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Green Energy Explained

Green claims are everywhere these days, attached to products from energy-efficient appliances to electric vehicles (EVs) to secondhand or recycled clothing. Green describes products with minimal impact on the environment, including zero or low carbon emissions and no or minimal contribution to other forms of pollution and ecological damage.

One of the major products advertised as green is energy. Today, around a third of UK households are supplied with green energy, meaning their energy supplier matches their usage with electricity generated by green technologies, primarily wind and solar power. However, what exactly qualifies as green energy is contentious, as are the claims some suppliers make about the green energy they provide.

Fergus Cole
Mike Rowe
Written by Fergus Cole
Edited by Mike Rowe
23 November 2025
13 mins read

What is green energy?

The government wants to promote the generation of green energy and your energy supplier claims to sell it. Maybe you’ve also heard the terms renewable energy and clean energy, which are often used interchangeably. But what exactly are these alternatives to fossil fuel?

While green, renewable, and clean energy are often used as synonyms, there are subtle differences:

Green Energy

Green energy is energy that is sourced or created with minimal impact on the environment. Green energy doesn’t produce greenhouse gases such as CO2, which contribute to global heating and air pollution, and doesn’t involve or strictly limits environmentally destructive practices such as mining, drilling, and deforestation.

While green might be applied to a lot of environmental products and energy sources colloquially and in advertising, according to this stricter definition, green energy forms include:

  • Wind power

  • Solar power

  • Small-scale hydropower

  • Geothermal energy, when drilling is carefully done to minimise environmental damage

  • Tidal and wave energy, when oceanic environments are protected

Renewable Energy

These listed green energy sources are all types of renewable energy, energy derived from natural sources that are replenished faster than they are consumed. However, there are other types of renewables.

Renewable energy sources include those in limitless supply, such as solar and wind power. But they also include those like biomass and biofuels, produced from organic waste matter, that are in more limited supply but can be replenished naturally within human lifetimes. For example, the plants burned in biomass plants or converted into biofuels can be regrown.

Forms of renewable energy include:

  • Wind power

  • Solar power

  • Biomass - if carefully managed

  • Hydropower

  • Geothermal

Some of these renewable energy sources don't qualify as green. For example, large hydropower geothermal installations may cause too much environmental disruption to be considered green.

Additionally, the burning of biomass and biofuels releases greenhouse gases, so these technologies aren't considered green either. In fact, biomass projects have to be undertaken carefully to keep their renewable credentials. Forests must be sustainably managed and harvesting shouldn’t exceed regrowth rates. Waste matter should be prioritised over crops grown purely to burn.

Clean Energy

Clean energy sources are those that don’t involve the release of greenhouse gases. That includes green energy sources and some that are classified as renewables, but notably not biomass.

To the surprise of some, nuclear power qualifies as clean energy because it produces very low to zero carbon emissions and no air pollution during safe operation. The carbon footprint of nuclear power is between 15 and 50g of CO2 per kilowatt-hour of electricity produced (gCO2/kWh), compared to around 450gCO2/kWh for gas-fired power stations and 1,050gCO2/kWh for coal.

Nuclear power stations do produce toxic, high-level radioactive waste, which must be carefully isolated for thousands of years, usually deep underground. However, the amounts produced are small compared to the electricity produced.

Forms of clean energy include:

  • Wind power

  • Solar power

  • Hydropower

  • Nuclear power

Types of green energy

Green energy taps natural sources of energy in our environment, including sunlight, heat from the Earth, and the movement of wind and water, and converts it into usable electricity and heat.

The most common types of green energy are:

Solar power

The conversion of solar radiation, or sunlight, into electrical or thermal energy. Sunlight can be converted into electricity using photovoltaic (PV) panels. When exposed to sunlight, the silicone cells in these panels release electrons, which can be captured as direct current (DC) electricity. In solar thermal energy installations, water absorbs heat from the sun, sometimes with the assistance of mirrors and lenses to concentrate the sun’s rays.

Wind power

The harnessing of the kinetic energy of the Earth’s atmosphere. For generations, humans have used the power of the wind to turn windmills and power sailboats. Today, we primarily use turbines, the blades of which turn even in the slightest breeze, spinning a generator that produces electricity.

Hydropower

Also known as hydroelectric power, the generation of electricity through the use of moving water, such as in rivers and waterfalls. Dams and reservoirs help to direct and concentrate water flow through spinning turbines connected to generators, transforming the water’s kinetic energy into electricity.

Geothermal energy

The heat energy beneath the Earth’s surface. Humans can tap geothermal energy for heating, cooling, and electricity generation. Ground-source heat pumps use geothermal energy just a few metres underground to heat buildings, while deep installations may drill more than 500m below the surface to access much hotter rocks, which warm pumped water that is then used for heating or electricity generation.

More unusual sources of green energy include:

Wave or tidal power

These emerging energy forms capture the kinetic energy of the ocean, including waves and tides, to produce electricity. There are two operational large-scale tidal power projects in the world, in France and South Korea, but two additional tidal stream projects are under construction in the North of Scotland and Anglesey in Wales.

Piezoelectric energy

The electrical charge produced when certain materials are subjected to mechanical stress. Piezoelectric floor tiles have been installed in high-traffic areas and dance floors to capture the energy of human footfalls.

Salinity gradient energy

Also known as blue energy and osmotic power, the energy released when seawater with high salt concentration meets fresh river water. A pilot blue energy project has been installed in the Netherlands, using reverse electrodialysis (RED) with ion-selective membranes to generate electricity.

Benefits of green energy

The UK government is investing billions in green energy. Why does it make sense to switch from fossil fuels to greener power? There are many benefits:

  • Low or no carbon emissions, reducing global heating

    Unlike fossil fuels, green energy sources don’t release the greenhouse gases that are causing the Earth’s temperature to rise. Widespread adoption of green energy forms is seen as essential to preventing potentially catastrophic climate change.

  • Reduced air and water pollution

    Unlike fossil fuels, green energy sources don’t release hazardous chemicals such as sulfur dioxide, nitrogen oxides, and carbon monoxide into the atmosphere. The extraction, transportation, and burning of fossil fuels can also pollute bodies of water, contaminating water supplies and damaging aquatic ecosystems, and soil, reducing crop yields and harming ecosystems.

  • Improved public health

    Globally, around 5 million deaths each year are attributed to air pollution caused by fossil fuel combustion. Limiting air and water pollution through the use of green energy sources can extend and improve lives and reduce health spending.

  • No resource exhaustion

    According to current projections, humans will exhaust our supply of fossil fuels during this century. As supplies of coal, oil, and natural gas are depleted, the cost and environmental impact of extraction rises. In contrast, green energy sources are in limitless supply.

  • Energy independence

    The UK’s abundant natural resources, especially wind power, could eliminate our need to import fossil fuels. Energy independence would increase national security, shield us from economic shocks such as that seen during the natural crisis in 2021-23, and reduce energy bills.

  • Reduced conflict over resources

    Competition for fossil fuels has driven numerous wars over the last few decades, notably in the Middle East. Switching to green energy forms has the potential to reduce global conflict.

  • Cost stability

    Once renewable capacity is installed, the energy it produces is fairly consistent, stabilising prices. In contrast, fossil fuel prices are highly volatile, closely linked to geopolitical events.

  • Job creation

    Renewable energy is expected to create 150,000 jobs in the UK by 2030.

How much green energy does the UK use?

In 2024, more than a third (36.2%) of the UK’s electricity was generated by true 'green' energy sources, according to data from the Department for Energy Security and Net Zero.

Wind power

Produced 29.2% of the UK’s total electricity

Solar power

Generated 5% of total electricity

Hydropower, including tidal

Generated 2% of total electricity

Biomass energy, which qualifies as renewable but not green, generated an additional 14.1% of our power. Nuclear power stations, which produce clean but not green electricity, generated 14.2% of our power, pushing the UK’s non-fossil fuel, low electricity generation to over 50%.

However, electricity represents only part of our energy use. We’re still heavily reliant on fossil fuels, specifically natural gas and petrol and diesel for heating and road transportation, respectively.

Around 85% of homes use fossil fuels - primarily natural gas but also LPG and oil - for heating, with an additional 8% using electric heat. However, biomethane, a renewable fuel produced by the anaerobic digestion of organic waste, is being increasingly added to the natural gas supply. In 2023, according to government data, 4,490 GWh of heat was generated from biomethane injected into the gas supply, enough to heat around 375,000 homes for a year.

On the roads, around 4.78% of vehicles are fully electric, with the rest powered by fossil fuels. However, biofuels, renewable fuels such as bioethanol and biodiesel made from organic matter, make up around 7.5% of the diesel and petrol supplied. The government plans to ban the sale of new petrol and diesel vehicles in 2035, pushing motorists toward EVs.

Which suppliers use green energy?

Environmentally conscious Britons may be interested in supporting green energy by selecting an energy company that supplies it.

A number of major UK energy suppliers brand themselves as “green." Other suppliers offer special green tariffs, matching your supply with green electricity.

However, not all green claims hold up to scrutiny. Energy suppliers can claim to supply green power not by generating it or directly buying it from renewable generators, but rather by purchasing Renewable Energy Guarantees of Origin (REGO) certificates. Originally issued by renewable generators, REGOs can be bought and sold, sometimes allowing the purchaser to claim green credentials with little direct connection to green electricity generation, a practice critics call “greenwashing.”

It’s seen as greener for suppliers to purchase green energy directly from generators through Power Purchase Agreements (PPA), long-term contracts that give the generators a revenue stream to stay viable and invest in new capacity. Additionally, some green energy suppliers directly operate or invest in renewable capacity themselves. They may also include renewable biomethane in their gas mix.

Green energy suppliers include:

Octopus Energy

Supplies 100% green electricity, 20% of which is generated by its own wind, solar, and hydro installations. While Octopus does use REGO certificates to cover some of its electricity, it also has PPA agreements with 700 renewable generators in the UK. Octopus has also pioneered innovative time-of-use tariffs that encourage consumers to use electricity when renewable generation is high, with cheaper rates, and offers discounted tariffs to communities near its wind turbines.

Ecotricity

Supplies 100% green electricity, with around 15% generated by its own wind and solar farms. The rest is sourced through power purchase agreements (PPA), although Ecotricity does use some REGO certificates as well. Around 1% of the natural gas it supplies is biomethane, including from its own green gasmill. Ecotricity is committed to supplying only biomethane produced from plant waste material, not animal byproducts, making its energy vegan.

Good Energy

Supplies 100% green electricity produced by more than 2,500 independent UK generators, all through PPAs, with no use of REGOs. 10% of the gas it supplies is renewable biomethane.

100Green

This small supplier supplies 100% green electricity, using a combination of PPAs and REGOs, and gas that is 100% biomethane—the only UK supplier to do so.

Other suppliers offer green energy tariffs, including:

Scottish Power

Offers several green energy tariffs with 100% green electricity sourced directly from its own 40 operating wind farms, which have a capacity of 2.8GW.

OVO

Customers can pay an additional fee to upgrade their tariffs to supply green electricity. OVO doesn’t use REGOs but rather purchases directly from renewable generators through PPAs. Some tariffs also include gas with up to 15% biomethane.

British Gas

Offers several green tariffs with green electricity backed by REGOs. Its Green Future Energy tariff also includes 10% biomethane.

EDF

Offers zero carbon tariffs, with clean energy sourced from EDF’s nuclear power plants and its substantial wind and solar power assets, and using REGOs.

E.ON

Offers some energy tariffs with 100% renewable energy generated by E.ON’s own wind farms or covered by REGOs.

It’s important to note that these green energy suppliers don’t directly pump their electricity or gas to your property. When you turn on your lights, you’re drawing power from the National Grid and when your boiler turns on, it uses gas from a national network of pipes. Energy suppliers are simply responsible for feeding enough electricity or gas into these systems to match your usage.

Can I generate my own green energy?

If you’re really committed to the energy transition and the environment, you may want to generate your own green power at home with solar panels or wind turbines.

The most popular way to make homegrown green energy is with solar panels. Around 5%, or 1.5 million, British homes are already outfitted with solar PV panels, most commonly on their roofs. New energy efficiency regulations are encouraging developers to add solar panels to new homes as well. More than 40% of new properties completed in the fourth quarter of 2024 were outfitted with PV arrays.

A smaller number of properties, primarily rural, have their own wind turbines. Battery systems can increase the usability of these systems, allowing you to, for example, store power generated during a sunny day or windstorm for use at other times.

Generating your own power reduces the amount you need to import and in turn, your energy bills. Still, renewable energy systems aren’t cheap to install. So to incentivise their uptake, the government also requires energy suppliers to purchase from small-scale generators the surplus green energy they produce but can’t themselves use, through the Smart Export Guarantee (SEG).

All large energy suppliers are required to offer export tariffs to homes and small businesses with qualifying wind and solar power systems. These energy suppliers pay between 1p and 40p per kilowatt-hour (kWh) of electricity, allowing homeowners and businesses to offset the cost of installing renewable technologies.

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