Environmental Engineering Reference
In-Depth Information
which circuit breakers are closed and open, which units are operating and
in which direction, power flow data, and other parameters are continually
monitored. Each individual electrical system component has provisions for
self protection against overloads and overheating, but the job of the system
controller is to ensure that no system configuration that may damage equip-
ment is enabled.
The user interface to the operation of the overall system is housed in
the system controller. This interface tells the user the status of the system,
including the output from local power sources, the status of the energy stor-
age, the loads that are energized, and the power flow specifics. The interface
also allows the user to configure the system in certain ways and shut down
components or sections.
Water Well
An aquifer UPHES system utilizes a deep, high flow capacity water well to
accomplish energy storage. The power capacity of the turbine is a function
of available head and flow. Analysis from previous sections shows how the
trade-off of head, flow, mound height, and aquifer transmissivity affects the
system design. In this section, well characteristics are reviewed and methods
to increase system power by modifying wells or using infiltration pits are
described.
Water well characteristics vary greatly in installations across the world
and also within the same aquifer system. The main characteristics of impor-
tance to the aquifer UPHES system are
• Transmissivity or hydraulic conductivity of the surrounding geo-
logic formation
• Depth to water
• Well diameter
• Well casing
• Confined or unconfined aquifer
As an example, a well having greater than 1000 gal/min (0.063 m
3
/s) injec-
tion flow capacity and 300 feet (91 meters) of head for turbine power genera-
tion is targeted. To achieve this, an aquifer with 350 feet (107 meters) depth
to water must have transmissivity of about 2.6 ft
2
/min (40.3 cm
2
/s) or greater.
Does this type of well exist? What can be done to retrofit a well to achieve the
necessary parameters?
Because typical irrigation wells have limited flow capacity, it follows that
one would consider ways to increase the injection flow capability of a well
to extract the maximum possible power. Aquifer recharge (AR) and aquifer
storage and recovery (ASR) wells are examples of systems designed to re-
inject water into an aquifer. To quote one source, “Currently, more than 60
