Environmental Engineering Reference
In-Depth Information
This makes it diffi cult for most of us to imagine that renewable energies will be
riding to the rescue of the environment in a few years. In reality, however, renew-
able energies already constitute over 99% of German energy resources if one looks
at the complete picture of energy use.
Winston Churchill supposedly said 'Do not trust any statistic that you did not fake'.
It is widely believed that fossil fuel sources cover the lion's share of our energy
needs. At least this is what all the usual statistics on energy claim. But it is only
true if we defi ne our energy requirements in a very narrow way.
The heat of a radiator, the light provided by a conventional light bulb and the driving
energy of a ship's diesel engine generally form an integral part of our energy
requirements. What is not included in any statistics on energy is the warming effect
of the sunshine streaming through windows, the sunlight that illuminates houses
and streets so that artifi cial lighting can be switched off during daylight, and the
wind that can propel sailing boats right across the Atlantic. A heated greenhouse
that uses artifi cial light to grow useful plants is included in the statistics on energy;
on the other hand, a covered early planting of vegetables that uses only natural
sunlight is not included. The fl oodlight illumination of a stadium during an evening
football game falls under our energy needs. If the football game takes place in the
bright sunlight, the statistics on energy will claim that the football arena that is
brightly lit up by the sun actually does not need any light. If we switch on snow
blowers to compensate for the ever-decreasing amount of snow available in ski
areas, this becomes a case for the statistics, whereas natural snow is not. When we
fi ll our drinking water storage containers using electric pumps, we have to pay for
the energy used. If rain fi lls the storage containers, this is not considered in the
statistics. The high amount of electricity needed to run electric dryers also increases
energy use. On the other hand, if the washing is dried by the wind and the sun on
a conventional clothesline, this does not constitute an energy need as far as the
statistics are concerned.
Natural and technically unconverted forms of energy are not a component in our
energy requirements in a conventional sense. Yet it should not make any difference
where we derive the energy needed to heat our bath water, grow our plants or
provide light. We take the availability of natural renewable energy forms such as
solar energy so much for granted simply because they are there anyway and thus
appear to have so little value that they do not even merit mention in the statistics.
However, this distorts our impression of our energy requirements and puts the pos-
sibilities of renewable energy in a false light. This can be illustrated using the
example of energy consumption in Germany.
Germany covers an area of 357 093 km 2 and the annual solar radiation is on average
1064 kilowatt hours per square metre. Germany therefore benefi ts from 380 trillion
kilowatt hours of energy from the sun each year. This is about 100 times as much
as the primary energy consumption recorded in the statistics for Germany and even
more than the entire primary energy needs of the world. Part of this radiation heats
the earth and the air; another part is converted into plant growth, thus producing
biomass.
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