Hydrail

Hydrail is the generic (not capitalized) adjective term describing all forms of rail vehicles, large or small, which use on-board hydrogen fuel as a source of energy to power the traction motors, or the auxiliaries, or both. Hydrail vehicles use the chemical energy of hydrogen for propulsion, either by burning hydrogen in a hydrogen internal combustion engine, or by reacting hydrogen with oxygen in a fuel cell to run electric motors. Widespread use of hydrogen for fueling rail transportation is a basic element of the proposed hydrogen economy. The term is used extensively by research scholars and technicians around the world.
Hydrail vehicles are usually hybrid vehicles with renewable energy storage, such as batteries or super capacitors, for regenerative braking, improving efficiency and lowering the amount of hydrogen storage required. Potential hydrail applications include all types of rail transport: commuter rail; passenger rail; freight rail; light rail; rail rapid transit; mine railways; industrial railway systems; trams; and special rail rides at parks and museums.
The term hydrail was first mentioned on August 22, 2003, in an invited presentation at the US Department of Transportation's Volpe Transportations Systems Center in Cambridge, MA. There, Stan Thompson, a former futurist and strategic planner at US telecoms company AT&T gave a presentation entitled the Mooresville Hydrail Initiative. However, according to authors Stan Thompson and Jim Bowman, the term first appeared in print on 17 February 2004 in the International Journal of Hydrogen Energy as a search engine target word to enable scholars and technicians around the world working in the hydrogen rail area to more easily publish and locate all work produced within the discipline.
Since 2005, annual International Hydrail Conferences have been held. Organised by Appalachian State University and the Mooresville South Iredell Chamber of Commerce in conjunction with universities and other entities, the Conferences have the aim of bringing together scientists, engineers, business leaders, industrial experts, and operators working or using the technology around the world in order to expedite deployment of the technology for environmental, climate, energy security and economic development reasons. Presenters at these conferences have included national and state/provincial agencies from the US, Austria, Canada, China, Denmark, the EU, Germany, France, Italy, Japan, Korea, Russia, Turkey, the United Kingdom and the United Nations (UNIDO-ICHET). In its early years, these conferences were largely dominated by academic fields; however, by 2013, an increasing number of businesses and industrial figures have reportedly been in attendance.
During the 2010s, both fuel cells and hydrogen generation equipment have been taken up by several transport operators across various countries, such as China, Germany, Japan, Taiwan, the United Kingdom, and the United States. Many of the same technologies that can be applied to hydrail vehicles can be applied to other forms of transport as well, such as road vehicles.
Technology.
Hydrogen is a common and easy to find element, being that each molecule of water has two atoms of hydrogen for every oxygen atom present. Hydrogen can be separated from water via several means, including steam reforming (normally involving the use of fossil fuels) and electrolysis (which requires large amounts of electricity and is less commonly used). Once isolated, hydrogen can serve as a form of fuel. It has been proposed that hydrogen for fuelling hydrail vehicles can be produced in individual maintenance depots, requiring only a steady supply of electricity and water; it can then be pumped into pressurised tanks upon the vehicle.
The development of lighter and more capable fuel cells has increased the viability of hydrogen-powered vehicles. According to Canadian company Hydrogenics, in 2001, its 25 kW fuel cell weighed 290 kg and had an efficiency ranging between 38 and 45 per cent; however, by 2017, they were producing more powerful and compact fuel cells weighing 72 kg and with an efficiency between 48 and 55 per cent, a roughly fivefold increase in power density. According to Rail Engineer, the use of hydrogen propulsion on certain types of trains, such as freight locomotives or high-speed trains, is less attractive and more challenging than on lower-powered applications, such as shunting locomotives and multiple units. The publication also observes that pressure to cut emissions within the railway industry is likely to play a role in stimulating demand for the uptake of hydrail.
A key technology of a typical hydrogen propulsion system is the fuel cell. This device converts the chemical energy contained within the hydrogen in order to generate electricity, as well as water and heat. As such, a fuel cell would operate in a manner that is essentially inverse to the electrolysis process used to create the fuel; consuming pure hydrogen to produce electricity rather than consuming electrical energy to produce hydrogen, albeit incurring some level of energy losses in the exchange. Reportedly, the efficiency of converting electricity to hydrogen and back again is just beneath 30 per cent, roughly similar to contemporary diesel engines but less than conventional electric traction using overhead catenary wires. The electricity produced by the onboard fuel cell would be fed into a motor to propel the train. Overhead wire electrification costs are around EUR 2m/km, so electrification is not a cost-efficient solution for routes with low traffic, and battery and hydrail solutions may be alternatives.
Railway industrial publication Railway Engineer has theorised that the expanding prevalence of wind power has led to some countries having surpluses of electrical energy during nighttime hours, and that this trend could offer a means of low-cost and highly available energy with which hydrogen could be conveniently produced via electrolysis. In this manner, it is believed that the production of hydrogen using off-peak electricity available from countries' electrical grids shall likely be one of the most economic practices available. As of January 2017, hydrogen produced via electrolysis commonly costs roughly the same as natural gas and almost double that of diesel fuel; however, unlike either of these fossil-based fuels, hydrogen propulsion produces zero vehicle emissions. A 2018 European Commission report states that if hydrogen is produced by steam methane reforming, hydrail emissions are 45 % lower than diesel trains.
According to Rail Engineer and Alstom, a 10MW wind farm is capable of comfortably producing 2.5 tonnes of hydrogen per day; enough to power a fleet of 14 iLint trains over a distance of 600 km per day. Reportedly, as of January 2017, production of hydrogen worldwide has been expanding in quantity and availability, increasing its attractiveness as a fuel. The need to build up a capable distribution network for hydrogen, which in turn requires substantial investments to be made, is likely to play a role in restraining the growth of hydrail at least in the short term.
It was observed by Railway Technology that the rail industry has been historically slow to adopt new technologies and relatively conservative in outlook; however, a successful large-scale deployment of this technology by an early adopter may be decisive in overcoming attitudes of reluctance and traditionalism. Additionally, there could be significant benefits to transitioning from diesel to hydrail propulsion. According to the results of a study performed by a consortium of Hitachi Rail Europe, the University of Birmingham, and Fuel Cell Systems Ltd, hydrail vehicles in the form of re-powered diesel multiple units could be capable of generating significant energy consumption reductions; reportedly, their model indicated a saving of up to 52 per cent on the Norwich to Sheringham line over conventional traction.
Hydrolley.
A "hydrolley" is a term for a streetcar or tram (trolley) powered by hydrail technology. The term (for "hydro"gen tro"lley") was coined at the Fourth International Hydrail Conference, Valencia, Spain, in 2008, as a research-simplifying search engine target word. Onboard hydrogen-derived power eliminates the need for overhead trolley arms and track electrification, greatly reducing construction cost, reducing visual pollution and eliminating the maintenance expense of track electrification. The term 'hydrolley' is preferred to 'hydrail light rail' or other combinations which might connote external electrification.
Safety.
Hydrogen is combustible in a wide range (4%—74%) of mixtures with air, and explosive in 18—59%.
Operating trains by country.
Germany.
In September 2018, the world's first commercial hydrogen-powered passenger train enters service in Lower Saxony, Germany. The Alstom developed train uses a hydrogen fuel cell which emits no carbon dioxide.