Renewable Energy
Renewable energy utilises natural resources such as sunlight, wind,
tides and geothermal heat, which are naturally replenished.
Renewable energy technologies range from solar
power, wind power, and hydroelectricity to biomass and biofuels for
transportation.
Climate change concerns, coupled with high oil
prices and increasing government support are driving renewable
energy legislation, incentives and commercialisation. EU leaders
reached agreement in principle in March 2007 that 20% of energy
should be produced from renewable sources by 2020. In relation to
house building, the following technologies are the most
relevant:
Wind power
Wind can be used to run turbines. Modern wind
turbines range from around 600kW to up to 5 MW of rated power,
although turbines with rated output of 1.5-3 MW have become the
most common for commercial use. The power output of a turbine is a
function of the cube of the wind speed so, as wind speed increases,
power output increases dramatically.
Solar power
‘Solar energy’ refers to radiant energy that
is collected from sunlight. Solar energy can be applied in many
ways, including the generation of electricity using photovoltaic
solar cells and heating water for domestic water and space heating
needs using solar-thermal panels.
Biomass heating
Plants use photosynthesis to grow and produce
biomass. Biomass can be used directly as a solid fuel or to produce
liquid biofuel. Typically biofuel is burned to release its stored
chemical energy. In domestic applications this would mean
purchasing locally sourced wood chip or pellets.
Geothermal energy
Geothermal energy is energy obtained by
tapping the heat of the earth itself and in domestic applications
usually takes the form of ground source heat pumps.
Combined Heat and Power (CHP)
CHP (or cogeneration) is the use of a heat engine or a power
station to simultaneously generate both electricity and useful
heat. On a domestic scale, where micro-CHP is used, instead of
burning fuel to heat merely space or water, some of the energy is
converted to electricity in addition to heat. This electricity can
be used within the home or business, or (if permitted by the grid
management) sold back into the electric power grid.