Environmental Engineering Reference
In-Depth Information
higher but wind resources are also better, so the
nal LCOE is not substantially
increased. Mini-wind turbines can be expected to be deployed jointly with PV solar
technology in the new distributed power generation and consumption mode. In
Europe and in OECD countries elsewhere, onshore resources are already exploited
to a substantial extent, but offshore may be the next trend in windpower. In other
emerging and less developed economies, the prospects for future deployments of
both on- and offshore technologies are good.
3.4 Hydro Power
Hydro power is an old, mature, highly competitive renewable energy source with
excellent properties and more installed capacity than any other renewable tech-
nology in the world. It is frequently the cheapest power generation technology,
including all types of fossil-fuel sources [
21
]. There are three main types of plant:
(1) reservoirs, which store water behind an arti
cial damn and enable power
demand to be decoupled from energy storage: designs may range from small to very
large, making this a highly scalable technology along the lines of PV; (2)
“
run of
”
the river
, with no storage; and (3) pumped storage, where water is pumped from a
low reservoir to a higher one to be used for power generation at a later time. It is
worth noting that it is usually electricity that is used to pump the water, so any
energy source that generates electricity can be stored in this way (solar PV and wind
power).
Since power consumption and energy storage are decoupled, the electricity is
dispatchable at will. Moreover, because turbines can be ramped up and down almost
instantly, it is dispatchable at all frequencies, from a fraction of a second to hours,
with no signi
cant extra costs, so it can offer all types of support to the electricity
network, from ancillary services to all kind of reserves (spinning, operating, etc.).
With pumped storage it can also provide greater dispatchability and back-up reserves
for long periods of weeks, months and even years. Because of these properties, it is
specially useful for balancing the intermittency of other renewables such as sun and
wind energy. Thus, it acquires greater added value when the penetration rate of these
energy sources is high.
Dispatchability means that there are two basic operating modes: (1) a continuous
mode to meet base-load demand, implying high capacity factors close to 80
90 %;
and (2) a peak demand mode, where the system is operated only at times when
demand and prices are high, and obtains larger income in those periods. This
implies lower capacity factors, typically in the range of 40
-
60 %. This mode allows
for a smaller reservoir, so that up-front costs are also lower. Which of these designs
(or any other in between) is preferred requires careful study in each speci
-
c case.
Finally, depending on the speci
c design used, other non grid services may be
offered such as
ood and drought control, irrigation and potable water. Adding all
of these up, a note of caution must be placed on the standard LCOE cost measure
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