Britannia rules the waves
Britain
leads the world in new technology for the generation of wave and tidal
power. Will this innovation lead to commercial success, providing
a reliable source of clean electricity?
If you have ever suffered through a cross-channel
ferry trip rocked by massive waves, or seen the tide flood over the
sands of Morecambe Bay faster than a man can run, you will be familiar
with the awesome power of the seas that surround our island nation.
Over the centuries, these stormy waters have proved a mixed blessing
- sometimes thwarting invading armadas, at other times wrecking friendly
vessels. Yet, as scientists develop ways of transforming the raw power
of the ocean into electricity we can use in our homes, the sea may
soon become provider, rather than destroyer.
Britain is the only place in the world where wave power is already
cooking people’s food and powering their TVs. British engineers
lead the world in technology for harnessing the power of the sea,
building underwater turbines driven by tidal currents, giant electric
sea snakes that ride ocean swells or wave generators built into sheer
cliff faces.
However, industry figures warn that the Government must substantially
increase its support for wave and tidal power if Britain wants to
turn this technological advantage into a successful industry.
Surf's Up
An average ocean wave, whipped up by the powerful winds that skim
along the surface of the world's oceans, can transport its energy
for thousands of kilometres. The immense energy produced by a tropical
storm in the mid-Atlantic can travel as far as Scotland before it
is expended in a spectacular collision with the shore. Coastlines
the world over, with their wave-beaten headlands and eroded bays testify
to the immense power stored in ocean waves.
A large slice of this energy washes up on British shores. Patricia
Hewitt, secretary of state for trade and industry, said last month
that, “The UK’s wave flows are the greatest in Europe,”
providing an, “immense natural resource to generate power for
the UK.” The Deparment of Trade and Industry (DTI) estimates
that we could generate around 15 per cent of our electricity from
wave power.
Britain
is the site of the world’s first commerical wave power generator.
For four years, Scottish company Wavegen's 500 kW Limpet generator
has been transforming wave energy into electricity and feeding it
into grid on Islay Island, off the coast of south-west Scotland.
The Limpet consists of a large tubular air chamber built into the
rocky shore of the island, surrounded by a concrete housing. The lower
portion of the air chamber is submerged in the sea and the water level
within rises and falls with each a wave. This oscillating column of
water in the chamber acts like a piston, pumping air up and down and
creating an air current strong enough to drive the Limpet’s
electricity-generating turbine.
The concept is simple. The biggest challenge for the Limpet is to
survive the relentless pounding of powerful Atlantic waves. But after
four years of trouble-free operation, its designers are confident
that it can withstand any punishment. "The plant has experienced
Islay's worst storm in living memory without suffering any structural
damage," says Wavegen spokeswoman Natalie Buxton.
The next step for Wavegen is to reproduce the Limpet's success on
a larger scale in the Faroe Islands, where they are partnering local
energy company SEV in a £7 million wave power project. These
islands in the North Atlantic have ample wave resources, but are surrounded
on all sides by steep cliffs. Ms Buxton says this project’s,
“key innovative feature will be the use of tunnels cut into
the cliffs on the shoreline to form the chamber that captures the
energy,” making it, “completely unobtrusive and well protected”.
“This new design will form the blueprint for wave power stations
in similar locations both in the Faroes and other parts of the world,”
she says.
Taking a very different approach to capturing wave energy is Ocean
Power Delivery (OPD), whose novel Pelamis wave energy converter has
just finished successsful sea trials.
Andrew Scott, head of project development at OPD, says the Pelamis
is the culmination of three decades of research into wave power. It
began in the 70s, when, “all the projects were really space-age
and were never going to come to commercial viability.” Now,
he says, “technologies have improved dramatically,” and
are far more reliable.
Even
so, the Pelamis’ appearance is still pretty “space-age”.
It looks very much like a big red snake, albeit one as long as five
train carriages. The snake’s head is moored to the seabed and
it generates electricity by surfing over the crests and troughs of
ocean waves.
As the Pelamis moves, the hinges between each of its four massive
sections bend, compressing fluid in its internal hydraulic system,
just as water in a hose is compressed if you bend it. This compression
forces the fluid through hydraulic motors that drive electrical generators,
giving the Pelamis a power output similar to a wind turbine.
As with the Limpet, the crucial factor in the success of the Pelamis
will be its ability to survive in the open seas. Mr Scott says this
is unlikely to be a problem. In small seas, its hydraulic system's
response can be turned up to maximise energy capture. In big storms,
Pelamis can go into "survival mode", minimising its response
to wave energies that could otherwise damage it. Mr Scott says it
can survive anything the sea can throw at it.
OPD is currently looking for the financial backing to build a few
small Pelamis farms of six or seven machines around the UK that could
feed into the national grid. Once the technology is proven reliable,
Mr Scott hopes larger farms will be possible.
Moon power
The periodic rise and fall of the tide is the kind everyday occurrence
that we take for granted. Few people would stop to consider the huge
amount of energy involved in these vast movements of water driven
by the gravitational pull of the Moon.
Britain has some of the biggest tides in the world. The many straits
and estuaries on our coast focus all the tide's movement into narrow
channels, causing the sea to surge with currents powerful enough to
drive a motor and generate electricity. The DTI says there are 42
sites around the UK that are appropriate for tidal power generation,
potentially supplying as much as 34 per cent of the UK's electricity.
The
idea of generating electricity from the tides is not new. The world's
first tidal power station, at La Rance in France, began operation
in 1965. But the tidal barrage method used at La Rance plant, which
requires damming a large estuary to trap water at high tide and then
flush it through electricity-generating turbines, has fallen out of
favour. Plans for a similar barrage scheme in the Severn Estuary were
abandoned after 13 years as they were considered too expensive and
too damaging to the Severn's delicate estuarine ecosystem.
Engineers have now turned to cheaper and more environmentally friendly
projects. Leading the industry in the UK is Marine Current Turbines
(MCT), whose prototype 500 kW tidal turbine, called the Seaflow, has
been operating off the north coast of Devon since May 2003.
Just as windmills are turned by fast moving air currents, so tidal
turbines are turned by water currents. In fact, a tidal farm would
look much like a submerged wind farm. While there are fewer suitable
locations in the UK for tidal farms, it does offer several advantages
over wind power. Its power supply is entirely predictable, since you
are guaranteed two tides every day, and peak tides also often correspond
to times of peak electricity demand.
However,
tidal turbines take a lot more punishment than wind turbines. "Millions
and millions of waves pass the thing," says Professor Peter Fraenkel,
technical director of the Seaflow project. "The biggest problem
is to design it so that things won't just break off." So far,
he says the Seaflow has performed above expectations. "It's had
five metre waves and force eight weather on a number of occasions.
There's no sign of anything breaking or failing."
After the Seaflow's success, MCT has designed a new turbine with double
the generating capacity that it plans to have operational in late
2005. By 2007 MCT hopes to have tidal farms feeding into the National
Grid. "The first few would probably only be half a dozen turbines,"
says Professor Fraenkel. "The idea would be to roll those out
into bigger projects."
Building a new industry
The prospects for both wave and tidal power look good and British
industry has a strong lead. However, it is not yet time to switch
off nuclear and forget about fossil fuels. While these technologies
have successfully made the leap from drawing board into reality, they
are still considerably more expensive than their main renewable energy
rival - wind power.
However, developers of these marine renewable technologies say this
is no reason to be discouraged. Mr Scott points out that when wind
power first started 25 years ago, it was selling electricity at about
15p per unit. It wasn't until the industry matured and reached a large
scale that the cost fell to its current level of around 3p per unit.
"We believe we will probably be starting at around half what
onshore wind started at 25 years ago," he says. "Although
we are more expensive now, we believe the technology can see the same
sort of cost reductions."
In order to reach this stage, all the key players in the renewable
industry agree that government support is crucial. "It's not
by chance that the world's leading wave and tidal developers are based
in the UK," says Mr Scott. "It's because the DTI research
and development programme has been very successful. However, we are
now progressing into commercialisation and it requires a different
kind of support."
"There
is a need for wave and tidal energy to have some kind of subsidy to
help it through the interim stage between prototype and commercial
implementation," says Professor Fraenkel. Subsidies like this
can shield developers from uncertainties in running and maintenance
costs that occur in new technologies and often scare off potential
investors, he says. Wind power currently receives a subsidy of 3p
per unit of electricity, but Professor Fraenkel says it would have
to be higher to make wave and tidal energy viable.
Mr Scott says something similar to Portugal, where the government
subsidises wave power by 23.5 Euro cents (15.8p) per unit, is desirable.
The government has given significant support to the fledgling wave
and tidal industry. Last month, Patricia Hewitt created a £50
million fund to support the industry’s further development.
However, the British Wind Energy Association says closer to £130
million is necessary if industry is to realise the full potential
of these technologies over the coming decade.
It is a hefty price tag, but wave and tidal developers say it would
be money well spent, creating a whole new industry that would restore
jobs lost in the marine engineering sector as North Sea oil and gas
goes into decline.
"In the light of what the wind industry has become in Denmark,
[this investment] is very reasonable," says Mr Scott. "There
are a lot of winnings to be had here."
