The following definitions reflect those used by the International Energy Agency (IEA); definitions used by other organisations and publications may vary.
research and development
research, development and demonstration
research, development, demonstration and deployment
renewable energy (renewables)
renewable energy costs and benefits for society
renewable energy sources
renewable energy technology(ies)
Regional Greenhouse Gas Initiative (in the United States)
rest of the world
revenue passenger kilometers
energy that is derived from natural processes (e.g. sunlight and wind) that are replenished at a higher rate than they are consumed. Solar, wind, geothermal, hydro, and biomass are common sources of renewable energy.