Environmental Engineering Reference
In-Depth Information
GWh of Energy at a Given Head per Acrefoot of H
2
O (78% Eff)
7
6
300 meters
600 meters
900 meters
1200 meters
1500 meters
1800 meters
5
4
3
2
1
0
0
2,000
4,000
Acre feet of H
2
O
6,000
8,000
10,000
FIGURE 3.3
Energy potential over volume of water necessary at increasing heads; plots beyond 600 m
approach or surpass current technology.
resources on the electric grid. It may be the case that the electric operation
areas needing storage resources have pump-back capacities that are either
not dispatched as pump-back or run solely as peaking resources. As greater
variability is injected into the electric grid based on increased variable gen-
eration systems and changing loads, it may benefit a system to redispatch
current resources in a different manner.
The two basic requirements for a PHES facility are elevation change (head)
and water. Alternative designs can make the challenges of water or head
availability less difficult to overcome. Head availability is traditionally
provided by above-ground elevation change. Where above-ground eleva-
tion change cannot be found, it may be possible to use the elevation change
between the ground surface and a location below the surface of the earth,
thus the head constitutes the difference between the surface elevation and
a below-ground reservoir. This may be feasible in a mine or possibly in line
with pumped water between a subsurface aquifer and a surface reservoir.
Society may also gain the advantage of dispatchable water pumping to
align the movement of water with the availability of energy; this strategy
combines pumped storage and demand response. The primary hurdle of
aligning timed water pumping and availability is transparent and regular
communication between those who plan and operate water systems and
those who plan and operate energy systems. Where water resources are not
plentiful, it may be possible to utilize creative planning or alternative design
to provide the needed water resources.
Examples of alternative water design include the coupling of an agricul-
tural water supply with a PHES facility and the utilization of water pro-
duced by the gas and oil extraction industry. In the latter case, the produced
water would have to be cleaned to an acceptable environmental standard to
avoid the distribution of organic and inorganic pollutants contained in the
water. It is possible that the revenue from a PHES facility could pay for the
