According to the definition of biofuels, which of the following would not be considered a biofuel?

The term biofuels usually applies to liquid fuels and blending components produced from biomass materials called feedstocks. Most biofuels are used as transportation fuels, but they may also be used for heating and electricity generation. Gaseous fuels produced from biomass that are used directly as a gas or converted to liquid fuels may qualify for use in government programs that promote or require use of biofuels.

The terminology for different types of biofuels used in government legislation and incentive programs and in industry branding and marketing efforts varies. For example, the names of biofuels may include preceding the type or use of the fuel with bio (such as biodiesel or biojet) or with the words advanced, alternative, clean, green, low-carbon, renewable, or sustainable (such as sustainable aviation fuel). The definitions for these biofuels may also differ depending on the language in government legislation and programs that require or promote their use and among industry and other organizations.

Production and consumption of biofuels in the United States have generally increased each year since the early 1980s. The increases are largely because of various government policies and programs intended to reduce the use of transportation fuels made from fossil fuels by promoting and/or requiring the use of biofuels. The Volumetric Ethanol Excise Tax Credit for blending ethanol into motor gasoline from 2005 through 2011 contributed to large increases in ethanol consumption during the period when the incentive was in effect. A tax credit of $1.00 per gallon currently in place for biodiesel and renewable diesel fuel blenders is helping to increase the use of those fuels. Major major government programs contributing to increases in U.S. biofuels production and consumption in the past 15 years are the federal Renewable Fuel Standard (RFS) Program and California’s Low Carbon Fuel Standard (LCFS). Oregon and Washington have also established clean fuel programs.

In 2021, about 17.5 billion gallons of biofuels were produced in the United States and about 16.8 billion gallons were consumed. The United States was a net exporter of about 0.8 billion gallons of biofuels in 2021, with fuel ethanol accounting for the largest share of gross and net exports of biofuels.

Most of biofuel consumption occurs as a blend with refined petroleum products such as gasoline, diesel fuel, heating oil, and kerosene-type jet fuel. However, some biofuels do not require blending with their petroleum counterparts and are referred to as drop-in biofuels.

The U.S. Energy Information Administration (EIA) publishes data on four major categories of biofuels that qualify for use in the federal RFS Program:1

• Ethanol—an alcohol fuel that is blended with petroleum gasoline for use in vehicles and accounted for the largest shares of U.S. biofuel production (85%) and consumption (82%) in 2021.
• Biodiesel—a biofuel that is usually blended with petroleum diesel for consumption and accounts for the second-largest shares of U.S. biofuel production (11%) and consumption (12%) in 2021.
• Renewable diesel—a fuel chemically similar to petroleum diesel fuel for use as a drop-in fuel or a petroleum diesel blend with small but growing U.S. production and consumption. Renewable diesel's percentage shares of total U.S. biofuels production and consumption were about 3% and 5% respectively in 2021.
• Other biofuels—include renewable heating oil, renewable jet fuel (sustainable aviation fuel, alternative jet fuel, biojet), renewable naphtha, renewable gasoline, and other emerging biofuels that are in various stages of development and commercialization.

Gaseous fuels that may be compressed for use as a gaseous biofuel or liquefied for use as a liquid biofuel include biogas (renewable natural gas) and hydrogen produced using renewable resources.

The table and graphs below provide annual data for the four types of biofuels for which EIA publishes data.

Last updated: July 19, 2022.

Biofuel is a type of renewable energy source derived from microbial, plant, or animal materials. Examples of biofuels include ethanol (often made from corn in the United States and sugarcane in Brazil), biodiesel (sourced from vegetable oils and liquid animal fats), green diesel (derived from algae and other plant sources), and biogas (methane derived from animal manure and other digested organic material).

Biofuels can be solid, liquid, or gaseous. They are most useful in the latter two forms as this makes it easier to transport, deliver, and burn cleanly.

• Biofuels are a class of renewable energy derived from living materials.
• The most common biofuels are corn ethanol, biodiesel, and biogas from organic byproducts.
• Energy from renewable resources puts less strain on the limited supply of fossil fuels, which are considered nonrenewable resources.

Global demand for energy is expected to continue growing substantially and it's widely recognized that alternative, sustainable solutions need to be found to address those needs. Lots of people in the energy industry believe biofuel could be the answer, viewing it as vitally important to future energy production because of its clean and renewable properties.

Biofuel functions similarly to nonrenewable fossil fuels. Both burn when ignited, releasing energy that can be used to power cars or heat homes. The main difference between them is that biofuels can be grown indefinitely and generally cause less damage to the planet.

Many of the world's major oil companies are now investing millions of dollars in advanced biofuel research, including Exxon Mobil Corp. (XOM). America's largest oil company is focusing on advanced biofuels that do not compete with food or water supplies, with most of its allocated funds dedicated to transforming algae and plant waste into fuel that can be used for transportation.

ExxonMobil has invested more than $300 million in biofuel research over the last decade.

Despite its enthusiasm, ExxonMobil did warn, however, that fundamental technology improvements and scientific breakthroughs are still necessary in both biomass optimization and the processing of biomass into viable fuels.

Individuals concerned about energy security and carbon dioxide emissions see biofuels as a viable alternative to fossil fuels. However, biofuels also have shortcomings.

For example, it takes more ethanol than gasoline to produce the same amount of energy, and critics contend that ethanol use is extremely wasteful because the production of ethanol actually creates a net energy loss while also increasing food prices. 

Biofuels have also become a point of contention for conservation groups, who argue that bio-crops would go to better use as a source of food rather than fuel. Specific concerns center around the use of large amounts of arable land that are required to produce bio-crops, leading to problems such as soil erosion, deforestation, fertilizer run-off, and salinity.

To help mitigate the problem of large arable land use, companies such as ExxonMobil are turning to water-based solutions in the form of algae production. Exxon claims that algae can be cultivated on land unsuitable for other purposes with water that can’t be used for food production.

In addition to using non-arable land and not requiring the use of freshwater, algae could potentially yield greater volumes of biofuels per acre than other sources. The other advantage to using algae over other bio-sources is that it can be used to manufacture biofuels similar in composition to today’s transportation fuels. This would go a long way to replacing the conventional fossil fuels of gasoline and diesel.