Biofuels

With all the discussions about biofuels, have you ever wondered, what exactly are biofuels, why they have achieved so much prominence, and where this is headed?

Biofuels are so relevant in the context of today’s energy crisis and global warming, because they have the potential for Co2 reduction. Biofuels are liquid fuels produced from biomass materials and are used primarily for transportation. The term biofuels most commonly refers to ethanol and biodiesel. In 2007, the United States consumed 6.8 billion gallons of ethanol and 491 million gallons of biodiesel. By comparison, 2007 consumption of motor gasoline and diesel was 139 billion gallons and 39 billion gallons, respectively.

Biofuels are made by converting various forms of biomass such as corn or animal fat into liquid fuels and can be used as replacements or additives for gasoline or diesel. Biofuels generally have lower life-cycle carbon dioxide emissions than do their fossil fuel counterparts.

What Is Ethanol?

Ethanol is a clear, colorless alcohol—the same as is found in alcoholic beverages. In fact, ethanol is produced when yeast ferments sugar in a process similar to that used to produce beer. Ethanol can be made from the starches or sugars found in various agricultural crops, such as corn, barley, and sugar cane.

Prior to the passage of the Energy Policy Act of 2005, gasoline sold in certain geographic areas was required to contain oxygen, which helps the fuel mixture combust more completely. Originally, a chemical called methyl tertiary butyl ether (MTBE) was the preferred oxygenate, but it was phased out due to concerns about seepage into groundwater and ethanol was mandated as a replacement. The usage of ethanol also gained market share due to the Renewable Fuel Standard requirements of the Energy Policy Act of 2005. Today, a little more than half of the gasoline in the United States has some amount of ethanol blended into it, and these blends are named by their ethanol content: for example, a blend of 90% gasoline and 10% ethanol (by volume) is known as E10. However, because ethanol contains approximately 67% the energy content of gasoline per gallon, usage of ethanol blends results in decreased gas mileage. Despite this reduced gas mileage, high crude oil prices and government incentives have resulted in the consumption of increasing amounts of ethanol.

While almost any regular gasoline car can run on blends of ethanol up to E10, special cars known as “flex-fuel” vehicles are required for use of blends above E10. Flex-fueled vehicles are currently available from every major American automobile manufacturer and are almost identical to regular gasoline vehicles, except for a few modifications to the fuel system and minor engine components. On a mass production basis, it costs less than $200 extra per car to make a flex-fuel automobile compared with a conventional gasoline vehicle.

What Is Biodiesel?

Biodiesel consists of chemicals known as fatty acid methyl esters (FAME) that can be used as a diesel fuel substitute or diesel fuel additive. Biodiesel is typically made from oils produced from agricultural crops such as soybeans or canola but can also be made from various other feedstocks such as animal fats.

Currently, most biodiesel in the United States is produced from soybean oil, but recent increases in soybean crop prices have caused producers to switch to other feedstocks such as waste animal fats from processing plants or recycled grease from restaurants. Biodiesel can be made from virtually any feedstock that contains an adequate amount of free fatty acids, which are the raw materials that are converted to biodiesel through a chemical process. Research is underway to harvest algae for biodiesel production because they contain fat pockets that help them float, and this fat can be collected and processed into biodiesel.

Biodiesel has chemical characteristics much like petroleum-based diesel and, therefore, can be used as a direct substitute for diesel fuel or blended with petroleum diesel in any percentage without suffering any significant loss of fuel economy.

In 2007, the United States consumed 6.8 billion gallons of ethanol and 491 million gallons of biodiesel. According to EIA’s Annual Energy Outlook 2008, ethanol usage is predicted to increase to nearly 24 billion gallons in 2030, which would represent approximately 16% of total gasoline consumption by volume in 2030. Biodiesel consumption is predicted to increase to 1.2 billion gallons by 2030, or approximately 1.5% of total diesel consumption.

Source: Energy Information Administration

http://tonto.eia.doe.gov/energy_in_brief/biofuels_use.cfm