Environmental Engineering Reference
In-Depth Information
While natural gas storage provides an important departure point for a dis-
cussion of CAES, several important differences must be considered, includ-
ing differences in physical properties of the working fluid (e.g., viscosity,
gas deviation factor) and new oxidation and corrosion mechanisms resulting
from the introduction of oxygen into a formation. Also, a CAES system used
for voltage regulation or backing wind power will likely switch between
compression and generation several times a day. In contrast, most natural gas
storage facilities are often only cycled once over the course of a year to meet
seasonal demand fluctuations for natural gas. These are important differ-
ences that must be considered, but a wide range of advanced design concepts
and mitigation techniques can be employed to address such requirements.
Although no commercial systems have been built to date, several suc-
cessful field tests have demonstrated the operational feasibility of using
an aquifer for compressed air storage applications. A 25 MW porous
rock-based CAES test facility operated for several years in Sesta, Italy.
Although the tests were successful, a geologic event disturbed the site and
led to closure of the facility [1]. In addition, EPRI and the U.S. Department
of Energy conducted tests on porous sandstone formations in Pittsfield,
Illinois, to determine their feasibility for CAES. Testing for the first com-
mercial CAES plant with a porous rock reservoir was scheduled to begin in
Dallas Center, Iowa, in 2010.
In addition to using saline aquifers for CAES, it is also possible to use depleted
oil and gas reservoirs that are fundamentally aquifers. Since the bulk of natu-
ral gas storage experience is in depleted fields, many issues related to residual
hydrocarbons have been extensively studied; however, the injection of oxygen
would present challenges not encountered when storing natural gas. In par-
ticular, the presence of residual hydrocarbons may introduce the risk of flam-
mability and in situ combustion upon the introduction of high pressure air.
The flammability of the natural gas-air mixture may be another concern
for CAES operation, but displacement of natural gas away from the active
bubble area can mitigate this risk considerably. In some cases, nitrogen injec-
tion may be desirable to further minimize air-natural gas mixing. Previous
studies indicate that these methods adequately address the challenge of
using depleted natural gas fields for CAES and that these structures can pro-
vide suitable air storage media [53].
ExistingandProposedCAESPlants
Huntorf
The Huntorf CAES plant near Bremen, Germany, the world's first such facil-
ity, was completed in 1978 (see Figure 5.8 and Figure 5.9). The 290 MW plant
was designed and built by ABB (formerly BBC) to provide black-start services
