Renewable energy

Renewable energy is energy generated from sources that replenish naturally on a human timescale, chiefly sunlight, wind, flowing water, geothermal heat, and biomass, rather than from finite underground deposits of coal, oil, or natural gas. Because these sources are continuously renewed rather than depleted by use, renewable energy is central to efforts to reduce the greenhouse gas emissions that come from burning fossil fuels.

Main types of renewable energy

Solar power converts sunlight directly into electricity using photovoltaic panels, or concentrates sunlight to generate heat for electricity production in some large installations. Wind power uses turbines to convert the kinetic energy of moving air into electricity, typically grouped into onshore or offshore wind farms. Hydropower generates electricity from the energy of falling or flowing water, usually at a dam, and is the oldest and historically the largest source of renewable electricity worldwide. Geothermal energy taps heat from within the Earth, most practically in regions with accessible volcanic or tectonic activity, while biomass energy burns organic material, including wood, agricultural waste, and purpose-grown crops, to generate heat or electricity, though its net climate benefit depends heavily on how the biomass is sourced and regrown.

Current scale and growth

Renewable sources supplied a record 32 percent of global electricity generation in 2024, according to the energy think tank Ember’s Global Electricity Review 2025. Wind alone supplied 8.1 percent of global electricity and solar 6.9 percent, and together wind and solar surpassed hydropower’s 14.3 percent share for the first time. Including nuclear power, which is low-carbon but not classified as renewable, clean sources together supplied 40.9 percent of global electricity in 2024, up from 39.4 percent the year before, while fossil fuels’ share fell to 59.1 percent from 60.6 percent even as global electricity demand itself rose about 4 percent year on year. That combination, a rising fossil fuel share loss alongside rising overall demand, reflects how fast new renewable capacity, especially solar, has been added in recent years.

A brief history of renewable power

Hydropower was the first renewable source harnessed for electricity at scale, with small hydroelectric plants appearing in the 1880s and large dam projects following through the twentieth century, which is why it still accounts for the largest share of installed renewable capacity in many countries even today. Wind power has an even older history as a mechanical energy source, from windmills used for centuries to grind grain and pump water, but wind turbines built specifically to generate electricity only became commercially significant from the 1980s onward, as turbine designs grew larger and more efficient. Solar photovoltaic technology dates to the 1950s, originally developed largely for spacecraft power where cost was a minor concern, and it remained an expensive, niche technology for decades before manufacturing scale-up and steady efficiency gains drove its cost down sharply enough, starting roughly in the 2010s, to make solar competitive with, and in many markets cheaper than, new fossil fuel power plants.

Intermittency and storage

Solar and wind generation depends on weather and time of day, which makes their output intermittent in a way that coal, gas, or nuclear plants generally are not. Grid operators manage this variability by combining different renewable sources that peak at different times, maintaining backup generation, expanding transmission so power can move between regions with different weather, and increasingly deploying battery storage to shift solar generation produced during the day toward evening demand. Pumped-storage hydropower, which pumps water uphill when electricity is cheap and plentiful and releases it to generate power when demand rises, remains one of the largest-scale storage technologies in use, though battery costs have fallen sharply enough in recent years to make large battery installations increasingly competitive alongside it.

Policy and economic drivers

The cost of solar panels and, to a lesser extent, wind turbines has fallen dramatically over roughly the past fifteen years, to the point that building new solar or wind capacity is now cheaper than building new fossil fuel capacity in much of the world, even before accounting for carbon emissions. Government policy has reinforced that trend through mechanisms such as renewable portfolio standards, feed-in tariffs, and tax credits, alongside international commitments under the Paris Agreement that push many countries toward net-zero emissions targets. These forces together, rather than any single policy or technology, explain why renewable capacity additions have consistently outpaced expectations in recent annual energy reviews.

Limits and trade-offs

Renewable energy is not free of environmental or social cost. Large hydropower dams can flood land, disrupt river ecosystems, and displace communities; wind and solar farms require substantial land or sea area and can affect local wildlife and landscapes; and manufacturing solar panels and batteries requires mined materials, including some whose extraction raises its own environmental and labor concerns. Advocates generally argue these impacts are smaller and more manageable than the climate and air-pollution costs of continued fossil fuel use, but the comparison is rarely as simple as renewable energy being cost-free once built.

FAQs

Is nuclear power considered renewable energy? No. Nuclear power is low-carbon and often grouped with renewables in discussions of clean electricity, but it relies on mined uranium, a finite resource, so it is classified separately from renewable sources such as solar, wind, and hydropower.

Why did wind and solar surpass hydropower’s share of global electricity for the first time in 2024? Falling technology costs drove a wave of new wind and especially solar capacity additions over the preceding decade, while hydropower’s share grew far more slowly since most of the best large-dam sites were already developed; combined, wind and solar reached 15 percent of global electricity in 2024 against hydropower’s 14.3 percent, per Ember.

Editorially reviewed by Specialty Digest Editorial TeamLast reviewed November 1, 2026Researched and drafted with AI assistanceReport an issue