Renewable energy sources, also called renewable energy or renewables, are energy sources that replenish (or renew) themselves naturally. Typical examples are solar energy, wind and biomass.


Renewable energy sources include the following:

Ambient heat (heat pumps)heat pumps that are driven by electricity or other supplementary energy, to extract (stored) energy from the air, the ground or the water and convert/transfer this into energy to be used elsewhere (e.g. to heat space via underfloor heating systems and/or water in domestic buildings). Heat pumps can be used by individual households as well as at larger scale in industry and in commercial and public services.

Biomass – organic, non-fossil material of biological origin (examples include wood, straw, plant and animal wastes, and purpose grown energy crops).  Energy can be extracted from biomass feedstock through converting it into biofuel (see below), combusting or gasifying it, it and using the heat (or syngas) for power production or digesting it to produce biogas which can be used in a number of ways. Using biomass as a fuel is deemed carbon neutral as carbon dioxide was trapped from the atmosphere during the growth of the biomass.  For biomass to be considered a sustainable energy resource, the rate of growth of biomass must exceed its harvesting, which is ensured in UK regulations.

Biofuels – fuels derived directly or indirectly from biomass. Biofuels can be split up into three categories:

  • Solid biofuels (covers solid organic, non-fossil material of biological origin (also known as biomass) which may be used as fuel for heat production or electricity generation. Examples include wood, straw. Solid biofuels are often referred to as biomass.
  • Liquid biofuels are liquids derived from biomass. They are often blended with or replace liquid fuels from fossil origin; bioethanol in petrol and biodiesel in diesel being the most common examples.
  • Gaseous biofuels. Biogas, a gas composed principally of methane and carbon dioxide is produced by anaerobic digestion.  Other examples are landfill gas and sewage gas.  Renewable methane can also be produced from the thermal treatment of biomass in a gasification or pyrolysis unit.

Energy from Waste from Municipal Solid Waste – derived from consumers’ waste collections, which is used to create power and heat in Energy from Waste plants, typically comprises around 65% biomass content.

Geothermal energy – the energy available as heat from within the earth’s crust, usually extracted via hot water or steam.

Hydropower the electricity generated from the potential and kinetic energy of water in hydroelectric plants (the electricity generated in pumped storage plants is a different source).

Solar energy – solar thermal energy (radiation exploited for solar heat) and solar photo-voltaic for electricity production.

Tidal, wave, ocean energy – mechanical energy derived from the tides (via tidal barrages/lagoons, which operate according to the height of the tide, or devices that are driven by the horizontal flow of the tide (or tidal current), wave motion.

Wind energy – the kinetic energy of wind converted into electricity in wind turbines, which can be located either onshore or offshore.


Renewable support mechanisms include:

Contracts for Difference (CfD) – Support for larger scale power generators, in the form of private law contracts distributed via an auction. Technologies are divided into two ‘Pots’ of ‘established’ and ‘non-established’ technologies.

Renewable Heat Incentive (RHI) – Support for domestic and non-domestic renewable heating projects. People who join the scheme and stick to its rules receive quarterly payments for seven years for the amount of clean, green renewable heat their system produces.

Smart Export Guarantee (SEG) – Support for smaller scale power generators, up to 5MW capacity. Each licensed supply company with over 150,000 customers must offer at least one SEG tariff. Technologies included are solar PV, onshore wind, micro-CHP, Anaerobic Digestion, hydro.

The Renewable Transport Fuels Obligation (RTFO) – The main support for renewable transport fuels and an obligation on transport fuel suppliers to supply minimum levels of renewable sourced fuels.

Some terms commonly used in renewable support schemes:

Deem, deeming – To estimate the output of an energy installation without metering it.

Degression – The setting of tariffs at lower (or different) levels at various intervals as the scheme progresses. The changes in level would apply only to new energy installations entering the scheme, not to tariff levels paid to existing installations (provided the principle of grandfathering is adopted).

Microgeneration – Defined in the Energy Act 2004 and generally accepted to mean:

(a) the generation of electricity up to 50 kilowatts peak;

(b) the production of heat up to 45 kilowatts thermal

Microgeneration Certification Scheme (MCS) – The UKAS-accredited scheme covering the certification of microgeneration products and the accreditation of their installers. SEG projects must be installed to MCS certified standards.

Renewable Energy Consumer Code (RECC) – The REA’s subsidiary, which all installers of SEG approved projects must be a member of (or an equivalent TSI approved body), in order for the project to be eligible for a SEG tariff.


Key stakeholders and other common terms used in the sector:

BEISThe Department for Business, Energy and Industrial Strategy (BEIS) which currently sets energy policy and direction in the UK and is responsible for the renewable support schemes aside from the RTFO.

DEFRA – Department for Environment Food & Rural Affairs

DFT – Department for Transport

EA – Environment Agency

Feed-in Tariff – A feed-in tariff (FIT, FiT) is a policy mechanism designed to accelerate investment in renewable energy technologies. It achieves this by offering long-term contracts to renewable energy generators and is usually based on the cost of generation of each technology. Schemes vary in design, but it is generally paid on the amount of renewable generated and/or exported.

Greenhouse Gas – is a gas that contributes to the greenhouse effect by absorbing infrared radiation. Examples of greenhouse gases include Carbon dioxide and chlorofluorocarbons.

MHCLG – Ministry of Housing, Communities & Local Government

OfgemThe energy regulator Ofgem (acting through the Gas and Electricity Markets Authority), which is responsible for regulating electricity and gas supply markets

OLEV – The Office for Low Emission Vehicles works across government to support the early market for ultra-low emission vehicles (ULEV).

P95 level – The level of output which an energy installation would be expected to exceed 99% of the time (i.e. for 19 years in 20)

Renewables Obligation (RO) – The Renewables Obligation, an historic scheme, now closed to new generators but responsible for the deployment of large amounts of renewable power

SAP – The standard assessment procedure for energy rating of buildings as used by building regulations, for example and the calculation of the energy rating for Energy Performance Certificates (EPCs)

Supply company – An electricity or fossil fuel heating fuel supplier responsible for paying tariffs, such as the Smart Export Guarantee

Syngas – Gas produced by a thermal (as opposed to a biological – see biogas) process of gasification.  The renewable proportion of syngas which may be eligible for tariffs will vary depending on the feedstock

Tariff – Payment for each kWh of eligible energy produced from a support scheme, e.g. ‘a SEG (Smart Export Guarantee) tariff’ the successor to the UK’s Feed-n Tariff scheme.