to global energy consumption and about 25% to the generation of electricity in
2016.
Source: International Renewable Energy Agency
Figure 8.12 Projected global renewable energy sourcesRenewable energy resources exist over wide geographical areas, in contrast
to other energy sources that are concentrated in a limited number of countries.
Rapid deployment of renewable energy and energy efficiency is resulting in
significant energy security, climate change mitigation, and economic benefits. At
least 30 nations around the world already have renewable energy, contributing to
more than 20% of their energy supply. As of 2016, the United States derived
17% of its energy needs from renewable energy resources.
Biogas
Anaerobic digestion is a collection of processes by which microorganisms break
down biodegradable material, in the absence of oxygen, to produce methane gas,
which can then be burned to produce energy. Biodegradable waste materials that
can be used in anaerobic digesters include waste paper, grass clippings, leftover
food, sewage sludge, and animal waste.