Renewable energy
Renewable energy is energy derived from natural sources that are replenished at a rate equal to or faster than their use on a relevant timescale. Sources include sunlight, wind, moving water, geothermal heat, ocean energy, and sustainably managed forms of biomass.
In simple terms
Renewable describes the source, not an assurance that every project has zero impact. Solar, wind, hydropower, geothermal, ocean, and bioenergy technologies convert replenishing flows into electricity, heat, or fuels. Their life-cycle greenhouse gas emissions are generally lower than fossil-fuel combustion, but effects on land, water, biodiversity, materials, and communities vary by technology and location. Reliable energy systems also require suitable networks, storage, flexibility, and demand management as variable generation grows.
Why it matters
Replacing fossil energy with well-planned renewables is a major route to reducing greenhouse gas emissions and supporting net-zero goals. It can also diversify supply and reduce air pollution from combustion. Energy efficiency can lower the amount of new supply required, while transparent carbon accounting helps distinguish physical electricity use from contractual renewable claims.
Example
For example, a municipality can combine rooftop solar, wind contracts, grid upgrades, storage, and demand flexibility to increase its renewable electricity share. It still assesses land, biodiversity, mineral, community, and end-of-life effects instead of assuming the renewable label makes every option equivalent.
How it differs
Energy efficiency
Renewable energy changes the source from which energy is supplied; energy efficiency reduces the energy input needed to deliver the same or an improved service.