By Lauren DeMates.
Put simply, biofuel is energy made from living matter, usually plants. Bioethanol, biodiesel, and biogas are types of biofuels. Biofuels are considered renewable energies, emit less than fossil fuels, and have received increasing attention in the transition to a low-carbon economy.
Bioethanol (aka ethanol) is the most well know biofuel and is an alcohol produced from corn, sorghum, potatoes, wheat, sugar cane, even cornstalks and vegetable waste. It is commonly blended with gasoline. However, plants grown specifically for any type of biofuel are not ideal due to the energy required, environmental impacts, and emissions associated with harvest and transport; not to mention the subsequent increase in global food prices. However, bioethanol production in the U.S. (mostly corn) has been increasing since the 1990s. Almost all gasoline currently sold in the U.S. is 10% ethanol due to the Renewable Fuel Standard (RFS), which dictates the amount of renewable fuel that refiners are required to blend. The requirement was put in place in 2005 and expanded as part of the 2007 Energy Dependence and Security Act. Support for ethanol is further built into the federal “Farm Bill,” which is revisited every 5 years. Ethanol is a complicated issue, but overall is helping ease demand on fossil fuels. Brazil and the United States are the biggest exporters and consumers of ethanol.
Biodiesel is oil from plants or animals used as an alternative to or blended with petroleum diesel in automobiles and industrial fleets with diesel engines. The leading exporter of biodiesel (soy) is Argentina, who as of December 2013 filed a third WTO complaint against the European Union for putting steep import taxes on biodiesel, but is responding to demand elsewhere by increasing exports to the United States. The United States creates its own biodiesel as well- 1.1 billion gallons in 2012 and the requirement for diesel was added to the Renewable Fuel Standard (RFS) in 2007. Grease or oil from cooking can also be converted to biodiesel and is more sustainable because it is a by-product of another process. Diesel engines can automatically run off blends with 20% or less biodiesel. Using more than 20% biodiesel or vegetable oil from cooking requires some infrastructure adjustments. Local and regional recycling centers have also been working to make biodiesel more accessible, but challenges in scalability hold biodiesel back as well as concerns over food prices if using raw material. Alternative fuel vehicles such as hybrids and electric cars also displace demand for biodiesel.
Biogas is created as a by-product of decomposing plant and animal waste in environments with low levels of oxygen: landfills, waste treatment facilities, and dairies. Biogas is made up primarily of methane and carbon dioxide (greenhouse gasses), thus the natural incentives are strong to keep biogas from entering the atmosphere. In practice, however, biogas is not captured and used as much as it should be despite being used for centuries. Biogas can be used for transportation, cooking, and electricity (more on the benefits here). In developing countries, micro-scale or household projects spread in the 1970s. As of 2013, there were about 4 million biogas plants in India and 27 million in China. However, a study shows that many plants in rural areas are not functioning due to a lack of maintenance and repairs needed. An operational network could be further developed in order to utilize biogas at this scale.
There are also large-scale commercial biogas projects. Nordic countries such as Norway and Finland are on board with 1/3 of Oslo city buses powered by biogas from sewage. The European Union and the United Kingdom, have their fair share of plants as well. In San Jose, California the world’s largest plant which uses dry fermentation anaerobic digestion went online in 2013 and plans to process 90,000 tons of organic waste each year. There are many other U.S. biogas plants such as Freshkills landfill in New York City, which produces enough methane to power 30,000 homes a year and generates approximately $3 million to $5 million a year in revenue for the city. Here is a map of all the biogas plants in the United States and a simplified diagram of the process. Biogas also receives tax incentives in the United States and will play an increasing role in the transition to a low-carbon economy due to its ability to capture potent greenhouse gas emissions, reduce waste, and all while creating energy from a by-product of other activities.
Updated January 2016