Environmental Engineering Reference
In-Depth Information
east coast, close to coal deposits. North-west Australia is one of the sunniest
places on earth.
Solar heat can be used to extend fossil fuels. For example, if natural gas
(CH
4
) is heated using a dish concentrator in the presence of steam (H
2
O)
then hydrogen and carbon monoxide (3H
2
+ CO) are produced. The energy
content of the hydrogen and carbon monoxide is about 30 per cent greater
than that of the methane, and so solar energy has been added to the original
methane.
Low temperature solar heat
Low temperature solar thermal technologies use the sun to generate heat
rather than electricity.
Solar water heaters are perhaps the most well known
type of solar thermal technology and are directly competitive with electricity
or gas in most parts of the world. Solar concentrator water heaters have been
combined with photovoltaic collectors to produce 60-70 per cent efficient
hot water and electricity systems. Solar thermal technologies can also be
used to heat buildings. Good building design, which allows the use of
natural solar heat and light, together with good insulation, minimises the
requirement for space heating.
Wind energy
Modern wind generators are very different from old-style water-pumping
windmills. For one thing, they are huge. They have 40-70 m high tubular
steel towers on a concrete foundation and have three blades, each 20-40 m
long. They are computer-controlled and centrally monitored, with many
safety features. They have capacities in the multi-megawatt range and will
operate reliably for more than 20 years. Wind generator towers occupy very
little land per machine. Many wind farms are located on cleared farming
land. Farming activities are scarcely affected, and lease fees from the wind
generators amount to a second cash crop for the farmer. A large fraction of
future wind farms will be located offshore to take advantage of higher wind
speeds and to avoid land use conflicts. Provided that a wind farm is not
located in an ecologically sensitive area, the only significant environmental
impact of wind energy is visual.
Wind energy is likely to generate 10 per cent of the world's electricity by
2020, and is now regarded as a conventional energy source (DWTA 2004;
EWEA 2004). The worldwide industry has grown at an average rate of 25 per
