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Frequently Asked Questions
What are agrofuels (biofuels)?
Agrofuels usually refers to liquid fuels from agricultural resources such as:
- Ethanol made from plants. Ethanol can be a substitute for, or blended with, gasoline made from petroleum.
- Agrodiesel (biodiesel) made from plant or animal oils. Biodiesel can be a substitute for, or blended with, diesel fuel made from petroleum.
What is ethanol?
Ethanol fuel is ethanol (ethyl alcohol), the same type of alcohol found in alcoholic beverages. It can be used as a fuel, mainly as a biofuel alternative to gasoline, and is widely used in cars in Brazil. Because it is easy to manufacture and process and can be made from very common crops such as sugar cane and corn, it is an increasingly common alternative to gasoline in some parts of the world.
Most cars on the road today in the United States can run on blends of up to 10 percent ethanol, and the use of 10 percent ethanol gasoline is mandated in some cities where harmful levels of auto emissions are common.
Ethanol can be mass-produced by fermentation of sugar or by hydration of ethylene (ethene CH2=CH2) from petroleum and other sources. Current interest in ethanol mainly lies in agro-ethanol, produced from the starch or sugar in a wide variety of crops, but there has been considerable debate about how useful agro-ethanol will be in replacing fossil fuels in vehicles. Concerns relate to the large amount of arable land required for crops, as well as the energy and pollution balance of the whole cycle of ethanol production. Recent developments with cellulosic ethanol production and commercialization may allay some of these concerns.
What is cellulosic ethanol?
Cellulosic ethanol is an agrofuel produced from wood, grasses or the non-edible parts of plants. Specifically, it is produced from lignocellulose, a structural material that comprises much of the mass of plants. Corn stover, switchgrass, miscanthus, woodchips and the byproducts of lawn and tree maintenance are some of the more popular cellulosic materials for ethanol production. Cellulose, however, is contained in nearly every plant, tree, and bush, in meadows, forests and fields. Production of ethanol from lignocellulose has the advantage of abundant and diverse raw material compared to sources like corn and cane sugars. But greater processing is needed to make the sugar monomers available to the microorganisms that are typically used to produce ethanol by fermentation. Various obstacles need to be surmounted before cost-effective mass production can happen.
According to U.S. Department of Energy, one of the benefits of cellulosic ethanol is that it can reduce greenhouse gas emissions (GHG) by 85 percent over reformulated gasoline. By contrast, starch ethanol (e.g., from corn), which most frequently uses natural gas to provide energy for the process, may not reduce GHG emissions at all depending on how the starch-based feedstock is produced. A study by Nobel Prize winner Paul Crutzen found ethanol produced from corn, and sugarcane had a "net climate warming" effect when compared to oil.
What is biodiesel (agrodiesel)?
Agrodiesel is a fuel made primarily from oily plants (such as the soybean or oil palm) and to a lesser extent from other oily sources (such as waste cooking fat from restaurant deep-frying). Biodiesel, which has found greatest acceptance in Europe, is used in diesel engines and usually blended with petroleum diesel fuel in various percentages. Agrodiesel is produced in pure form (100 percent agrodiesel or B100), but is usually blended with petrodiesel at low levels, between two percent (B2) to 20 percent (B20) in the United States. It is often blended at higher levels in other parts of the world, particularly in Europe, where higher-level blends up to B100 are used.
Is there a trade-off between meeting the world’s need for renewable energy and the need for food?
Not if agrofuels are developed sustainably. Unfortunately, the influence corporations and agribusiness have on public policy make this a BIG if. Public policy could potentially regulate and provide incentives for sustainable agrofuel development that ensure the needs of people and the environment come first.
Producing large quantities of fuel from farms could affect food supply and result in higher priced food and shortages. After all, even now, with over-production of most staple crops in many countries, there are still a billion people suffering from hunger across the world. Critics have also raised concerns that intensive, monoculture crops, such as corn and soybeans, grown for conversion to agrofuels, may not be the best use of prime farmlands. It is important to note that starch based ethanol and agrodiesel both produce a rich, high protein animal feed that can help feed a hungry world, so all of the food value is not lost.
Western Organization of Resource Councils (WORC) has adopted a set of Sustainability Criteria  to guide its policies on these and other questions. Intensive, high input agriculture should not be the primary feedstock for agrofuels over time, for a variety of reasons, including sustainability. Initially, corn based ethanol and soybean based agrodiesel have helped to jumpstart agrofuels production in the United States. But in the long run, if agrofuels are to be efficient, environmentally sustainable and economically competitive, they will need to rely primarily on feedstocks other than corn and soybeans. |
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