Biofuels

Cellulosic biofuel technology will generate low-cost green fuel, says major study

Cellulosic biofuels offer similar, if not lower, costs and very large reductions in greenhouse gas emissions compared to petroleum-derived fuels. That’s one of the key take-home messages from a series of expert papers on “The Role of Biomass in America’s Energy Future (RBAEF)” in a special issue of Biofuels, Bioproducts and Biorefining.

Three papers from the special issue of Biofuels, Bioproducts and Biorefining (Volume 3, issue 2) can be viewed free of charge on the journal’s website until 31 May 2009:

  • The role of biomass in America’s energy future: framing the analysis. Lynd et al. 3:113-123 (2009). DOI: 10.1002/bbb.134
  • Co-production of ethanol and power from switchgrass. Laser et al. 3:195-218 (2009). DOI: 10.1002/bbb.133
  • Comparative analysis of efficiency, environmental impact and process economics for mature biomass refining scenarios. Laser et al. 3:247-270 (2009). DOI: 10.1002/bbb.136


Experts: Time is right to rekindle wood energy in America
Study says small-scale power plants could be a source of clean, affordable energy

Increased use of sustainable wood energy could yield long-term economic, social and environmental benefits in many regions of the United States, according to newly published analysis by a Duke University-led team of experts.

“Wood energy is one of America’s most important renewable fuels. Our forests could sustainably produce at least 368 million dry tons of wood for energy annually, yet it’s really not on the national radar screen when we talk about renewable energy sources,” said Daniel D. Richter, lead author of the study and professor of soils and forest ecology at Duke’s Nicholas School of the Environment. “It’s time to reconsider this.”

An article detailing the benefits of increased U.S. investment in sustainable wood energy, written by Richter and a multi-institutional team of ecologists, engineers, forest conservationists and energy specialists, appears in the Policy Forum section of the March 13 issue of the journal Science.

Thanks to improved pollution-control and efficiency technologies developed over the last two decades, small-scale power plants fueled partly or solely by advanced wood combustion (AWC) could be a source of clean, affordable energy for communities … “This is not your grandfather’s smoky wood stove,” Richter said. “These facilities release remarkably low quantities of air pollutants and have systemwide thermal efficiencies approaching 90 percent. …


2009-03
SciAm Earth 3.0: The Next Generation of Biofuels
Companies are poised to go commercial with gasoline substitutes made from grass, algae and the ultimate source: engineered microorganisms

Americans burn through 140 billion gallons of gasoline a year. And even if drivers switch to more fuel-efficient cars and trucks, the nation’s fuel needs are expected to increase by a fifth over the next 20 years, thanks to dramatic increases in car and airplane use. Which is why, in addition to developing solar, wind and geothermal energy, policy makers, including President Barack Obama, are advocating biofuels to transform the transportation culture.

They’re not talking about ethanol from corn, however, which has already proved wasteful and environmentally damaging. Instead eyes are on a handful of high-tech labs around the U.S. that are perfecting ways to make the equivalent of gasoline and diesel from the lowest life-forms on the totem pole: yeast, algae and bacteria. The challenge is to make enough of these fuels economically and in a form compatible with today’s vehicles. …


2009-06-23
PNAS: The water footprint of bioenergy : doi: 10.1073/pnas.0812619106

All energy scenarios show a shift toward an increased percentage of renewable energy sources, including biomass. This study gives an overview of water footprints (WFs) of bioenergy from 12 crops that currently contribute the most to global agricultural production: barley, cassava, maize, potato, rapeseed, rice, rye, sorghum, soybean, sugar beet, sugar cane, and wheat. In addition, this study includes jatropha, a suitable energy crop. Since climate and production circumstances differ among regions, calculations have been performed by country. The WF of bioelectricity is smaller than that of biofuels because it is more efficient to use total biomass (e.g., for electricity or heat) than a fraction of the crop (its sugar, starch, or oil content) for biofuel. The WF of bioethanol appears to be smaller than that of biodiesel. For electricity, sugar beet, maize, and sugar cane are the most favorable crops [50 m3/gigajoule (GJ)]. Rapeseed and jatropha, typical energy crops, are disadvantageous (400 m3/GJ). For ethanol, sugar beet, and potato (60 and 100 m3/GJ) are the most advantageous, followed by sugar cane (110 m3/GJ); sorghum (400 m3/GJ) is the most unfavorable. For biodiesel, soybean and rapeseed show to be the most favorable WF (400 m3/GJ); jatropha has an adverse WF (600 m3/GJ). When expressed per L, the WF ranges from 1,400 to 20,000 L of water per L of biofuel. If a shift toward a greater contribution of bioenergy to energy supply takes place, the results of this study can be used to select the crops and countries that produce bioenergy in the most water-efficient way.
Full text (pdf)

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