Renewable Energy

Renewable Energy

Renewable energy describes energy occurring naturally in the environment, such as energy from the wind or sun. As these sources are essentially inexhaustible, developing renewable technologies can provide clean energy which will reduce our ‘carbon footprint’ and significantly reduce our dependence on fossil fuels. Renewable energy has the potential to provide around 40% of the UK’s total energy requirements through a range of technologies, from directly using the energy from the sun to heat water to using mechanical devices such as wind turbines to convert the kinetic energy in the wind into electrical energy. In 2006 the UK generated around 4% of its electricity requirements from renewable sources. The successful transformation into a ‘low carbon’ economy will necessitate a wholesale change in the way in which we generate electricity, and heat and power our existing homes and buildings. The development of renewable energy is seen as integral to the achievement of the Government’s longer term aim of reducing CO2 emissions by 60% by 2050.

Before installing any micro generation technology in your home, it’s important that you reduce your energy demand by ensuring you have adequate insulation, effective controlled ventilation and low energy lighting and appliances. These should be the first steps when addressing energy/carbon reduction in your home.
You can find out more about cutting your carbon use at home by using the Energy Savings Trust’s Carbon Cutter to find out more about these measures.

Renewable energy or ‘micro generation’ technologies include:

  • Solar Thermal – solar water heating
  • Solar Photovoltaics (PV) – electricity from the sun
  • Air Source Heat Pump
  • Ground Source Heat Pump
  • Wood Fuelled Heating
  • Wind Turbines – small scale wind power
  • Small Scale Hydroelectricity

‘Feed-in Tariff’ (Clean Energy Cashback) scheme

Feed-in Tariffs (FITs) are now available in the UK and came into effect as of 1st April 2010. This scheme requires energy suppliers to make regular payments to householders and communities who generate their own electricity from renewable or low carbon sources such as solar electricity (PV) panels or wind turbines.

The scheme guarantees a minimum payment for all electricity generated by the system, as well as a separate payment for the electricity exported to the grid. These payments are in addition to the bill savings made by using the electricity generated on-site.

About the scheme

The scheme covers the following electricity-generating technologies, up to 5 Mega Watts:

  • Solar electricity (PV) (roof mounted or stand alone)
  • Wind turbine (building mounted or free standing)
  • Hydroelectricity
  • Anaerobic digestion
  • Micro combined heat and power (mCHP) (limited to a pilot at this stage)

The tariffs available and the process for receiving them vary, depending on when the technology was installed, and whether the system and the installer were certificated under the  Microgeneration Certification Scheme (MCS).

You will qualify for the full FIT payments if:

  • The technology was installed between 15th July 2009 and 31st March 2010; or
  • It is installed on or after 1st April 2010 using an MCS certificated product and installer.

The Microgeneration Certification Scheme (MCS) is an independent scheme that certificates microgeneration products under 50kW and installers in accordance with consistent standards. Any systems over 50kW and all anaerobic digestion installations must apply directly through the ROO-FIT process as they are not covered by the MCS.

For more information about the Feed-In Tariff, including how to take part and details of payments visit: http://www.energysavingtrust.org.uk

Solar thermal – solar water heating

Solar water heating systems use free heat from the sun to warm domestic hot water. A conventional boiler or immersion heater is then used to make the water hotter, or to provide hot water when solar energy is unavailable.

How do solar water heating systems work?

Solar water heating systems use solar panels, called collectors, fitted to your roof. These collect heat from the sun and use it to warm water which is stored in a hot water cylinder.

There are two types of solar water heating panels, they are evacuated tubes and flat plate collectors. Collectors can be fixed on the roof tiles or integrated into the roof. A boiler or immersion heater can be used as a back up to heat the water further to reach the temperature set by the cylinders thermostat when the solar water heating system does not reach that temperature. (The cylinder thermostat should be set at 60 degrees centigrade.)

Larger solar panels can also provide energy to heat your home as well – though usually only in the summer months when home heating is unnecessary.

The benefits of solar water heating

  • Hot water throughout the year: the system works all year round, though you’ll need to heat the water further with a boiler or immersion heater during the winter months.
  • Cut your bills: sunlight is free, so once you’ve paid for the initial installation your hot water costs will be reduced.
  • Cut your carbon footprint: solar hot water is a green, renewable heating system and doesn’t release any harmful carbon dioxide or other pollutants

For further details on solar hot water, please visit the Energy Saving Trust at:
http://www.energysavingtrust.org.uk

Solar photovoltaics (PV) – electricity from the sun

Solar electricity systems capture the sun’s energy using photovoltaic (PV) cells. The cells convert the sunlight into electricity, which can be used to run household appliances and lighting.

How do photovoltaic (PV) cells work?

PV cells are panels you can attach to your roof or walls. Each cell is made from one or two 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.

PV cells come in a variety of shapes and colours, from grey “solar tiles” that look like roof tiles to panels and transparent cells that you can use on conservatories and glass.

The strength of a PV cell is measured in kilowatt peak (kWp) – that’s the amount of energy the cell generates in full sunlight.

The benefits of solar electricity

  • Cut your carbon footprint: solar electricity is green, renewable energy and doesn’t release any harmful carbon dioxide or other pollutants. A typical home PV system could save around 1200 kg of carbon dioxide per year – that’s around 30 tonnes over its lifetime.
  • Cut your electricity bills: sunlight is free, so once you’ve paid for the initial installation your electricity costs will be greatly reduced. A typical home PV system can produce around 40% of the electricity a household uses in a year.
  • Sell electricity back to the National Grid: if your system is producing more electricity than you need, or when you can’t use it, someone else can use it – and you could make a bit of money.
  • Store electricity for a cloudy day: if your home isn’t connected to the national grid you can store excess electricity in batteries to use when you need it.

For further details on solar electricity (PV), please visit the Energy Saving Trust at:
http://www.energysavingtrust.org.uk

Air source heat pump

Air source heat pumps absorb heat from the outside air. This heat can then be used to warm water for radiators or underfloor heating systems, or to warm the air in your home.

How do air source heat pumps work?

An air source heat pump extracts heat from the outside air in the same way that a fridge extracts heat from its inside. It can extract heat from the air even when the outside temperature is as low as minus 15° C.

There are two main types:

An air-to-water system uses the heat to warm water. Heat pumps heat water to a lower temperature than a standard boiler system would, so they are more suitable for underfloor heating systems than radiator systems.

An air-to-air system produces warm air which is circulated by fans to heat your home.
The efficiency of air source heat pump systems is measured by a coefficient of performance (CoP) which is the amount of heat they produce compared to the amount of electricity needed to run them. A typical CoP for an air source heat pump is around 2.5.

The benefits of air source heat pumps

  • Reduce your fuel bills: air source heat pumps run on electricity, so there’s no need to pay for gas, oil or solid fuels to heat your home.
  • Cut down on wasted electricity: heating your home with an air source heat pump is much more efficient than using electric radiators.
  • Save space: an air source heat pump system is compact, and requires no storage space for fuel.

For further details on air source heat pumps, please visit the Energy Saving Trust at:
http://www.energysavingtrust.org.uk

Ground Source Heat Pump

Ground source heat pumps use pipes buried in the garden to extract heat from the ground. This is usually used to warm water for radiators or underfloor heating systems. It can also be used to pre-heat water before it goes into a more conventional boiler.

Beneath the surface, the ground stays at a constant temperature, so a ground source heat pump can be used throughout the year – even in the middle of winter.

How does a ground source heat pump work?

A ground source heat pump circulates a mixture of water and antifreeze around a loop of pipe – called a ground loop – which is buried in the garden. When the liquid travels around the loop it absorbs heat from the ground – used to heat radiators, underfloor heating systems and even hot water.

The length of the ground loop depends on the size of your home and the amount of heat you need – longer loops can draw more heat from the ground. Normally the loop is laid flat, or coiled in trenches about two metres deep, but if there is not enough space in your garden you can install a vertical loop to a depth of up to 100 metres.
The efficiency of a ground source heat pump is measured by a coefficient of performance (CoP) – the amount of heat it produces compared to the amount of electricity needed to run it. A typical CoP for a ground source heat pump is around 3.2 without any reductions for the type of distribution system.

The benefits of ground source heat pumps

  • Reduce your CO2 emissions: on average a ground source heat pump could save around 540kg of carbon dioxide every year when replacing an oil boiler.
  • Eliminate your fuel bills: ground source heat pumps run on electricity, so there’s no need to pay for gas, oil or solid fuels to heat your home.
  • Cut down on wasted electricity: heating your home with a ground source heat pump is much more efficient than using electric radiators.

For further details on ground source heat pumps, please visit the Energy Saving Trust at:
http://www.energysavingtrust.org.uk

Wood fuelled heating

Wood fuelled heating systems generally burn wood pellets, chips or logs to power central heating and hot water boilers or to provide warmth in a single room.

How do wood fuelled heating systems work?

There are two main ways of using wood to heat your home:

  • A standalone stove burning logs or pellets to heat a single room. Some can also be fitted with a back boiler to provide water heating as well.
  • A boiler burning pellets, logs or chips connected to a central heating and hot water system.

Log burning stoves and boilers have to be filled with wood by hand. Some pellet and chip burners use automatic fuel feeders which refill them at regular intervals from fuel storage units called hoppers.

The benefits of wood fuel heating

  • A low carbon option: the carbon dioxide emitted when wood fuel is burned is the same amount that was absorbed over the previous months and years as the plant was growing. As long as new plants continue to grow in place of those used for fuel, the process is sustainable. There are some carbon emissions caused by the cultivation, manufacture and transportation of the fuel, but as long as the fuel is sourced locally, these are much lower than the emissions from fossil fuels.
  • A good use for waste wood: burning wood can be a convenient means of disposing of waste that might otherwise be sent to a landfill site.

For further details on wood fuelled heating, please visit the Energy Saving Trust

Wind turbines – small scale wind power

Wind turbines harness the power of the wind and use it to generate electricity. Small systems known as “microwind” or “small-wind” turbines can produce electricity to help power the lights and electrical appliances in a typical home.

40% of all the wind energy in Europe blows over the UK, making it an ideal country for small domestic turbines.

How do wind turbines work?

Wind turbines use large blades to catch the wind. When the wind blows the blades are forced round, driving a turbine which generates electricity. The stronger the wind, the more electricity produced.

There are two types of domestic-sized wind turbine:

  • Mast mounted: these are free standing and are erected in a suitably exposed position, often around 2.5kW to 6kW.
  • Roof mounted: these are smaller than mast mounted systems and can be installed on the roof of a home where there is a suitable wind resource. Often these are around 1kW to 2kW in size.

If your small wind system is connected to the National Grid then you can make money by selling any generated electricity to an electricity supply company.

The benefits of wind electricity

Harness a plentiful energy source: in the UK we have 40% of Europe’s total wind energy.

  • Cut your carbon footprint: wind electricity is green, renewable energy and doesn’t release any harmful carbon dioxide or other pollutants.
  • Cut your electricity bills: wind is free, so once you’ve paid for the initial installation your electricity costs will be reduced.
  • Store electricity for a calm day: if your home isn’t connected to the National Grid you can store excess electricity in batteries and use it when there is no wind.

For further details on small scale wind turbines, please visit the Energy Saving Trust at
http://www.energysavingtrust.org.uk

Small scale hydroelectricity

Hydroelectricity systems generate electricity from running water – usually a small stream. Small or “micro” hydroelectricity systems can produce enough electricity for lighting and electrical appliances in an average home. Hydroelectricity systems are also called hydro power systems or just hydro systems.

How do hydro power systems work?

Hydro power systems use running water to turn a small turbine which generates electricity. The faster the water flows and the more water there is, the more electricity can be generated.

The amount of electricity a system actually generates depends on how efficiently it converts the power of the moving water into electrical power. Hydro power systems convert potential energy stored in water held at height to kinetic energy

The benefits of hydro systems:-

  • Cut your carbon footprint: hydroelectricity is green, renewable energy and doesn’t release any harmful carbon dioxide or other pollutants.
  • Cut your electricity bills: hydroelectricity is free, so once you’ve paid for the initial installation you’ll reduce or even eliminate your electricity bills.
  • A lower cost option: installing a hydro system can be expensive, but in many cases it’s less than the cost of getting a connection to the National Grid.
  • Cheap heating and hot water: a hydro system may generate more electricity than you need for lighting your home and powering your electrical appliances – so you can use the excess to heat your home and your hot water too.

For further details on small scale hydroelectricity, please visit the Energy Saving Trust at
http://www.energysavingtrust.org.uk

Source: Energy Saving Trust