Biofuels: Innovations Needed

Given the permanent loss of government subsidies (as of January 1 of this year), the industry has little economic incentive for expansion beyond meeting the Renewable Fuel Standard. And there would appear to be little room for innovation in corn ethanol production aside from small gains to increase corn yields.

Biofuels must be part of any future energy strategy—specifically “advanced biofuels.” The feedstock for an advanced biofuel would meet these criteria:

• The feedstock would not compete with the food chain.
• The feedstock would not be grown on low-quality land, a practice that causes environmental harms.
• The feedstock would have a low energy input and a high energy output.

Advanced biofuels are defined as renewable fuels (other than corn-based ethanol) that have lifecycle greenhouse gas emissions at least half of that of the baseline lifecycle greenhouse gas emissions (that is, the greenhouse gas emissions from gasoline). This essentially means ethanol from cellulose, crop residues, bio-based diesel, biogas, biobutanol and hemicellulose or lignin (see our last blog post, The Cellulose Quandary).

There also is need to advance the knowledge of Fischer-Tropsch synthesis, which has the potential to produce liquid fuels and heavy oils from cellulosic materials at competitive prices. The Fisher-Tropsch synthesis was invented by the Germans during World War II to make fuels. The process involves thermal combustion in a closed chamber of coal, methane or biomass to provide a mixture of carbon monoxide and hydrogen. These gases are passed over catalysts to produce hydrocarbon fuels.

Besides liquid fuels for transportation, Fisher-Tropsch–synthesized fuels may be used in generators to produce electricity, or for propane and heating oils.

Potential cellulosic feedstocks include:

• Miscanthus, a high-yielding source of cellulose
• Switchgrass, a fast-growing native grass that yields well in warm climates and that has drawbacks including difficulty of harvest and storage
• Crop residues, particularly corn stover. Corn stover, which is the plant material remaining after grain harvest, is the most widely considered cellulosic feedstock.

Each feedstock will have unique requirements to improve efficiency. At least two commercial-scale ethanol plants are being constructed in the Midwest.

Innovations most needed include improvement in feedstock yields, harvesting, collection, storage and preparation.

The primary gains in the conversion of cellulose to ethanol are the development of enzymes capable of converting the diverse plant cell wall constituents to starches. Several proprietary enzymes have been developed and are in the process of evaluation.

The Joint BioEnergy Institute (JBEI) has been established to advance new biofuels through a well-funded and focused interdisciplinary research approach. The San Francisco–based Institute has a Feedstocks Division to develop new and improved plant energy crops; the Deconstruction Division will investigate new ways to convert lignocelluloseic plant materials to biofuels; and the Technologies Division will develop tools to support the JBEI mission. For example, JBEI has developed a number of potential genetic breakthroughs that may lead to new E. coli strains better able to digest switchgrass to obtain biofuels.

In summary, ongoing research—much of it sponsored and conducted by the federal government and some private labs—is advancing the efficiency of the use of cellulosic biomass for liquid fuels. It is doubtful if we see breakthroughs anytime soon though, as these type of innovations often come slowly. But they are necessary if biofuels are to advance and become an important part of our energy mix.