The term ‘renewable energy’ is an all-encompassing term which describes energy that is not finite. The majority of our energy needs on earth right now are met by non-renewable sources, such as fossil fuels. Oil, coal and gas are all products of millions of years of biological decomposition; they are not infinite, and will eventually run out. Even nuclear power relies upon a finite supply of uranium, and therefore is not a ‘renewable’ source.
Renewable sources of energy are ever replenishing. The energy is produced by something that occurs naturally and constantly, such as the sun or the wind, or through something which can be sustainably managed such as fast growing crops or trees. Energy suppliers, such as British Gas and Npower, are utilising more renewable energy than ever before.
Here are our main sources of renewable energy, and some of the technologies we have developed to capture this energy:
Sun
The sun is a major source of energy all over the world. The energy from sunlight is converted into sugars through photosynthesis by plants, and forms the beginning of all terrestrial food chains on earth. Over the years, we have developed ways to capture this energy ourselves, and turn it into usable fuel for our homes:
Solar thermal: Solar thermal panels capture the heat from sunlight, even on cooler days, and use it to heat water for use in our homes.
Photovoltaic: Photovoltaic or PV panels use a chemical reaction to convert sunlight into electricity, which can then be used in a variety of electrical applications.
Passive solar gain: Capturing heat from the sun to use in our homes has been done for many years, simply by opening the curtains. However, housebuilders are now starting to build porches and conservatories facing south, purposefully to provide an area of solar heat gain for the house.
Solar energy is perhaps the most predictable and consistent source of renewable energy we have at our disposal, and the technology is the most accessible in terms of both suitability and affordability.
Wind
When the North wind doth blow, we shall have snow… and electricity! The UK occupies one of the best locations for wind power in the world, and is said to have more capacity for wind energy generation than anywhere else in Europe. All over the country, we are already harnessing the power of wind to generate electricity for our homes and communities.
Large scale wind turbines: Big, commercial wind turbines can be seen all over the UK. These monolithic giant windmills are often arranged in a group across a windy hillside, forming a wind farm which collects the energy of the wind. This electricity is sent to the National Grid and distributed around the country from there.
Offshore wind turbines: Even bigger wind farms can be seen out at sea, where the wind is much more predictable and constant, and where there are no obstructions such as hills, trees or houses. Again, this electricity is fed into the grid and then distributed around the country.
Small scale wind turbines: Smaller, privately owned wind turbines can sometimes be seen on farms, schools and at country estates. These shorter, smaller windmills will primarily supply the house or business they are owned by, although excess energy can be sent back to the grid.
Roof mounted turbines: For a while, householders were offered small roof mounted wind turbines for domestic energy supply. However, these were found to be ineffective, due to the disturbance to the wind flow caused by the building and surrounding obstacles.
Overall wind contributed around 17 per cent of our total electricity requirement during 2015, with most of this coming from the huge offshore wind farms which have recently been commissioned. Wind is, so far, not viable for the majority of domestic installations, but designs for new types of small turbines are being tested all the time, so in the future we may be able to enjoy these in our homes too.
Water
Water is another amazing source of free, untapped energy, whether it’s the ocean rushing towards the shore or the river flowing down from the mountains. Here are some of the renewable energy technologies we have developed to harness the power of water:
Wave generators: Numerous designs and technologies have been developed to harness the power of the constant rise and fall of the waves. However, many of these are not performing as well as had been hoped, although testing is still ongoing at the ground-breaking Cornwall Wave Hub.
Tidal generators: As well as the waves going up and down, the ocean is also predictable in that the tide will always rise and fall twice a day. So far, technologies to harness this energy are still being tested, with one of the biggest test sites in the world located at the European Marine Energy Centre (EMEC)in Orkney, Scotland.
Large scale hydroelectricity: Big hydropower plants have been around for decades now, and currently provide 1.3 per cent of the UK’s total electricity production. These systems use a dam to hold back a lake of water, forcing some of the water down a narrow pipe or outlet, where the force of it turns a turbine to generate electricity.
Small scale hydroelectricity: Some lucky householders are able to use hydropower in their homes because they have a river or stream running through their property. In this situation, they can use a purpose designed generator, also known as a micro hydro installation, to turn the kinetic energy of the stream into energy for the home.
Water source heat: If you have a body of water on your property but it is not moving fast enough for micro hydro, then a water source heat pump could be for you. These heat pumps take the small amounts of heat in contained within the water, and compress them into useful heat for your home.
Water is all around us, and useful energy is there for the taking, as soon as we figure out how. With plenty of research and development happening all the time in this field, there is no doubt that more water sourced renewable energy will be available in the future.
Ground
The ground under our feet holds many kilowatts of energy, in the form of heat. There are two main ways we have discovered to harness the heat energy from underground.
Geothermal heat: Geothermal energy is a hot topic right now and is being explored and exploited by many companies around the UK. In Southampton, a geothermal bore hole has collected heat energy and delivered it, via a district heating scheme, to numerous homes and businesses in the city. Stoke on Trent have recently announced plans for a £52 million geothermal district heating network, and the City of London are investigating using heat from the extensive ‘Tube’ network to heat homes around the capital.
Ground source heat pumps: More understandable, and accessible, for the layman is the ground source heat pump technology, designed to use used in the home. Here, coils of heat exchanger piping are laid either vertically downwards into a deep bore hole or horizontally over a large area of ground. The liquid in the pipes gains heat from the ambient heat of the earth, which is then compressed into useful heat for the home.
The possibilities for more heat to be extracted from the ground are endless, and are just starting to be explored now. With low carbon heating high on the government agenda, it is expected that many more solutions for ground sourced heat will be developed over the coming years.
Trees and plants
Trees and plants are, strictly speaking, not entirely ‘renewable’. While they can be renewed, via careful management, they are not completely self-renewing, and therefore a contentious topic. However, they are themselves carbon sinks, taking up as much carbon from the atmosphere during their growth as they do when they are burned, and so are described as ‘carbon neutral’ when sustainably managed. Collectively we call energy from plants and trees biomass, and there are many ways to use it around the home and business.
Biomass stoves: Biomass stoves can burn logs, woodchip or pellets. They are usually only used to heat one room in your house, unless you have a particularly well insulated and open plan dwelling. You can also install a back boiler to a biomass stove, which serves to heat hot water for the property too.
Biomass boilers: These boilers can be used in place of a typical oil or gas fired boiler, and provide heat for the central heating and the domestic hot water requirements. Again, you can choose whether to use logs, pellets or woodchip with these, although pellets arte typically the most efficient and easy to use.
Large scale biomass boilers: Biomass boilers come in many sizes, and can be used to heat whole groups of houses or blocks of flats if they are big enough. Large installations will need to use woodchip for the fuel.
Using biomass for heat is a good way to cut down harmful CO2 emissions, and to reduce the use of fossil fuels. However, it is important to ensure you have a good local supplier for your fuel, otherwise you could end up undoing all that good by having to have your pellets shipped from overseas or the other end of the country.
These are just some of the technologies which are available to harness the power of renewable energy. Many more products are being launched all the time, helping us to shrink our carbon footprint and live a greener life. These are exciting times for renewable energy, and the future will no doubt bring much more innovation and many more exciting products.