How much green energy can UK get from renewable sources
Renewable energy is so named because it can never run out as it is sourced from forces of nature as wind, sun, and tide. The UK is fortunate in having among the world’s largest resources of wind, wave and tidal energy. The renewable energy has the potential to fulfill the global energy needs. For instance, an area 200 miles square covered with solar panels could provide all the electricity the world needs; and wind can potentially provide around a 10th of the world's power. That would cut down dioxide emissions by a billion tons a year.
Britain's current electricity generation capacity from coal, gas, nuclear and other power stations is 75 GW but less than 0.5 GW comes from wind, while planning has already been granted to 3 GW and the government wants to raise the level to 8 GW. The UK is in an enviable position to generate between 20% to 50% of its energy requirements from wind source alone. Wind turbines usally grouped together in wind farms have a rated output at full power of between 1000 to 2000 kilowatts.In principle, the wind turbines cited in the windy parts of the UK could produce upto 20% of the UK’s electricity. There is even greater potential inherent in shallow water off-shore. Turbines mounted in off-shore shallow water could perhaps generate upto 50% of the UK’s electricity needs, but this would be a costlier option in comparison to on-land machines.
Energy can also be extracted from waves created by wind moving over water. Wave energy potential in the UK could be 20% or more of UK electricity requirements if suitable floating devices could be located in ‘deep-sea’ systems. Units sited at in-shore or on-shore systems could generate smaller amounts of power, at less cost.
The UK enjoys a huge tidal barrage potential of around 20% of its electricity needs. The rotation of the earth in combination with gravitational pull of the sun and the moon produces two tides every day, which can be trapped behind a barriage on suitable estuaries. The water head can then be released so as to drive turbines. This is quite similar to low head hydro-electric plants. Some barrages like mega hydro-projects can be large. The Severn Estuary scheme for instance, is proposed to generate around 8000 megawatts of installed generating capacity and could supply 6% of UK electricity requirements.
Tidal streams, especially fast moving tidal streams around Scotland and the Channel Islands, can also be exploited to generate electricity using propeller type devices located in the flow. Together, all suitable tidal stream sites have the potential to provide up to 19% of UK electricity demand.
Hydro electricity is the more conventional but the cheapest source of electricity in UK with their construction of dams paid off. Hydro electricity is produced from the flow of rivers and streams through small low head hydro electric turbines as well as larger hydro electric dams.
In addition to the options detailed above, the UK has significantly quite enormous solar energy potential. Individual households and dwelling units can harvest this energy via well insulated passive solar houses. These houses are designed with lqarge south facing windows that can trap solar heat. Solar energy can be converted into electricity via solar photovoltaic cells. While it is well known that solar energy in the form of photosynthesis is the basis of animal and plant life, harvesting of energy crops can be potentially a great source of energy known as bio-fuels. Bio-fules can be obtained in solid, liquid, as well as gaseous forms. Ethanol and bio-diesel in liquid form can be used in transport, and methane gas or solid wood can be used for heating or producing electricity. A major source of new energy can be sourced from short rotation 'coppicing' of rapid growing willow or poplar. The wood chips can be placed in a gasifier plant to produce hot gases. Electricity producing gas and steam turbines run on these hot gases.
While industrial and household wastes can be used to produce electricity, there are environmental concerns over emissions from such wastes. Whether waste can strictly be categorised as renewable is debatable. While geo-thermal heat is a great source of energy, collecting heat from such deep underground sources cannot be strictly speaking placed under renewable, for geo-thermal wells can get exhausted. However, 10% of UK electricity requirement can be met from deep underground dry hot rocks.
At present, the UK obtains around 2% of its energy needs from renwable sources. The major contribution among renewable sources is of large to medium scale hydro-electric plants. However, there still exists potential for expansion of medium and small scale hydro electricity, but the major focus is currently being put on wind and waste projects. Next to wind and waste, energy crops have received the attention of the government. The other potentially significant sources of energy like offshore wind, wave, and tidal energy deserve equal attention but the government at the moment seems to have relegated them to the long term category on the basis of cost involved in their development. However, we cannot afford to ignore them indefinitely especially in view of the advantages the nation have in developing these sources as well as the UK’s maritime history and off-shore engineering expertise that can be applied with relative ease.