Julian_Boucher 18/6/09 08:42 Page 5
How do we satisfy our need for energy and sustain our environment?
measures 1,347W/m
2
, commonly known as the solar constant. The The remaining non-fossil alternatives, such as hydroelectric
global mean of solar radiation absorbed by surfaces averages at generation, geothermal generation and the incredibly broad-ranging
168W/m
2
. Existing techniques of solar energy conversion allow us to area of biofuels, have all seen commercial applications but have
convert densities as low as 20–60W/m
2
. This is the highest average lacked the large-scale development of the technologies behind them.
performance of any renewable resource, not forgetting, of course, Also, they often have geographically variable resources; for example,
that solar energy is indirectly harnessed in photosynthesis of plants, hydroelectric power contributes 99% of Norway’s TPES due to the
which can be used to manufacture biofuels. To give a sense of scale natural topography of the land and the rivers that flow over it. The
to this, an average household uses between 20 and 100W/m
2
. same goes for geothermal and Iceland. One non-fossil alternative,
nuclear, has had an unclear future, but it could well hold the key to
The technology most used globally is likely to be central solar power environmentally sustainable power generation for the future.
systems (CSPS), which see solar radiation concentrated to generate
superheated steam to drive a conventional turbine. They can be Fourteen per cent of global TPES comes from nuclear power
combined with conventional fossil-fuelled generation to cope with days generation (fission, fusion, fast-breeder, etc.), yet it looks set to be
with low sunlight and peak demand. Conversion efficiencies range completely eradicated in the not too distant future. Is this perhaps
from 20 to 30%, with peak power densities of 60W/m
2
of collecting unjust? The greatest obstacle nuclear power faces is public opinion,
surface. Solar energy is a very real and economically viable option for which has improved but is still not categorically in favour, and
the future, with naturally no consequences for the environment. In unfortunately for the future of nuclear power never will be for three
fact, the only problem is the same as that for all renewable energies: major reasons. The first can be pinned on two major events: the
transportation and potential storage, because places well-embellished Three Mile Island accident in 1979 and the Chernobyl disaster in
with any one renewable resource are often remote. 1986. Although a disaster on the scale of the latter is impossible in
a typical modern nuclear reactor, it still haunts the western world
The best locations globally for solar power are sparsely populated and has unfortunately been the centre of so many arguments
hot to arid areas where solar radiation is plentiful. This does mean against nuclear power. The second lies in the storage of waste and
the land is used efficiently, but the distribution of electricity from the third in the political impact of nuclear production in enabling
that area is likely to be costly and inefficient. Although largely fossil- countries to build up an entire nuclear arsenal. Despite the
fuel-based, a classic example of this is the national grid in the UK. production of no greenhouse gases, the fact that so many agree that
Energy is often redistributed from the north to the south of England it is the future of sustainable energy and immense energy densities
to meet varying demand. However, this is a very inefficient process (just 1kg of uranium can produce 50MWh compared with 3kWh/kg
and around 12% of electricity produced in the UK is lost in of coal), nuclear energy has begun an inevitable decline.
distribution partly due to this procedure.
Forecasts of energy futures have a manifest record of failure, so
The biggest boom in a single renewable’s production was seen in instead more general likely outcomes that together will enable us to
wind power. The now iconic tri-bladed wind turbine is seen as a satisfy our need for energy while shaping a sustainable future for the
symbol of the global ‘green’ movement. This is perhaps surprising environment will be given. Most statistics for energy are soaring:
given the very low power densities, inefficient energy conversion and efficiency, usage and new technologies. What is declining? Nuclear
very uneven distribution in both time and space of wind as a natural power stations and fossil fuel resources. These must be addressed by
resource. On top of this are the potentially harmful ultra-low- replacement technologies for nuclear, whether CCT, renewable or
frequency vibrations, although research is ongoing. just more fossil-fuelled stations. Fossil fuel resource decline will
arguably be halted by the price mechanism, but is most likely to be
In places averaging 450W/m
2
, such as is seen in North and South slowed by increased efficiency in energy conversion and the
Dakota in the US, machines with a 50m hub height would intercept increasing usage of renewable and alternative energies.
only 7 W/m
2
, and would then convert 25% of that and lose 25% of
that to blade soiling and wakes, ending up with a power output of No-one knows what lies ahead, although many people have tried to
approximately 1.3W/m
2
. Some more optimistic figures would predict it. What we do know is that human reliance on energy for
produce a figure a little more than double that. improving wellbeing will never cease and that reliance will have an
ever-increasing effect on the environment. There is no doubt that in
The other obvious problem with wind power is the wind turbines 20 years, 50 years, 100 years, the questions civilisation asks about
themselves. Structures up to 80m high and rotor diameters of 80m energy will be different. Efficiency will most likely be the next
protrude out of previously unspoilt landscapes and untouched seas. buzzword, and greater efficiency means a sustained environment in
Some may see them as an enhancement to a landscape, but the vast the future. It is instinctive for human civilisation to eradicate
majority see them as a visual intrusion on a much sought-after vista. inefficiencies and the overconsumption of resources, as we have
However, when concern is about the long-term integrity of the already seen with the renewable boom. So much power is held by
biosphere, this becomes decidedly unimportant compared with the the political authorities of the world that all that is needed is the will
environmental impact arising from fossil-fuelled generation. for the technologies outlined above to become a reality today, which
Certainly, wind power cannot be discounted from the future of takes determination from today’s political masterminds. We need to
energy production; almost the exact opposite is true – wind power stop predicting and questioning our future and start working with
conversions will become more efficient, construction costs will fall what we have, so that our next steps can be the first steps to a
and TPES can be ever increasingly supplemented by wind generation. brighter, more sustainable, more efficient future. ■
2009 SCHOOLS ENERGY AWARDS
5
Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27