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New Advance in Biofuel Production
May 9, 2013 — Advanced biofuels — liquid fuels synthesized from the sugars in cellulosic biomass — offer a clean, green and renewable alternative to gasoline, diesel and jet fuels. Bringing the costs of producing these advanced biofuels down to competitive levels with petrofuels, however, is a major challenge. Researchers at the U.S. Department of Energy (DOE)’s Joint BioEnergy Institute (JBEI), a bioenergy research center led by Berkeley Lab, have taken another step towards meeting this challenge with the development of a new technique for pre-treating cellulosic biomass with ionic liquids — salts that are liquids rather than crystals at room temperature. This new technique requires none of the expensive enzymes used in previous ionic liquid pretreatments, and makes it easier to recover fuel sugars and recycle the ionic liquid. “Most of our ionic liquid efforts at JBEI have focused on using enzymes to liberate fermentable sugars from lignocellulosic biomass after pretreatment, but with this new enzyme-free approach we use an acid as the catalyst for hydrolyzing biomass polysaccharides into a solution containing fermentable sugars,” says Blake Simmons, a chemical engineer who heads JBEI’s Deconstruction Division and was the leader of this research. “We’re then able to separate the pretreatment solution into two phases, a sugar-rich water phase for recovery and a lignin-rich ionic liquid phase for recycling. As an added bonus, our new pretreatment technique uses a lot less water than previous pretreatments.” Simmons is the corresponding author of a paper describing this research that has been published in the journal Biotechnology for Biofuels. With the burning of fossil fuels continuing to add 9 billion metric tons of excess carbon dioxide to the atmosphere each year, the need for carbon neutral, cost-competitive renewable alternative fuels has never been greater. Advanced biofuels, produced from the microbial fermentation of sugars in lignocellulosic biomass, could displace gasoline, diesel and jet fuel on a gallon-for-gallon basis and be directly dropped into today’s engines and infrastructures without impacting performance. If done correctly, the use of advanced biofuels would not add excess carbon to the atmosphere. Environmentally benign ionic liquids are used as green chemistry substitutes for volatile organic solvents. While showing great potential as a biomass pretreatment for dissolving lignocellulose and helping to hydrolyze the resulting aqueous solution into fuel sugars, the best of these ionic liquids so far have required the use of expensive enzymes. Recent studies have shown that acid catalysts, such as hydrochloric or Brønsted, can effectively replace enzyme-based hydrolysis, but the subsequent separation of sugars and ionic liquids becomes a difficult and expensive problem can require the use of significant amounts of water. Guided by molecular dynamics simulations carried out at DOE’s National Energy Research Scientific Computing Center (NERSC), Simmons and his colleagues at JBEI solved this problem by deploying the ionic liquid imidazolium chloride in tandem with an acid catalyst. “Imidazolium is the most effective known ionic liquid for breaking down lignocellulose and the chloride anion is amenable with the acid catalyst,” Simmons says. “The combination makes it easy to extract fermentable sugars that have been liberated from biomass and also easy to recover the ionic liquid for recycling. By eliminating the need for enzymes and decreasing the water consumption requirements of more traditional ionic liquid pretreatments we should be able to reduce the costs of sugar production from lignocellulose.” Complete separation of the pretreatment solution into sugar-rich water and lignin-rich ionic liquid phases was attained with the addition to the solution of sodium hydroxide. The optimized sodium hydroxide concentration for both phase separation and sugar extraction was 15-percent, resulting in the recovery of maximum yields of 54-percent glucose and 88-percent xylose. The JBEI researchers believe these sugar yields can be increased by optimizing the process conditions and using more advanced methods of phase separation and sugar recovery. “After optimizing the process conditions, our next step will be to scale the process up to 100 liters,” Simmons says. “For that work we will use the facilities at the Advanced Biofuels Process Demonstration Unit.” This research was supported by the DOE Office of Science, which also supports NERSC. Continue reading
Biofuel From Wood: Researchers Look For Best Enzymes
Mark Hoffman First Posted: May 13, 2013 04:18 PM EDT Huge amounts of fossil fuel could be replaced by biofuels if it was possible to extract them from the very plentiful waste product lignocellulose. Importantly, its use in biofuel production does not interfere with the animal or human food chain. Researchers are currently trying to find the best enzymes to make bioethanol production as efficient as possible and elucidating the mechanisms behind the key process of enzymatic hydrolysis. Lignocellulose is the main component of currently poorly used waste materials from agriculture, forestry and wood-based industries, including straw, corn leaves and stalks as well as paper mill waste. Composed of carbohydrate polymers tightly bound to the tough material lignin, enzymatic breakdown and microbial fermentation of the carbohydrates can be used for production of bioethanol, the researchers explained. (Photo : Flickr) On the downside, however, lignocellulose is what makes woody material so indestructible and so difficult to decompose. The EU-funded project DISCO aimed to develop and test more efficient and cost-effective enzymes for breakdown of carbohydrates in lignocellulose for production of bioethanol over the past years. To achieve this goal, DISCO researchers reported that they isolated naturally occurring enzymes from fungi and bacteria in soil samples, culture collections and metagenomic libraries. Altogether, almost 700 lignocellulytic strains were screened, yielding tens of interesting fungi for cellulose and hemicellulase activity. Genome mining from the fungus Myceliphthora thermophila resulted in nearly 20 novel cellulases and hemicellulases and multiple bacterial carbohydrate active enzymes were discovered from soil metagenomic libraries. Knowledge on the mode of enzyme action is crucial to the success of lignocellulose breakdown. Lignocellulose is composed of cellulose fibrils linked together with hemicelluloses, all embedded in lignin. The researchers said that they thus specifically looked for synergy, efficiency and ability to degrade the entire backbone of the hemicellulose molecule. Besides hemicellulose, the inhibiting effect of lignin on cellulases/hemicellulases was also analyzed. Project scientists also investigated the effects of different pre-treatments on chemistry and enzymatic digestibility of agricultural residues. On hydrothermally pre-treated wheat straw, temperature and residence time had a marked effect on enzyme digestibility. Discovery of new recyclable enzymes promises to supply biofuel to supplement other less sustainable forms of energy. Further details and research papers can be found on the DISCO website ( http://www.disco-project.eu ). Continue reading
Carbon Market ‘Champions’ Undeterred: EU Climate Chief
10 May 2013 Carbon-market supporters from China to California will push for emissions trading even as they prepare for the end of the United Nations Kyoto Protocol in seven years, Europe’s top climate negotiator said. Nations including China and New Zealand and some US states have formed an informal group, “kind of the champions of the carbon market,” Artur Runge-Metzger said in a May 2 interview in Bonn, Germany. “It’s that club that’s going to set international standards” rather than UN talks, he said. Countries are increasing links between markets outside of the climate-protection targets set by the UN, which has led global efforts to reduce emissions since 1992. California last month approved rules that allow companies in the world’s ninth largest economy to trade pollution rights in Quebec, while Australia in 2012 agreed to use European permits to cut costs. The 1997 Kyoto Protocol sets market-based emission- reduction targets for the EU and 37 countries. The US and China, the biggest polluters, never signed, making the agreement “something that ended up in a kind of cul-de-sac,” Runge- Metzger said during the climate talks last week. Under the EU’s cap-and-trade system, designed to meet the bloc’s Kyoto targets, tradable permits are allocated to polluters that must surrender enough of them to cover their emissions or pay a fine. The euro area’s second recession since 2008 cut demand for allowances and UN credits, sending prices to record lows last month and reducing incentives to invest in low- carbon technologies. US scepticism Future agreements under the UN’s 1992 Framework Convention on Climate Change may never be implemented in “the real world,” US climate negotiators led by Todd Stern, said in a March 11 submission ahead of the Bonn talks. China has joined the World Bank’s Partnership for Market Readiness, a program which seeks to cut emissions at a faster pace than set out by existing national targets. The biggest energy user is preparing seven domestic carbon markets, covering 28 per cent of its economy. China is unlikely to link its existing and proposed carbon markets to those with emissions targets set by the UN, including the EU market, Su Wei, the nation’s lead climate negotiator, said May 2 in Bonn. “It’s too early to talk of a linkage with the EU market because that is a failed market,” Wei said in an interview. “If there are no ambitious targets there will be no demand. The carbon markets aren’t running very well.” Step back The UN has effectively “stepped back” from managing emissions programs partly because of resistance from countries against market-based climate strategies such as Bolivia, Venezuela and Cuba, Runge-Metzger said. Both international and national efforts to combat climate change are “absolutely critical” because efforts by countries and industries don’t match what’s required to stop temperatures from rising 2 degrees celsius, Christiana Figueres, executive secretary of the UN Framework Convention on Climate Change, told reporters in Bonn. Governments are seeking to keep any increase in global average temperatures below that level. Climate envoys are debating whether allowances and credits used to comply with the Kyoto treaty can be used under a new market system beyond 2020 that may include more nations. Russia has the biggest stockpile of Kyoto units, according to UN data on Bloomberg. The debate over the use of the credits is “going to be quite political,” Runge-Metzger said. “The majority of countries don’t have them.” Price drop EU carbon for December plunged to a record 2.46 euros ($3.20) on April 17 on the ICE Futures Europe exchange in London after the European Parliament rejected a proposal to enable the reduction of the surplus of allowances. They slid 44 per cent in the past year and closed at 3.79 euros today. The EU’s change in emphasis toward nation-led markets is a “sensible shift in policy,” Daniel Rossetto, the London-based managing director of emissions markets adviser Climate Mundial Ltd., said in a May 7 interview. The UN approach “is probably destined to fail, while bilateral negotiations between like- minded countries is more likely to proceed,” he said. Bloomberg Read more: http://www.smh.com.au/business/carbon-economy/carbon-market-champions-undeterred-eu-climate-chief-20130510-2jbgu.html#ixzz2TGXtvt6E Continue reading
