A Beginners Guide to Renewable Energy Technologies
A large amount of the energy we buy today comes from fossil fuel and nuclear power. During the burning of these fossil fuels emissions are released into the atmosphere, which have a negative impact upon our environment. These include carbon dioxide – the main greenhouse gas that contributes to climate change and sulphur dioxides which cause acid rain. Both fossil and nuclear fuels depend on limited resources, often sourced from unstable parts of the world, and there are specific issues about the disposal of nuclear waste.
Renewable sources of energy do not contribute to climate change, produce acid rain or have the safety and waste issues of nuclear energy. Also they will not run out, offering a more sustainable option for our future energy supply. Most renewable energy sources are derived from the sun, including the direct use of solar energy for heating or generating electricity and indirectly such as energy from wind, waves and running water, and heat from the sun stored in the ground.
This website offers guides on how you might consider renewable energy on your farm, as well as summarising the main renewable energy sources that you can consider installing at home. There is an interactive "toolkit" to help you find the most suitable forms for your own home, or if you would like more information about a specific technology, you can follow the links below.
Solar Energy
Many buildings today are designed to utilise the energy of the sun as efficiently as possible, reducing but not eliminating the need for space heating using another fuel source. Natural daylight can also be brought into the heart of a building through light tubes (SunPipes).
This is known as passive solar design and is achieved by careful orientation of buildings, avoiding overshading from the winter sun and preventing too much summer sun that could cause overheating.
There are also two active forms of solar heating:
Solar Water Heating
This uses tubes or flat black pates to warm water that is generally used in the domestic hot water heating system. It can also be used, less commonly, to pre heat water for central heating, to heat swimming pools and solar thermal techniques can also be used in a warm air heating system, to pre-heat air.
Photovoltaic (solar electric)
Solar electric systems (often called PV systems) use the sun's energy to generate electricity directly, generally using special silicon crystals mounted in panels on a roof. PV can however also be incorporated into special solar tiles, or SunSlates, or bonded to a commercial roofing system. PV systems are quite expensive to install, but offer clean reliable electricity.
Heat Pumps
Heat Pumps can upgrade or downgrade the heat energy from the surrounding atmosphere to heat or cool a building or confined space. As both types extract the actual heat from the surrounding air or ground, the only energy used is that to pump the system or compress the air inside the heat exchanger, so it is possible to gain several times as much useful heat as the amount of energy used to drive the system. There are two types of system that are used in domestic situations:
Ground Source Heat Pumps
These use a collector loop (a pipe containing a mix of water and antifreeze) laid in a trench or down a borehole beside a building (or more rarely laid in a lake or river). As the soil temperature is relatively constant throughout the year below the ground's surface, they can extract low grade heat energy from the surrounding soil, and then convert it into useful heating in a heat exchanger inside the building. They are typically fitted in buildings with underfloor heating systems, which work best at relatively low water temperatures.
Air Source Heat Pumps
These take in air from outside a building and, similarly to ground source heat pump-s, extract heat energy from it to provide warm air inside the building. (They in fact work in exactly the same way as a room air-conditioner, but in reverse).
Biomass (Wood Pellets and Logs)
Biomass is carbon neutral because although carbon dioxide is emitted when the woody fuel is burnt, an equal amount is captured from the atmosphere when the fuel is grown. The two most common types for homes are wood pellets, which are a processed fuel that looks like cat litter and is made from compressed sawdust, and traditional wood logs. Pellets can be used in stoves and boilers that have automatic feeding and ignition, and so are almost as easy to use as a gas or oil heater. Logs need more effort from the user, but can often be bought quite inexpensively in rural areas. Logs can also be used in boilers or in specialist wood burning stoves; both are much more efficient than burning them in an open fire.
Wind Power
Wind turbines have become a common sight in parts of the UK over the past decade. At a smaller scale, it is possible to buy turbines that can be installed in a small area of open land, such as a smallholding, or to install micro-wind turbines that can be fitted to the gable of a house.
Small-scale Hydro-electric
Although most people associate hydro-electric power with large dams and power stations, it is also possible to have small systems that can be retro-fitted to an old mill pond or stream, or as a small "run of river" scheme.
Green Electricity
If it's not possible to generate your own electricity, it is always possible to buy "green" electricity that has been generated from renewable sources elsewhere. There are several competing products available, and not all are as green as they may seem, as it's not as simple as just buying electricity from someone who owns a wind turbine.
