When evaluating different methods of power generation some of the
main questions inevitably concern the fuel proposed. Is there enough of
it? Is it in the right places? It is available when you want it? What
does it cost? What emissions does it have?
What residue does it leave? For wind power generation, wind is of course the ‘fuel’ and these questions are as relevant as they are for any other source.
The
last of these questions has the simplest answer: unlike fuels that are
burnt, wind is free and clean. Questions about how much wind there is,
where it is to be found, and when it is available, however, are very
pertinent.
On
a global scale numerous studies confirm the enormity of the resource,
and how it could theoretically meet global electricity demand many times
over. A recent addition to this sequence is a collaboration by
researchers at Harvard University in the United States and VTT in
Finland that concluded that ‘a network of land-based, 2.5 MW turbines,
restricted to non-forested, ice-free and non-urban areas, operating at as
little as 20% of their rated capacity could supply more than 40 times
current worldwide consumption of electricity’.
A slightly earlier
comprehensive study by researchers from Stanford University’s Global
Climate and Energy Project based its conclusions on five years of data
from the US National Climatic Data Center. Using an extensive set of
surface and balloon measurements, they concluded that 13% of the sites
tested had a good wind resource(Class 3) at 80 meters off the ground, and using one in five of these
sites for power generation would allow wind energy to meet the world’s
electricity demand (using the figure from the year 2000) seven times
over.
Similarly, an earlier study in 2003 by the German Advisory
Council on Global Change calculated that the global technical potential
for energy production from both onshore and offshore wind
was 270,000 T Wh per year. Assuming 10%–15% of this was realizable in a
sustainable fashion, the resulting 39,000 T Wh would meet more than
double the current global electricity demand. A literature search shows
up numerous similar studies with broadly similar conclusions.
Each
of the studies varies in its outcome, depending on the assumptions
used. One variable concerns the size, capacity factor and rated power of
the turbines used for estimations of wind power potential. In addition,
the higher the turbine is mounted, the better the wind resource.
Further, higher turbines are less prone to be affected by turbulence
caused by obstructions, topography, surface roughness or thermal
effects. In addition, advances in technology can not only increase the
capacity factor of wind turbines, but also the range of wind speeds in
which they can operate, thus broadening the range of sites at which they
can be used.
Another
variable concerns assumptions about the land areas on which turbines
can be deployed. While most studies will rule out conservation areas,
forests and urban sites, some types of agricultural land such as
pastures are easily compatible with wind farms without constraining the
overall wind potential of a region. Methodologies for assessing offshore
wind resources also differ in terms of the underlying assumptions used.
An
assumption needs to made concerning the areas in which wind farms can
be built, both for practical reasons (maximum distance to shore, water
depth etc), as well as taking into account environmental and regulatory
limitations (nature reserve areas, shipping lanes, minimum distance to
shore, etc).
Some new configurations that deploy turbines on
floating structures and are thus suitable for use in deep water are at a
preliminary stage of test deployment.
World wide 5 km Wind Map at 80m |
These
could dramatically increase the technically usable fraction of the
offshore wind potential. Evidence from a large number of studies into
the world’s wind resources suggests that there is no shortage of
suitable sites for wind power development. However, it is worth noting
that the rate of deployment of wind power in each county has largely
been dependent on political will rather than resource criteria. Germany
has a lower wind potential than many other European countries, yet its
favourable political climate has led to rapid and large-scale deployment
of wind power.
On the other hand, there are numerous parts of the
world with a good wind resource – places such as Argentina, Russia and
South Africa – where development of wind power has barely started.
Overall,
it is clear that the wind’s energy offers a practically unlimited,
clean and emissions free power source of which only a tiny faction is
currently being exploited. There may be concerns about ‘Peak Oil’ but
‘Peak Wind’ is not a concept that need worry us!
No comments:
Post a Comment