Biofuels: A Glossary of Terms
Renewable Petroleum Alternatives Made from Abundant Biomass
With concerns for the environment and national security growing daily, scientists are looking for ways to produce ethanol and other biofuels from renewable sources.
Here are basic definitions of terms used in biofuels research:
- Bioenergy. Bioenergy is actually solar energy—it uses organic (living) materials, which ultimately get their energy from the sun. For example, plants use sunlight and carbon dioxide from the atmosphere to make food, in the form of sugars and starches. When plants are harvested and processed, that food becomes energy we can use in cars engines or power plants.
- Biomass. Biomass is any organic material, including plants and animals. Biomass in the form of wood was probably the first “renewable fuel” in history. But, especially in the tropics, slash cutting of rainforests is destroying important ecosystems.
- Biofuels. Biofuels are liquid fuels, such as ethanol or biodiesel, made from biomass. Biofuels can be used to run cars, trucks, and hopefully in the future, ships and airplanes.
- Bioreactor. A bioreactor is a large, deep container designed to hold biomass and the microbes that digest and ferment the biomass into biofuel.
- Cellulose. Cellulose is the main substance inside plant cell walls that provides the shape and structure of the plant. Cellulose is actually chains of molecules, including glucose, linked together into a strong matrix. This protects the plant from being torn apart by wind, insects or disease. That’s why it’s so hard to break up cellulose to get to the glucose inside.
- Glucose. Glucose is the sugar found in plant cells that can be fermented to make ethanol.
- Enzymes. Enzymes are specialized chemicals that help living organisms perform a task. In bioreactors, enzymes created by tiny microorganisms attack the plant cell wall and break it up to get out the glucose.
- Ethanol. Ethanol is an alcohol fermented from glucose, a sugar found in plants such as corn. Like any alcohol, ethanol can burn, giving off heat energy. Ethanol can also mix well with gasoline. This makes it useful for fueling car engines. And the carbon dioxide emissions from ethanol are almost balanced by the amount of CO2 used by plants to make biomass.
- E10. E10 is fuel that is 10 percent ethanol, mixed with 90 percent gasoline. E10 is the biofuel mixture that has been on the market for years. As long as the ethanol concentration is 10 percent or less, it can be used in standard automobile engines without causing problems.
- E85. E85 is a mixture of 85 percent ethanol with 15 percent gasoline. This mixture won’t work in standard cars, although several models are now sold that can run on E85 without damaging the engine.
See biofuels research updates here.
The copyright of the article Biofuels: A Glossary of Terms in Engineering is owned by Holly Bigelow Martin. Permission to republish Biofuels: A Glossary of Terms must be granted by the author in writing.
