Anaerobic digestion is a series of steps in which tiny living things called microorganisms break down materials that can be decomposed in the absence of oxygen. This process is used in industries and homes to manage waste or create fuels. Many types of fermentation used to make food and drinks, as well as home-based fermentation, rely on anaerobic digestion.
Biogas is a type of renewable fuel made from organic materials such as farm waste, animal manure, city trash, plants, sewage, wastewater, garden waste, and food scraps. It is created through a process called anaerobic digestion, which uses bacteria in a special container called an anaerobic digester, biodigester, or bioreactor. The gas mainly contains methane (CH₄) and carbon dioxide (CO₂), and may also include small amounts of hydrogen sulfide (H₂S), water, and siloxanes.
Bioenergy is a type of renewable energy made from plants and animals. The materials used for bioenergy come from recently living organisms that are now dead, mostly plants. Fossil fuels are not considered biomass in this context.
Biomass is material from recently living organisms that are now dead and used to produce energy. Examples include wood, leftover wood pieces, plants grown specifically for energy, leftover parts of crops like straw, and waste from industries and homes. Wood and leftover wood pieces are the largest source of biomass energy today.
An enhanced geothermal system (EGS) creates geothermal electricity even when natural heat and water resources are not easily available. In the past, geothermal power systems could only work in places where heat, water, and rocks that let water flow were naturally present. However, much of the geothermal energy that can be reached using traditional methods is found in rocks that are dry and do not allow water to pass through easily.
Hydrothermal vents are openings on the ocean floor where hot water flows out. This water is heated by the Earth’s internal heat. These vents are often found near areas with volcanic activity, such as mid-ocean ridges, ocean basins, and hotspots where tectonic plates move apart.
Geothermal power in Iceland is the use of geothermal energy to generate electricity. Iceland’s active geology creates natural conditions that are especially suitable for using geothermal energy. For many years, Icelanders have used geothermal energy directly, such as for heating homes and public baths.
Geothermal energy is heat taken from the Earth’s crust. It comes from the Earth’s formation and radioactive decay. People have used geothermal energy for heat and electricity for thousands of years.
Osmotic power, also called salinity gradient power or blue energy, is the energy that comes from the difference in salt levels between seawater and river water. Two practical ways to use this energy are reverse electrodialysis (RED) and pressure retarded osmosis (PRO). Both methods use osmosis with special membranes.
blueEnergy is a non-profit group that builds systems for clean energy and water on the Caribbean coast of Nicaragua. The group started in October 2002 with a class project that won an award, created by co-founder Mathias Craig when he was a student at MIT. The main office is in San Francisco, and the work is done at their shop in Bluefields, managed by Guillaume Craig.