What is biofuel and bioenergy?

Biofuel is renewable energy produced by living things like plant matter or by the waste that living creatures produce, such as manure. These living things and their waste products are called biomass. Since this biomass can be replenished readily, biofuel is considered to be a source of renewable energy, unlike fossil fuels such as petroleum, coal, and natural gas. Biofuel is perceived by its advocates as a cost-effective and environmentally benign alternative to petroleum and other fossil fuels, particularly within the context of rising petroleum prices and increased concern over the contributions made by fossil fuels to global warming.

Types of biofuels

Biofuels come in all three forms of matter: solid, liquid, and gas. Solid biofuels are solid pieces of organic matter that release their energy through burning. Solid biofuels include the following:

Animal waste (manure)
Bagasse (the fiber left over after the sugar juice has been squeezed out of sugarcane stalk
Charcoal
Garbage
Straw, dried plants, and grains
Wood

Liquid biofuel is any kind of liquid derived from matter that has recently been alive and that can be used as fuel. Types include the following:

Biodiesel, which is diesel fuel made of vegetable oils and animal fats instead of petroleum.
Ethanol and other alcohol fuels, which are made from corn, grain, and other plant matter and can be mixed with or substituted for gasoline.
Vegetable oil fuel, including straight vegetable oil (SVO) and waste vegetable oil (WVO).
New fuels, such as P-Series fuels, which combine ethanol, natural gas traces or leftovers, and a substancemade from garbage

Biofuel can also come in the form of a gas, or biogas, particularly that is given off by decaying plants, animals, and manure. This gas is largely methane, which is the main component of the fuel natural gas. Biogas is becoming increasingly interesting as an alternative to natural gas. It is especially useful that the composition is practically identical, so the same burners can be used for both fuels. Biogas can be produced from plant or animal waste, or a combination of both.

How biofuels work

Biofuels work by burning either directly (such as putting wood logs on a fire) or indirectly as through an engine. They are similar to fossil fuels, which also release their energy when they burn. Biofuels are the alternative fuels most similar to fossil fuels. In many cases they function as direct replacements of, or supplements to, fossil fuels.

Vegetable oil was one of the first fuels used in internal combustion engines. Today most vegetable oil is consumed in the form of biodiesel, which functions almost exactly like diesel made from petroleum, called petrodiesel. Vegetable oil, either new or used, can be used for fuel by itself in diesel engines, though the engines must be modified for this to work well. In the twenty-first century large companies are taking more of an interest in biodiesel; commercially prepared biodiesel is becoming more widely available, either straight or mixed with petrodiesel.

Ethanol, which is the same alcohol used in alcoholic beverages, has a long history of use as a fuel. Other alcohols, such as methanol, can also be used as fuel. Ethanol is easy to make from corn, grain, sugarcane, or other plant material. Ethanol can be mixed with gasoline to power internal combustion engines. Normal cars can use small amounts of ethanol in their fuel. Flexible fuel vehicles (FFVs) can use fuel that is nearly all ethanol. (Few vehicles in the early twenty-first century can use straight ethanol with no gasoline in it.) In some parts of the world, ethanol is routinely mixed in fuel, reducing the use of fossil fuels.

Scientists are also working to develop new types of fuels. P-Series fuel is a fuel that is made from a combination of ethanol, the leftovers from natural gas processing, and a substance made from garbage. It works in flexible fuel vehicles and appears to be a stable substitute for gasoline. Whether these fules are pollutants or not has not been concluded. Some scientists believe that they are non-polluting, but others believe that they give off significant nitrogen oxide emissions.