Environmental Engineering Reference
In-Depth Information
Figure 1.2 Energy consumed in United States
in 2009 totals to 94.82Quads
only 0.7% of the total U.S. power consumption.
(U.S. Energy Information Administration/
Renewable Energy Consumption and Electricity,
Preliminary Statistics, 2009).
10
19
J. Of
this figure, 8.16% (7.745 Quads) is classified as
renewable, as broken out on the right. In the
renewable category, wind accounts for 9%, thus
¼
9.99
(Renewables 2011: Global Status Report http://www.ren21.net/Portals/97/docu-
ments/GSR/GSR2011_Master18.pdf, see also http://www.aps.org/units/gera/meet-
ings/march10/upload/CarlsonAPS3-14-10.pdf and Global Trends in Renewable
Energy Investment 2011 (Bloomberg New Energy Finance) available at http://
fs-unep-centre.org/publications/global-trends-renewable-energy-investment-2011.)
estimates that in 2010 installed windpower capacity worldwide is 198 GW and
growing at 30% per year. If this rate continues (which is not assured), it will be
less than 20 years from 2010 until windpower reaches 5 TW, the present power from
coal. This can thus be crudely extrapolated to happen by 2030. In a similar vein, in
2010 installed photovoltaic PV capacity is 40 GWand increasing at 43% per year. On
this basis, it will take 13.5 years from 2010 to reach 5 TW, thus estimated in 2024.
These are long extrapolations, inherently uncertain in their accuracy. One may
question that a 5 TW level fromwindpower is attainable from the point of view of land
area and suitable sites, apart fromcapital investment, grid linkage and storage issues.
The limiting capacities are not easy to estimate. However, one detailed study of
China [1], based on windspeed data, predicted that installation of 1.5MW turbines on
mainland China could provide up to 24.7 PWh of electricity annually, which works
out to an average power of 2.82 TW. This suggests that 5 TWwind capacity worldwide
may be achievable. On the other hand, the New York Times [2] has recently published
an analysis of power investment in China and
finds that coal is by far the largest and
most rapidly growing source of energy, and that windpower capacity is scarcely
increasing.
Estimates of the power potentially available fromdirect photovoltaic conversion are
straightforward. To reach 5 TW, assuming an average power density of 205W/m
2
with 10% ef
cient solar cells requires an area (5
10
12
/20.5) m
2
10
11
m
2
¼
2.44
