your hands so soft?" in an advertisement for the washing-up product Fairy Liquid. She was educated at the independent Italia Conti Academy stage school, and then started a career as a fashion model appearing on the cover of a number of teenager magazines, including "Pink", and "Jackie", for which she was photographed by David Bailey.


title: Leslie Ash

text: Having appeared with her sister Debbie in the 1978 British slapstick comedy "Rosie Dixon – Night Nurse"; her first major film role was playing the romantic lead in "Quadrophenia" in 1979. In 1980, Ash appeared in the Iron Maiden music video, "Women in Uniform" and one of the two Dire Straits music videos of Tunnel of Love. In 1982 she played the role of a fast food chef in the fifth series of Shelley entitled "When the Chip hits the Fan", and appeared opposite Joan Collins in the film "Nutcracker". In 1983, she had the starring role in "The Balance of Nature", a film about a Cockney girl from a tower block with aspirations to win the Miss United Kingdom competition. The same year, she played Julie Morgan, "alias" Juletta Shane, in "Curse of the Pink Panther", and also appeared opposite Nicky Henson as Nancy in the ITV situation comedy "The Happy Apple" playing a secretary whose opinions successfully reflected public opinion. She then played a regular role in crime series "C.A.T.S. Eyes". From 1983 until 1987, she was a co-presenter on the Channel 4 music programme "The Tube" alongside Jools Holland and Paula Yates. In 1984 she appeared opposite Roger Daltrey and former "Quadrophenia" co-star Toyah Willcox in the thriller "", and played Carol Landau in the 1985 comedy film "Shadey", directed by Philip Saville.


title: Leslie Ash

text: In 1987, Ash appeared in the first episode of the third series of the ITV comedy series "Home to Roost", entitled "Human Interest," where Ash played the role of the flamboyant cleaner, Susie Perkins.


title: Leslie Ash

text: Ash's best known role was playing Neil Morrissey's romantic interest Deborah (Debs) in the situation comedy "Men Behaving Badly". She continued in the role for six series. She subsequently acted in BBC police drama "Merseybeat" and the ITV drama "Where the Heart Is".


title: Leslie Ash

text: In 1996, during her time on "Men Behaving Badly", Leslie released a single "Tell Him" with co-star Caroline Quentin, under the name of "Quentin & Ash". It reached number 25 in the UK singles chart.


title: Leslie Ash

text: Ash appeared in BBC Radio 4's comic radio series, "Vent" (2007), alongside Neil Pearson, Fiona Allen and Josie Lawrence.


title: Leslie Ash

text: In May 2008, Ash worked with Transparent Television to make a documentary about the unregulated cosmetic beauty industry whilst exploring her own experiences. The programme, "Leslie Ash: Face to Face" was broadcast on ITV on 23 September 2008.


title: Leslie Ash

text: In 2009, Ash appeared on daytime TV panel programme "Loose Women" to discuss her new role in "Holby City" and her previous health problems. Leslie reappeared on "Loose Women" on 17 February 2012 where she discussed her on stage tour of "All the Single Ladies".


title: Leslie Ash

text: In 2014, Leslie was a contestant on the BBC programme, "Celebrity Masterchef". In 2020, she appeared opposite many of her "Quadrophenia" co-stars in the unofficial semi-sequel "To Be Someone". In 2021, it was announced that she would be reprising her role as Vanessa Lytton in an episode of "Holby City"s sister series "Casualty". In the same year, she also appeared in an episode of the BBC soap opera "Doctors" as Mary McRae.


title: Leslie Ash

text: Ash is married to former footballer Lee Chapman, and they have two sons. Her sister is former 'Hot Gossip' dancer Debbie Ash. They appeared together as sisters in "Rosie Dixon – Night Nurse".


title: Leslie Ash

text: Ash contracted toxoplasmosis two months into her pregnancy while in France, where it is more common than in the United Kingdom. She told the BBC that she wished to raise awareness of the issue in Britain.


title: Leslie Ash

text: Ash was hospitalised at the Chelsea and Westminster Hospital in April 2004 after suffering two cracked ribs. She was discharged after a few days, but was readmitted after losing all feeling in her legs. In June 2004 while she was still in hospital, it was announced that a "Staphylococcus aureus" infection might have rendered her permanently unable to walk.


title: Leslie Ash

text: In January 2007 Ash confirmed she was suing the hospital. Papers lodged at the High Court asserted that Ash would never return to active TV roles. The hospital admitted breach of duty over part of her treatment but denied responsibility for the extent of her injuries and in January 2008 paid out a record £5m compensation in an out-of-court settlement. Steve Walker, chief executive of the NHS Litigation Authority, said the payout set a new record for compensation following a hospital-acquired infection. The previous highest amount was £500,000. The payment was justified by the NHS compensation body as being "because of the amount Leslie was earning at the time she fell ill and takes into account how much she might have earned in the future".


title: Leslie Ash

text: In her thirties, Ash had a collagen injection to 'plump up' her lips. When she was forty she decided to repeat the procedure with the same plastic surgeon, the mother of a Venezuelan friend. In the second procedure, liquid silicone was injected resulting in extreme swelling of her lips, a condition dubbed as "trout pout" in the press. Subsequent medical analysis showed that the silicone had set and the condition is permanent. During this time Ash starred in a series of advertisements for the DIY chain Homebase (again, with Neil Morrissey) and starred in "Merseybeat", which evoked further ridicule from the media about her appearance.


title: Leslie Ash

text: Ash has since spoken out about the press ridicule she received as a result of her botched implants, commenting: "If I'd lost a leg in a car crash, people wouldn't have felt able to take the mickey out of me so mercilessly ... People don't laugh at Heather Mills because she lost a leg."


title: Leslie Ash

text: Ash and Chapman sued the "News of the World" for breach of privacy over suspicions that their voicemails, and those of their two sons, were illegally accessed by private investigator Glenn Mulcaire. They wrote to the police over their suspicions, and the police informed them that there were four pieces of paper referring to Ash in Mulcaire's notebooks, and five items relating to Chapman. There were further items relating to their children.


title: Leslie Ash

text: In August 2011, Ash and Chapman settled a claim against the paper and Mulcaire for an undisclosed sum and received an apology. They planned to take action against other newspapers.


title: Cameron (wrestler)

text: Ariane Nicole Andrew (born November 3, 1987) is an American professional wrestler, singer, model and dancer. Andrew is best known for her time in WWE under the ring name Cameron (shortened from Cameron Lynn). Under her real name, Ariane joined the 2011 season of "Tough Enough" where she was the first competitor eliminated. She later signed with WWE and joined Naomi in forming The Funkadactyls. From July 2013 to March 2015, Andrew was one of the main cast members of the reality television show "Total Divas".


title: Cameron (wrestler)

text: Andrew was born on November 3, 1987, and raised in Northridge, Los Angeles, California. She is of African American descent. She graduated from Granada Hills Charter High School, where she was active in track and cross country, and was a member of the school's drama club. She later graduated from California State University, Northridge with a Bachelor of Arts in business marketing and a Bachelor of Science in psychology. After graduating, she moved to North Hollywood, where she worked as a behavior therapist for autistic children.


title: Cameron (wrestler)

text: In 2011, Andrew competed in a non-televised "Diva Search" with World Wrestling Entertainment (WWE). Later that year, Andrew was one of fourteen contestants on the revival of "Tough Enough", where she was the first eliminated.


title: Cameron (wrestler)

text: Immediately after being eliminated from "Tough Enough", Andrew confirmed on her Twitter account that WWE had signed her to a contract. She was then assigned to WWE's then-developmental territory, Florida Championship Wrestling (FCW), and made her debut on July 7, 2011, as a ring announcer at an FCW house show. On July 9, she made her in-ring debut, under the ring name Cameron Lynn, in a Divas battle royal, which consisted of Audrey Marie, Caylee Turner, Kaitlyn, Maxine, Raquel Diaz, Sonia, and Aksana, in which Lynn was eliminated first. On the October 9, 2011, episode of "FCW TV", she made her televised debut with Byron Saxton, accompanying Naomi Knight to ringside during her match against Leah West, which Knight won. On the October 23 episode of FCW TV, Lynn teamed with Knight in a winning effort against Caylee Turner and Kaitlyn.


title: Cameron (wrestler)

text: On the January 9, 2012 episode of "Raw", she (billed simply as Cameron) made her WWE main roster debut as one of the dancers and valets, along with Naomi, for the returning Brodus Clay. She made her WrestleMania debut at WrestleMania XXVIII alongside Naomi in a segment with Clay. On the pre-show on December 16, 2012, Cameron participated in her first televised match on the main roster, which was a "Santa's Little Helpers" battle royal which was won by her fellow Funkadactyl Naomi, who would go on to face Eve Torres later that night for the Divas Championship.


title: Cameron (wrestler)

text: On the February 6, 2013 episode of "Main Event", The Funkadactyls got into a backstage altercation with Tamina Snuka and Aksana, after Snuka and Aksana began to persuade Brodus Clay to fire The Funkadactyls and hire them as his backup dancers instead. This led to Cameron and Naomi's first match as a team, in which they defeated Snuka and Aksana.


title: Cameron (wrestler)

text: On the March 15 episode of "SmackDown", The Funkadactyls were attacked by the returning Bella Twins in a backstage segment. On the March 22 episode of "SmackDown" and March 25 episode of "Raw", The Funkadactyls attacked the twins after they interfered both times in Tons of Funk (Brodus Clay and Tensai)'s match against Team Rhodes Scholars (Cody Rhodes and Damien Sandow).<ref name="Raw3/25/13"></ref> The four women eventually faced off in a tag team match on the March 27 episode of "Main Event", where the Bella Twins emerged victorious when Nikki Bella pinned Naomi after an interference by Rhodes.<ref name="MainEvent3/27/13"></ref> Cameron and Naomi were set to team up with Brodus Clay and Tensai against Team Rhodes Scholars and the Bella Twins at WrestleMania 29 in an eight-person mixed tag team match, however the match was cancelled due to time restraints. The match instead took place the following night on "Raw", where Tons of Funk and The Funkadactyls emerged victorious.


title: Cameron (wrestler)

text: On the August 26 episode of "Raw", Cameron and Naomi accompanied Natalya to an unsuccessful singles match against Brie Bella, until AJ Lee interrupted and ignited a feud on the cast of "Total Divas", criticizing them as undeserving. On the September 27 episode of "Smackdown!", Cameron was defeated by Lee in singles match. Cameron joined Team "Total Divas" in a 7-on-7 elimination tag-team match against Team "True Divas" (Alicia Fox, Aksana, AJ Lee, Kaitlyn, Rosa Mendes, Tamina Snuka, and Summer Rae) at the Survivor Series pay-per-view and the following night on "Raw" in a rematch; although Cameron was eliminated by Mendes in the former event and by Snuka in the latter, her team was ultimately victorious in both competitions. On December 15 at the pay-per-view, Cameron, along with fellow Funkadactyl Naomi and Tensai, abandoned Brodus Clay because of his attitude, effectively disbanding Tons of Funk. The following night on an episode of "Raw", Cameron and Naomi aligned themselves with R-Truth and Xavier Woods, and began accompanying them to their matches.


title: Cameron (wrestler)

text: In January 2014, The Funkadactyls began feuding with AJ Lee and her bodyguard Tamina Snuka, when Naomi received a push and defeated Lee in various tag team matches on both "Raw" and "SmackDown". However, their rivalry was cut shortly after Naomi suffered a legitimate eye injury during her match with Aksana on the February 3 episode of "Raw". On the February 10 episode of "Raw", Cameron pinned Aksana during a six-Diva tag team match, and on the February 19 episode of "Main Event", Cameron defeated her in a singles match. On February 23 at Elimination Chamber, Cameron received her first shot at the Divas Championship, a match which she won by disqualification after Tamina Snuka accidentally hit a superkick on AJ Lee. Cameron received a rematch on the February 28 episode of "SmackDown", which she would lose. At WrestleMania XXX, Cameron failed to capture the title in the "Vickie Guerrero Divas Championship Invitational" match, which was ultimately won by Lee.


title: Cameron (wrestler)

text: In June 2014, after the Payback pay-per-view, Cameron started a brief feud with new Divas Champion Paige, in which Cameron would begin displaying signs of a villainous persona and would unsuccessfully challenge Paige in three non-title matches on "Superstars" and "Raw", all of which Paige would win. Paige then lost to a non-title match to Cameron's tag team partner Naomi, who would get a shot at the Divas Championship at Money in the Bank, after which The Funkadactyls began to fall out and had several disagreements during and after their matches.


title: Cameron (wrestler)

text: On the July 7 episode of "Raw", Cameron and Naomi were defeated by AJ Lee and Paige after Cameron tagged herself in and was pinned by Paige. After the match, Cameron and Naomi began brawling in and out of the ring, and as a result, Cameron cemented her villainous turn and the team was disbanded. The following night on an episode of "Main Event", Cameron was scheduled to team with Naomi, Natalya, Eva Marie, Rosa Mendes, and Summer Rae against Nikki Bella in a six-on-one handicap match, but only showed up to attack Naomi and Nikki. Cameron competed in her first match as a villain on the July 15 episode of "Main Event" losing to Emma and attacked her after the match, only to be scared off by Naomi. This led to a match between the two on the Battleground pre–show, where Cameron defeated Naomi after grabbing her tights. Throughout the summer, Cameron continued her rivalry with Naomi and competed in various handicap, singles and tag team matches. In November, at Survivor Series, Cameron participated in a four-on-four elimination tag team match, where she was eliminated by Naomi before her team ultimately lost the match. In early 2015, Cameron competed in various singles matches losing to the likes of Summer Rae, Naomi and Paige. On the April 13 episode of "Raw", Cameron competed in a number one contender's battle royal for Nikki Bella's WWE Divas Championship, which would be won by Paige. After being the special guest referee for a match between Alicia Fox and Natalya, Cameron would attack both Divas on the April 9 episode of "Smackdown", which would lead to a triple threat match the following week, with Cameron coming out victorious. A few weeks later, on the April 30 episode of "SmackDown", Cameron confronted Nikki Bella during a backstage segment that led to a non–title match between the two, which Cameron lost.


title: Cameron (wrestler)

text: After taking a hiatus from WWE television, Cameron was moved to WWE NXT and made her return on the November 4 episode of "NXT", losing to Asuka. On the January 13, 2016, episode of "NXT", Cameron competed in a battle royal to determine the number one contender for Bayley's NXT Women's Championship, which was won by Carmella. On the February 10 episode of "NXT", Cameron faced Alexa Bliss in a losing effort.<ref name="NXT10/02/16"></ref> After two months of inactivity, WWE announced on May 6 that Andrew had been released from her contract.


title: Cameron (wrestler)

text: After a 6 year absence from WWE programming, Cameron made a surprise return at the number 13 spot in the 2022 Royal Rumble to her old Funkadactyls music. She was eliminated by Sonya Deville who was feuding with her former tag-team partner, Naomi.


title: Cameron (wrestler)

text: Andrew made her All Elite Wrestling debut on the July 29, 2020 episode of "AEW Dynamite", as she was revealed to have chosen the same color token as Nyla Rose in the Deadly Draw lottery system, meaning the two would team for the AEW Women's Tag Team Cup Tournament. They were eliminated in the first round after losing to Anna Jay and Tay Conti.


title: Cameron (wrestler)

text: Andrew played a main role for the reality television show "Total Divas" produced by WWE and E!, which began airing in July 2013. In May 2015, it was announced that Andrew would not be featured as a full-time cast member on the show for season 4, although she still appears as a guest star.


title: Cameron (wrestler)

text: Cameron has appeared in four WWE video games. She made her in-game debut at "WWE 13" as an NPC along her then-tag team partner Naomi as "The Funkadactyls" appearing during Brodus Clay's entrance and winning celebration as well as in "WWE 2K14", she later made her playable character debut in "WWE 2K15" and was playable once again in "WWE 2K16".


title: Cameron (wrestler)

text: Cameron has previously lived in Tampa, Florida. Cameron was in a relationship with Vincent Isayan, and their relationship was featured on "Total Divas". On the May 24, 2016 episode of Stone Cold Steve Austin's podcast, Cameron revealed that she and Isayan had broken up. She has a younger brother, Quentinn, and a younger sister, Aniyah. She has two degrees. She cites Maryse, Melina, and Alicia Fox as her inspirations.


title: Cameron (wrestler)

text: In August 2012, Cameron was arrested for allegedly driving under the influence and trying to bribe the arresting officer, which she said on season 2 of Total Divas was a false accusation stemming from stereotyping.


title: Schema therapy

text: Schema therapy was developed by Jeffrey E. Young for use in treatment of personality disorders and chronic DSM Axis I disorders, such as when patients fail to respond or relapse after having been through other therapies (for example, traditional cognitive behavioral therapy). Schema therapy is an integrative psychotherapy combining theory and techniques from previously existing therapies, including cognitive behavioral therapy, psychoanalytic object relations theory, attachment theory, and Gestalt therapy.


title: Schema therapy

text: Four main theoretical concepts in schema therapy are "early maladaptive schemas" (or simply "schemas"), "coping styles", "modes", and "basic emotional needs":


title: Schema therapy

text: The goal of schema therapy is to help patients meet their basic emotional needs by helping the patient learn how to:


title: Schema therapy

text: Techniques used in schema therapy including limited reparenting and Gestalt therapy psychodrama techniques such as imagery re-scripting and empty chair dialogues. See , below.


title: Schema therapy

text: Early maladaptive schemas are self-defeating emotional and cognitive patterns established from childhood and repeated throughout life. They may be made up of emotional memories of past hurt, tragedy, fear, abuse, neglect, unmet safety needs, abandonment, or lack of normal human affection in general. Early maladaptive schemas can also include bodily sensations associated with such emotional memories. Early maladaptive schemas can have different levels of severity and pervasiveness: the more severe the schema, the more intense the negative emotion when the schema is triggered and the longer it lasts; the more pervasive the schema, the greater the number of situations that trigger it.


title: Schema therapy

text: Schema domains are five broad categories of unmet needs into which are grouped 18 early maladaptive schemas identified by :


title: Schema therapy

text: In 2022, these have been subsequently further developed by schema researcher and Clinical Psychologist Ozgur Yalcin, finding that the emotional inhibition and punitiveness schemas can each be split into 4 new sub-schemas.


title: Schema therapy

text: Schema modes are momentary mind states which every human being experiences at one time or another. A schema mode consists of a cluster of schemas and coping styles. Life situations that a person finds disturbing or offensive, or arouse bad memories, are referred to as "triggers" that tend to activate schema modes. In psychologically healthy persons, schema modes are mild, flexible mind states that are easily pacified by the rest of their personality. In patients with personality disorders, schema modes are more severe, rigid mind states that may seem split off from the rest of their personality.


title: Schema therapy

text: identified 10 schema modes grouped into four categories. The four categories are: Child modes, Dysfunctional Coping modes, Dysfunctional Parent modes, and the "Healthy Adult" mode. The four Child modes are: "Vulnerable Child", "Angry Child", "Impulsive/Undisciplined Child", and "Happy Child". The three Dysfunctional Coping modes are: "Compliant Surrenderer", "Detached Protector", and "Overcompensator". The two Dysfunctional Parent modes are: "Punitive Parent" and "Demanding Parent".


title: Schema therapy

text: Treatment plans in schema therapy generally encompass three basic classes of techniques: cognitive, experiential, and behavioral (in addition to the basic healing components of the therapeutic relationship). "Cognitive" strategies expand on standard cognitive behavioral therapy techniques such as listing pros and cons of a schema, testing the validity of a schema, or conducting a dialogue between the "schema side" and the "healthy side". "Experiential and emotion focused" strategies expand on standard Gestalt therapy psychodrama and imagery techniques. "Behavioral" pattern-breaking strategies expand on standard behavior therapy techniques, such as role playing an interaction and then assigning the interaction as homework. One of the most central techniques in schema therapy is the use of the therapeutic relationship, specifically through a process called "limited reparenting".


title: Schema therapy

text: Specific techniques often used in schema therapy include "flash cards" with important therapeutic messages, created in session and used by the patient between sessions, and the "schema diary"—a template or workbook that is filled out by the patient between sessions and that records the patient's progress in relation to all the theoretical concepts in schema therapy.


title: Schema therapy

text: From an integrative psychotherapy perspective, limited reparenting and the experiential techniques, particularly around changing modes, could be seen as actively changing what psychoanalysis has described as object relations. Historically, mainstream psychoanalysis tended to reject active techniques—such as Fritz Perls' Gestalt therapy work or Franz Alexander's "corrective emotional experience"—but contemporary relational psychoanalysis (led by analysts such as Lewis Aron, and building on the ideas of earlier unorthodox analysts such as Sándor Ferenczi) is more open to active techniques. It is notable that in a head-to-head comparison of a psychoanalytic object relations treatment (Otto F. Kernberg's transference focused psychotherapy) and schema therapy, the latter has been demonstrated to be more effective in treating Borderline Personality Disorder.


title: Schema therapy

text: Dutch investigators, including Josephine Giesen-Bloo and Arnoud Arntz (the project leader), compared schema therapy (also known as schema focused therapy or SFT) with transference focused psychotherapy (TFP) in the treatment of borderline personality disorder. 86 patients were recruited from four mental health institutes in the Netherlands. Patients in the study received two sessions per week of SFT or TFP for three years. After three years, full recovery was achieved in 45% of the patients in the SFT condition, and in 24% of those receiving TFP. One year later, the percentage fully recovered increased to 52% in the SFT condition and 29% in the TFP condition, with 70% of the patients in the SFT group achieving "clinically significant and relevant improvement". Moreover, the dropout rate was only 27% for SFT, compared with 50% for TFP.


title: Schema therapy

text: Patients began to feel and function significantly better after the first year, with improvement occurring more rapidly in the SFT group. There was continuing improvement in subsequent years. Thus investigators concluded that both treatments had positive effects, with schema therapy clearly more successful.


title: Schema therapy

text: Dutch investigators, including Marjon Nadort and Arnoud Arntz, assessed the effectiveness of schema therapy in the treatment of borderline personality disorder when utilized in regular mental health care settings. A total of 62 patients were treated in eight mental health centers located in the Netherlands. The treatment was less intensive along a number of dimensions including a shift from twice weekly to once weekly sessions during the second year. Despite this, there was no lessening of effectiveness with recovery rates that were at least as high and similarly low dropout rates.


title: Schema therapy

text: Investigators Joan Farrell, Ida Shaw and Michael Webber at the Indiana University School of Medicine Center for BPD Treatment & Research tested the effectiveness of adding an eight-month, 30-session schema therapy group to treatment-as-usual (TAU) for borderline personality disorder (BPD) with 32 patients. The dropout rate was 0% for those patients who received group schema therapy in addition to TAU and 25% for those who received TAU alone. At the end of treatment, 94% of the patients who received group schema therapy in addition to TAU compared to 16% of the patients receiving TAU alone no longer met BPD diagnostic criteria. The schema therapy group treatment led to significant reductions in symptoms and global improvement in functioning. The large positive treatment effects found in the group schema therapy study suggest that the group modality may augment or catalyze the active ingredients of the treatment for BPD patients. As of 2014, a collaborative randomized controlled trial is under way at 14 sites in six countries to further explore this interaction between groups and schema therapy.


title: Smoking (cooking)

text: Smoking is the process of flavoring, browning, cooking, or preserving food by exposing it to smoke from burning or smoldering material, most often wood. Meat, fish, and "lapsang souchong" tea are often smoked.


title: Smoking (cooking)

text: In Europe, alder is the traditional smoking wood, but oak is more often used now, and beech to a lesser extent. In North America, hickory, mesquite, oak, pecan, alder, maple, and fruit-tree woods, such as apple, cherry, and plum, are commonly used for smoking. Other biomass besides wood can also be employed, sometimes with the addition of flavoring ingredients. Chinese tea-smoking uses a mixture of uncooked rice, sugar, and tea, heated at the base of a wok.


title: Smoking (cooking)

text: Some North American ham and bacon makers smoke their products over burning corncobs. Peat is burned to dry and smoke the barley malt used to make Scotch whisky and some beers. In New Zealand, sawdust from the native manuka (tea tree) is commonly used for hot smoking fish. In Iceland, dried sheep dung is used to cold-smoke fish, lamb, mutton and whale.


title: Smoking (cooking)

text: Historically, farms in the Western world included a small building termed the "smokehouse", where meats could be smoked and stored. This was generally well separated from other buildings both because of the fire danger and because of the smoke emanations; the smoking of food could possibly introduce polycyclic aromatic hydrocarbons which may lead to an increased risk of some types of cancer; however, this association is still being debated.


title: Smoking (cooking)

text: Smoking can be done in four ways: cold smoking, warm smoking, hot smoking, and through the employment of a smoke flavoring, such as liquid smoke. However, these methods of imparting smoke only affect the food surface, and are unable to preserve food, thus, smoking is paired with other microbial hurdles, such as chilling and packaging, to extend food shelf-life.


title: Smoking (cooking)

text: The smoking of food likely dates back to the paleolithic era. As simple dwellings lacked chimneys, these structures would probably have become very smoky. It is supposed that early humans would hang meat up to dry and out of the way of pests, thus accidentally becoming aware that meat that was stored in smoky areas acquired a different flavor, and was better preserved than meat that simply dried out. This process was later combined with pre-curing the food in salt or salty brine, resulting in a remarkably effective preservation process that was adapted and developed by numerous cultures around the world. Until the modern era, smoking was of a more "heavy duty" nature as the main goal was to preserve the food. Large quantities of salt were used in the curing process and smoking times were quite long, sometimes involving days of exposure.


title: Smoking (cooking)

text: The advent of modern transportation made it easier to transport food products over long distances and the need for the time and material intensive heavy salting and smoking declined. Smoking became more of a way to flavor than to preserve food. In 1939 a device called the Torry Kiln was invented at the Torry Research Station in Scotland. The kiln allowed for uniform mass-smoking and is considered the prototype for all modern large-scale commercial smokers. Although refinements in technique and advancements in technology have made smoking much easier, the basic steps involved remain essentially the same today as they were hundreds if not thousands of years ago.


title: Smoking (cooking)

text: Cold smoking differs from hot smoking in that the food remains raw, rather than cooked, throughout the smoking process. Smokehouse temperatures for cold smoking are typically done between . In this temperature range, foods take on a smoked flavor, but remain relatively moist. Cold smoking does not cook foods, and as such, meats should be fully cured before cold smoking. Cold smoking can be used as a flavor enhancer for items such as cheese or nuts, along with meats such as chicken breasts, beef, pork chops, salmon, scallops, and steak. The item is often hung in a dry environment first to develop a pellicle; it can then be cold smoked up to several days to ensure it absorbs the smoke flavor. Some cold smoked foods are baked, grilled, steamed, roasted, or sautéed before eating.


title: Smoking (cooking)

text: Cold smoking meats is not something that should be attempted at home, according to the US National Center for Home Food Preservation: "Most food scientists cannot recommend cold-smoking methods because of the inherent risks."


title: Smoking (cooking)

text: Cold smoking meats should only be attempted by personnel certified in HACCP [...] to ensure that it is safely prepared.


title: Smoking (cooking)

text: Hot smoking exposes the foods to smoke and heat in a controlled environment such as a smoker oven or smokehouse. Hot smoking requires the use of a smoker which generates heat either from a charcoal base, heated element within the smoker or from a stove-top or oven; food is hot smoked by cooking and flavored with wood smoke simultaneously. Like cold smoking, the item may be hung first to develop a pellicle; it is then smoked from 1 hour to as long as 24 hours. Although foods that have been hot smoked are often reheated or further cooked, they are typically safe to eat without further cooking. Hams and ham hocks are fully cooked once they are properly smoked, and they can be eaten as is without any further preparation. Hot smoking usually occurs within the range of . When food is smoked within this temperature range, foods are fully cooked, moist, and flavorful. If the smoker is allowed to get hotter than , the foods can shrink excessively, buckle, or even split. Smoking at high temperatures also reduces yield, as both moisture and fat are cooked away.


title: Smoking (cooking)

text: Liquid smoke, a product derived from smoke compounds in water, is applied to foods through spraying or dipping.


title: Smoking (cooking)

text: Smoke-roasting refers to any process that has the attributes of both roasting and smoking. This smoking method is sometimes referred to as barbecuing or pit-roasting. It may be done in a smoke-roaster, a closed wood-fired oven, or a barbecue pit, any smoker that can reach above , or in a conventional oven by placing a pan filled with hardwood chips on the floor of the oven so that the chips can smolder and produce a smoke-bath. In North America, this smoking method is commonly referred to as "barbecuing", "pit baking", or "pit roasting".


title: Smoking (cooking)

text: Hardwoods are made up mostly of three materials: cellulose, hemicellulose, and lignin. Cellulose and hemicellulose are the basic structural material of the wood cells; lignin acts as a kind of cell-bonding glue. Some softwoods, especially pines and firs, hold significant quantities of resin, which produces a harsh-tasting soot when burned; these woods are not often used for smoking.


title: Smoking (cooking)

text: Cellulose and hemicellulose are aggregate sugar molecules; when burnt, they effectively caramelize, producing carbonyls, which provide most of the color components and sweet, flowery, and fruity aromas. Lignin, a highly complex arrangement of interlocked phenolic molecules, also produces a number of distinctive aromatic elements when burnt, including smoky, spicy, and pungent compounds such as guaiacol, phenol, and syringol, and sweeter scents such as the vanilla-scented vanillin and clove-like isoeugenol. Guaiacol is the phenolic compound most responsible for the "smoky" taste, while syringol is the primary contributor to smoky aroma. Wood also contains small quantities of proteins, which contribute roasted flavors. Many of the odor compounds in wood smoke, especially the phenolic compounds, are unstable, dissipating after a few weeks or months.


title: Smoking (cooking)

text: A number of wood smoke compounds act as preservatives. Phenol and other phenolic compounds in wood smoke are both antioxidants, which slow rancidification of animal fats, and antimicrobials, which slow bacterial growth. Other antimicrobials in wood smoke include formaldehyde, acetic acid, and other organic acids, which give wood smoke a low pH—about 2.5. Some of these compounds are toxic to people as well, and may have health effects in the quantities found in cooking applications.


title: Smoking (cooking)

text: Since different species of trees have different ratios of components, various types of wood do impart a different flavor to food. Another important factor is the temperature at which the wood burns. High-temperature fires see the flavor molecules broken down further into unpleasant or flavorless compounds. The optimal conditions for smoke flavor are low, smoldering temperatures between . This is the temperature of the burning wood itself, not of the smoking environment, which uses much lower temperatures. Woods that are high in lignin content tend to burn hot; to keep them smoldering requires restricted oxygen supplies or a high moisture content. When smoking using wood chips or chunks, the combustion temperature is often raised by soaking the pieces in water before placing them on a fire.


title: Smoking (cooking)

text: The main characteristics of the offset smoker are that the cooking chamber is usually cylindrical in shape, with a shorter, smaller diameter cylinder attached to the bottom of one end for a firebox. To cook the meat, a small fire is lit in the firebox, where airflow is tightly controlled. The heat and smoke from the fire are drawn through a connecting pipe or opening into the cooking chamber.


title: Smoking (cooking)

text: The heat and smoke cook and flavor the meat before escaping through an exhaust vent at the opposite end of the cooking chamber. Most manufacturers' models are based on this simple but effective design, and this is what most people picture when they think of a "BBQ smoker". Even large capacity commercial units use this same basic design of a separate, smaller fire box and a larger cooking chamber.


title: Smoking (cooking)

text: The upright drum smoker (also referred to as an ugly drum smoker or UDS) is exactly what its name suggests; an upright steel drum that has been modified for the purpose of pseudo-indirect hot smoking. There are many ways to accomplish this, but the basics include the use of a complete steel drum, a basket to hold charcoal near the bottom, and cooking rack (or racks) near the top; all covered by a vented lid of some sort. They have been built using many different sizes of steel drums, such as , , and for example, but the most popular size is the common 55-gallon drum.


title: Smoking (cooking)

text: This design is similar to smoking with indirect heat due to the distance from the coals and the racks, which is typically . The temperatures used for smoking are controlled by limiting the amount of air intake at the bottom of the drum, and allowing a similar amount of exhaust out of vents in the lid. UDSs are very efficient with fuel consumption and flexible in their abilities to produce proper smoking conditions, with or without the use of a water pan or drip pan.


title: Smoking (cooking)

text: A vertical water smoker (also referred to as a bullet smoker because of its shape) is a variation of the upright drum smoker. It uses charcoal or wood to generate smoke and heat, and contains a water bowl between the fire and the cooking grates. The water bowl serves to maintain optimal smoking temperatures and also adds humidity to the smoke chamber. It also creates an effect in which the water vapor and smoke condense together, which adds flavor to smoked foods. In addition, the bowl catches any drippings from the meat that may cause a flare-up. Vertical water smokers are extremely temperature stable and require very little adjustment once the desired temperature has been reached. Because of their relatively low cost and stable temperature, they are sometimes used in barbecue competitions where propane and electric smokers are not allowed.


title: Smoking (cooking)

text: A propane smoker is designed to allow the smoking of meat in a somewhat more temperature controlled environment. The primary differences are the sources of heat and of the smoke. In a propane smoker, the heat is generated by a gas burner directly under a steel or iron box containing the wood or charcoal that provides the smoke. The steel box has few vent holes, on the top of the box only. By starving the heated wood of oxygen, it smokes instead of burning. Any combination of woods and charcoal may used. This method uses much less wood but does require propane fuel.


title: Smoking (cooking)

text: This more traditional method uses a two-box system: a fire box and a food box. The fire box is typically adjacent or under the cooking box, and can be controlled to a finer degree. The heat and smoke from the fire box exhausts into the food box, where it is used to cook and smoke the meat. These may be as simple as an electric heating element with a pan of wood chips placed on it, although more advanced models have finer temperature controls.


title: Smoking (cooking)

text: The most convenient of the various types of smokers are the insulated electric smokers. These devices house a heating element that can maintain temperatures ranging from that required for a cold smoke all the way up to with little to no intervention from the user. Although wood chunks, pellets, and even in some cases automatically fed wood pucks are used to generate smoke, the amount of flavor obtained is less than traditional wood or charcoal smokers.


title: Smoking (cooking)

text: In this method the firebox is a narrow trench cut down a slope pointing into the prevailing wind. The middle part of the trench is covered over to make it into a tunnel. At the upper end of the trench is a vertical framework covered to form a chimney within which is placed the rack of foodstuff. At the lower upwind end of the trench is lit a small smokey fire, and sustained day and night until the foodstuff is cured.


title: Smoking (cooking)

text: Commercial smokehouses, mostly made from stainless steel, have independent systems for smoke generation and cooking. Smoke generators use friction, an electric coil or a small flame to ignite sawdust on demand. Heat from steam coils or gas flames is balanced with live steam or water sprays to control the temperature and humidity. Elaborate air handling systems reduce hot or cold spots, to reduce variation in the finished product. Racks on wheels or rails are used to hold the product and facilitate movement.


title: Smoking (cooking)

text: A pellet smoker is a temperature controlled smoker that burns wood pellets made of dried out sawdust, about an inch long and 1/4 inch wide. The wood pellets are stored in a gravity-fed hopper that feeds into a motor controlled auger by the temperature regulator. This auger pushes the pellets into the fire pot. An ignition rod within the auger ignites the pellets where a combustion fan keeps them smouldering. The motor and the combustion fan regulate the temperature of the smoker by feeding it more pellets and increasing airflow in the auger. Above the auger is a heat shield to disperse the direct heat before it reaches the heat box to allow the wood smoke to keep the heat box at an even temperature throughout. The heat sensor inside the heat box relays the current temperature inside the box back to the temperature regulator that controls the fan speed and pellet hopper motor, which either increase or decrease the amount of pellets in the auger or the amount of air available to the fire to maintain the desired temperature for the cook.


title: Smoking (cooking)

text: The popularity of this type of smokers is on the rise after many BBQ pit-masters started using them for competition barbeque.


title: Smoking (cooking)

text: Smoke is both an antimicrobial and antioxidant, however it is insufficient alone for preserving food as smoke does not penetrate far into meat or fish; it is thus typically combined with salt-curing or drying.


title: Smoking (cooking)

text: Smoking is especially useful for oily fish, as its antioxidant properties inhibit surface fat rancidification and delay interior fat exposure to degrading oxygen. Some heavily salted, long-smoked fish can keep without refrigeration for weeks or months.


title: Smoking (cooking)

text: Artificial smoke flavoring (such as liquid smoke) can be purchased to mimic smoking's flavor, but not its preservative qualities.


title: Smoking (cooking)

text: Competition BBQ Smoking is becoming increasingly popular among smoking enthusiasts, especially in the Southern American States, where BBQ enthusiasts come together over a weekend to cook various cuts of meat such as a whole hog or beef brisket to become the best at BBQ.


title: Smoking (cooking)

text: Regularly consuming smoked meats and fish may increase the risk of several types of cancer and cardiovascular disease.


title: Hydrogen economy

text: The hydrogen economy is using hydrogen to decarbonize economic sectors which are hard to electrify, essentially, the "hard-to-abate" sectors such as cement, steel, long-haul transport etc. In order to phase out fossil fuels and limit climate change, hydrogen can be created from water using renewable sources such as wind and solar, and its combustion only releases water vapor to the atmosphere.


title: Hydrogen economy

text: Hydrogen is an energetic fuel, frequently used as rocket fuel, but numerous technical challenges prevent the creation of a large-scale hydrogen economy. These include the difficulty of developing long-term storage, pipelines and engine equipment; a relative lack of off-the-shelf engine technology that can currently run safely on hydrogen; safety concerns regarding the high reactivity of hydrogen fuel with oxygen in ambient air; the expense of producing it by electrolysis; and a lack of efficient photochemical water splitting technology. Hydrogen can also react in a fuel cell, which efficiently produces electricity in a process which is the reverse of electrolysis of water. The hydrogen economy is nevertheless slowly developing as a small part of the low-carbon economy.


title: Hydrogen economy

text: , hydrogen is mainly used as an industrial feedstock, primarily for the production of ammonia and methanol, and in petroleum refining. Although initially hydrogen gas was thought not to occur naturally in convenient reservoirs, it is now demonstrated that this is not the case; a hydrogen system is currently being exploited in the region of Bourakebougou, Mali, producing electricity for the surrounding villages. More discoveries of naturally occurring hydrogen in continental, on-shore geological environments have been made in recent years and open the way to the novel field of natural or native hydrogen, supporting energy transition efforts. , almost all (95%) of the world's 70 million tons of hydrogen consumed yearly in industrial processing, significantly in fertilizer for 45 percent of world's food, are produced by steam methane reforming (SMR) that also releases the greenhouse gas carbon dioxide.


title: Hydrogen economy

text: Small amounts of hydrogen (5%) are produced by the dedicated production of hydrogen from water, usually as a byproduct of the process of generating chlorine from seawater. there is not enough cheap clean electricity (renewable and nuclear) for this hydrogen to become a significant part of the low-carbon economy, and carbon dioxide is a by-product of the SMR process, but it can be captured and stored.


title: Hydrogen economy

text: The idea of hydrogen economy has been heavily criticized from the moment it was proposed. The main issues with the H2E scenario are as follows:


title: Hydrogen economy

text: In the current hydrocarbon economy, heating is fueled primarily by natural gas and transportation by petroleum. Burning of hydrocarbon fuels emits carbon dioxide and other pollutants. The demand for energy is increasing, particularly in China, India, and other developing countries. Hydrogen can be an environmentally cleaner source of energy to end-users, without release of pollutants such as particulates or carbon dioxide.


title: Hydrogen economy

text: Hydrogen has a high energy density by weight but has a low energy density by volume. Even when highly compressed, stored in solids, or liquified, the energy density by volume is only 1/4 that of gasoline, although the energy density by weight is approximately three times that of gasoline or natural gas. Hydrogen can help to decarbonize long-haul transport, chemicals, and iron and steel and has the potential to transport renewable energy long distance and store it long term, for example from wind power or solar electricity.


title: Hydrogen economy

text: The term "hydrogen economy" was coined by John Bockris during a talk he gave in 1970 at General Motors (GM) Technical Center. The concept was proposed earlier by geneticist J.B.S. Haldane.


title: Hydrogen economy

text: A hydrogen economy was proposed by the University of Michigan to solve some of the negative effects of using hydrocarbon fuels where the carbon is released to the atmosphere (as carbon dioxide, carbon monoxide, unburnt hydrocarbons, etc.). Modern interest in the hydrogen economy can generally be traced to a 1970 technical report by Lawrence W. Jones of the University of Michigan.


title: Hydrogen economy

text: A spike in attention for the concept during the 2000s was repeatedly described as hype by some critics and proponents of alternative technologies. Interest in the energy carrier resurged in the 2010s, notably by the forming of the Hydrogen Council in 2017. Several manufacturers released hydrogen fuel cell cars commercially, with manufacturers such as Toyota and industry groups in China planning to increase numbers of the cars into the hundreds of thousands over the next decade.


title: Hydrogen economy

text: Hydrogen production globally was valued at over US$120 billion and is expected to grow over 5% annually through 2028.


title: Hydrogen economy

text: This market demand is usually met by pyrolysis of hydrocarbons to produce the hydrogen, which results in emissions.


title: Hydrogen economy

text: The other half of current hydrogen production is used to convert heavy petroleum sources into lighter fractions suitable for use as fuels. This latter process is known as hydrocracking. Hydrocracking represents an even larger growth area, since rising oil prices encourage oil companies to extract poorer source material, such as oil sands and oil shale. The scale economies inherent in large-scale oil refining and fertilizer manufacture make possible on-site production and "captive" use. Smaller quantities of "merchant" hydrogen are manufactured and delivered to end users as well.


title: Hydrogen economy

text: The large market and sharply rising prices in fossil fuels have also stimulated great interest in alternate, cheaper means of hydrogen production.


title: Hydrogen economy

text: The two major consumers are oil refineries and fertilizer plants (each consumes about half of all production).


title: Hydrogen economy

text: , more than 95% of global hydrogen production is sourced from fossil gas and coal without carbon abatement.


title: Hydrogen economy

text: Hydrogen is often referred to by various colors to indicate its origin. As shown below, some production sources have more than one label with the more common listed first. Although the usage of color codes is not standardized, it is not completely arbitrary.


title: Hydrogen economy

text: Molecular hydrogen was discovered in the Kola Superdeep Borehole. It is unclear how much molecular hydrogen is available in natural reservoirs, but at least one company specializes in drilling wells to extract hydrogen. Most hydrogen in the lithosphere is bonded to oxygen in water. Manufacturing elemental hydrogen requires the consumption of a hydrogen carrier such as a fossil fuel or water. The former carrier consumes the fossil resource and in the steam methane reforming (SMR) process produces greenhouse gas carbon dioxide. However, in the newer methane pyrolysis process no greenhouse gas carbon dioxide is produced. These processes typically require no further energy input beyond the fossil fuel.


title: Hydrogen economy

text: Decomposing water, the latter carrier, requires electrical or heat input, generated from some primary energy source (fossil fuel, nuclear power or a renewable energy). Hydrogen produced by zero emission energy sources such as electrolysis of water using wind power, solar power, nuclear power, hydro power, wave power or tidal power is referred to as green hydrogen. When derived from natural gas by zero greenhouse emission methane pyrolysis, it is referred to as turquoise hydrogen.


title: Hydrogen economy

text: When fossil fuel derived with greenhouse gas emissions, is generally referred to as grey hydrogen. If most of the carbon dioxide emission is captured, it is referred to as blue hydrogen. Hydrogen produced from coal may be referred to as brown hydrogen.


title: Hydrogen economy

text: Hydrogen is industrially produced from steam reforming (SMR), which uses natural gas. The energy content of the produced hydrogen is less than the energy content of the original fuel, some of it being lost as excess heat during production. Steam reforming emits carbon dioxide, a greenhouse gas, unless it is captured and stored.


title: Hydrogen economy

text: Pyrolysis of methane (natural gas) with a one-step process bubbling methane through a molten metal catalyst is a "no greenhouse gas" approach to produce hydrogen that was perfected in 2017 and now being tested at scale. The process is conducted at high temperatures (1065 °C). Producing 1 kg of hydrogen requires about 5 kWh of electricity for process heat. The pyrolysis of methane can be expressed by the following reaction equation.


title: Hydrogen economy

text: The industrial quality solid carbon may be sold as manufacturing feedstock or landfilled (no pollution).


title: Hydrogen economy

text: Hydrogen can be made via high pressure electrolysis, low pressure electrolysis of water, or a range of other emerging electrochemical processes such as high temperature electrolysis or carbon assisted electrolysis. However, current best processes for water electrolysis have an effective electrical efficiency of 70-80%, so that producing 1 kg of hydrogen (which has a specific energy of 143 MJ/kg or about 40 kWh/kg) requires 50–55 kWh of electricity.


title: Hydrogen economy

text: In parts of the world, steam methane reforming is between $1–3/kg on average excluding hydrogen gas pressurization cost. This makes production of hydrogen via electrolysis cost competitive in many regions already, as outlined by Nel Hydrogen and others, including an article by the IEA examining the conditions which could lead to a competitive advantage for electrolysis.


title: Hydrogen economy

text: A small part (2% in 2019) is produced by electrolysis using electricity and water, consuming approximately 50 to 55 kilowatt-hours of electricity per kilogram of hydrogen produced.


title: Hydrogen economy

text: The Kværner process or Kvaerner carbon black and hydrogen process (CB&H) is a method, developed in the 1980s by a Norwegian company of the same name, for the production of hydrogen from hydrocarbons (CH), such as methane, natural gas and biogas.


title: Hydrogen economy

text: Of the available energy of the feed, approximately 48% is contained in the hydrogen, 40% is contained in activated carbon and 10% in superheated steam.


title: Hydrogen economy

text: Fermentative hydrogen production is the fermentative conversion of organic substrate to biohydrogen manifested by a diverse group of bacteria using multi enzyme systems involving three steps similar to anaerobic conversion. Dark fermentation reactions do not require light energy, so they are capable of constantly producing hydrogen from organic compounds throughout the day and night. Photofermentation differs from dark fermentation because it only proceeds in the presence of light. For example, photo-fermentation with "Rhodobacter sphaeroides" SH2C can be employed to convert small molecular fatty acids into hydrogen. Electrohydrogenesis is used in microbial fuel cells where hydrogen is produced from organic matter (e.g. from sewage, or solid matter) while 0.2 - 0.8 V is applied.


title: Hydrogen economy

text: Biological hydrogen can be produced in an algae bioreactor. In the late 1990s it was discovered that if the algae is deprived of sulfur it will switch from the production of oxygen, i.e. normal photosynthesis, to the production of hydrogen.


title: Hydrogen economy

text: Biological hydrogen can be produced in bioreactors that use feedstocks other than algae, the most common feedstock being waste streams. The process involves bacteria feeding on hydrocarbons and excreting hydrogen and CO. The CO can be sequestered successfully by several methods, leaving hydrogen gas. In 2006–2007, NanoLogix first demonstrated a prototype hydrogen bioreactor using waste as a feedstock at Welch's grape juice factory in North East, Pennsylvania (U.S.).


title: Hydrogen economy

text: Besides regular electrolysis, electrolysis using microbes is another possibility. With biocatalysed electrolysis, hydrogen is generated after running through the microbial fuel cell and a variety of aquatic plants can be used. These include reed sweetgrass, cordgrass, rice, tomatoes, lupines, and algae


title: Hydrogen economy

text: High pressure electrolysis is the electrolysis of water by decomposition of water (HO) into oxygen (O) and hydrogen gas (H) by means of an electric current being passed through the water. The difference with a standard electrolyzer is the compressed hydrogen output around 120-200 bar (1740-2900 psi, 12–20 MPa). By pressurising the hydrogen in the electrolyser, through a process known as chemical compression, the need for an external hydrogen compressor is eliminated, the average energy consumption for internal compression is around 3%.


title: Hydrogen economy

text: European largest (1 400 000 kg/a, High-pressure Electrolysis of water, alkaline technology) hydrogen production plant is operating at Kokkola, Finland.


title: Hydrogen economy

text: Hydrogen can be generated from energy supplied in the form of heat and electricity through high-temperature electrolysis (HTE). Because some of the energy in HTE is supplied in the form of heat, less of the energy must be converted twice (from heat to electricity, and then to chemical form), and so potentially far less energy is required per kilogram of hydrogen produced.


title: Hydrogen economy

text: While nuclear-generated electricity could be used for electrolysis, nuclear heat can be directly applied to split hydrogen from water. High temperature (950–1000 °C) gas cooled nuclear reactors have the potential to split hydrogen from water by thermochemical means using nuclear heat. Research into high-temperature nuclear reactors may eventually lead to a hydrogen supply that is cost-competitive with natural gas steam reforming. General Atomics predicts that hydrogen produced in a High Temperature Gas Cooled Reactor (HTGR) would cost $1.53/kg. In 2003, steam reforming of natural gas yielded hydrogen at $1.40/kg. In 2005 natural gas prices, hydrogen costs $2.70/kg.


title: Hydrogen economy

text: High-temperature electrolysis has been demonstrated in a laboratory, at 108 MJ (thermal) per kilogram of hydrogen produced, but not at a commercial scale. In addition, this is lower-quality "commercial" grade Hydrogen, unsuitable for use in fuel cells.


title: Hydrogen economy

text: Using electricity produced by photovoltaic systems offers the cleanest way to produce hydrogen. Water is broken into hydrogen and oxygen by electrolysis – a photoelectrochemical cell (PEC) process which is also named artificial photosynthesis. William Ayers at Energy Conversion Devices demonstrated and patented the first multijunction high efficiency photoelectrochemical system for direct splitting of water in 1983. This group demonstrated direct water splitting now referred to as an "artificial leaf" or "wireless solar water splitting" with a low cost thin film amorphous silicon multijunction sheet immersed directly in water.


title: Hydrogen economy

text: Hydrogen evolved on the front amorphous silicon surface decorated with various catalysts while oxygen evolved off the back metal substrate. A Nafion membrane above the multijunction cell provided a path for ion transport. Their patent also lists a variety of other semiconductor multijunction materials for the direct water splitting in addition to amorphous silicon and silicon germanium alloys. Research continues towards developing high-efficiency multi-junction cell technology at universities and the photovoltaic industry. If this process is assisted by photocatalysts suspended directly in water instead of using photovoltaic and an electrolytic system, the reaction is in just one step, which can improve efficiency.


title: Hydrogen economy

text: A method studied by Thomas Nann and his team at the University of East Anglia consists of a gold electrode covered in layers of indium phosphide (InP) nanoparticles. They introduced an iron-sulfur complex into the layered arrangement, which when submerged in water and irradiated with light under a small electric current, produced hydrogen with an efficiency of 60%.


title: Hydrogen economy

text: In 2015, it was reported that Panasonic Corp. has developed a photocatalyst based on niobium nitride that can absorb 57% of sunlight to support the decomposition of water to produce hydrogen gas. The company plans to achieve commercial application "as early as possible", not before 2020.


title: Hydrogen economy

text: Very high temperatures are required to dissociate water into hydrogen and oxygen. A catalyst is required to make the process operate at feasible temperatures. Heating the water can be achieved through the use of water concentrating solar power. Hydrosol-2 is a 100-kilowatt pilot plant at the Plataforma Solar de Almería in Spain which uses sunlight to obtain the required 800 to 1,200 °C to heat water. Hydrosol II has been in operation since 2008. The design of this 100-kilowatt pilot plant is based on a modular concept. As a result, it may be possible that this technology could be readily scaled up to the megawatt range by multiplying the available reactor units and by connecting the plant to heliostat fields (fields of sun-tracking mirrors) of a suitable size.


title: Hydrogen economy

text: There are more than 352 thermochemical cycles which can be used for water splitting, around a dozen of these cycles such as the iron oxide cycle, cerium(IV) oxide-cerium(III) oxide cycle, zinc zinc-oxide cycle, sulfur-iodine cycle, copper-chlorine cycle and hybrid sulfur cycle, aluminum aluminum-oxide cycle, are under research and in testing phase to produce hydrogen and oxygen from water and heat without using electricity. These processes can be more efficient than high-temperature electrolysis, typical in the range from 35% - 49% LHV efficiency. Thermochemical production of hydrogen using chemical energy from coal or natural gas is generally not considered, because the direct chemical path is more efficient.


title: Hydrogen economy

text: None of the thermochemical hydrogen production processes have been demonstrated at production levels, although several have been demonstrated in laboratories.


title: Hydrogen economy

text: A 97% recovery of hydrogen has been achieved through microwaving plastics for a few seconds that have been ground and mixed with iron oxide and aluminium oxide.


title: Hydrogen economy

text: The industrial production of chlorine and caustic soda by electrolysis generates a sizable amount of Hydrogen as a byproduct. In the port of Antwerp a 1MW demonstration fuel cell power plant is powered by such byproduct. This unit has been operational since late 2011. The excess hydrogen is often managed with a hydrogen pinch analysis. The world's first hydrogen electric plant, in Italy, had a capacity of 12MW, cost about 6 times more than conventional means, and was shut down in less than two years.


title: Hydrogen economy

text: Gas generated from coke ovens in steel production is similar to Syngas with 60% hydrogen by volume. The hydrogen can be extracted from the coke oven gas economically.


title: Hydrogen economy

text: Although molecular hydrogen has very high energy density on a mass basis, partly because of its low molecular weight, as a gas at ambient conditions it has very low energy density by volume. If it is to be used as fuel stored on board the vehicle, pure hydrogen gas must be stored in an energy-dense form to provide sufficient driving range.


title: Hydrogen economy

text: Increasing gas pressure improves the energy density by volume making for smaller container tanks. The standard material for holding pressurised hydrogen in tube trailers is steel (there is no hydrogen embrittlement problem with hydrogen gas). Tanks made of carbon and glass fibres reinforcing plastic as fitted in Toyota Marai and Kenworth trucks are required to meet safety standards. Few materials are suitable for tanks as hydrogen being a small molecule tends to diffuse through many polymeric materials. The most common on board hydrogen storage in today's 2020 vehicles is hydrogen at pressure 700bar = 70MPa. The energy cost of compressing hydrogen to this pressure is significant.


title: Hydrogen economy

text: Pressurized gas pipelines are always made of steel and operate at much lower pressures than tube trailers.


title: Hydrogen economy

text: Alternatively, higher volumetric energy density liquid hydrogen or slush hydrogen may be used. However, liquid hydrogen is cryogenic and boils at 20.268 K (–252.882 °C or –423.188 °F). Cryogenic storage cuts weight but requires large liquification energies. The liquefaction process, involving pressurizing and cooling steps, is energy intensive. The liquefied hydrogen has lower energy density by volume than gasoline by approximately a factor of four, because of the low density of liquid hydrogen – there is actually more hydrogen in a litre of gasoline (116 grams) than there is in a litre of pure liquid hydrogen (71 grams). Like any other liquid at cryogenic temperatures, the liquid hydrogen storage tanks must also be well insulated to minimize boil off.


title: Hydrogen economy

text: Japan has a liquid hydrogen (LH2) storage facility at a terminal in Kobe, and was expected to receive the first shipment of liquid hydrogen via LH2 carrier in 2020. Hydrogen is liquified by reducing its temperature to -253 °C, similar to liquified natural gas (LNG) which is stored at -162 °C. A potential efficiency loss of 12.79% can be achieved, or 4.26kWh/kg out of 33.3kWh/kg.


title: Hydrogen economy

text: Distinct from storing molecular hydrogen, hydrogen can be stored as a chemical hydride or in some other hydrogen-containing compound. Hydrogen gas is reacted with some other materials to produce the hydrogen storage material, which can be transported relatively easily. At the point of use the hydrogen storage material can be made to decompose, yielding hydrogen gas. As well as the mass and volume density problems associated with molecular hydrogen storage, current barriers to practical storage schemes stem from the high pressure and temperature conditions needed for hydride formation and hydrogen release.


title: Hydrogen economy

text: For many potential systems hydriding and dehydriding kinetics and heat management are also issues that need to be overcome. A French company McPhy Energy is developing the first industrial product, based on Magnesium Hydrate, already sold to some major clients such as Iwatani and ENEL. Emergent hydride hydrogen storage technologies have achieved a compressed volume of less than 1/500.


title: Hydrogen economy

text: A third approach is to adsorb molecular hydrogen on the surface of a solid storage material. Unlike in the hydrides mentioned above, the hydrogen does not dissociate/recombine upon charging/discharging the storage system, and hence does not suffer from the kinetic limitations of many hydride storage systems. Hydrogen densities similar to liquefied hydrogen can be achieved with appropriate adsorbent materials. Some suggested adsorbents include activated carbon, nanostructured carbons (including CNTs), MOFs, and hydrogen clathrate hydrate.


title: Hydrogen economy

text: Underground hydrogen storage is the practice of hydrogen storage in caverns, salt domes and depleted oil and gas fields. Large quantities of gaseous hydrogen have been stored in caverns by ICI for many years without any difficulties. The storage of large quantities of liquid hydrogen underground can function as grid energy storage. The round-trip efficiency is approximately 40% (vs. 75-80% for pumped-hydro (PHES)), and the cost is slightly higher than pumped hydro.


title: Hydrogen economy

text: Another study referenced by a European staff working paper found that for large scale storage, the cheapest option is hydrogen at €140/MWh for 2,000 hours of storage using an electrolyser, salt cavern storage and combined-cycle power plant. The European project Hyunder indicated in 2013 that for the storage of wind and solar energy an additional 85 caverns are required as it cannot be covered by PHES and CAES systems.


title: Hydrogen economy

text: A German case study on storage of hydrogen in salt caverns found that if the German power surplus (7% of total variable renewable generation by 2025 and 20% by 2050) would be converted to hydrogen and stored underground, these quantities would require some 15 caverns of 500,000 cubic metres each by 2025 and some 60 caverns by 2050 – corresponding to approximately one third of the number of gas caverns currently operated in Germany. In the US, Sandia Labs are conducting research into the storage of hydrogen in depleted oil and gas fields, which could easily absorb large amounts of renewably produced hydrogen as there are some 2.7 million depleted wells in existence.


title: Hydrogen economy

text: Power to gas is a technology which converts electrical power to a gas fuel. There are 2 methods, the first is to use the electricity for water splitting and inject the resulting hydrogen into the natural gas grid. The second (less efficient) method is used to convert carbon dioxide and water to methane, (see natural gas) using electrolysis and the Sabatier reaction. The excess power or off peak power generated by wind generators or solar arrays is then used for load balancing in the energy grid. Using the existing natural gas system for hydrogen Fuel cell maker Hydrogenics and natural gas distributor Enbridge have teamed up to develop such a power to gas system in Canada.


title: Hydrogen economy

text: A natural gas network may be used for the storage of hydrogen. Before switching to natural gas, the UK and German gas networks were operated using towngas, which for the most part consisted of hydrogen. The storage capacity of the German natural gas network is more than 200,000 GWh which is enough for several months of energy requirement. By comparison, the capacity of all German pumped storage power plants amounts to only about 40 GW·h. Similarly UK pumped storage is far less than the gas network. The transport of energy through a gas network is done with much less loss (<0.1%) than in a power network (8%). The use of the existing natural gas pipelines for hydrogen was studied by NaturalHy.


title: Hydrogen economy

text: Ad van Wijk, a professor at Future Energy Systems TU Delft, also discusses the possibility of producing electricity in areas or countries with abundant sunlight (Sahara, Chile, Mexico, Namibia, Australia, New Zealand, ...) and transporting it (via ship, pipeline, ...) to the Netherlands. This being economically seen, still cheaper than producing it locally in the Netherlands. He also mentions that the energy transport capacity of gas lines are far higher than that of electricity lines coming into private houses (in the Netherlands) -30 kW vs 3 kW-.


title: Hydrogen economy

text: The hydrogen infrastructure would consist mainly of industrial hydrogen pipeline transport and hydrogen-equipped filling stations like those found on a hydrogen highway. Hydrogen stations which were not situated near a hydrogen pipeline would get supply via hydrogen tanks, compressed hydrogen tube trailers, liquid hydrogen trailers, liquid hydrogen tank trucks or dedicated onsite production.


title: Hydrogen economy

text: Over 700 miles of hydrogen pipeline currently exist in the United States. Although expensive, pipelines are the cheapest way to move hydrogen over long distances. Hydrogen gas piping is routine in large oil-refineries, because hydrogen is used to hydrocrack fuels from crude oil.


title: Hydrogen economy

text: Hydrogen piping can in theory be avoided in distributed systems of hydrogen production, where hydrogen is routinely made on site using medium or small-sized generators which would produce enough hydrogen for personal use or perhaps a neighborhood. In the end, a combination of options for hydrogen gas distribution may succeed.


title: Hydrogen economy

text: Hydrogen embrittlement is not a problem for hydrogen gas pipelines. Hydrogen embrittlement only happens with 'diffusible' hydrogen, i.e. atoms or ions. Hydrogen gas, however, is molecular (H), and there is a very significant energy barrier to splitting it into atoms.


title: Hydrogen economy

text: The IEA recommends existing industrial ports be used for production and existing natural gas pipelines for transport: also international co-operation and shipping.


title: Hydrogen economy

text: South Korea and Japan, which as of 2019 lack international electrical interconnectors, are investing in the hydrogen economy. In March 2020, a production facility was opened in Namie, Fukushima Prefecture, claimed to be the world's largest.


title: Hydrogen economy

text: In a future full hydrogen economy, primary energy sources and feedstock would be used to produce hydrogen gas as stored energy for use in various sectors of the economy. Producing hydrogen from primary energy sources other than coal and oil would result in lower production of the greenhouse gases characteristic of the combustion of coal and oil fossil energy resources. The importance of non-polluting methane pyrolysis of natural gas is becoming a recognized method for using current natural gas infrastructure investment to produce hydrogen and no greenhouse gas.


title: Hydrogen economy

text: One key feature of a hydrogen economy would be that in mobile applications (primarily vehicular transport) energy generation and use could be decoupled. The primary energy source would need no longer travel with the vehicle, as it currently does with hydrocarbon fuels. Instead of tailpipes creating dispersed emissions, the energy (and pollution) could be generated from point sources such as large-scale, centralized facilities with improved efficiency. This would allow the possibility of technologies such as carbon sequestration, which are otherwise impossible for mobile applications. Alternatively, distributed energy generation schemes (such as small scale renewable energy sources) could be used, possibly associated with hydrogen stations.


title: Hydrogen economy

text: Aside from the energy generation, hydrogen production could be centralized, distributed or a mixture of both. While generating hydrogen at centralized primary energy plants promises higher hydrogen production efficiency, difficulties in high-volume, long range hydrogen transportation (due to factors such as hydrogen damage and the ease of hydrogen diffusion through solid materials) makes electrical energy distribution attractive within a hydrogen economy.


title: Hydrogen economy

text: In such a scenario, small regional plants or even local filling stations could generate hydrogen using energy provided through the electrical distribution grid or methane pyrolysis of natural gas. While hydrogen generation efficiency is likely to be lower than for centralized hydrogen generation, losses in hydrogen transport could make such a scheme more efficient in terms of the primary energy used per kilogram of hydrogen delivered to the end user.


title: Hydrogen economy

text: The proper balance between hydrogen distribution, long-distance electrical distribution and destination converted pyrolysis of natural gas is one of the primary questions that arises about the hydrogen economy.


title: Hydrogen economy

text: Again the dilemmas of production sources and transportation of hydrogen can now be overcome using on site (home, business, or fuel station) generation of hydrogen from off grid renewable sources.


title: Hydrogen economy

text: Distributed electrolysis would bypass the problems of distributing hydrogen by distributing electricity instead. It would use existing electrical networks to transport electricity to small, on-site electrolysers located at filling stations. However, accounting for the energy used to produce the electricity and transmission losses would reduce the overall efficiency.


title: Hydrogen economy

text: One of the main offerings of a hydrogen economy is that the fuel can replace the fossil fuel burned in internal combustion engines and turbines as the primary way to convert chemical energy into kinetic or electrical energy, thereby eliminating greenhouse gas emissions and pollution from that engine. Ad van Wijk, a professor at Future Energy Systems TU Delft also mentions that hydrogen is better for larger vehicles - such as trucks, buses and ships - than electric batteries. This because a 1 kg battery, , can store 0.1 kWh of energy whereas 1 kg of hydrogen has a usable energy content of 33 kWh.


title: Hydrogen economy

text: Although hydrogen can be used in conventional internal combustion engines, fuel cells, being electrochemical, have a theoretical efficiency advantage over heat engines. Fuel cells are more expensive to produce than common internal combustion engines.


title: Hydrogen economy

text: Hydrogen gas must be distinguished as "technical-grade" (five nines pure, 99.999%) produced by methane pyrolysis or electrolysis, which is suitable for applications such as fuel cells, and "commercial-grade", which has carbon- and sulfur-containing impurities, but which can be produced by the slightly cheaper steam-reformation process that releases carbon dioxide greenhouse gas. Fuel cells require high-purity hydrogen because the impurities would quickly degrade the life of the fuel cell stack.


title: Hydrogen economy

text: Much of the interest in the hydrogen economy concept is focused on the use of fuel cells to power hydrogen vehicles, particularly large trucks. Hydrogen fuel cells suffer from a low power-to-weight ratio. Fuel cells are more efficient than internal combustion engines. If a practical method of hydrogen storage is introduced, and fuel cells become cheaper, they can be economically viable to power hybrid fuel cell/battery vehicles, or purely fuel cell-driven ones. The combination of the fuel cell and electric motor is 2-3 times more efficient than an internal-combustion engine. Capital costs of fuel cells have reduced significantly over recent years, with a modeled cost of $50/kW cited by the Department of Energy.


title: Hydrogen economy

text: Other fuel cell technologies based on the exchange of metal ions (e.g. zinc–air fuel cells) are typically more efficient at energy conversion than hydrogen fuel cells, but the widespread use of any electrical energy → chemical energy → electrical energy systems would necessitate the production of electricity.


title: Hydrogen economy

text: In the short term hydrogen has been proposed as a method of reducing harmful diesel exhaust. For example, by 2050, the energy requirement for transportation might be between 20% and 30% fulfilled by hydrogen and synthetic fuels.