Page 322 - Alternative Energy Systems in Building Design

296 OCEAN ENERGY TECHNOLOGIES

Stuart MacDonald of Nova Scotia Power remembers the thrill of seeing the plant in action for
the first time. He loves the elegant simplicity of its engineering and its reliability, but accepts
that tidal power has its limitations.

BUILT FOR PURPOSE
It may be a predictable source of electricity, but only while the tide is going out. And it is not
the sort of thing that can be bought off the shelf; machinery has to be purpose-built for the site,
which makes it expensive for a power station which is always going to be idle for at least
12 hours a day.
But at least the fuel is free, and although the plant was designed for a 70-year lifespan, Stuart
MacDonald believes that with proper maintenance it could last 200 years. The technology,
though, has yet to take off in a significant way.

The biggest tidal station in world is in France, near St Malo, 12 times larger than
Annapolis Royal. Russia has a much smaller plant, whereas China has constructed
several small facilities.
With fossil fuels getting scarce and expensive and increasing concern about the
damage they are causing to the atmosphere, interest in tidal power is growing because
these plants produce no greenhouse gas emissions.
Other projects are planned, and designers are now working on plans involving indi-
vidual turbines moored in the middle of the tidal flow, easier to build and less envi-
ronmentally controversial than the fixed barrages used by the existing stations.

Islay LIMPET LIMPET stands for “Land-Installed Marine-Powered Energy
Transformer,” and Islay LIMPET is the world’s first wave power device connected to
a national grid. The project has been located on the Scottish island of Islay since
2000. The project was sponsored and developed by Wavegen, an investment-based
company, in collaboration with Queen’s University in Belfast. It is the result of
research on the island, where the demonstration plant was capable of generating 75 kW
of power (Fig. 9.6).

TURBINE

CAPTURE CHAMBER

AIR IS COMPRESSED
WAVES INSIDE THE CHAMBER

Figure 9.6 Diagram of the Islay LIMPET tidal turbine operation.