Renewable Energy Technologies
Renewable energy refers to any energy source which is constantly replenished such as sunlight, wind, waves and geothermal energy, as well as energy derived from biomass.
Use of renewable energy sources can reduce dependence on fossil fuels and lower emissions of greenhouse gasses.
Renewable energy projects can be run effectively on a small scale and are ideally suited to community energy generation. The most common renewable energy sources used are:
The power of the wind can be harnessed to turn a turbine to generate electricity. The scale of these installations can vary depending on the setting or scope of the scheme. Small building mounted vertical axis turbines are now available which can be fitted to buildings for use in an urban environment. Wind speeds are affected by factor including height above the ground, and obstructions such as trees and buildings.
The concept of using water flows to generate force is not new, watermills have utilised the natural power of rivers for centuries. The energy of water, whether it is the flow of a river or tidal stream, or the movement of waves or the potential energy of water behind a dam can be used to drive a turbine and generate electricity.
The energy available in a water source is dependent on the flow per second and the head or height the water falls.
Hydro power installations require a permit from the Environment Agency as well as the usual planning permission.
The radiation from the sun can be captured and used to generate either heat or electricity using solar thermal and solar photovoltaic technologies. Panels can be mounted on buildings or on the ground. In recent years the price of solar panels has fallen as their efficiency has increased, making them more viable. They are also eligible for the feed-in-tariff. Suitability depends on the area of southeast or southwest facing roof or land on which to mount the panels.
Biomass covers a wide range of natural organic energy sources from food and animal waste used in anaerobic digestion to wood used to fire boilers or to fuel wood stoves.
Anaerobic digestion uses bacteria to break down organic matter in the absence of oxygen to produce biogas (methane) which can be burnt to power a turbine and produce electricity and generate heat.
Heat pumps work on the same principal as a refrigerator, only in reverse, so as to extract heat from the ground or the air to provide space heating for buildings.
Ground source heat pumps extract heat from the ground via a loop of pipe buried in the ground, filled with a mixture of water and antifreeze; air source heat pumps absorb heat from the outside air and can work at temperatures as low as minus 15 degrees.