Memorandum submitted by Fells Associates
Wave and Tidal Energy technologies have been
neglected by successive governments. In the case of wave energy,
after some initial enthusiasm some 15 years ago and some financial
support, a report was produced by ETSU effectively condemning
wave energy as uneconomic for the foreseeable future and funding
was withdrawn in favour of wind power, which became the preferred
renewable technology, and still is. Tidal power did not reach
It is now appreciated that water based technologies
have an advantage over wind and solar in that the energy flux
is an order of magnitude higher, typically 4kW per metre squared
compared with 400W, often much less for wind and solar. The average
power in 1 metre length of North Sea wave is 40kW rising in storm
conditions to as much as 3MW!
Wave energy, despite the cold water poured onto
it by ETSU (sic), was developed jointly by WaveGen and Professor
Whittaker from the University of Belfast. A shoreline device,
now called Limpet, was constructed on the Island of Islay, more
famous for malt whisky. It operated successfully for 10 years
and has now been superseded by the Mk2 device which has been operating
since November 2000 and generates 500kW from waves rolling in
from the Atlantic. The technology is well developed and operating
experience is being accumulated. A major problem is transmitting
the power to the grid. There is a modest grid line to the remote
south west of the island but it must be strengthened to take the
500kW output from the wave generator. The initial quotation was,
I understand, £1 million which was later reduced to £500,000,
still impossibly large. A compromise has been reached but only
140kW can be transmitted leaving a surplus of renewable electricity
looking for an application.
This problem of grid connection is common to
all renewable sources, especially wind, and in many instances
makes a development totally uneconomic. There are several fundamental
reasons for this:
1. Distribution grids are "tapered"
towards the end and this is often where the renewable energy is
2. The current National Grid network was
never designed for receiving power from multiple sources as well
as delivering it.
3. The cables connecting England and Scotland
are running at full capacity and there is no mechanism for supplying
renewable energy generated in Scotland south of the border.
It is no good pointing to the potential for
wave energy around the coast of Scotland, or wind for that matter,
if grid connections are so expensive that the initiative is stillborn.
The quality of the electricity can also be an expensive problem.
It must synchronise with the grid if it is to be acceptable and
this requires additional electronic equipment. And then the intermittent
nature of the supply puts it at a disadvantage with the new electricity
trading arrangements (NETA) where fluctuating supply attracts
a penalty. It is perhaps surprising that enthusiasts persevere
with the technology considering the barriers to success.
Tidal stream energy is 10 years behind wave
power. One 200kW unit is about to be installed by Marine Current
Turbines of Lynmouth in Devon and The Engineering Business have
demonstrated a small model device which they would like to upgrade
to a demonstration stage but are having difficulty in financing
the venture. The science is well understood but the technology
requires further development. It is not even included in the Renewable
Obligation list of acceptable technologies despite considerable
Neglect of wave and tidal stream power is not
confined to the UK, indeed the Limpet advice is one of the most
advanced systems world-wide. There are smaller systems powering
buoys and remote instrumentation at sea. The Japanese TWG-3 is
currently used by Trinity House Light House Service and in Denmark
and Japan. Blue Energy in Canada have developed, and tested, a
25kW Darrieus vertical axis turbine or Davis turbine prior to
a 30MW version to be constructed in the Philippines. Numerous
designs have been developed and tested around the world and over
the last 10 years a composite set of generating predictions shows
initial generating cost of 20 p/kWh in 1980 down to 6 p/kWh in
Wind power is regarded as the most developed
renewable technology and is growing rapidly but from a small base.
If all the wind farms in the world were assembled on the South
Downs they would only generate 10 per cent of UK electricity.
The potential for building wave and tidal stream devices is just
as good as onshore wind and the highly concentrated nature of
the energy helps in the difficult economics of going offshore;
but the technology needs to be demonstrated and encouraged by
subsidy of some kind, if it is to develop.
Tidal stream devices are judged to be considerably
less obtrusive than wind turbines and barrages and the likely
hazard to navigation is no different from that exhibited by current
offshore installations. The impact on marine life has yet to be
assessed. The success rate for planning applications for new wind
turbines is rapidly falling off as public pressure against wind
turbines increases and this highlights the advantages that wave
and tidal stream based technologies could have in providing a
significant amount of renewable energy.
In the UK, the latest New and Renewable Consultation
Document describes the new arrangements for encouraging renewable
energy. This replaces the system where developments were granted
NFFO contracts guaranteeing a good price for all the electricity
generated. These contracts were bankable and attracted investors.
The new arrangements whereby suppliers (RECs) are obliged to provide
10 per cent of their supply from renewable sources by 2010 or
pay a penalty, require suppliers to enter into contracts with
renewable energy suppliers. But the price of the renewable electricity
has been effectively capped at 5p per unit. Wave and tidal stream
(and offshore wind for that matter) all come in above this figure
so it is difficult to see why suppliers should enter into such
contracts when they can buy themselves out at 5p per unit. Such
contracts will be short term in any event and not therefore bankable.
This is making life difficult for renewable energy developers.
It is clear that further encouragement should
be given to the less developed technologies such as wave and tidal
stream. Grants for research and development will not be enough
to grow these technologies however, their developers must see
a viable business ahead of them with the necessary return on capital
to make investment attractive.
9 February 2001