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20 November 2009
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Is it possible to mitigate the effects of man-made climate change? It
would be very difficult in the long term and impossible in the short.
If, by some miracle, it were possible to stop all use of fossil fuels
today, it would take centuries before the greenhouse gas levels were
down to 1980 levels. This is partly due to depletion of natural sinks
because of deforestation and urban sprawl, increased methane emissions
from rice paddies and landfills etc. and partly due to recycling
sequestered carbon dioxide in biomass burning etc.
If we wished just to keep it at its present level, we would have to
reduce fossil fuel consumption by about 58 per cent. Even then, it would
continue to increase for several decades before stabilising back down to the
current 385 ppm in the atmosphere.
There is no miracle cure!
I propose, in this essay, to skim through what needs to be said, without
going into much detail. Although this introduction concerns the global
problems, where possible, I'll mention the issues within the Cyprus context. If you wish to know more about a particular aspect,
then please use the Search box under the logo (top left of this page); the
chances are that the subject has been treated elsewhere on this site.
Fossil fuels
We must reduce fossil fuel use as much as possible, whether it be
natural gas, oil or coal, for all applications. Do not be misled into
thinking that any of the fossil fuels are better than any of the others,
in terms of greenhouse gas emissions. The overall emissions are quite
similar in terms of the energy produced by their combustion. It is true
that natural gas is better than the others for concomitant pollution but
not for greenhouse gas emissions when viewed holistically.
The three major applications for fossil fuels electricity generation,
transport and heating. I shall briefly discuss each of these
applications in turn, showing the various means of mitigation.
Electricity generation
There are various ways of reducing the emissions from fossil fuels
used for generating electricity. The most obvious one is to reduce the
consumption of electricity by careful management and the use of energy
saving equipment and appliances. This can be easily done in both
industrial and household applications.
The other methods depend on substituting the electricity generated by
means which do not permit fossil carbon dioxide to be emitted. There are three basic
methods for doing this:
- constant renewable sources
- variable renewable sources
- nuclear power
The constant renewable sources may include hydroelectric generation,
biomass fuels, waste-to-energy power plants and, possibly, variable
renewable energy in cases where the energy may be stored. These are all
characterised by the possibility of generating electricity 24/7 with
pauses only for maintenance. In the Cyprus context, only waste-to-energy
plants are feasible and, indeed, are to be encouraged.
Variable renewable sources are sometimes called intermittent,
although this implies all or nothing, whereas many of them produce
electricity at anything between zero and full capacity. The most common
ones are wind, solar and tidal. Because the output is variable, they
cannot be used by themselves where a constant supply is necessary. At
the best, they have to be backed up by some constant means which can be
brought online as required. It should be noted that wind generation, in
particular, is especially liable to sudden changes in output, even over
large areas of wind farms. In addition, it is relatively rare for the
average wind farm to produce more than about 20 to 30%, sometimes as low
as 10%, of its
theoretical capacity, averaged over the year, except in particularly
favourable locations. It is quite common for proponents of variable
renewable sources to suggest that it has a capacity of so many megawatts
when, in practice, it may only produce one-fifth or one-tenth of this power, averaged
over the year. In Cyprus, there are no sites which are likely to run at
more than about 10% of the theoretical capacity. A figure of 450 MW
capacity has been bandied around, so the average production is unlikely
to exceed 45 MW or less than 5% of average consumption. It is also important to note that, because of this
variability, electricity grids may become unstable with very sudden
changes if the background capacity of constant supply is less than about
80% of the total. The use of variable renewable sources generally
requires accurate forecasting of the quantity of electricity that can be
produced over a given period of time. As this often depends on
meteorological conditions, close cooperation with major forecasting
networks is necessary. This problem is particularly unfavourable for
Cyprus, with sudden and unpredictable changes in wind speed.
Solar energy would seem ideal for Cyprus. Unfortunately, the
photovoltaic system is too expensive and government subsidies are
largely insufficient to make it interesting for any but the most
altruistic property owners, as the pay-back time is longer than the
lifetime of the panels. Some noise has been made in recent months of a
mirror-tower solar thermal system with capacities mentioned of up to 1
GW. This is theoretically feasible but suffers from one problem. It
requires about 5-6 m² of more or less flat land (or with a suitable
slightly south-facing slope) for each kWe
of capacity and one can ask where there is a well-oriented 5-6 km² plot
of available land on the island, condemning it for any
agricultural use.
Nuclear power is the key method for electricity generation with
negligible emissions of greenhouse gases. This can be used by small and
large countries alike and, with third-generation power plants. safety
concerns can be overcome. There are two negative aspects, both of which
are more political than technical. Following Chernobyl, there is much
public concern over the safety from radiation. It need not be necessary
to mention that the Chernobyl plant was very primitive and the accident
was caused by human stupidity; this could simply not happen with
third-generation plants. The other problem is the disposal of nuclear
waste; again there is no technical reason why this cannot be done
perfectly safely. Both these problems really boil down to the "not in my
backyard" syndrome. Several countries which have been reticent about
nuclear energy have recently revised their ideas, because they realise
they have little alternative if they are to satisfy the needs of their
populations and their environmental commitments. It would seem unlikely
that a nuclear power station would be politically acceptable on Cyprus,
although a single EuroPR Generation IIIa plant would be the ideal
long-term solution; unfortunately, politicians never think beyond their
re-election after five years, i.e., in the short term, so let's forget
the ideal solution!
Transport
It is probably more difficult and costly to mitigate the emissions
from transport than from electricity generation. This often requires
political decisions and major changes of infrastructure to reduce the
number of road vehicles by the transport of goods and persons by rail,
rather than road. Such infrastructure is, unfortunately missing in
Cyprus. Both small and large countries require a concerted
public transport system to reduce the number of road vehicles. In the
current state of technology, road vehicles generally require liquid
fuel, the majority of which is from fossil sources. It is true that
small amounts of fuel from biological sources may be added but these are
not going to make reductions exceeding 10 to 20% and, even then, at the
cost of reducing the availability of food. Electric cars are not
generally feasible for mainstream requirements, as a major study
conducted in France has pointed out. In this country, we don't have
sufficient electricity reserve capacity to allow electric vehicles to
become mainstream, anyway. In any case, the overall efficiency
of using an electric car charged from electricity generated by fossil
fuels is lower than using fossil fuels in a conventional car of
equivalent performance and size, with increased emissions of greenhouse
gases. On the other hand, if the electricity is generated exclusively by
renewable or nuclear sources, then an electric car would be a feasible
solution provided that it had sufficient autonomy for its required use. In
the meantime, the best solution is a car specifically designed for
minimal emissions. This may be either the very small runabout for city use,
a hybrid car or a fuel-electric car. One important point that must be
considered is that there is never one solution for all problems. Some
people do require large four-wheel-drive vehicles for professional use
and there is a market for them. It would be desirable to have some means
to prevent or at least discourage people who have no real need for this
kind of vehicle from purchasing them, possibly by swingeing taxes except
for bona fide use.
Heating and air conditioning
Heating space, such as in houses, factories etc., and water consumes
vast amounts of energy throughout the world. It is probable that,
directly or indirectly, well over half these applications use fossil
fuels as the source of energy, with emissions of carbon dioxide - even
if this happens at an electricity generating plant a long distance away.
In most places, this is partially or completely unnecessary, at least
for modern constructions. In suitable places - and Cyprus is included
here, of course - heat can be supplied by
the sun, geothermically, waste heat from electrical appliances, waste
heat from industrial plants, including power stations, waste-to-energy
plants, future crematoriums etc. The secret is in the architecture of the
buildings which must be designed with thermal considerations in mind and
this means insulation and more insulation, as well as the optimisation
of energy capture. In places where additional heat is required, then the
most efficient and least polluting method is the heat pump, even when
the electricity is generated from coal or other fossil fuels.
For the anecdote, the house I live in is a fairly middle-class
standard type of house, whose construction was finished in 1997. I chose
one whose profile was as near a cube as possible, conscious of essential
heating costs in winter and cooling costs in summer. Because of earthquake
regulations, the construction is an anchored reinforced concrete
skeleton with the walls filled in with a single layer of air-gap bricks,
the whole rendered on both sides with cement. There is no insulation,
nor in the roof. The windows, including 6 French windows, were my
bugbear. They were 3-12-3 mm double glazed in 28 mm thick aluminium
profile frames, of sliding construction in more aluminium profiles, with
considerable air gaps. The outside doors were also badly fitting with
aluminium profiles. Our heating and cooling bills were stupendous.
Earlier this year, I took the bull by the horns and replaced all the
windows, French windows and outside doors with UPVC ones with 70 mm
multi-celled profiles and glass of 4-16-5 mm construction. The first thing
I noticed was that sound levels from external sources were a guestimated 30 dB lower,
testifying to the improved seals, as well as the thicker construction.
It is possibly early days yet, but my heating bills since they were
installed have gone down by between 40 and 50%, compared to the same
period for the previous year. The difference in air-conditioning costs
when it is 40°C++ outside remains to be seen. The
next step will be to insulate the roof, a rather major job. Hot water is
already solar for about 300 days/year. However, I permit myself to cite
this personal anecdote just to show how much energy (and carbon dioxide
emissions) can be saved by relatively simple modifications to a modern
"standard construction" villa which was designed with no thought to
thermal considerations.
Methane
Other than renounce the use of fossil fuel gas for heating
and cooking with its concomitant emissions back up to the well-head
(note that much LPG is separated from natural gas),
there is little that the individual householder can do to help reduce
methane emissions. Some vegetarian activists have suggested not eating
meat. Whereas it is true that raising animals for meat does cause
methane emissions, these are comparatively small to those from wild
animals. In any case, I have never seen these same groups suggest we
stop eating rice, even though rice paddies are the single worst cause of
man-made methane emissions, about on a par with natural wetlands.
There is one way that the householder can reduce methane emissions.
In the UK, it is estimated that 6.7 million tonnes of good edible food
are thrown away each year. There is little reason to believe that
proportionally similar figures do not occur in Cyprus. Buying only the quantity of food you can eat is the key along
with using leftovers. You can save a lot of money, too!
Another major cause of man-made methane emissions is the landfill. If
waste-to-energy techniques were more widespread, this would be a great leap forward
in mitigating this problem. Unfortunately, there is little that the individual can do
except use democratic means to pressure the appropriate authorities to implement such plants
to produce electricity and heat rather than send garbage to landfills.
In some countries, landfills are capped to capture some of the methane; this
is good when a landfill is finished with, but it is very difficult when
new garbage is being added. The same applies to industrial-scale
composting and animal litter treatment. Of course, any captured methane
is a non-fossil natural gas and is a valuable source of energy.
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