[Due to the increasing size of the archives, each topic page now contains only the prior 365 days of content. Access to older stories is now solely through the Monthly Archive pages or the site search function.]
New engineered metabolic pathways in yeast enable efficient fermentation of xylose from biomass
March 05, 2015
Researchers with the Energy Biosciences Institute (EBI), a partnership that includes Berkeley Lab and the University of California (UC) Berkeley, have introduced new metabolic pathways from the fungus Neurospora crassa into the yeast Saccharomyces cerevisiae to increase the fermentative production of fuels and other chemicals from biomass. An open access paper on the work is publised in the journal eLife.
While S. cerevisiae is the industry mainstay for fermenting sugar from cornstarch and sugarcane into ethanol, it requires substantial engineering to ferment sugars derived from plant cell walls such as cellobiose and xylose. The new metabolic pathways enable the yeast to ferment sugars from both cellulose (glucose) and hemicellulose (xylose)—the two major families of sugar found in the plant cell wall—efficiently, without the need of environmentally harsh pre-treatments or expensive enzyme cocktails.
Engineered yeast produces ethanol from three important cellulosic biomass components simultaneously; higher yields, lower cost
February 11, 2015
A team led by researchers from the University of Illinois at Urbana−Champaign has, for the first time, integrated the fermentation pathways of both hexose and pentose sugars from biomass as well as an acetic acid reduction pathway into one strain of the yeast Saccharomyces cerevisiae using synthetic biology and metabolic engineering approaches.
The engineered strain co-utilized cellobiose, xylose, and acetic acid to produce ethanol with a substantially higher yield and productivity than the control strains. The results showed the unique synergistic effects of pathway coexpression, the team reported in a paper in the journal ACS Synthetic Biology.
New LCFS pathway applications show Abengoa cellulosic ethanol with CI of 29.52 and 23.36 g CO2e/MJ
February 06, 2015
California Air Resources Board (ARB) staff has posted thirteen new Low Carbon Fuel Standard (LCFS) fuel pathway applications to the LCFS public comments website. Among them are two pathways for cellulosic ethanol produced by Abengoa Bioenergy at its Hugoton, Kansas plant. One pathway uses corn stover for feedstock, the other uses wheat straw. The carbon intensity (CI) for corn stover cellulosic ethanol is estimated to be 29.52 g CO2e/MJ; for wheat straw ethanol, the CI is estimated to be 23.36 g CO2e/MJ. The 2015 LCFS compliance schedule target for gasoline and fuels used as a substitue for gasoline is 96.48 g CO2e/MJ.
Corn stover comprises the dried leaves, stalks, husk, and cobs left on the ground after the harvest of the corn crop. Wheat straw is the dried stalk of the wheat crop after the grain and chaff have been removed. The carbon intensities of both pathways include the GHG emissions impacts associated with the nutrients that must be applied to fields from which stover and straw have been removed to make up for the nutrients lost when residues are removed.
Study finds wide range in GHG intensities and production costs of cellulosic ethanol from corn stover, switchgrass and miscanthus
February 04, 2015
A team led by researchers from the University of Illinois at Urbana-Champaign has developed an integrated framework to determine and to compare greenhouse gas (GHG) intensities and production costs of cellulosic ethanol derived from corn stover, switchgrass, and miscanthus grown on high and low quality soils for three representative counties in the Eastern United States.
In their study, published in the ACS journal Environmental Science & Technology they found that—compared to gasoline—the GHG savings from miscanthus-based ethanol ranged between 130% and 156% whereas that from switchgrass ranged between 97% and 135%. The corresponding range for GHG savings with corn stover was 57% to 95% and marginally below the threshold of at least 60% for biofuels classified as cellulosic biofuels under the Renewable Fuels Standard.
IU researchers find Z. mobilis can use N2 gas in cellulosic ethanol production; potential major cost savings
February 03, 2015
Researchers at Indiana University have shown—for the first time to their knowledge—that the ethanol-producing bacterium, Zymomonas mobilis, can use nitrogen (N2) gas in lieu of traditional nitrogen supplements. The finding, reported in a paper in Proceedings of the National Academy of Sciences (PNAS), could make cellulosic ethanol more competitive with corn ethanol and gasoline.
The raw materials for cellulosic ethanol are low in nitrogen, a nutrient required for ethanol-producing microbes to grow, so cellulosic ethanol producers are estimated to spend millions of dollars annually on nitrogen fertilizers such as corn steep liquor and diammonium phosphate. The IU team led by biologist James B. McKinlay showed that Z. mobilis can use N2 as a nitrogen source, something that the more traditional ethanol-producer, baker’s yeast, cannot do.
EPA delays issuing 2014 RVO standards for RFS until sometime in 2015
November 21, 2014
The US Environmental Protection Agency (EPA) will not finalize the 2014 applicable percentage standards (the 2014 Renewable Volume Obligations, RVOs) under the Renewable Fuel Standard (RFS) program until sometime next year. In a notice to be published in the Federal Register, the agency said that it intends to take action on the 2014 standards rule in 2015 prior to or in conjunction with action on the 2015 standards rule.
Because of the delay in issuing the 2014 RFS standards, EPA is moving the compliance demonstration deadline for the 2013 RFS standards to 2015. EPA will make modifications to the Moderated Transaction System (EMTS) to ensure that Renewable Identification Numbers (RINs) generated in 2012 are valid for demonstrating compliance with the 2013 applicable standards.
Study casting doubt on GHG benefits of corn stover ethanol draws sharp criticism by other researchers; Liska responds
October 30, 2014
A study published earlier this year in the journal Nature Climate Change that cast doubt on whether biofuels produced from corn residue could meet federal mandates for cellulosic biofuels to reduce greenhouse gas emissions by 60% compared to gasoline (earlier post) has drawn critical response published as correspondence in the same journal.
The study led by University of Nebraska-Lincoln assistant professor Adam Liska, funded through a three-year, $500,000-grant from the US Department of Energy, used carbon dioxide measurements taken from 2001 to 2010 to validate a soil carbon model that was built using data from 36 field studies across North America. Among their findings were that using corn crop residue to make ethanol and other biofuels reduces soil carbon and under some conditions can generate more greenhouse gases than gasoline.
California Energy Commission to award up to $3M for advanced biofuel projects
October 28, 2014
The California Energy Commission’s Alternative and Renewable Fuel and Vehicle Technology Program (ARFVTP) announced (PON-14-602) the availability of up to $3 million in grant funds for biofuels projects that are in the early/pre-commercial technology development stage. This solicitation is emphasizing transformative technology solutions to significant biofuels industry problems that increase yields, productivity, or cost effectiveness of biofuel production; and/or that target a significant unmet need in California’s biofuels industry.
The ARFVTP has an annual budget of approximately $100 million and provides financial support for projects that increase the use of alternative and renewable fuels and advanced vehicle technologies.
Abengoa opens cellulosic ethanol plant in Hugoton; 1st commercial deployment of Abengoa enzymatic hydrolysis
October 17, 2014
|The Hugoton cellulosic ethanol plant covers 400 acres, more than 380 of which will be used to store biomass from local farmers. Click to enlarge.|
Abengoa held the grand opening of its cellulosic ethanol plant in Hugoton, Kansas, located about 90 miles (145 km) southwest of Dodge City. Abengoa’s new biorefinery finished construction in mid-August and began producing cellulosic ethanol at the end of September with the capacity to produce up to 25 million gallons (94.6 million liters) per year. Abengoa received a $132.4-million loan guarantee and a $97-million grant through the Department of Energy to support construction of the Hugoton facility.
The plant utilizes only “second generation” (2G) biomass feedstocks for ethanol production—i.e.non-edible agricultural crop residues (such as stalks and leaves) that do not compete with food or feed grain. The facility also features an electricity cogeneration component allowing it to operate as a self-sufficient renewable energy producer. By utilizing residual biomass solids from the ethanol conversion process, the plant generates 21 megawatts (MW) of electricity—enough to power itself and provide excess clean renewable power to the local Stevens County community.
DEINOVE and MBI partner on cellulosic biofuels using DEINOL and AFEX
October 16, 2014
France-based DEINOVE and US-based MBI have formed a technological partnership to demonstrate the effectiveness of the DEINOVE’s DEINOL technology for producing biofuels based on lignocellulosic biomass (2G biofuels) using MBI’s AFEX (ammonia fiber expansion) pretreatment system.
DEINOL uses Deinococcus bacteria to break down the complex sugars contained in pre-treated lignocellulosic biomass and then to convert them into ethanol in a single operation, replacing the microorganisms that are traditionally used and a large part of the enzyme treatment that precedes fermentation. (Earlier post.) MBI, in close collaboration with Michigan State University (MSU), has developed and is scaling up its AFEX pretreatment technology. (Earlier post.)
GranBio begins producing cellulosic ethanol in Brazil; very low carbon intensity of 6.98 gCO2e/MJ for California LCFS
September 26, 2014
GranBio, a 100% Brazilian industrial biotech company, has begun production at the first commercial-scale plant for second-generation (cellulosic) ethanol in the Southern Hemisphere. The Bioflex 1 unit, built in São Miguel dos Campos, Alagoas, has an initial production capacity of 82 million liters (21.6 million gallons US) of ethanol per year with sugarcane straw and bagasse residues as the feedstocks.
GranBio’s facility uses the PROESA pre-treatment technology from the Italian company BetaRenewables (a company in the M&G Group); enzymes from Novozymes in Denmark; and yeast from DSM in Holland.
BIO says EPA inaction on RFS rule causing an increase in GHG emissions
September 23, 2014
Increased greenhouse gas emissions equal to 4.4 million additional cars on US roads are likely as a result of EPA inaction on finalizing the 2014 Renewable Fuel Standard (RFS) rules, according to a new white paper issued by The Biotechnology Industry Organization (BIO). The white paper updates earlier BIO’s March 2014 study, “Estimating Greenhouse Gas Emissions from Proposed Changes to the Renewable Fuel Standard Through 2022.”
That study demonstrated that if EPA reduced biofuel use under the RFS, as the agency proposed in November 2013, the United States would experience an increase in greenhouse gas emissions and forego an achievable decrease in emissions.
Promising results from Mercedes-Benz fleet test of Clariant high-octane cellulosic E20
Clariant, Haltermann and Mercedes-Benz have fleet-tested high-octane sunliquid 20 fuel—containing 20% cellulosic ethanol produced from straw—since January. (Earlier post.) The test found that the use of sunliquid 20 improves engine efficiency—more than compensating for its 4% lower energy content compared to E10. For drivers, this means with sunliquid 20, CO2emissions are reduced while consumption remains the same.
Use of sunliquid 20 also resulted in a 50% improvement in particle emissions count in contrast to the EU 5 reference fuel. The cellulosic ethanol in sunliquid 20 demonstrates greenhouse gas emission savings of up to 95% across the entire value chain (well-to-wheel perspective) without competing with food production or agricultural acreage.
California Energy Commission awards $5M grant to AltAir Fuels to expand renewable diesel production; $3M to GFP Ethanol for sorghum feedstock
September 11, 2014
The California Energy Commission approved $8 million in grants to two biofuel companies stemming from a solicitation issued earlier this year (PON-13-609: Pilot-Scale and Commercial-Scale Advanced Biofuels Production Facilities).
AltAir Fuels LLC (earlier post) will receive $5 million to expand production of renewable diesel fuels at its Paramount facility in Los Angeles County from 30 million gallons per year to 40 million gallons per year, and allow for processing of additional feedstocks. This facility will also co-produce renewable jet at commercial scale and a byproduct chemical and gasoline component. GFP Ethanol is receiving $3 million to support the development of sorghum as a feedstock for lower carbon intensity ethanol.
UGA-led team engineers bacterium for the direct conversion of unpretreated biomass to ethanol
June 03, 2014
A team led by Dr. Janet Westpheling at the University of Georgia has engineered the thermophilic, anaerobic, cellulolytic bacterium Caldicellulosiruptor bescii, which in the wild efficiently uses un-pretreated biomass—to produce ethanol from biomass without pre-treatment of the feedstock. A paper on the work is published in Proceedings of the National Academy of Sciences (PNAS).
In January, Dr. Westpheling and her colleagues reported in the journal Science their discovery that an enzyme (the cellulase CelA) from C. besciia can digest cellulose almost twice as fast as Cel7A, the current leading component cellulase enzyme on the market. (Earlier post.)
Study finds removing corn residue for biofuel production can decrease soil organic carbon and increase CO2 emissions; may miss mandated 60% GHG reduction
April 21, 2014
|Contribution of modeled CO2 emissions from SOC to the life cycle of biofuel from corn residue. Error bars are ± one standard deviation. Liska et al. Click to enlarge.|
Using corn crop residue to make ethanol and other biofuels reduces soil carbon and under some conditions can generate more greenhouse gases than gasoline, according to a major, multi-year study by a University of Nebraska-Lincoln team of researchers published in the journal Nature Climate Change. The findings cast doubt on whether biofuels produced from corn residue can be used to meet federal mandates for cellulosic biofuels to reduce greenhouse gas emissions 60% compared to gasoline.
The study, led by assistant professor Adam Liska, was funded through a three-year, $500,000-grant from the US Department of Energy, and used carbon dioxide measurements taken from 2001 to 2010 to validate a soil carbon model that was built using data from 36 field studies across North America, Europe, Africa and Asia. Using USDA soil maps and crop yields, they extrapolated potential carbon dioxide emissions across 580 million 30-meter by 30-meter geospatial cells in Corn Belt states.