Last
year, wind generated power in the United States was
enough to supply 1.6 million families with their total
electric power needs. A
single 750-kilowatt wind turbine operating for a year
can be expected to displace 2.7 million pounds of carbon
dioxide, 14,000 pounds of sulfur dioxide, and 8600 pounds
of nitrogen oxides. Yet opponents of
wind power argue that wind power is a fraud because
a) wind fails to produce significant power at economical
rates, and b) wind power is unreliable. Let’s consider
these claims.
Wind
energy is economical and competitive with fossil fuel
generation. Wind turbines produce electric power by
converting wind energy into rotation of turbine blades,
which then turn a mechanical generator. With modern
aerodynamic blades, this process is nearly 100% efficient
for all wind speeds within designed wind speed range.
Because wind speed varies, over, say a year’s time,
wind plants operate as an average around 30% of maximum
rated capacity. That is their availability factor is
around 30%. Depending on the site, some may have a much
higher availability factor. Fossil fuel power generation
is a two-step process. First, chemical energy is converted
to heat (usually in the form of hot gas) through the
combustion of hydrocarbon fuels. While the combustion
itself is very efficient, conservation of matter requires
that there be products of the combustion; a major product
of combustion is carbon dioxide gas, a greenhouse gas.
The second step is the extraction of the heat produced
by combustion, and conversion of that heat into electrical
energy. The conversion often is done by generating steam,
and using steam turbines to run electric generators.
This second step is accomplished at efficiencies of
about 30% to 40%. (This is a limitation imposed by the
Second Law of Thermodynamics.) In
effect, burning one pound of fossil fuel will result
in about one pound of emission gas, but only 30% to
40% of the heat of combustion will actually be used
to produce power; the rest of the heat is wasted.
Also, fossil fuel plants are subject to an availability
factor because of maintenance, etc. This factor is around
80%. Both forms of power generation have a similar overall
performance factor (efficiency times availability factor),
and are economically competitive.
Misunderstandings
about how electric power generation is managed have
led opponents of wind power to the flawed conclusion
that because wind is variable, wind power is unreliable.
What this view fails to grasp is the fact that all electric
power, regardless of the mode of its generation, is
managed and distributed through regional networks or
‘grids’. Power distribution is managed by control systems
that employ highly complex mathematical algorithms to
determine when and where to generate power in response
to fluctuating demand. In fact, a very important variable
in power generation is the variability of demand. As
a component in a managed grid, wind generated power
can be used whenever it is produced and, depending on
the demand at the time, other power generating facilities
in the grid can reduce their production.
The grid management algorithms are very flexible and
can be fine-tuned to adapt quickly as conditions change.
On any given day, the power you use can be coming from
a fossil fuel, hydroelectric, nuclear, or wind generator.
So,
how does this help us understand the role of wind power?
Simply this: While wind at any given location is variable,
it is not by that fact, unreliable. Wind farms are sited
at their locations only after several years of data
have been collected to determine the pattern of variability.
Not every windy place is a good candidate for investment
in the development of a ‘wind farm’- a system of wind
turbines delivering electricity into a power grid. The
details of what goes into site determination for such
an installation can be found at the US Dept. of Interior,
Bureau of Land Management web site
Wind
plants produce power but by converting kinetic energy
of wind into power with no fuel cost; fossil fuel plants
convert chemical energy into power but have high and
unpredictable fuel cost, as well as producing waste
heat and pollution. The wind plant can
replace significant fossil fuel produced power with
no fuel cost and no pollution. No one is claiming wind
power will replace all fossil fuel power in the near
future. The two forms of power generation are complimentary.
The bottom line is that a wind plant is competitive
with an equivalent capacity fossil fuel plant, and can
offset significant fossil fuel generated energy and
do so with no fuel cost and no pollution. While there
may be numerous reasons for concern about, and perhaps
opposition to, a specific wind turbine site project,
opposition based on attacking wind power in general
is unlikely to be very credible. For information on
the many technical aspects of wind power go to:
