By Gerard Wynn
LONDON, April 23 As countries go offshore to
generate more consistent wind power and avoid blight to their
landscapes caused by onshore turbines, they will be increasingly
limited to unproven, floating turbine designs, adding to doubts
The problems underline the fraught issues behind a modern
energy strategy, balancing carbon emissions, security of supply
The state of technology development in offshore wind shows
how wide open the field is between low-carbon technologies
including nuclear, wind, solar and carbon capture and storage.
As far newer technologies, offshore wind and CCS have most
to prove, but doubts over nuclear (cost and safety) and solar
(cost, according to latitude, and space) make CCS and offshore
wind demonstration programmes worthwhile.
The deepest commercial turbines so far deployed anywhere are
around 30 metres deep. In theory they can go as deep as 60
These are turbines attached to the sea bed directly, either
with a single steel post hammered into the rock, or (in a more
innovative approach) at greater depths using a "jacket" of three
or four legs joined together in a latticework frame of
crisscrossing steel, also driven into the sea bed.
World offshore wind leader Britain has now leased most of
the wind resource accessible to these standard, fixed turbines,
according to a study published two years ago by the "Offshore
Valuation Group", a government-industry collaboration.
That leasing programme has so far licensed a potential 47
gigawatts, more than half the country's entire generating
capacity using all technologies now.
Only a fraction has been constructed, however, at 1.9 GW.
By tapping deeper waters, floating platforms would increase
potential wind power generation even more, by four times, the
Offshore Valuation Group estimated.
That's because Britain's windier coastline is on the more
steeply shelving western seaboard, with shallower waters on a
more sheltered, eastern shore.
Off northwest Europe higher average wind speeds are found
almost exclusively in deeper waters, motivating interest in
Norway's Hywind project is leading early-stage innovation.
The Statoil project tests a floating turbine with a
deep keel (called a spar buoy), which is a single steel post
plunging 100 metres below the turbine to keep it upright, and
additionally moored to the sea bed.
Two alternative approaches to remaining upright are: first,
using the wide surface area of a half-submerged platform, moored
to the sea floor using anchors; or, second, a system of cables
tethered to piles driven into the sea bed (called a submerged
A version of the first approach is presently being tested
off the coast of Portugal.
Britain will decide by early next year which of these latter
two to support in a 25 million pound ($40 million)demonstration
The United States Department of Energy recently announced
$180 million for advanced projects in offshore wind.
Britain and the United States announced on Monday an
intention to coordinate research and development.
Onshore wind is less predictable and potent than offshore,
but has the advantage of cheaper servicing and grid connection.
The upfront capital cost and ongoing servicing and running
costs of energy technologies can be combined in a measure called
the levelised cost of energy (LCOE).
At present, onshore wind generation costs in Britain are
approximately 0.09 pounds ($0.15) per kilowatt, according to
various consultancy estimates, and will hardly fall through
That compares with a gas-fired power plant LCOE started in
Britain today of about 0.08 pounds per KWh.
Offshore wind generation costs, using fixed turbines, are
presently around 0.17 pounds ($0.27) per KWh, projected to fall
to as little as 0.10 pounds by 2020.
The UK-based Energy Technologies Institute is involved in
Britain's present floating turbine demonstration programme, and
estimates these can generate electricity at around 0.09 pounds
per KWh, "post 2020".
That's an estimate for a well-understood but nevertheless
unproven technology. As ETI Strategy Director Andrew Haslett
states, the cost range "could be a lot more (than 9 pence), it's
not likely to be a lot less."