What is green electricity?
Have you ever stopped to think about where
your electricity comes from? In the UK about
two thirds of our electricity is generated by
burning coal and gas in power stations. This
releases millions of tonnes of carbon dioxide,
the main gas responsible for climate change,
every year. The other third of electricity mainly
comes from nuclear power, which has other
worryingly severe environmental impacts.
‘Green electricity’' means electricity produced
from sources which do not cause these
impacts upon the environment. Of course,
every type of electricity generation will have
some impact, but some sources are much
greener than others. The cleanest energy
sources are those which utilise the natural
energy flows of the Earth. These are usually
known as renewable energy sources, because
they will never run out.
Wind power
The winds that blow across the UK can be
harnessed by turbines to provide electricity.
Wind turbines sited in suitable locations
already provide a small, but growing
percentage of the UK's electricity, and are
used successfully all around the world. In fact
wind power is one of the world’s fastest
growing energy sources! Wind turbine
technology has greatly improved over the last
ten years, making wind turbines quieter and
more efficient so that electricity generated
from the wind is now often competitive with
traditional coal-fired and nuclear power
stations. Wind turbines are also beginning to
be built at sea — in the future much of our
electricity could come from these offshore
windfarms.
Solar power
Many people believe that we don't get much
solar energy here in the UK. In fact solar
power is already being used to provide
essential power for many types of equipment
being used in both remote and urban areas
across the country. A solar photovoltaic (PV)
module works by converting sunlight directly
into electricity (even on cloudy days) using
semiconductor technology. The vast majority
of solar modules available today use ‘waste’
silicon from the computer chip industry as the
semiconductor material. They can be
integrated into buildings and even made into
roof tiles virtually indistinguishable from
normal tiles.
Solar energy can also be used to heat water
directly using specially designed collectors.
Even in winter a useful amount of hot water
can be produced from roof top collectors. A
third way to use solar energy is simply to
design buildings to make maximum use of the
sun. Using this so-called 'passive solar'
approach, much of the energy that we
currently use for heating, lighting and air
conditioning can be saved.
Hydro power
Water turbines have been used to provide
electricity for over 100 years and presently
provide over 1% of the UK’s electricity.
Although most of the possible sites for large
hydropower stations in the UK have already
been developed, there is a large potential for
smaller schemes. These can either use a small
dam or work as a 'run of the river' system
which has a minimal impact on the local
environment.
Wave power
Britain is blessed with some of the most
powerful waves in the world. Many different
devices have been designed over the years to
try and capture some of this huge energy
resource. With the proper support, wave power
could provide a significant proportion of the
UK's electricity needs in the future.
Tidal power
Tidal power has been used in Britain for over
a thousand years — at the time of the
Doomsday book over 5,000 tide powered mills
were recorded. Unlike other renewable energy
sources, which depend on the weather, tidal
power is as predictable as the tides
themselves. One way to capture tidal energy is
to build a barrage across an estuary, storing
water behind it as the tide rises and then
releasing the stored water through turbines at
low tide. Several sites around the UK could be
suitable for this type of tidal system, the
largest being the Severn Estuary. Another way
is to use ‘marine current turbines’, which work
like underwater wind turbines, harnessing tidal
currents instead of the winds.
Geothermal
Geothermal energy comes from hot rocks deep
underground. In some parts of the world steam
comes to the surface and can be used to run
steam turbines to produce electricity directly.
In other places water can be pumped down
and heated by the rocks to make steam.
Geothermal energy can also be used to
provide hot water and heating for buildings.
Biomass
Either agricultural wastes or specially grown
plants can be used as a fuel to run small
power stations. As plants grow they absorb
carbon dioxide (the main gas responsible for
climate change) which is then released when
the plants are burnt. So using biomass does
not add any extra carbon dioxide into the
atmosphere. Specially grown 'energy crops'
provide not only an environmentally sound
source of electricity, but also an important
new opportunity for farmers. However, there
are concerns about the sustainability of
sourcing biomass from countries where forests
are being cleared to make way for fast growing
plants that are then used as biomass.
Landfill gas
As rubbish decomposes in the landfill sites
where our household waste is dumped, it gives
off methane gas. This gas can be captured and
burnt in a gas turbine to produce electricity.
Burning the gas does give off carbon dioxide
but since methane, which is emitted from the
landfill site, is in fact a much more powerful
greenhouse gas it is better to burn it than to
allow the methane to escape into the
atmosphere. There are already many landfill
gas systems operating in the UK.
Waste incineration
The UK generates an enormous amount of
waste, and space at landfill sites is quickly
running out. The best solution would be to
recycle as much of the waste as possible, but
instead incinerators are being constructed to
burn the waste. In some cases the energy is
being used to generate electricity. However
many environmentalists are still concerned
about the emission of harmful dioxins and
also about the loss of a valuable resources
that could have been recycled.
Green Electricity Marketplace (GEM) receives
referral fees from some electricity suppliers. It
is not associated with any general switching
site and is committed to promoting renewable
electricity through the provision of information
and independent assessment of Green
electricity tariffs.
We aim to provide accurate and up-to-date
pricing, but given the volatility of the
electricity market, please confirm current
pricing with your chosen supplier.
