Renewable adj. & n.
adj. 1. able to be renewed; 2. (of a fuel source or energy) not depleted by utilization.
n. a renewable fuel or source of energy.
The key to all renewable energy use is the reduction of carbon emissions. Carbon dioxide in the atmosphere is widely attributed as a major cause of global warming.
The use of renewable energy sources is a massive topic, open to much debate. Here I have tried to provide an introduction to the main technologies and suggested further reading.
At a time when global warning has been acknowledged by many as a major threat to our existence and the Earth’s natural resources are running out, renewable energy sources represent a cleaner, greener, sustainable solution…
Photo Voltaic Cells – ‘Solar Panels’
Generate electricity through the action of sunlight falling on a reactive surface. On a bright, sunny day, the sun shines approximately 1,000 watts of energy per square meter of the planet's surface, and if we could collect all of that energy we could easily power our homes and offices for free. Solar cells produce direct current electricity from light, which can be used to power equipment or to charge a battery for later use.
http://www.howstuffworks.com/solar-cell.htm
http://www.nef.org.uk/greenenergy/solar.htm
Solar Water Heating
Probably the most cost effective solution for most homes. Water is pumped through a bank of heat exchangers mounted on your roof. As the water passes through these ‘finned pipes’ it is warmed by the Sun. In warm climates, a solar heating system can provide a very high percentage (50-75%) of domestic hot water energy. In the UK, solar water heating can provide almost all of your hot water during the summer months and about 50% year round.
http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2007/05/21/easolar121.xml
Wind Turbines
The most controversial of the renewable energy sources due to their size and the need to locate them in areas of high winds, typically moorland and hillsides. The use of offshore wind farms has been suggested as an alternative and less intrusive solution. It is now possible to buy small wind turbines for your home, although the return is relatively small and is best combined with other alternative technologies.
http://www.bwea.com/ref/faq.html
http://www.bbc.co.uk/climate/adaptation/wind_power.shtml
http://www.lowcarbonbuildings.org.uk/micro/wind
Wave Energy
Waves, particularly those that have travelled across large distances of open ocean, hold a massive amount of energy. Some research suggests that less than 0.1% of the renewable energy within the world’s oceans could supply more than 5 times the global demand for energy!
The Atlantic coasts of the UK are ideally located to take advantage of this method of energy production. The first commercial wave power station has been built on the island of Islay and is capable of generating enough electricity to power 500 homes.
http://news.bbc.co.uk/1/hi/sci/tech/1032148.stm
At the other end of the country, the Wave Hub is a proposed ‘socket’ to be sited 10 miles off the coast of St Ives in Cornwall. A variety of different technologies can then
be plugged in to the hub for testing.
http://www.sas.org.uk/campaign/climate_chaos/clean_and_offshore_energy.php
http://news.bbc.co.uk/1/hi/england/cornwall/3477639.stm
http://www.southwestrda.org.uk/news/release.asp?ReleaseID=1450
Tidal Energy
Differs from wave energy in that the regular rise and fall of sea levels within the tidal range is used to turn turbines and generate electricity. Up to 20% of the UK’s energy needs could be met using tidal power. The difficulty is in harnessing this power and converting it into electricity. At present only France has an active tidal power generator - the 240MW La Rance experimental tidal power plant in Brittany (which has been in operation for over 40 years).
http://www.esru.strath.ac.uk/EandE/Web_sites/01-02/RE_info/tidal1.htm
http://www.reuk.co.uk/La-Rance-Tidal-Power-Plant.htm
Geothermal Energy
The temperature underground remains at a more constant, and warmer, level than on the surface. By pumping water to a depth of approximately 15m it is warmed and can be used to heat buildings efficiently. Up to 80% can be cut from electricity bills. In volcanic regions such as Iceland extreme heat close to the surface can be used to produce steam, drive turbines and generate electricity.
http://www.reuk.co.uk/Introduction-to-Geothermal.htm
http://www.bbc.co.uk/climate/adaptation/geothermail_energy.shtml
Biomass
Biomass is a collective term for all plant and animal material. A number of different forms of biomass can be burned or digested to produce energy. It is a carbon neutral process as the CO 2 released when energy is generated from biomass is balanced by that absorbed during the fuel's production.
Sweden has the world's first biogas powered train running along the 75 mile coastal stretch between the cities of Linkoeping (south of Stockholm) and Vaestervik (Eastern Baltic). "Amanda", as the train is named, has been carrying passengers since summer 2005. Currently 25% of all energy use in Sweden is derived from biomass and the country intends to become carbon free by 2050. All the buses in Linkoeping are already powered by biogas.
High street retailer Marks and Spencer has announced plans to become carbon neutral within 5 years. As part of the plan it intends to trial using waste food to help heat some of its 500 stores using anaerobic digestion to generate biogas.
http://www.nef.org.uk/greenenergy/biomass.htm
http://www.biomassenergycentre.org.uk
http://www.energysavingtrust.org.uk/generate_your_own_energy/types_of_renewables/biomass
What can you do?
Whilst installing solar water heating or a wind turbine may not be to everyone’s taste, there are other steps that you can take to reduce your carbon footprint.
Change to a green tariff with your energy provider.
Properly insulate your home.
Turn off electrical equipment, don’t leave it on standby.
Turn off lights as you leave a room.
http://www.reuk.co.uk
http://www.energysavingtrust.org.uk
http://www.ecotricity.co.uk
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