Geoscience Reference
In-Depth Information
209m
3
/MWh
Recirculating Cooling Once-Through Pond Dry Non-thermal
Cooling Cooling Cooling Technologies
Figure 12
Ranges of rates of
operational water consumption by
thermal and non-thermal electricity-
generating technologies based on
a review of available literature (m
3
/
MWh). Bars represent absolute ranges
from available literature, diamonds
single estimates; n represents the
number of estimates reported in the
sources. Note that upper values for
hydropower result from few studies
measuring gross evaporation values,
and may not be representative
Non Renewables
Renewables
N: 18 4 1 5 4 1 16 2 7 3 1 3 3 9 1 1 1 7 11 2 1 2 4 2 2 1 4
Sources: 11 3 1 5 4 1 8 1 2 1 1 3 3 4 1 1 1 2 4 2 1 2 2 2 2 1 2
(where water emissions mix with ambient surface water) not exceed a standard related
to impacts on river wildlife. Some regions, such as the Ohio River Basin, have multiple
plants sharing the same water body and have regulatory constraints on the cumulative
heat discharge, river temperature rise, and maximum river temperature.
Historically, especially during seasonal droughts and/or heat waves, increases in am-
bient water temperature have sometimes required reductions in power output in order
to avoid exceeding the EPA standard (i.e., to reduce warmer water discharges from the
power plant). The alternative for many thermal power plant operators in the long run,
if ambient temperature increases cannot be avoided, would be to invest in recirculating
cooling systems, with high capital costs and some energy costs.
The eiciency and output of thermal power plants, fossil or nuclear, is sensitive
to ambient air temperatures as well; higher temperatures reduce power outputs.
Steam cycles, which are used in most base load generation, are sensitive to cooling
water temperature while combustion turbines used primarily for peaking generation are
primarily sensitive to ambient air temperature. Gas turbines, which are dispatched pri-
marily for daily and seasonal peaking service, are sensitive to ambient air temperatures.
