Cheat Sheet: Biofuel


Biofuels are a growing topic of debate, especially in the past five years as national sentiments supporting energy independence and alternative fuels have gained momentum.

As the U.S. continues legislating, developing and promoting alternative fuels to supplement, and possibly replace, fossil fuels such as coal and oil (e.g. some of the provisions in the House-approved Clean Energy and Security Act), a refresher, and possibly an introduction, to biofuels might be helpful in sorting through this important issue.

What’s in a Name

To start, there are various types of biofuels. For example, it’s important to note the distinction between biodiesel, which only works with diesel engines (such as those found in semi-trucks) and ethanol, which is blended with gasoline and can be used to power a variety of vehicles.

Photo: Amanda Wills,

In the beginning, scientists tested corn ethanol, however several problems made working with the vegetable harder than researchers initially thought. Photo: Amanda Wills,

All biofuels can provide an alternative combustion fuel source to gasoline and diesel. The main types of biofuels include:

  • Biodiesel
  • Corn, sugar beet or sugar cane ethanol
  • Switchgrass cellulosic ethanol
  • Waste-derived cellulosic ethanol

Biodiesel is a clean-burning, biodegradable, nontoxic fuel. It is made from a variety of sources, including plant oils (such as vegetable oil), recycled grease and animal fats. Also, algae biodiesel is an up-and-coming biodiesel source that turns algae into vegetable oil.

Because algae thrive off of carbon dioxide, it is also a promising carbon sequestration technology. One start-up company, Solix Biofuels, envisions algae stations set up at natural gas processing plants to absorb the CO2 coming from vents.

According to the National Biodiesel Board, although it does not contain petroleum, biodiesel can be blended with petroleum to create a biodiesel-petroleum diesel blend. Addtionally, biodiesel can be used directly in a conventional diesel engine, requiring little to no modifications to existing engines.

Corn, sugar beet and sugar cane ethanol are made from these respective crops and are often grown directly for the purpose of creating fuel. The most common type of ethanol is made from corn, and the most common method for turning a corn crop into a fuel source is called “wet milling,” where the starch is extracted from the grain, fermented and transformed into alcohol, the building-block for ethanol.

Switchgrass cellulosic ethanol is made from switchgrass, a perennial grass native to Central and North America. As evidenced by the fact that it can grow up to 10 feet tall, it is a highly productive plant, producing enough biomass to make it appealing for ethanol production.

Waste-derived cellulosic ethanol comes mainly from agricultural “waste” that either remains after harvest (such as the stalks of a crop left in a field), or is produced after the processing of a crop (such as the corn cobs that remain after the kernels have been removed). Additionally, other sources of cellulosic ethanol come from waste paper, wood waste, pulp sludge and grass straw, according to Biomass Energy.

How It All Began

Ever since the oil crises of the 1970s, U.S. interest in ethanol fuel has increased. The idea that the U.S. could grow the energy it needed, and not buy from potentially hostile areas of the globe, was extremely appealing at the time.

Because of this, the U.S. government has since promoted the production of homegrown energy solutions such as biofuels, with more recent federal policies put in place like the Energy Policy Act of 2005.

Photo: Jamie Lantzy, Wikimedia

Waste-derived cellulosic ethanol is a product of agricultural waste such as corn stalks left in a field after harvesting. Photo: Jamie Lantzy, Wikimedia

This legislation worked mainly by enacting standards that raised the amount of renewable fuels that were to be incorporated into the total U.S. fuel supply and by providing subsidies to farmers who produced corn.

By requiring the production and use of 4 billion gallons of renewable fuels in 2006,  increasing to 7.5 billion gallons in 2012, the law assured biofuel producers that a stable market would exist, thereby providing an incentive to ramp up production.

The act also makes the proclamation that “For calendar year 2013 and each year thereafter, the minimum required volume of renewable fuels would be an amount equal to the percentage of total gasoline sold in the Nation in 2012.”

To have as much biofuel as gasoline fuel available for energy consumption by the year 2013 will likely prove no small feat.

Early expectations for biofuels, mainly in the form of corn ethanol, included:

  • Helping farmers obtain a better price for their crop by supporting the corn ethanol market. This could raise demand and help lower the excessive supply that was keeping corn prices low.
  • Promoting national security by lessening the United States’ dependence on foreign oil
  • Reducing carbon emissions by growing a plant, thus absorbing CO2
  • Helping the environment by growing a fuel rather than drilling for one

But the promises offered by corn ethanol were not to be, and biofuels derived from corn have increasingly become a lightening rod of criticism.

Unintended Consequences

The rapid rise of corn’s prominence in the biofuel arena has presented a host of issues that landed corn ethanol in the hot seat. Since 2005, some of the main problems with corn ethanol discovered by researchers include:

  • Devoting fresh water to growing a fuel, rather than making it available for human consumption, could pose problematic as fresh water becomes an increasingly stressed natural resource.
  • Shifting cropland from food to fuel is suggested to be a contributing factor to the food crisis of 2007, in which food costs rose dramatically around the world.
  • Corn ethanol takes almost as much energy to produce as it provides. It also requires copious amounts of pesticides and fertilizers, contributing to the hypoxic (without adequate amounts of oxygen) dead zone in the Gulf of Mexico where agricultural chemical runoff has killed off marine life.
  • Because biofuel crops such as corn fetch higher prices than in the recent past, more farmers are clearing land from forests or grasslands and converting it in to cropland. Because of this, corn ethanol may actually increase global carbon emissions.

Cellulosic vs. Corn Ethanol

With these concerns in mind, alternatives to corn-based ethanol already exist. And although corn ethanol still reigns, waste-derived cellulosic ethanol is appealing because, unlike corn ethanol, it does not require extra fertilizers, pesticides, energy or water to grow. It takes a would-be waste product and turns it in to a valuable fuel.

Switchgrass cellulosic ethanol holds promise too, as the grass could be established on marginal land where other crops are not easily grown. To highlight this, a recent regulatory announcement from the EPA recommended that a higher percentage of total renewable fuel volume comes from cellulosic ethanol sources.

With renewable fuel standards pushing for more cellulosic ethanol, research and development may begin to trend toward cellulosic and away from corn ethanol production.

It should be noted that demonizing one biofuel and fully advocating another will not solve the biofuel debate, as many factors contribute to the benefits and detriments of a particular fuel. The local ecology of the geographic regions where biofuels are grown must be considered to determine what is the best option for a specific location.