Environmental Engineering Reference
In-Depth Information
prior studies have analyzed the costs and emissions of hybrid wind-CAES
systems [9-18].
Among the geologic options for air storage, porous rock formations
offer the best availability and potentially lowest cost. Moreover, geo-
graphical distributions of aquifers and good wind resources are strongly
correlated in the U.S. Therefore, the potential for CAES to play a major
role in balancing wind output and producing low GHG emitting power
will depend to a large degree on the availability of aquifer structures
suitable for CAES.
EvolvingMotivationsforBulkEnergyStorage
CAES emerged in the 1970s as a promising peak shaving option [19]. High
oil prices together with an expanding nuclear power industry sparked an
interest in energy storage technologies such as CAES to be used in load-
following applications. The high price of peak power and the perceived
potential for inexpensive baseload nuclear power made attractive the option
of storing inexpensive off-peak electricity and selling this electricity during
peak demand periods [20,21].
These conditions initially fueled a strong interest in CAES by many
utilities, but as the nuclear power industry lost momentum and oil prices
retreated from their peaks, the market conditions for CAES began to change.
During the 1980s, gas turbines and combined cycle generation emerged as
the leading low cost options for peaking and load-following markets. The
new options along with overbuilt generating capacity on the grid and the
perception that domestic natural gas supplies were abundant led to erosion
of market interest in energy storage.
Recent trends in wind power development have fostered new interest in
energy storage, not as a way to convert baseload power into peak power,
but as a way mitigate the variability of wind energy [16,18]. Global wind
power capacity has grown rapidly in recent years from 4.8 GW in 1995 to 121
GW by the end of 2008 (Figure 5.1). The variability of wind output requires
standby reserve capacity to ensure output during peak demand. Gas turbines
can respond quickly to shortfalls in wind output and thus gas fired spinning
reserve units are good candidates for dispatch to meet the challenge of bal-
ancing this growing wind segment of the power mix.
Energy storage represents an alternative wind balancing strategy, and the
low fuel consumption of CAES makes it especially attractive during times
of high and/or volatile gas prices. Although wind balancing has long been
acknowledged as a potential application for bulk energy storage [22], only
recently has wind penetration reached levels that require additional balanc-
ing measures for maintaining system stability [23].
