7/29/2019 Powering Britain's Next Century
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POWERING BRITAINS NEXT CENTURY
NuclearThis method uses controlled nuclear reactions to generate
power. It
does not produce CO2 emissions or air pollution but it is not
considered
a green or renewable power source because it relies on
radioactive
materials for fuel and produces radioactive waste.
Nuclear fission is used in all existing nuclear
power plants. During a fission reaction
heavy nuclei are split into lighter ones byneutrons; this
releases energy and more
neutrons. Energy from the reaction heats
water into steam which is used to turn tur-
bines and generate electricity. The reaction
is controlled by moderating the amount of
neutrons present.
Currently, nuclear power generates 13% of Britains electricity.
Other
European countries like France produce a much greater proportion
of
their power in this way. The technology has the potential to be
Britains
major source of energy but this will require a large investment
in
infrastructure and expertise. Nuclear power may become the
national-
level power supply.
Britain faces a challenge. The national grid today is powered
mainly by
dwindling fossil fuel reserves. The coming century brings
increased
prices for scarcer supplies coal, oil and gas and also a growing
sense that
it is inappropriate for a developed nation like Britain to be
polluting the
environment and consuming irreplaceable resources when it is
well-placed to do otherwise.
The path is clear; Britain must undergo a revolution in power
generation.
Alternatives to current electricity supplies must be found a nd
exploited -
not as an addition to the existing grid but as a replacement
suitable for
the 21st
Century. The path will not be easy. Looking back from the end
of
the next century, the conversion from fossil fuel to renewable
sources of
energy may appear as significant as the industrial
revolution.This report is intended to form an early
step on that path. A range of possible
energy sources are analysed to see how
suitable they are for use in Britain and
how much of the electricity demand
they can supply. The ultimate aim of this
project is to develop a vision for
Britains next power solution.
Britains current electricity consumption is about 400 terawatt
hours a
year, supplied mainly by coal and gas combustion, supplemented
by
nuclear, hydroelectric and imported energy.
BiomassRenewable energy can be created from biological
materials, typically
plant matter. Energy is usually produced as heat or electricity.
Britain
mainly uses thermal conversion - burning material in air
(aerobic
digestion) or in the absence of air (anaerobic digestion) - but
biomass
can be processed in various other ways including chemical and
bio-
chemical.
Biomass generation is renewable in the sense that the material
con-sumed is easily replacedfor each tree burned in a bioreactor an
new
tree can be planted. Unlike burning fossil fuels biomatter
combustion is
carbon neutral.
Different types of biomass reactions have
different products: Bio-fertilisers are
created in mesophilic reactions occurring
at low temperatures. Gas is created using
faster thermophilic reactions above 50
degrees centigrade. Fuels like ethanol
which may replace fossil fuels in motor
vehicles can be produced by alcohol
fermentation of liquid from the biomass.
GeothermalA home uses 20% of its energy budget on heating space
and water.
Commercial buildings can use even more. Geothermal technology
can
supply some of this energy and reduce the demand on the national
grid.
Geothermal boreholes make use of heat energy stored deep in
the
Earth. Boreholes can be up to 80m in depth but are customised to
the
place of installation.
A small amount of electricity is used torecoup a larger amount
of heat energy
from the Earth. This works by using a
pump (the only power needed) to
circulate a liquid down a pipe in the
ground. The liquid is heated by the Earth
and is returned to the surface.
Heat from the ground is exchanged to a system where, through the
use
of a refrigerant and increased pressure, the temperature is
increased.
Energy is transferred into the building where it can be put to
use in the
heating system. Using geothermal power this way can reduce
the
heating energy cost of heating a home by up to 80%. This equates
to a
total saving of energy of 16%.
HydroelectricThere are many ways to generate hydroelectricity;
almost anywhere that
water flows can be a source of power. Britain has access to
many
suitable sites mainly in the sea and along the numerous rivers
and
streams.
Different technologies are appropriate
for different sites; the Pelamis water
snake (right), for example, is a surface
following device that generates power
from the motion of the waves. Inland,
a reverse Archimedes screw can be
employed on weirs this is a simple
technology in which the falling water
rotates a screw that turns a
generator to produce electricity.
Hydroelectricity is a clean, renewable and versatile power
solution.
Britain, unfortunately, has few opportunities for large-scale
installations
like the USAs Grand Coulee Dam so it is unlikely that
hydroelectricity will
ever supply as much power as nuclear generation can.
Hydroelectricity is
recommended as a region-level power solution.
If coal and gas power stations are to be totally replaced, all
of the
technologies looked at here will need to be utilised in parallel
in order to
meet Britains electricity demand of 400 terawatt hours a year.
Of the
technologies that are available today only nuclear power has
the
potential to form the backbone of Britains national grid by
reliably
supplying a large amount of power.
This does not mean nuclear power is the only answer;
hydroelectricity
and wind power produce large amounts of electricity but due to
their
reliance on location and their unreliability in day to day
production only
provide a regional supplement to national electricity
production.
Biomass has a range of applications including creating carbon
neutral
fuels for motor vehicles but, again, is limited in scale of
production. Solar
power and geothermal provide buildings with heating and
electricity at a
residential level reducing demand on the national grid.
Britains impending energy crisis can be solved using a
combination of
the technologies discussed here to provide a reliable 21st
century power
solution.
WindWind power is a simple, clean, renewable technology. The
energy of the
wind is used to generate electricity by turning a dynamo. Today
wind
turbines are an increasingly familiar sight but how much can
wind con-
tribute to powering Britains next century?
A single wind turbine can generate 2MW of power. A farm of 40
turbines
can supply 290 GWh to the grid in a year. There are many
locations in
Britain with suitable weather for wind farms, particularly
coastal areas,
north Wales and Scotland.
Being dependant on the weather, wind
power is intrinsically variable. Reliabil-
ity of wind generation is improved as
infrastructure is spread over a wider
area. Regions with less wind at any
one time will average out with those
that have more wind.
Wind power has the potential to provide power at a regional
level as an
addition to nuclear generation. Wind can in turn be supplemented
at the
household level by solar and geothermal s olutions.
SolarSolar power harnesses energy from the
sun in the most direct way possible. We
can achieve this with a photovoltaic
cell. Using the photoelectric effect the
cell uses the energy carried by photons
to excite electrons in a semiconductor.
By doping the semiconductor we can
create and control a flow of electronsto generate
electricity.
Efficiencies are currently low in practical applications
(15-25%) but as
research continues the technology behind photovoltaics is
constantly
improving. Under lab conditions efficiencies of 40% have been
achieved.
Though Britain only gets 60% of the light intensity seen at the
equator
there is still enough s unlight to generate significant
quantities of power;
using current technology as much as 40% of a homes electricity
needs
can be supplied.
Solar power can provide a residential supplement to power
supplied at
the national and regional levels.
Daniel Brady Karl Golding Matthew Haynes Miran Ladwa Colin
MacRae Bevan Rowlands Supervised by Prof. R.J. Newport
Spring 2010
Implementation level Power source
National Nuclear
Regional Hydroelectric, wind and biomass
Residential Solar and geothermal
