U.S. researchers have proposed a hybrid hydrogen-carbon process that could supply the entire U.S. transportation sector with fuel generated from biomass.
In an article published Monday online in the early edition of the proceedings of the National Academy of Sciences, researchers explain how their "H2CAR" process would completely convert biomass to fuel by recycling the CO2 that is lost while making biofuel and reacting it with hydrogen generated from solar power.
Oil prices and global warming concerns have made fuels made from biomass attractive. However, conventional biomass-to-fuel processes require large amounts of biomass, because two-thirds of the material is lost as CO2 during conversion.
The U.S. transportation sector constitutes 16 percent of global oil consumption and produces 8 percent of the total carbon dioxide (CO2) released from fossil fuels.
Rakesh Agrawal and his colleagues from the School of Chemical Engineering at Purdue University calculate that to provide the entire U.S. transportation sector with this fuel would require 1.4 billion tons of dry biomass per year, one-third the amount needed for conventional processes.
With improvements in biomass growth rates, 10 percent of U.S. land area would need to be dedicated to biomass production. Alternatively, the United States has 1 billion tons of dry biomass available per year from agriculture and forestry wastes. This amount could be increased by modifying agricultural practices.
To implement the process, the researchers say cost-effective hydrogen production methods and biomass gasifiers that can use recycled CO2 need to be developed.