A forthcoming 20-megawatt energy storage system will use advanced battery technologies to help maintain the stability of the electric power grid.
The New
York State Public Service Commission recently approved construction of a 20-megawatt
(MW) energy storage system to be built in Union, N.Y. The $22.3 million project,
owned by AES ES Westover, will use advanced battery
technologies to help maintain the stability of the electric power grid.
This is
just the latest of many new and innovative energy storage initiatives being
undertaken around the world. These projects are being driven by the increased
use and incorporation of renewable energy sources into power grids.
There are
two main reasons of this growing interest in energy storage solutions.
First, most
renewable energy (be it generated from solar, wind or tidal sources) are highly
variable. Distribution and transmission systems have already been showing signs
of strain in handling these highly variable sources of electricity. For
example, in 2008, a New York Times
article reported that the Maple Ridge Wind farm, in upstate New York, had
to shut down at times because the “regional electric lines have been so
congested.” Unfortunately, the situation is expected to get worse as more power
comes from renewables.
Second, there
is a need to address the mismatch between peak power generation and demand. For
example, in many locations, wind energy can be quite significant at night when
electricity demands are at their lowest. Similarly, peak solar productivity is
often close to midday, while peak electricity
usage is frequently later in the afternoon.
Pushing the Envelope
The New York deployment will make use
of new lithium-ion battery cells and power control technologies. The system will
be able to provide or absorb up to 20 MW. “[This] will help improve the ability
to store energy, a critical component needed to help us further strengthen and
expand our use of renewable energy,” says New York State Public Service Commission
Chairman Garry Brown.
Other energy
storage efforts are exploring a variety of new technologies, or at least new
twists to using existing technologies. The latter is certainly the case with something
called Energy Island.
Energy Island is a concept under
evaluation by the energy consulting firm KEMA and the civil engineering firm Bureau Lievense. The idea is to build
an artificial island in the North Sea near deep-water wind
turbines. The impetus for this project is that the anticipated excess wind
power from offshore North Sea turbines, especially at night, will require large-capacity
energy storage solutions.
Energy Island would form a large,
below-sea-level basin to hold a reservoir of water. During peak energy
generation times, the excess energy would be used to pump water out of the
basin into the ocean. When winds die down and the turbines are not producing
much power, the flood gates to the reservoir would be opened. Gravity would
cause water to flow down into the basin, driving turbines to generate
electricity.
Energy Island (Source: KEMA and
Lievense)
Like wind
energy, solar energy is also variable and presents another obvious challenge—namely,
there is no sun at night. One solar energy storage solution that is gaining
favor is the use of molten salt to retain solar heat.
Molten
salt has a much higher heat capacity than water, so it can store more heat in a
given volume. For example, molten salt in tanks can be heated to 1,000 degrees.
Such a heated salt mixture can be used to create steam to drive turbines that
produce electricity. Molten salt also retains heat longer than a water-only
solution. A molten salt tank can also be used as the equivalent of a heat
capacitor or battery, storing heat that can be used at night or during a cloudy
period to sustain the generation of electricity.
Molten
salt storage has been used on a small scale for years, but last year
SolarReserve announced plans for a molten salt-based plant that would store
hours’ worth of energy, enabling the proposed plant to provide electricity 24
hours a day.
And yet another approach under consideration in
several parts of the world is to use underground storage of compressed air to
help address the mismatch between wind energy production and capacity to handle
the electricity by the local grid. For example, the Iowa Stored Energy Park will use wind and
off-peak energy from various sources to compress air and store it underground.
Compressed
air energy storage (Source: Sandia National Laboratories)
When winds
die down and electricity is needed, the compressed air can be used to drive
turbines to regenerate electricity for the grid. The project is being funded by
the U.S. Department of Energy, managed by Sandia National Laboratories, and
includes contributions from more than 100 municipal utilities in Iowa, Minnesota and the Dakotas.
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Energy Island is a wild ideaPosted on: 04-29-10 | By: AnonymousThe Energy Island idea is definitely a good example of thinking outside the box. Wow!
