The 2009 Renewable Energy Directive set a target for the UK to achieve 15% of its energy consumption from renewable sources by 2020. Innovation in low carbon and other renewable energy technologies is essential if the UK is to meet this target, as well as the future climate change goal of an 80% reduction in greenhouse gas emissions by 2050. Following advice taken from the Committee on Climate Change in July 2011 the government and devolved administrations published the UK Renewables Energy Roadmap which sets out the plan for accelerating the deployment and use of renewable energy to help meet the 2020 target.
There are many reasons to use renewables, from saving the planet to saving yourself money. The once futuristic concept of no fuel bills is already a reality for many households. Instead of buying energy from suppliers, renewable technologies (also referred to as low carbon or micro-generation technology) can enable us all to become energy producers, generating our own electricity and selling what we don’t use back to the grid. Here's some common examples of how:
AIR SOURCE HEAT PUMPS
These pumps absorb heat from the outside air which is used to heat radiators, underfloor or warm air heating systems, as well as hot water in a domestic dwelling. The air source heat pump extracts heat from outside in the same way that a fridge extracts heat from its inside, even when the temperature is as low as -15° C. There are two main types of air source heat pump systems. An air-to-air system produces warm air which is circulated by fans to heat your home although is unlikely to provide you with hot water, whereas an air-to-water system distributes heat via your wet central heating system. As heat pumps work more efficiently than a standard boiler at lower temperatures they are more suitable for underfloor heating or large radiators which emit low rates of heat over longer periods of time.
GROUND SOURCE HEAT PUMPS
These pumps use pipes which are buried in the garden to extract heat from the ground. This heat can then be used to heat radiators, underfloor or warm air heating systems, as well as hot water in a domestic dwelling. A ground source heat pump circulates a mixture of water and antifreeze around a ground loop buried in your garden. Heat from the ground is absorbed into the fluid and then passes through a heat exchanger into the heat pump. The ground stays at a fairly constant temperature under the surface allowing the heat pump to be used throughout the year.
Biomass power is carbon neutral electricity generated from renewable organic waste. When burned, the energy in biomass is released as heat. In a domestic dwelling biomass energy is produced from wood-fuelled heating systems to provide warmth in a single room or to power central heating and hot water boilers. A stove burns logs or pellets to heat a single room and may be fitted with a back boiler to provide water heating as well. A boiler burns logs, pellets or chips and is connected to a central heating and hot water system.
MICRO-CHP (MICRO COMBINED HEAT & POWER)
A micro-CHP unit will heat a domestic dwelling and generate electricity simultaneously from the same energy source. Whilst the main output of a micro-CHP system is heat, the typical ratio for electricity generation is about 6:1 for domestic appliances. A typical domestic system will generate up to 1kW of electricity once warmed up and any electricity generated but not used can be sold back to the grid. Domestic micro-CHP systems are currently powered by mains gas or LPG although future models may be powered by oil or bio-liquids. Although gas and LPG are fossil fuels rather than renewable energy sources, the technology is still considered to be a ‘low carbon technology’ because it can be more efficient than just burning a fossil fuel for heat and getting electricity from the national grid. Micro-CHP systems are similar in size and shape to ordinary domestic boilers and can be wall hung or floor standing. The only difference to a standard boiler is that they are able to generate electricity whilst they are heating water.
SMALL SCALE HYDRO-ELECTRICITY
Hydro technology uses running water to generate electricity. Micro hydroelectricity or hydropower systems can produce enough electricity for lighting and electrical appliances in an average home. All streams and rivers flow downhill and hydropower systems convert the potential energy of the waterflow into kinetic energy in a turbine which drives a generator to produce electricity. The greater the height and the more water there is flowing through the turbine, the more electricity that can be generated. Needless to say, hydropower is site specific as most homes will not have access to a suitable resource even if they have a water course running nearby. If there is a good hydro resource in or near a community it could be worth developing it as a community energy project to supply more than one home.
Solar panel electricity systems, also known as solar photovoltaics (PV), capture the sun's energy using photovoltaic cells. The cells convert the sunlight into electricity which can be used to run household appliances and lighting. PV cells are made from layers of semi-conducting material, usually silicon. When light shines on the cell it creates an electric field across the layers. The stronger the sunshine, the more electricity is produced although these cells don't need direct sunlight to work and can still generate some electricity on a cloudy day. Groups of cells are mounted together in panels or modules that can either be fixed to your roof or on the ground.
SOLAR THERMAL WATER HEATING
These systems use free heat from the sun to warm domestic hot water using solar panels called collectors fitted to the roof of a domestic dwelling. These collect heat from the sun and use it to heat up water which is stored in a hot water cylinder. The system works all year round although a conventional boiler or immersion heater will be needed to increase the water temperature or as a back-up when solar energy is unavailable during the winter months.
Domestic sized wind turbines can harness the power of the wind and use it to generate electricity. Wind turbines use large blades to catch the wind. As the wind blows the blades are forced round, driving a turbine which generates electricity. The stronger the wind, the more electricity produced. About 40 per cent of all wind energy in Europe blows over the UK, making it an ideal country for domestic turbines (known as microwind or small-wind turbines). A typical system in an exposed site can generate more than sufficient power for your lights and electrical appliances. They can be pole or building mounted where there is a suitable wind resource.
With many renewable technologies potential income can be earned through the government’s Renewable Heat Incentive, receiving payments for the heat you produce. Many of these technologies are also eligible measures under the government’s Green Deal, a financing mechanism that lets people pay for energy-efficiency improvements through savings on their energy bills. There are comprehensive guides available from the Energy Saving Trust containing advice for consumers on different renewable technologies, their suitability and benefits, the types of financial support available for renewable heat and how to find installers and products.