Geography Reference
In-Depth Information
of these lines, as well as the sites of the new converter stations needed to transform
high voltage direct current into alternating current, are being opposed by local resi-
dents, so progress is likely to be impeded. Also, more of these lines need to be able
to cope with two-way flows, rather than the one-way flow from generating plants
to customer, especially if more households wish to sell their excess solar energy.
A fourth difficulty lies in
intermittency
problems, especially of solar and wind,
for solar does not work at night and winds do not always blow. So both the sources
need back-ups from other power sources, or transmission via long distant lines from
places where the sun is shining or winds are blowing. In addition, the intermit-
tency leads to power surges on windy, sunny days, reducing the wholesale price of
electricity, not simply to the detriment of renewable sources but to the decreasing
profitability of many large generating companies in Germany. One result of these
price depressions is that companies claim that the installation of modern, efficient
and less polluting gas-fired power plants is uneconomic since they do not operate
full time. So they keep the old, polluting brown coal stations that have covered their
capital costs to produce cheaper electricity in the back-up periods.
The fifth problem is that of
storage
. Although energy from wind and solar can
be used directly, it is still difficult to store the excess amounts generated at peak
periods. The technology to create the very large and powerful batteries to store this
excess still do not exist, although in a few locations the excess is used to pump
water to upland reservoirs that can then be released to generate hydro power on
demand, or to pump water underground and retrieve it later for use if deep reser-
voirs exist.
A sixth major problem comes when a full evaluation of all the
costs and results
of renewables
is made, for many disadvantages may be concealed For example,
more electric cars may reduce pollution in cities compared to oil-powered vehicles,
but will increase electricity demand, which may be from fossil-fuel burning power
generators that produce more pollutants, unless distributed-generation takes off,
through the development of cheap batteries in residences to store power from wind
or solar sources, enabling consumers to 'go off the main electricity grid'. Another
example comes from ethanol production for fuel. If farm land is used to grow food
crops that are turned into ethanol, food production is reduced. It will lead to higher
food costs, especially given projections that show global warming will reduce crop
yields in many areas. Hence high subsidies for ethanol production can be ques-
tioned, while the necessary use of fuel for tractors and fertiliser production will
increase energy use and pollutants. Similarly the demand for wood pellets to fuel
electricity generating plants that depend on this fuel may well lead to the destruc-
tion of wilderness areas in hotter parts of the world where trees grow more quickly
than in the northern climes and which are likely to be the sources of this increased
demand. Indeed, the amount of biomass and hence land area needed to create large
amounts of bio-fuel, even from non-food crops, is very considerable.
The seventh problem, one of
environmental damage
comes from the very move-
ment that is calling for the growth of renewables, those interested in environmental
protection. It is rather ironic that the expansion of wind turbines in particular is be-
ing increasingly opposed by local environmental groups that see wind turbines as
