03 October 2011 00:00 [Source: ICB]
New processes can convert sugar and starch in plants to produce chemicals Credit: zlady
New processes can convert sugar and starch in plants to produce chemicals
Concerns over fossil fuels are increasingly motivating companies to look at biomass as feedstock for chemicals production. Most bio-based chemicals are derived from food-based feedstocks but the trend is to develop technologies that can take advantage of non-food-based sources such as agricultural and municipal waste and energy crops.
Bio-based chemicals have a favorable greenhouse-gas balance compared with fossil fuels and oil or gas-derived petrochemicals, but competition with food crops has led to harsh criticism of the biofuels industry and emerging bio-based chemicals ventures. Concerns were heightened following a peak in agricultural commodity prices in 2007-2008.
"We have to get away from food-based feedstocks," says Ron Cascone, biofuels development manager at Nexant's energy and chemicals consulting business. Converting cellulosic materials, which form the structural components of plants, into chemicals building blocks using fermentation or thermochemical pathways is a more sustainable approach, he says.
Cellulosic materials include agricultural waste products such as sugar-cane bagasse, corn stover and empty palm fruit bunches, as well as wood, grasses and the organic content of municipal solid waste. The move towards "second-generation" cellulosic feedstocks reflects the trend in the biofuels sector, currently based on agricultural feedstocks such as maize (corn or canola), sugar cane, cassava, soya bean and palm oils. The chemicals industry has a long history of converting natural oils into fatty acids and alcohols, Cascone says, but supplies of natural oils are limited and companies have developed processes to convert sugar and starch in plants to produce a wide range of chemicals, such as ethylene from ethanol, and polylactic acid (PLA).
DARK FERMENTATION TANKS
Brazilian resins producer Braskem, for example, began production of ethylene from sugar-cane ethanol in Brazil last year, and US producer NatureWorks produces maize-based PLA in the US and is planning a new investment in Asia. Braskem, NatureWorks and other bio-based chemicals producers are looking at cellulosics feedstocks. Dow Chemical is also planning an ethylene and polyethylene (PE) complex based on sugar-cane ethanol in Brazil, and is looking at bagasse as a feedstock.
The US company is investigating technologies for other bio-based chemicals including propylene and acrylic acid, and earlier this year announced a partnership with US renewable oil and bioproducts producer Solazyme to develop algae-derived oils for use in bio-based dielectric insulating fluids.
Solazyme produces algae oils heterotrophically - by feeding microalgae with sugar feedstock in dark fermentation tanks - and said it is looking at biomass sources including cellulosics-derived sugars. With elevated crude prices, the investment sector is becoming more serious about bio-based chemicals.
Bio-based routes to products such as propylene and butanediol (BDO) are expected to revolutionize the technologies that underpin production of the chemical and bring new players into the market, Nexant says.
"We are at a turning point towards a green industrial revolution to secure our feed and fuel needs in the future," Feike Sijbesma, CEO of Dutch health, nutrition and materials company DSM, said when announcing a bio-based succinic acid project in Italy. DSM and French starch derivatives company Roquette Freres plan to start up the commercial-scale biosuccinic acid plant at Roquette's site in Cassano Spinola in the second half of 2012.
It will use starch derivatives as feedstock but plan to switch to cellulosic biomass feedstock. The project demonstrates the shift from a fossil-based economy to a bio-based economy, Sijbesma said, and much of the action involves biotech start-ups partnering established agricultural or chemicals companies.
For example, Italy's M&G has partnered US biotechnology start-up Genomatica to adapt M&G's cellulosic process for producing bio-based chemicals, including BDO. BDO will be produced using M&G's Proesa technology to convert cellulosic biomass to fermentable sugars, combined with Genomatica's bio-BDO process. The bio-BDO will be produced at a demonstration-scale plant in Rivalta, Italy, with start-up expected in 2012. The project is expected to use local cellulosic feedstocks such as Arundo donax cane and wheat straw.
Genomatica is about to start up a demonstration plant for bio-BDO based on conventional sugars at Tate & Lyle's corn wet mill in Decatur, Illinois. The bio-BDO facility is expected to start up in the third quarter of this year. Mitsubishi Chemical also has a research agreement with Genomatica and intends to base its entire production of C4 chemicals on plant-derived feedstocks by 2025.
It wants to build a 40,000-50,000 tonne/year bio-based BDO plant in Asia by 2015. Biological routes to BDO offer tremendous promise, particularly considering high prices for petroleum-based feedstock butadiene (BD). "The global BDO industry appears to be on the cusp of a technological revolution," Nexant states in a report on prospects for bio-BDO. While Genomatica seeks a direct route to BDO, the main method is via succinic acid, which is being pursued by multiple coalitions with several new projects announced in Europe. These biosuccinic acid projects are currently based on sugar beet, but the feedstock is expected to switch to cellulosic biomass once technologies are ready. "Many of the developers of these technologies have said that, as soon as a good, clean cellulosic biomass hydrolysate becomes available, they have microbes that are ready to metabolize those feeds," Cascone says.
US renewable chemicals company BioAmber already operates a biosuccinic acid plant in Pomacle, France, and is planning a biosuccinic acid and BDO project in Sarnia, Ontario, Canada. It is also looking to build a biosuccinic acid plant in Thailand in partnership with Mitsui & Co. and Mitsubishi Chemical. Like its competitors, BioAmber, is exploring the use of non-food feedstocks.
Thermochemical routes, such as gasification and pyrolysis, also offer good prospects for converting non-edible biomass to chemicals, Cascone says. They are more flexible in terms of feedstock than fermentation routes, which are more sensitive to the quality of the mixture of sugars.
wood waste is a potential source of chemical feedstocks in northern Europe Credit: Sarah Cady
Suitable materials for gasification include municipal solid waste, forest products waste, straw, manure and energy crops. The materials can be gasified to produce syngas, a mixture of carbon monoxide and hydrogen, which can be converted into chemical building blocks using bio-propylene, which can be manufactured by converting syngas to a mixed-alcohol stream composed of ethanol, propanol and butanols.
wood waste is a potential source of chemical feedstocks in northern Europe
Credit: Sarah Cady
The propanol can be dehydrated to propylene, while the ethanol and butanols can be converted to their corresponding olefins and metathesised to give additional propylene. The mixed-alcohol synthesis stage is in early commercialization, Nexant says.
Another thermochemical route to bio-propylene involves converting syngas to methanol, which is converted to propylene or an ethylene/propylene mix using Lurgi's methanol-to-propylene or UOP's methanol-to-olefins processes, Nexant says.
With significant investments in fermentation routes, thermochemical routes have been overlooked, Cascone says. There is a view it is preferable to convert existing sugars, rather than destroying them and rebuilding, he suggests. "But in fact, the thermochemical route is much similar to the way we produce petrochemicals - destroying them and bringing them back to materials such as ethylene."
Cascone says the development of thermochemical routes has lagged investments in fermentation because they have not gone through the learning process using food-based feedstocks. "Fermentation is further ahead because it has traditionally been based on easy-to-ferment feeds. Only now are they are going for harder-to-ferment but cheaper materials."
Commercial thermochemical projects for biochemicals production are expected within five years, Nexant says. One example is a partnership between Genomatica and US-based waste-collection giant Waste Management to develop a process using carbon monoxide from gasified municipal waste. Also in the US, INEOS Bio, a subsidiary of UK-based chemicals major INEOS, is developing a gasification platform to produce bioethanol from yard, vegetative and household waste.
BioAmber has moved quickly to build its production capability Credit: Rex Features
Production of bio-based chemicals, whether first or second generation, will need to be based near feedstock sources. The availability of agricultural cellulosic materials such as wheat straw, corn stover and bagasse is geographically limited - bagasse is only available in the sub-tropics.
BioAmber has moved quickly to build its production capability
Credit: Rex Features
Energy grasses, on the other hand, can thrive in most climates. Switchgrass is expected to succeed in the US, while miscanthus is being championed in Europe.
In Southeast Asia, biochemical and biofuel production is mainly based on sugar cane, cassava and palm oil, with second-generation feedstocks such as jatropha and bagasse at an early stage, says Deepan Kannan, industry analyst for Frost & Sullivan.
"In future, due to the increasing focus on sustainability, these feedstocks will gain increased acceptance," he says.
A significant amount of palm oil, a major resource in Malaysia, is cultivated via unsustainable practices and some sugar-cane processing plants in countries such as Indonesia and Thailand are outdated and in need of modernization, Kannan, notes.
These factors reduce the overall sustainability of the feedstock. In more temperate climates such as northern Europe, forest products waste is a potential source of feedstock.
US-based cellulosic ethanol producer ZeaChem is demonstrating platforms using silva culture in the US, while in Europe M&G has experimented with wood chips, grasses and cane.
Large-scale production of green feedstocks in Europe is limited by land availability. The European Chemical Industry Council (Cefic) is campaigning for a change in farm policy to encourage the production of crops such as beets for industrial processes to avoid distortions in food supply.
Relying on imported renewable feedstock for the emerging bio-based chemicals sector is not a viable option, Cefic said in a policy paper published in May.
Import duties should also be reduced, Cefic says. "The permanent removal of import duties on renewables such as sugars, cereals, and bioethanol would give a clear signal to the market that would attract more bio-based investment in Europe," Cefic director general Hubert Mandery says. "This would be the major step to attract investments in the bio-based industry in Europe."
Political support for technological developments and demonstration projects will be essential but, ultimately, bio-based chemicals will have to compete with petroleum-based products on price.
The bio-based economy will play an increasingly significant role in the chemical industry and the speed of growth will depend on the relative prices of oil and agricultural raw materials, combined with the speed of technological progress.
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