How Realistic is the Potential of Renewable Energy?
Donald Bruce and David Pickering
Contents
The Potential of Renewable Energy
Some Drawbacks of Renewable Energy
Economic Barriers
SRT's Other Energy Pages
Further Information about SRT
How Realisitic is the Potential of Renewable Energy?
In contrast to fossil and nuclear fuels, renewable energy offers
alternative sources of energy for the future that will not run
out, which in general add little to the pollution and waste
problems caused by fossil fuels, without the risks attendant on
nuclear power. The major sources are:
- hydroelectricity, which is the only source currently used to any great extent in Europe
- electricity from wind, waves and tides
- heat from wastes from various natural and man-made sources
- heat from geothermal reservoirs in the earth's crust
- energy crops, either for direct combustion, or to produce synthetic fuels from biological systems such as oil seed
- solar energy, either converted into electricity, or used as a heat source, e.g. for hot water
Apart from hydro and wind, most of these renewable resources are at a
relatively early stage of development, compared with fossil
fuels. This makes it difficult to make accurate judgements
about the scale of their potential. This is reflected in the
large variations often found in published estimates of the
amount of energy obtainable from renewables. Optimistic
predictions claim that they could meet as much as 60% of the
world's energy needs. Norway has been able to develop hydro
resources on a scale sufficient to produce over 40% of their
energy, but even this is not 100% or even 60%. More cautious
estimates speak of renewables meeting 10-20% of the energy
requirements of certain countries which have significant
renewable resources, such as the UK.
It is most important to
appreciate what assumptions are being made in such estimates,
and whether they refer to percentages of total energy or just of
electricity. The variations depends, in part, on the criteria
applied for what is meant by "potential". Typically there are
three different meanings:
- the maximum theoretical potential - simply based on how big the resource is, before taking other factors into consideration;
- the accessible potential - considers how much of the resource it is technically possible to use taking account of only the most basic constraints, e.g. geography, intermittency;
- the realistic potential that is achievable in practical terms allowing for the planning, economic and social constraints in place or which are likely to prevail.
When the second two are taken into account, the realistic
potential of a given renewable resource may be dramatically
lower than its maximum theoretical potential. This must be
borne in mind in assessing the realistic potential for
renewables. Nevertheless, it is clear that there is a large scope to deploy
renewable energy in Europe, both in natural resources and in the
technological expertise to develop it.
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Before considering how this may be realised, we must be careful, as with fossil and
nuclear energies, not only to look at the advantages, but also
to consider the drawbacks as well. Some of these are listed
below.
Type of Energy Produced
A large number of the renewable energy sources under development
produce electricity rather than heat or prime fuel. Although,
we can anticipate some of the switching to electricity, the
greatest long-term need is to replace the direct burning fossil
fuels to provide primary heat or power. Generally, the main
renewables which are capable of meeting this need are biomass
and burning waste. These would need to be deployed on a vast
scale to replace our current use of fossil fuels.
Renewables as "Dilute" Energy
Renewables are, in general, a much more dilute form of energy
than the chemical energy in fossil fuels and especially than
nuclear energy. Consequently, to get an equivalent amount of
renewable electricity produced to, say, a 1000MW power station
needs a large number of separate installations, for example a
very large area of wind generators.
Environmental and Safety Impact
Although renewable energy sources are generally thought of as
"clean", naturally they all make some environmental impact. The
most familiar example is large hydroelectric dams, which change
the character of the local visual environment, interfere with
water courses, wildlife habitats, and sediment and mineral
deposition patterns downstream. Tidal power has similar
problems. Depending on location, dam failure can also present a
safety and environmental risk - like a nuclear accident, rare,
but with devastating consequences. Wind power needs
installations in exposed areas which, by their nature, are often
areas associated with beauty. Impacts that are small at the
level of a single unit, unlike the noise of a wind turbine or
risk of blades shearing off, can assume significant proportions
when you multiply the number of installations to, say, thousands
of units. Offshore wind or wave power carry the risk associated
with major offshore installations. Broadly speaking, the less
energy you have bound up in a resource, the less its impact, but
also the less is its usefulness. Thus, small scale hydro,
run-of-river schemes impact minimally, but they also produce
proportionately less electricity.
Geographical and Seasonal Factors
Several sources, notably wind, waves, tidal and solar, are
either intermittent by nature, or vary greatly according to time
of day or season. Since large scale energy storage technology
is still very difficult, notwithstanding the amount of research
resources devoted to it, this restricts how much we can rely on
these sources, for example on a still, freezing cold, winter's
night! Many sources of renewable energy are also limited by
geographical factors (e.g. exposed places for wind, hot rocks
within reasonable reach of the surface for geothermal,
mountainous terrain for hydro) and are often remote from the
major centres of demand, requiring extensive power lines.
Gaseous Emissions from Heat Producing Renewables
Many of these do not add to the greenhouse effect either because
they return the same CO2 to the atmosphere which had the same
biological system had absorbed, or the same CO2 would have been
produced by decay of wastes anyway. But CO2 emissions are still
involved, if our aim is to reduce emissions as fast as possible.
In some cases, such as burning municipal, industrial and some
agricultural wastes, care must be taken to minimise the toxic
products being released.
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After taking account of these disadvantages, we still have a
great, and largely untapped, potential for energy sources, which
removes many. The major problem facing renewables is that of
economic barriers. They tend to be capital intensive, so often
compare unfavourably in cost terms with existing fossil sources,
especially when operating in a privatised energy market. Open
markets tend to favour a fast return on capital which acts
against most renewable energy sources, which are capital
intensive, and often still need significant development work.
Another economic barrier which ought to be mentioned is the
unequal distribution of R&D subsidies. Temporary instruments
have been introduced to encourage niche markets for renewables
to be developed, but these are generally short-to-medium term
only. As such they are insufficient to make the scale of
deployment of renewables which we have concluded is needed. To
enable some of the more capital intensive sources such as tidal
or wave power to be exploited, either costs will have to fall or
substantial very long-term subsidies be given.
This raises the problem that renewable sources are viewed by
many as competing in an unfair climate against conventional
fossil fuels. One of the benefits of many renewable energy
sources is their low impact on the environment, but this benefit
cannot be utilised economically because the polluting effects of
fossil fuels are usually not subject to a charge. For example,
the real cost of fossil fuels should include the environmental
impact of acid rain and global warming, but these are not
included in the pricing. Such costs are, of course, notoriously
very difficult to allow for, but the real problem is the
political and economic penalties incurred in imposing them. Not
only would fuel bills soar, but trade would suffer unless other
comparable action was taken by international competitors. Yet
without making such a true costing, renewable sources are
unlikely to obtain the market share needed to displace
conventional fossil fuel sources, and so begin to address the
second main problem we face in achieving a policy of sustainable
energy for Europe.
Conclusion on Energy Policy
The real question is not "What is the policy that will answer
all our environmental energy problems?", but rather "Which
combination of benefits, costs and risks do we want to accept?"
How we answer this question is vital and urgent, as it will
affect our lives and our environment for generations to come.
This article is an extract from a report entitled "The Dominant Economic Model and Sustainabel Development - Are they Compatible" produced by a working group of the European Ecumenical Commission for Church and Society, in Brussels. It is copyright, European Ecumenical Commission for Church and Society, 1996. This extract was written Donald M.Bruce and David Pickering. To reproduce all or part of this article, please write or email the Society Religion and Technology Project of the Church of Scotland for permission, at our address below.
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This page has been produced by the Society Religion and Technology Project of the Church of Scotland. For more about our work on other issues, see our Other SRT Project pages, or our SRT Publications List.
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This page was last revised on 4 January 2000
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