Page 612 - Environment: The Science Behind the Stories

Wind turbines Figure 2 Wind turbines kill birds
Wind turbines kill that fly into them. Yet far more birds
Towers 100,000–440,000 are killed by other human causes.
birds per year in Shown are ranges of recent estimates
Pesticides U.S. of yearly bird mortality in the United
Roads and cars States from several main causes.
Habitat alteration is responsible for still
Glass windows more than any of the causes shown.
Data from American Bird Conservancy, from
Domestic cats 1.4–3.7 billion
sources dating through 2010; and Loss,
0 100 200 300 400 500 600 700 800 900 1000 S.R. et al., 2012. The impact of free-ranging
Millions of birds killed in U.S. per year domestic cats on wildlife of the United States.
Nature Communications 4: Article 1396.

to protect farmland; minimize aesthetic with PV solar power would prevent initially feared, but uncertainty remains.
impacts; and lessen disturbance to tule 89–98% of greenhouse gas emissions. For instance, one European study indi-
elk, kit foxes, pronghorn antelope, bur- Scientists have also studied health cated that migrating seabirds fly past
rowing owls, and seasonal freshwater impacts of PV panels. PV cells can offshore turbines without problem, but
pools. pose risks to workers manufactur- other data show that resident seabird
On the U.S. Great Plains, research- ing them, because they contain toxic densities have declined near turbines.
ers from the National Renewable Energy chemicals such as cadmium and On land, the wind industry esti-
Laboratory are currently studying arsenic and release fine silicon dust that mates that about two birds are killed
impacts of solar installations on prairie can damage lung tissue. Researchers per 1-megawatt-turbine per year. This
ecosystems by comparing a developed have concluded that proper attention to is far fewer than the hundreds of mil-
site and an undeveloped control site. worker safety can greatly reduce these lions of birds being killed each year
Given the impacts of large-scale risks and that the exposure risks are by television, radio, and cell phone
solar facilities, researchers have deter- not much different from other exposure towers; pesticides; automobiles; glass
mined that installing photovoltaic panels risks we all face in our modern industri- windows; and domestic cats (Figure 2).
on rooftops of buildings is a low-impact alized society. If you own a cat and let it outside, you
alternative. Simply adding PV panels or The overall messages from studies may be killing more wildlife than most
roofing tiles to a rooftop has no effect so far are that (1) solar power, even with wind farms.
on the landscape. One study, led by its impacts, is still cleaner and more At this point, bat mortality appears
five Dutch, German, and American sustainable than fossil fuel power; and to be a more severe problem at
researchers, compared impacts of that (2) we can minimize the impacts wind turbines, but further research is
various ground-based and rooftop PV of solar power by using rooftop panels needed. We can reduce wildlife impacts
systems in Germany and in Arizona. The and developing better technologies. by avoiding development at sites on
researchers assessed impacts over the Similar messages are emerging known migratory flyways or amid prime
systems’ entire life cycles (from produc- from the science on wind power. One habitat for bat and bird species that are
tion to installation to operation). They major concern is that birds and bats likely to fly into the blades.
found that besides avoiding land use are killed when they fly into the spin- Continued studies on the impacts
impacts, the rooftop systems also emit- ning blades of turbines. At California’s of wind and solar development should CHAPTER 21 • N E w R ENE wA bl E E NER gy AlTERN AT iv E s
ted significantly fewer greenhouse gases. Altamont Pass wind farm, turbines killed help us find ways to harness renew-
A different study in 2008 measured dozens of golden eagles and other able energy and attain a sustainable
the amount of energy required by PV raptors in the 1990s. Studies since then energy future while minimizing the
cells throughout their life cycles and at other sites suggest that bird deaths environmental and social impacts of
found that replacing fossil fuel energy may be a less severe problem than was this development.

A second drawback is that solar energy is an intermit- (p. 592) can sometimes help by compensating for periods of
tent resource. Daily or seasonal variation in sunlight can limit low solar power production.
stand-alone solar systems if storage capacity in batteries or The third disadvantage of current solar technology is the
fuel cells is not adequate or if backup power is not available up-front cost of the equipment. Because of the investment
from a municipal electric grid. Pumped-storage hydropower cost, solar power remains the most expensive way to produce 611

M21_WITH7428_05_SE_C21.indd 611 12/12/14 4:29 PM