Cellulosic Ethanol: Benefits and Challenges

How will cellulosic ethanol production and use impact the environment?

When fossil fuels are consumed, carbon sequestered from the global carbon cycle for millions of years is released into the atmosphere, where it accumulates. Biofuel consumption can release considerably less CO2, depending on how it is produced. The photosynthetic production of new generations of biomass takes up the CO2 released from biofuel production and use. Life-cycle analysis at Argonne National Laboratory shows CO2 emissions from cellulosic ethanol to be 85% lower than those from gasoline. See the brochure Ethanol: The Complete Energy Lifecycle Picture (PDF) for more information on this analysis. Sequestration of CO2 produced during ethanol fermentation could result in greater reductions of emissions.

Perennial grasses and other bioenergy crops have many significant environmental benefits over traditional row crops. Perennial energy crops provide a better environment for more-diverse wildlife habitation. Their extensive root systems increase nutrient capture, improve soil quality, sequester carbon, and reduce erosion. Ethanol, when used as a transportation fuel, emits less sulfur, carbon monoxide, particulates and greenhouse gases.

How would an expanded fuel ethanol industry benefit the economy and national security?

Today the United States is dependent on oil for transportation. Developing domestic sources of renewable energy is essential to ensuring national security. America accounts for 25% of global oil consumption yet holds only 3% of the world's known oil reserves. About 60% of known oil reserves are found in sensitive and volatile regions of the globe. Increasing strain on world oil supply is expected as developing countries become more industrialized and use more energy.

Any strategy to reduce U.S. reliance on imported oil will involve a mix of energy technologies including conservation. Biofuels are an attractive option to be part of that mix because biomass is a domestic, secure, and abundant feedstock. In addition fuels from biomass are the only renewable liquid-fuel alternatives to today's petroleum-based transportation fuels. Global availability of biomass feedstocks also would provide an international alternative to dependence on an increasingly strained oil-distribution system as well as a ready market for biofuel-production technologies.

In 2005 the United States spent more than $250 billion on oil imports, and the total trade deficit has grown to more than $725.8 billion. Oil imports, which make up 35% of the total, could rise to 70% over the next 20 years. See Issue Brief: Energy Security (PDF) from Ethanol Across America for more information.

A biofuel industry would create jobs and ensure growing energy supplies to support national and global prosperity. According to the Renewable Fuels Association, in 2004 the ethanol industry created 147,000 jobs in all sectors of the economy and provided more than $2 billion of additional tax revenue to federal, state, and local governments. Conservative projections of future growth estimate the addition of 10,000 to 20,000 jobs for every billion gallons of ethanol production.

Among national economic benefits, a biofuel industry could revitalize struggling rural economies. Bioenergy crops and agricultural residues can provide farmers with an important new source of revenue and reduce reliance on government funds for agricultural support. An economic analysis jointly sponsored by USDA and DOE found that the conversion of some cropland to bioenergy crops could raise depressed traditional crop prices by up to 14%. Higher prices for traditional crops and new revenue from bioenergy crops could increase net farm income by $6 billion annually.

Is there enough land for large-scale biofuels production?

Yes. In 2005, a study jointly supported by the U.S. Departments of Energy and Agriculture examined whether land resources in the United States are sufficient to sustain production of over 1 billion dry tons of biomass annually, enough to displace 30% or more of the nation's current consumption of liquid transportation fuels. By assuming relatively modest changes in agricultural and forestry practices, the report of this study projects that 1.3 billion dry tons of biomass could be available for large-scale bioenergy and bio-refinery industries by mid-21st Century while still meeting demand for forestry products, food, and fiber. This supply of biomass would be a sevenfold increase over the 190 million dry tons of biomass per year currently used for bioenergy and bioproducts. Most of this biomass is burned for energy, with only 18 million dry tons used for biofuels (primarily corn-grain ethanol) and 6 million dry tons used for bioproducts.

Land area in the United States is about 2 billion acres, with 33% forestlands and 46% agricultural lands consisting of grasslands or pasture (26%) and croplands (20%). In its analysis of forest biomass availability the "Billion Ton Study" excluded environmentally sensitive areas, lands without road access, and regions reserved for non-timber uses (e.g., parks and wilderness). A total of 448 million acres of agricultural lands, largely active and idle croplands, were included in this study; lands used permanently for pasture were not considered. This study assumed that 55 million acres of idle cropland would be dedicated to production of perennial bioenergy crops, and all other cropland would continue to be used for traditional food, feed, and fiber crops. Harvesting agricultural residues (e.g., stalks, stems, and leaves that are not currently utilized) from these traditional crops would be a significant source of cellulosic biomass.

Does it take more energy to produce ethanol than it can provide as a fuel?

No. The energy content of ethanol, whether it comes from corn grain or cellulosic biomass, is greater than the amount of energy needed to produce ethanol. Although there has been a considerable amount of media attention given to one report that claims ethanol has a negative net energy value requiring more energy to produce than it contains as a fuel, a majority of the studies published in the last ten years find that ethanol's net energy value is positive.