Biofuel potential in Mexico
September 17th, 2010 by CATF,Article: Valdez-Vazquez, I., Acevedo-Benitez,J.A., Hernandez-Santiago,C. Distribution and potential of bioenergy resources from agricultural activities in Mexico. Renewable and Sustainable Energy Reviews 14 (2010) 2147-2153.
The Valdez-Vasquez et al (2010) article is a “first step towards estimating the bioenergy production capacity from crop residues.” From there, “it will be necessary to propose the best technology [direct combustion, anaerobic fermentation, etc.] for their [crop residue] use at the local level.”
Mexico has the third largest cropland area in the Latin-American Caribbean region which constitutes 13% or the worlds cropland production. For these reasons, Mexico is expected to have high bioenergy potential from primary and secondary crop residues. The objective of this study is to evaluate crop residue types, quantities and locations (broken down by municipality).
Valdez-Vasquez et al (2010) estimated the crop residue index (CRI) as the ratio of dry weight crop residue to total crop production. Both primary and secondary crop residues were evaluated. ARCGIS was then used to represent the biomass potential of the region in thematic maps.
The results of the study found an estimated 60.13 million tons of dry matter from primary crop residue and 16.5 million tons of dry matter frm secondary crop residue. However, not all of the estimated dry matter is available for bioenergy production as crop residues constitute an estimated 23.6% of animal feed in the region. Typically the animal feed comes from primary crop residues.
Corn by-products followed by Sorghum by-products were found to have the highest biomass potential of the primary crop residues while sugarcane, coffee, and maguey bagasse were found to be the highest of the secondary crop residues.
Overall, Baja California, Campeche, Chiapas, Chihuahua, Guanajuato,Hidalgo, Jalisco, Oaxaca, Quintana Roo, San Luis Potosi, Sinaloa, Sonora, Tobasco, Tomaulipas, and Veracruz municipalities were found to have the highest estimated bioenergy potential in Mexico.
The full article can be downloaded here.
Lignocellulosic feedstocks offer atmospheric GHG reductions
August 22nd, 2010 by CATF,Article: Gonzalez-Garcia et. al. (2010). Comparative environmental performance of lignocellulosic ethanol from different feedstocks. Renewable and Sustainable Energy Reviews (14) pp.2077-2085.
Sara Gonzalez-Garcia, M. Teresa Moreira, and Gumersindo Feijoo of the Uiversity of Santiago do Compostela find that, “using ethanol derived from lignocellulosic feedstocks as liquid fuel would reduce fossil fuel dependence and greenhouse gas emissions but would increase acidification, eutrophication and photochemical smog, compared to using gasoline as liquid fuel.”
Gonzalez et al (2010) compare 5 lignocellulosic feedstocks ( alfalfa stems, poplar, Ethiopian mustard, flax stives, and hemp hurds) as substitutes for conventional motor vehicle gasoline at E10 and E85 concentrations. The study was conducted using standard life cycle analysis methods to evaluate which feedstock had the largest environmental benefit when considering global warming, photochemical oxidant formation, eutrophication, and acidification.
The results of the analysis demonstrated reductions in GHGs for all feedstocks, however for some of the feedstocks the carbon sequestered did not make up for the methane and nitrous oxide emissions from the agricultural practices at the E10 concentration. Ethiopian mustard offered reductions at both E10 and E85 concentrations. E10 concentrations were found to be more beneficial than E85 with respect to photochemical smog, acidification and eutrophication due to emissions from upstream processes such as agricultural practices and machinery. Ethopian mustard was found to offer a 10% reduction in fossil fuel extraction at the E10 concentration and a 63% reduction for E85.
Different feedstocks performed better in different categories. For example, poplar had the least impact on photochemical oxidation formation where flax shives were best for acidification. Ethopian mustard was found to offer the greatest greenhouse gas reduction as well as more significant reductions in fossil fuel extraction rates. Overall, lignocellulosic ethanol is expected to reduce greenhouse gas emissions while increasing acidification, eutrophication and photochemical oxidation.
The Gonzalez-Garcia et. al (2010) paper concludes that in order for lignocellulosic ethanol to become a more economically viable transportation fuel alternative, the biorefinery process must become more efficient and production must occur in much larger quantities.
The full article can be downloaded here.
RESEARCH: Expanding the scope of traditional life cycle analyses through the inclusion of nitrogen and land use intensity to assess the environmental impacts of biofuel generation
June 14th, 2010 by CATF,Article: Miller, S.A. (2010). Minimizing Land Use and Nitrogen Intensity of Bioenergy. Environmental Science and Technology. Vol.4(10) pp.3932-3939.
Synopsis: Shelie A. Miller of Clemson University developed a system of ranking biofuel feedstocks based on land use and nitrogen intensity in order to determine which feedstocks were the most environmentally favorable with respect to these factors. Miller’s results suggest that, “current energy policies either undervalue or do not consider nitrogen and land use impacts.”
This paper explains that widely practiced lifecycle analysis methods tend to focus almost entirely on greenhouse gas emissions, despite the evidence that many environmental systems are negatively impacted by bioenergy production. In particular, most biofuels are known to be water, nutrient and land intensive. This study ranked feedstocks according to nitrogen and land use intensity as these two factors are almost entirely limited to feedstock cultivation stages, whereas water and energy are factors throughout cultivation, manufacturing and “end-of-life” stages.
In terms of the ranking system, 14 biofuel feedstocks were evaluated to determine the “minimum nitrogen and land required to produce 1000GJ of unprocessed energy.” The calculations represent ideal values for maximum energy yield (Maximum Energy Yield = harvestable yield x high heating value) and maximum nitrogen requirements (Maximum nitrogen requirements = harvestable yield x percent nitrogen composition) of each system averaged for a range of conditions and regions for each feedstock but do not account for thermodynamic losses. Land use and nitrogen intensity were weighted equally and the feedstocks were then ranked relative to one another.
The results of the Miller article indicate that sugar crops and algae are the least land intensive when accounting for nitrogen and land intensity, with sugarcane ranking as the most favorable feedstock overall. Food crops, soy and rapeseed in particular, ranked consistently low.
Environmental damages are not limited to greenhouse gas emissions; water, land and nutrient cycling are all vital ecosystem services that may be impacted by biofuel production. Going forward, this research suggests that efforts taken to determine the ecological viability of a particular fuel should include a wider scope of environmental impacts and should not be limited to greenhouse gas emissions.
The full article can be downloaded here.
RESEARCH: Biofuel feedstocks may offer a sustainable electricity alternative
April 21st, 2010 by CATF,Article: Evans, A., Strezov, V., Evans, T.J. (2010). Sustainability considerations for electricity generation from biomass. Renewable and Sustainable Energy Reviews. Vol. 14 pp.1419-1427. doi:10.1016/j.rser.2010.01.010.
Synopsis: The paper, “Sustainability considerations for electricity generation from biomass,” synthesizes available research relating to the feasibility of electricity generated from biofuel feedstocks. The article explains that while electricity generated from biofuels only accounts for approximately 2% of total global generation, it may offer a sustainable alternative to existing generation methods going forward.
The Evans et al. article includes information on residue feedstocks as well as dedicated feedstocks and the trade-offs between the two. Generally, residues from agriculture and forestry practices have lower fuel densities and are therefore less competitive once transportation costs have been taken into consideration. Evans et al suggest that dedicated feedstocks, or feedstocks grown specifically for energy, will be essential for biofuel electricity generation on a larger scale, however, there are environmental and social implications to this type of agriculture. The authors explain that ideal feedstocks will not be chemical, energy or water intensive, will not compete with food crops, will have high yields, and will have shorter rotation periods. Corn and wheat are deemed inappropriate for a variety of these listed reasons. Favored crops include willow, poplar, and non-woody perennial grasses.
Evans et al evaluate the crops based on available research on price of production, investment costs, efficiency and greenhouse gas emissions. The results were highly variable across these subject areas. On the subject of greenhouse gas emissions, the authors find that most available research suggests there are low net emissions associated with biofuel generated electricity, however, even “the highest emission is less than one third of the lowest natural gas and one-fifth of the lowest coal fired power station emissions proven at present.”
Evans et al conclude that relative to traditional energy sources, the generation of electricity from biofuels “appears favorable” with respect to “electricity price, efficiency and greenhouse gas emissions.” The authors do note that there are still significant barriers to overcome by way of land and water intensity as well as social implications including food competition, biodiversity and labor.
The complete article can be downloaded here .
RESEARCH: An economic evaluation of existing biofuel policies
April 6th, 2010 by CATF,Article: Babcock, Bruce A. Mandates, Tax Credits and Tariffs: Does the U.S. Biofuels Industry Need Them All? CARD Policy Brief 10-PB1. March 2010.
Synopsis: The article “Mandates, Tax Credits, and Tariffs: Does the U.S. Biofuels Industry Need Them All?” by researcher Bruce A. Babcok of the Center for Agricultureal and Rural Development explains that the way in which the “new mandates will be implemented shows that biofuel producers will receive little or no additional benefit from tax credits” and that “ethanol import tariffs will provide U.S. corn ethanol producers a cost advantage over imported Brazilian sugarcane ethanol until at least 2013.”
Biofuel mandates specify certain volumes of consumer fuel demand that must be met through the use of conventional biofuels, noncellulosic advanced biofuels, or biodiesel each year. Despite this guaranteed demand for ethanol, the U.S. biofuels industry continues to push to maintain tax credits and foreign ethanol import tariffs. Babcock conducts a simple economic analysis of these policies.
Babcock finds that given the established mandates, unless oil prices climb high enough to push the demanded quantity of ethanol higher than the mandated volume, the tax credits will have no effect on biofuel industry profits. Babcock also explains that after 2013 the import tariff will become redundant as Brazilian sugarcane ethanol will be used to meet the mandate for advanced noncellulosic biofuels and will no longer be in direct competition with the U.S. corn ethanol industry.
The complete article can be viewed here.
RESEARCH: Using macroalgae as a biofuel feedstock can reduce land and fertilizer requirements
March 25th, 2010 by CATF,Article: Goh, C.S. and K.T. Lee. A visionary and conceptual macroalgae-based third-generation bioethanol (TGB) biorefinery in Sabah, Malaysia as an underlay for renewable and sustainable development. Renewable and Sustainable Review. Vol.14(2), Pp. 842-848
The large majority of biofuels produced worldwide come from terrestrial plants, increasing competition for agricultural land and reducing some of the original benefits of the fuel source. This paper proposes that macroalgae such as seaweed could be a better biofuel feedstock, since the production of these algae does not require arable land or fertilizers. The feasibility of converting seaweed carbohydrates to ethanol is still in question, but recent research is outlined in this paper. Additionally, the operation of a potential biorefinery site for this material in Malaysia is described in detail.
The complete article can be downloaded here.
RESEARCH: Second-generation biofuel technology potential
March 25th, 2010 by CATF,Article: SN Naik et al (2010). Production of first and second generation biofuels: A comprehensive review. Renewable and Sustainable Review. Vol. 14(2), pp.578-597
Due to a number of environmental factors, it appears that it will be difficult for first-generation biofuel production (the creation of simple sugars directly from OM) to be a sustainable fuel source. However, second-generation production, which uses more advanced chemical processes to produce more complex fuel productions, has the potential to be environmentally feasible. This paper gives a comprehensive review of the current available technologies for converting biomass into a number of useful chemical products through second-generation processing.
The full article can be downloaded here.
RESEARCH: Biofuel production from microalgae
March 25th, 2010 by CATF,Article: TM Mata et al (2010). Microalgae for biodiesel production and other applications: A review. Renewable and Sustainable Review. Vol. 14(1), pp. 217-232
Given the land use issues that arise from producing biofuels from terrestrial plants, some scientists have recommended the use of microalgae as an alternative biofuel feedstock. This paper outlines the current status of biofuel production from microalgae, discussing current methods and research in cultivation, harvesting and processing. A great overview for those with little understanding of how microalgae would work as a fuel source.
The full article can be downloaded here.
RESEARCH: Algae may have a higher environmental impact than conventional feedstocks
March 25th, 2010 by CATF,Article: A.F. Clarens et al (2010). Environmental Life Cycle Comparison of Algae to Other Bioenergy Feedstocks. Environ Sci Techno., 44 (5), pp 1813–1819
Given the land use issues associated with producing crops or grasses for biofuels, some scientists have recommended that algae be used as a primary fuel feedstock. A new life cycle analysis finds that in terms of energy use, GHG emissions, and water use, the algae feedstock actually has a higher environmental impact than using conventional crops as feedstocks; its only advantage appears to be it consumes a lower total land area. However, if wastewater (specifically source-separated urine) is used to cultivate algae, its net environmental benefit becomes larger than terrestrial crops.
CATF Applauds EPA Decision to Regulate Biofuels’ Full Effect on Climate … But Remains Deeply Concerned About Model Outcomes
February 3rd, 2010 by CATF,In a final rule revising the RFS, EPA agreed to calculate the extent to which biofuel production mandate indirectly affects land use patterns around the world by increasing demand for farmland. CATF applauds the decision to account for the impact those land use changes have on global warming. However, much work remains to be done to ensure US biofuel policy promotes fuels that truly benefit the environment.
Click here for complete press release.
