Tag Archives: biofuels
Rapid And Effective Oxidative Pretreatment Of Woody Biomass At Mild Reaction Conditions And Low Oxidant Loadings
One route for producing cellulosic biofuels is by the fermentation of lignocellulose-derived sugars generated from a pretreatment that can be effectively coupled with an enzymatic hydrolysis of the plant cell wall. While woody biomass exhibits a number of positive agronomic and logistical attributes, these feedstocks are significantly more recalcitrant to chemical pretreatments than herbaceous feedstocks, requiring higher chemical and energy inputs to achieve high sugar yields from enzymatic hydrolysis. We previously discovered that alkaline hydrogen peroxide (AHP) pretreatment catalyzed by copper(II) 2,2 -bipyridine complexes significantly improves subsequent enzymatic glucose and xylose release from hybrid poplar heartwood and sapwood relative to uncatalyzed AHP pretreatment at modest reaction conditions (room temperature and atmospheric pressure). In the present work, the reaction conditions for this catalyzed AHP pretreatment were investigated in more detail with the aim of better characterizing the relationship between pretreatment conditions and subsequent enzymatic sugar release. Results: We found that for a wide range of pretreatment conditions, the catalyzed pretreatment resulted in significantly higher glucose and xylose enzymatic hydrolysis yields (as high as 80% for both glucose and xylose) relative to uncatalyzed pretreatment (up to 40% for glucose and 50% for xylose). We identified that the extent of improvement in glucan and xylan yield using this catalyzed pretreatment approach was a function of pretreatment conditions that included H2O2 loading on biomass, catalyst concentration, solids concentration, and pretreatment duration. Based on these results, several important improvements inpretreatment and hydrolysis conditions were identified that may have a positive economic impact for a process employing a catalyzed oxidative pretreatment. These improvements include identifying that: (1) substantially lower H2O2 loadings can be used that may result in up to a 50-65% decrease in H2O2 application (from 100 mg H2O2/g biomass to 35–50 mg/g) with only minor losses in glucose and xylose yield, (2) a 60% decrease in the catalyst concentration from 5.0 mM to 2.0 mM (corresponding to a catalyst loading of 25 mumol/g biomass to 10 mumol/g biomass) can be achieved without a subsequent loss in glucose yield, (3) an order of magnitude improvement in the time required for pretreatment (minutes versus hours or days) can be realized using the catalyzed pretreatment approach, and (4) enzyme dosage can be reduced to less than 30 mg protein / g glucan and potentially further with only minor losses in glucose and xylose yields. In addition, we established that the reaction rate is improved in both catalyzed and uncatalyzed AHP pretreatment by increased solids concentrations. Conclusions: This work explored the relationship between reaction conditions impacting a catalyzed oxidative pretreatment of woody biomass and identified that significant decreases in the H2O2, catalyst, and enzyme loading on the biomass as well as decreases in the pretreatment time could be realized with only minor losses in the subsequent sugar released enzymatically. Together these changes would have positive implications for the economics of a process based on this pretreatment approach. Author: Zhenglun LiCharles H ChenEric L HeggDavid B Hodge Credits/Source: Biotechnology for Biofuels 2013, 6:119 Continue reading
USDA FSA Solicits Bids For Feedstock Flexibility Program
By Erin Voegele | August 20, 2013 USDA Surplus sugar is one step closer to entering the U.S. biofuels industry as feedstock. The USDA Farm Service Agency recently published a notice soliciting bids under the Feedstock Flexibility Program for Bioenergy Producers. The program encourages domestic production of biofuels from surplus sugar. Information published by the USDA explains that the program was created by Congress in the 2008 Farm Bill. It essentially requires the USDA to purchase sugar and sell it as feedstock to bioenergy producers in order to avoid forfeiture of sugar pledged as collateral by processors when securing nonrecourse community loans from the Commodity Credit Corp. The USDA further explains that federal law allows sugar producers to obtain loans from the CCC with maturities of up to nine months at the beginning of the crop year. When the loan matures, the sugar processor may repay the loan or forfeit the sugar used as collateral. According to the USDA, the last time forfeitures occurred was in 2004, but atypical market conditions have caused it to take action this year to avoid forfeitures. Within the announcement , the USDA FSA specifies that any sugar purchased by the CCC under the Feedstock Flexibility Program will be sold on a competitive basis to bioenergy producers. That sugar must be used to produce biofuel. A fact sheet published by the USDA FSA in August specifies that bioenergy producers buying sugar under the program must take possession of the sugar no more than 30 days from the date of the CCC’s purchase. According to the notice, quantify offers are due by 1:30 p.m. CT on Aug. 21. By 6:30 p.m. that same day, a catalog listing with all offered quantities will be available on the FSA website here . Price offers will be due on Aug. 28, and the CCC will notify those with successful offers the following day. Additional information on the Feedstock Flexibility Program final rule, which was published in July, is available here . Continue reading
US Ethanol Biofuels Mix Hits The Oil ‘Blendwall’
http://www.ft.com/cms/s/0/3dad8ae0-04fc-11e3-9ffd-00144feab7de.html#ixzz2cJfyChEp August 14, 2013 6:31 pm US ethanol biofuels mix hits the oil ‘blendwall’ By Gregory Meyer in New York In the slow-motion collision between US biofuels policy and the “blendwall”, it looks like the wall will be left standing. The blendwall is shorthand for the maximum amount of ethanol that the US oil industry will mix into petrol. Given demand constraints in the US, this is a tad more than 13bn gallons this year. But the federal Renewable Fuel Standard (RFS) requires 13.8bn gallons of corn-based ethanol to be blended this year, and even more when “advanced” biofuels are counted. Next year the law dictates a further rise. So policy is crashing into the reality of the blendwall. Congress has failed to address the problem, so the White House stepped in last week. In obscure bureaucratic language, the Environmental Protection Agency invoked powers to signal a reduction in the mandate next year. The move has implications for commodity markets from corn to petrol. It could reverberate not only in US farm states such as Iowa and Nebraska, but Brazil and Europe as they respectively export ethanol and petrol to the US. The US Energy Independence and Security Act of 2007 sharply increased how much ethanol fuel companies must blend into petrol each year. The law was passed just before the financial crisis and a shift towards more efficient cars. The increase could have been achieved in spite of weaker petrol demand if fuel companies had increased the ratio of ethanol in each gallon of petrol. But they have in most cases refused to go beyond 10 per cent, citing potential damage to engines. The EPA in past years rebuffed concerns about the blendwall. But last week it acknowledged that the maths did not work. For 2014, “the ability of the market to consume ethanol in higher blends . . . is highly constrained as a result of infrastructure- and market-related factors”, the agency said. It plans to reduce renewable fuel volume requirements in its rules for next year. Scott Irwin, a University of Illinois agricultural economist, called the move a “fairly significant strategic defeat for the ethanol and corn interests”, as their dreams of higher ethanol blend levels “are unlikely to ever be fulfilled”. The shift had an immediate effect on the volatile market for credits that fuel companies can use to comply with blending requirements. “Renewable identification numbers,” or RINs as the credits are known, have plunged 30 per cent since the EPA announcement. The EPA noted it would examine “advanced” biofuels requirements for fuels not distilled from corn. This could trim not only experimental biofuels refined from things like wood waste, but sugarcane ethanol imported from Brazil. Joel Velasco, adviser to Unica, the Brazilian sugar industry group, says: “How much? That’s the million-dollar question, or the billion-gallon question. That’s what the concern is about: how much are they going to have to reduce?” If Brazilian imports take a hit it could be slightly bullish for corn prices in the short term, Prof Irwin says. That is because corn ethanol refiners such as Archer Daniels Midland and Valero Energy would see less foreign competition. The sharp fall of the real, the Brazilian currency, and a rebound in the country’s sugar crop have made its ethanol exports more attractive. But even if advanced biofuels were eliminated the mandate would still require 14.4bn gallons of corn-based ethanol to blend. As the US Energy Information Administration projects 133bn gallons in total motor gasoline demand next year, this surpasses the 13.3bn gallons of ethanol needed under the 10 per cent blending ratio. Bob Dinneen, head of the US Renewable Fuels Association trade group, draws a line at 14.4bn gallons, dismissing as “nonsense” the idea it could not be met. “The narrative that the oil companies are suggesting that the RFS needs to be reduced to the level of the blendwall ignores the fact that one of the purposes was to move beyond 10 per cent ethanol in the motor fuel market,” he says. The oil industry is taking the opposite tack: this week it petitioned EPA to cut the ethanol mandate to below 10 per cent of petrol demand, warning the alternative will be “significant increases in the cost of fuel and substantial fuel supply shortages in the US”. As the political drama plays out, expect more sharp market moves ahead. Continue reading
