Wind turbine producing energy at G24 Innovations, Cardiff. Photo: Chris Brown, Cardiff Friends of the Earth
In 2002 Wales used about 19.5 Tera Watt hours (TWhrs) of electricity. Friends of the Earth Cymru estimate that Wales could generate from 27 per cent to 53 per cent of its electricity (5.4 to 10.6 TWhrs a year) using renewable technologies by 2015. Half of this could be generated on land and half out to sea.
It is possible to mount wind turbines on piles driven into the sea bed in shallow costal waters. Wind speeds are higher offshore than on land.
There are 30 turbines at the North Hoyle offshore windfarm off the north Wales coast with a maximum installed capacity of 60MW. The Rhyl Flats scheme next to it has a further 25 turbines with a maximum installed capacity of 90MW. Together they can power about 101,000 homes each year.
The Gwynt y Môr offshore windfarm, currently under construction, is very close to them. It is due to be fully operational by the end of 2014. It will consist of 160 turbines with an installed capacity of 576MW and be capable of generating enough energy to meet the energy needs of about 400,000 homes.
RWE is due to apply for planning permission in 2013 to construct the Atlantic Array offshore wind farm in the Bristol Channel near Tenby. It would have 240 turbines with a maximum capacity of 1200MW.
Other possible sites for offshore wind farms in Wales include north-west Anglesey; the Llyn Peninsular; Carmarthen Bay; and South Pembrokeshire.
It is possible to produce at least 0.87 TWhrs a year of electricity from offshore wind farms by 2015, or about 5% of Welsh electricity.
In 2003 there were about 393 onshore wind turbines in Wales. They supplied about 0.48 TWhrs a year, or about 2.7% of Welsh electricity use.
Between them the 20 wind turbines at Taff Ely Wind Farm at Gilfach Goch in Rhondda Cynon Taff generate 9 MW of power - enough to power 5,631 homes.
The number of onshore wind turbines could be increased to between 550 and 800 turbines (depending on the turbine sizes) by 2015. This would raise the amount to about 1.16 TWhrs a year, or 7.2 per cent of Welsh electricity.
Visit the British Wind Energy Association website for more information on wind power.
Biofuels include waste from agriculture or forestry. They could generate 1.3 TWhrs of electricity a year, or 8% of Welsh electricity demand, and 2.6 TWhrs of hot water a year, which is equivalent to 16 per cent of Welsh electricity use.
The straw-fired power station near Ely in Cambridgeshire burns about 200,000 tonnes of straw a year. If we built a similar one in Wales it would generate about 0.27 TWhrs a year (about 1.4 per cent of Welsh demand).
The power station at Thetford in Norfolk burns 450,000 tonnes of poultry litter and other agricultural biomass. It generates 38.5 MW of electricity – enough to power 93,000 homes.
Fuel crops use carbon from the atmosphere to help them grow. Burning the crop releases it. The growing biomass fuel absorbs the same amount of carbon as is released by the burnt fuel. This means that using biomass fuels for power generation does not contribute to climate change.
Fuel crops can be stored until we need to use them. Growing fuel crops would also give a welcome boost to Welsh farming.
Friends of the Earth do not support converting farmland used for growing food or the destruction of uncultivated land to produce biofuels.
It is possible to produce at least 0.6 TWhrs a year more electricity from biofuels by 2015, or about 3 per cent of Welsh electricity.
Wales gets between 3,000 mm of rain a year (Snowdonia) and 840 mm of rain (Anglesey) on average. We can generate electricity from rivers and streams by using turbines.
Sites need 1 m or more difference between the height of the water surface and the level of the turbine. Modern turbines can be from 60 to 90 percent efficient.
At the moment small and medium scale hydroelectric schemes in Wales generate 0.21 TWhrs of electricity a year. This is about 1% of current demand. The potential damage to sensitive rivers limits the maximum amount of electricity that hydroelectric schemes can generate.
In 1980 a study by Salford University identified 560 potential small hydroelectric sites in Wales. Together they could generate 0.30 TWhrs of electricity a year, or 1.7%% of current demand. There are also many smaller potential sites. A 1989 study by the University of Salford found 58 Small-scale hydroelectric schemes in Wales generating 6.5 MW in total.
Visit the British Hydro Power Association website for more information on hydro-electric power.
There are two types of solar power, solar electric and solar photovoltaic (PV).
Solar PV cells can convert sunlight directly into electricity. They are clean, safe and silent in operation. They can generate electricity even on overcast days. The cost of installing solar PV is reducing rapidly and technological advances are increasing the amount of energy they produce. Solar PV tiles or panels can be used in a new building to replace a conventional roof reducing the cost.
The largest solar PV array in Wales supplies 12 KW of electricity at the Centre for Alternative Technology in Machynlleth.
A £1bn investment in photo-voltaic (PV) electricity could provide 1,000 MW of electricity for the same price as nuclear today within five years.
The Department of Energy and Climate Change found that in 2013 199 per 10,000 Welsh homes had photovoltaic solar panels installed, well above the British average of 933. About 0.4 TWhrs a year of electricity is likely be produced by solar PV by 2015, or about 2 per cent of Welsh electricity.
Visit the UK Energy Saving website for more information on PV power.
Solar thermal schemes use the sun's energy use large south-facing windows to collect the sun’s heat directly. The alternative is to use either flat-plate solar collectors or the more efficient, but more expensive, vacuum or parabolic collectors to heat a liquid such as water. Solar thermal schemes are still relatively expensive.
Visit the Energy Saving Trust website for more information on solar thermal power.
Mines and Landfill (rubbish) tips produce and leak methane, this is a powerful climate change gas. We can collect the gases and burn them to produce electricity.
The decomposition of waste in landfill sites produces gas for between 15 and 25 years. About half of the gas is methane. A ton of waste produces the energy equivalent of 100 litres of heating oil.
Burning the gas from the Lamby Way Landfill Site in Cardiff produced 2.93 MW of electricity in May 2004.
The formation of coal from wood and other organic substances produces methane and carbon dioxide. These gasses are trapped within the coal seam and are released by mining. This happens even in closed mines.
Burning the mine gas from Shirebrook Colliery in Derbyshire produces 10 MW of electricity – enough to power 10,000 homes.
Existing landfill gas schemes supply about 1% of Welsh electricity demand. New landfill and mine gas schemes could increase the amount to about 2% by 2015.
Sea currents, especially around headlands can be very powerful.
Marine Current Turbines Ltd. Ltd. has suggested placing underwater turbines in the fast-flowing currents off the north Anglesey coast, Penllyn and the south Wales coast.
The company installed the first commercially operating tidal turbine in 2008 at Strangford Lough in Northern Ireland. They now plan to install a 10MW array of marine turbines at The Skerries off the north-west coast of Anglesey.
The commercial schemes in Wales could generate up to 0.69 TWhrs a year of electricity by 2015, or 3.9 per cent of Welsh electricity use.
Tidal lagoons generate energy by trapping, and releasing, sea water during the rising and falling tides. They have similar walls to rock breakwaters which contain generators.
The tides are predictable, but they happen at a different time each day. By creating several lagoons next to each other and moving water between them you can increase the time-span over which you can generate electricity.
Tidal Lagoon (Swansea Bay) propose to build a 400,000 MWh/year lagoon in Swansea Bay that could supply over 120,000 homes. They submitted a planning application in February 2014.
Tidal Electric have estimated that tidal lagoons in the Severn Estuary could generate about 32.9 TWh/year. This is equivalent to 9% of Welsh electricity use. Choosing tidal lagoons instead would avoid most of the environmental problems that a barrage would cause.
This is an energy-efficient technology which converts mainly gas directly into electricity and heat to power groups of buildings. Its share could be 30% of all electricity generation if the government invested £1bn spread over 10 years.
This is an energy storage method. It runs on hydrogen gas and produces almost no pollutants if the energy stored is from renewables. A £500m investment would almost certainly produce a workable technology.