A glance at any good U.S. wind resource map reveals that almost all of
the U.S. wind power resource, on the order of 99-plus percent as it
turns out, lies in our flat agricultural regions and offshore. This is
because commercial grade wind resources in mountainous regions are
available only on very narrow and widely spaced ridges, whereas row upon
row of wind turbines can be placed in flat regions and offshore. As a
case in point, Vermont's entire commercial wind resource is only 1
percent of Iowa's, and only 4 percent of the Gulf of Maine's.
SMALL RESOURCE
Vermont's relatively small resource has two major consequences. First,
to achieve anything even approaching a significant contribution to clean
energy production will require developing most or all of it. For this
reason, incidentally, claims by wind proponents that they are seeking
only a few projects in Vermont should be discounted. If so, then what's
the point?
Secondly, developing most of all of Vermont's wind resource will have
tremendously negative and permanent ecological and scenic, and hence
economic, impacts to the state.
To illustrate this concretely, suppose Vermont attempts to merely supply
the equivalent of its own relatively meager electricity consumption
with wind power - say, each town with its own set of turbines. This
turns out to require approximately 2,400 megawatts of wind generation
capacity in total today. Suppose this was implemented with two megawatt
turbines spaced closely at an average of five to a mile. Then this would
yield 10 megawatts per mile, and so would require at least 240 miles of
ridgeline. This is substantially greater than the entire length of the
state. Industrial scale roads would have to be blasted and bulldozed
down a great many ridgelines to achieve this, along with the creation of
flat, cleared areas with roughly the same diameter as the "swept area"
of the turbines (several hundred feet).
SOLAR POWER
Is this really necessary? It turns out that Vermont's major renewable
energy source is not wind power after all - it's solar. Vermont's total
raw solar capacity is nearly 4,000 gigawatts - more than 600 times
larger than Vermont's puny six-gigawatt wind resource - even factoring
in the modest 15 percent efficiency of today's photovoltaic modules.
Some might still suppose that Vermont is not sunny enough for solar, but
this turns out not to be the case. The solar resource in Vermont
provides about 50 percent of the energy available in the sunniest
regions of the U.S. per unit area, which is quite workable both
technically and economically.
Like wind power, reliance on solar will also require energy storage and
some degree of backup generation to collectively create a fully reliable
or "baseload" source of electricity. But if only a few days of energy
storage are available, I find, using highly realistic computer
simulations based on a "typical meteorological year" weather data, that
the total energy required from the backup can be minimized to about 5
percent of the total on average, and less if solar is widely distributed
around Vermont. This implies that the backup itself could be supplied
sustainably from lesser but more reliable forms of renewable energy,
such as a combination of small hydro and biomass generation.
Some will suggest that wind power is still useful as a complement to
solar. But this argument is weak: Unless very long-term energy storage
is available (weeks to months) a fully reliable backup source, such as
biomass and/or hydro, will still be needed, because it's still possible
that neither wind nor solar will be available over a prolonged period
from time to time. Solar is more reliable and correlate with demand on a
day-to-day basis and has the greatest potential capacity and
distribution by far, so it makes sense to base a renewable energy grid
primarily on solar together with other fully reliable renewable energy
sources as backup. It is true that some wind in the mix would further
lessen the amount of energy required from the backup, but the required
energy from backup can already be made very small (5 percent or less),
and the minimum required amount of backup capacity (peak generation
capability) would not be reduced significantly by the addition of wind.
And the backup could also be renewable to begin with. So wind would not
be necessary as a compliment, even if it helps slightly.
How much land area would be required to produce the equivalent of
Vermont's electricity consumption with solar? Assuming a very
conservative figure for average solar "insolation" in Vermont of just
three kWh per day per square meter, it turns out that the total solar
module collection area would be well less than 1 percent of Vermont's
farmland. This small figure implies that much of this collection could
be done on rooftops. The rest would at least be low to the ground, close
to load, require no new roads, no clearing of forests, no blasting or
bulldozing, and no disruption of ecosystems. The small total area
required also means that solar generation can and should still be
carefully sited from an aesthetic standpoint.
The economics of solar power have also improved dramatically of late and
are now rapidly converging with retail power prices. The prospects for
further and major technical improvements in solar technology are also
very good. So it can no longer be claimed that we must install lots of
wind here in Vermont now on purely economic grounds.
All of this does not mean that wind power does not have a place in our
energy economy. But there is simply not a compelling argument that we
must develop all wind resources everywhere, and especially those that
incur very strong negative impacts on a particular region. We are
actually immersed in renewable energy, and we can tailor the generation
type appropriately to each region.
Ben Luce is a former Warren resident who now lives in Lyndon.
