Written Evidence from The Environment
The Environment Trust is working to bring the
UK's first community owned tidal lagoon to Swansea Bay. Tidal
lagoons use an offshore impoundment structure that looks like
a rocky island. The impoundment is fitted with conventional low-head
hydroelectric generating equipment and produces predictable power.
The technology works best in areas with high tidal ranges, and
Wales has the second highest tidal range in the world. Wales has
the potential to lead the world in tidal energy.
We hope to develop schemes in Newport and Rhyl
after Swansea. There are 22 sites across the UK where this technology
could be applied, and we believe that it could eventually supply
up to 20% of the UK's energy needs.
1.1 About the Environment Trust
The Environment Trust is a registered charity
and a company limited by guarantee. We improve the social, economic
and physical environment for community benefit. We were established
in 1979, and have built an award winning millennium park in Mile
End, a number of affordable "green homes" in London
and now in Sheffield, and improved numerous green spaces in London.
We also run environmental education programmes and established
Fair Finance, the UK's first Financial Services Authority accredited
community finance institution.
1.2 The Environment Trust's interest in Welsh
The Environment Trust has recently acquired
the Welsh Biofuels wood pellet factory in Bridgend. We turned
around its business plan and the business is now processing 10,000
tonnes of wood pellet a year. The business has expanded from six
to 16 employees, is controlled by a majority Welsh board, including
Win Griffiths, the ex-MP for Bridgend, and is committed to using
its profit for community benefit in Wales. We are hoping to establish
other factories in the UK using the Welsh Biofuels brand.
1.3 The Environment Trust is working to
install a tidal lagoon in Swansea Bay. This tidal lagoon, and
the position and potential of tidal energy in Wales more generally,
will be the main focus of this written evidence.
1.4 The Trust welcomes this opportunity
to give evidence to the committee, and will be pleased to appear
as a witness, or to offer further information if necessary.
2. TIDAL LAGOONSGENERAL
2.1 Until now, the main way of generating
energy from the sea has been tidal barrages, notably La Rance
Barrage in France. Environmental problems have made tidal barrage
technology unattractive because navigation is blocked, fish migration
is impeded, shoreline habitats altered and the tidal regime is
2.2 Offshore tidal lagoon technology is
a new way of generating electricity from the ocean. The technology
is similar to conventional low-head hydroelectric technology,
but by using tidal pools built from loose rock and located offshore,
potential environmental damage is eliminated.
2.3 Electricity is generated as the tidal
lagoon fills and empties on the ebb and flow of the tide. The
hydroelectric generating equipment is housed in a self-contained
offshore impoundment structure or atoll built from loose rock.
Using this offshore impoundment structure, water is impounded
at high tide and delivered to turbines at low tide, and then the
water is held out at low tide and delivered through the turbines
at high tide.
2.4 This diagram illustrates the power generation
cycle of a tidal lagoon. At high tide the lagoon appears as a
circle on the surface of the water, almost invisible from the
shore. At low tide, it looks like a rocky island. As the structure
is built from locally sourced rock, it can provide a vital habitat
for wildlife. It can be located as little as a mile offshore,
so it has no effect on shipping or navigation.
3. A TIDAL LAGOON
3.1 The Environment Trust is working to
create the UK's first tidal lagoon in Swansea Bay, with a declared
net capacity (DNC) of 60MW. This would provide the whole of Swansea
3.2 This plant would save up to 194,332
tonnes of carbon emissions per year, which over the 50 year life
of the plant amounts to 3,886,641 tonnes of carbon saved. Tidal
lagoons could therefore play a vital part in allowing the UK to
meet its carbon emissions targets.
3.3 Subject to ERDF and Welsh Assembly support,
the Environment Trust would make the lagoon in Swansea Bay community
ownedthe first community owned power plant in Britain.
This would ensure that the profits from the sale of the electricity
(estimated to be £8 million a year after the first three
3.4 Because tides are totally predictable
the output from a tidal lagoon can be estimated very accurately.
The projected cost of electricity is likely to be 3.5p per KWh.
For larger project in locations with higher tidal ranges, cost
could be as low as 2p per KWh.
3.5 Developing the Swansea Bay scheme will
take three years, including the community consultation and consents
process. Private loan finance for half the cost has been offered
but, because this is the first scheme, private equity investment
is proving difficult. Paradoxically, this offers a unique opportunity
to translate government grant into community equity and provide
a revenue stream to pay for community led regeneration into the
3.6 In response to earlier concerns by Welsh
Development Agency and Department of Trade and Industry officials,
a detailed study by WS Atkins was commissioned. The Executive
Summary is attached as an annex, but the main findings are as
3.7 Feasibility confirmed
Atkins investigated the feasibility of construction,
operation and eventual decommissioning of a tidal lagoon installation,
with proposed capacity of 60 MW and annual generation of 187,000MWh.
The installation concept envisaged an impounded area of some five
kilometres square, in a water depth of 15 metres at mean
low tide, with 24 bi-directional turbines each of 2.5MW capacity.
3.9 The Atkins study has confirmed both
the technical feasibility of the project and its ability to deliver
the specified output, on a predictable basis with minimal regular
maintenance and negligible operating costs. It further confirms
that practical design solutions exist for all necessary structures
and equipment. Working with the local utility, Western Power Distribution,
a way has been found of connecting to the grid.
3.10 No exceptional problems
Atkins engineers studied the full range of exceptional
issues related to the location, such as tide and weather conditions,
likely settlement of structures on the seabed, disturbance of
seawater circulation in Swansea Bay and possible ship navigational
hazards. It was concluded that there were no inherent exceptional
3.11 The study finds that it should be possible
to obtain all the plant, equipment and building materials and
complete construction of the facility within 36 months. Looking
well ahead, de-commissioning issues relating to the proposed installation
were reviewed and found to present no particular technical problems.
Indicative costs were drawn up, based on investigations
with various suppliers and contractors. If given the go-ahead,
the next phase would be to put a specific design out to competitive
tender, which would allow for more accurate capital cost estimates.
Based on the Atkins findings, it is possible
to produce electricity from the Swansea Bay scheme at a cost of
3.5 pence per kilowatt hour.
3.13 River Tawe Test Project
Despite the conventional hydroelectric technology
used to generate electricity in a tidal lagoon, there has been
some debate over the use of hydroelectric generators in this context.
In response to this, the Environment Trust is working with the
City and County of Swansea to bring back into use the currently
unused turbine in the River Tawe. This would both be a valuable
renewable energy scheme in its own right and a scaled down demonstration
of how a larger lagoon would work.
4. THE WIDER
4.1 Wind energy dominates the renewable
energy policy landscape in Wales, and lack of government support
for or interest in tidal lagoons has made it difficult to secure
financial backing for the pilot scheme in Swansea. The Crown Estate,
who lease the land necessary to build the scheme is Swansea Bay,
are adamant that they cannot proceed without a strategic lead
from the DTI, in the form of the Offshore Renewables Strategy.
4.2 The Offshore Renewables Strategy went
for public consultation in 2002, but has not yet been published.
The consultation document dealt solely with offshore wind power,
and we are concerned that the potential of tidal power is being
ignored. However, we do have a note of a meeting with DTI officials
where they indicated they would look on tidal lagoon technology
4.3 Tidal lagoon technology was dealt with
favourably in the 2004 House of Lords Science and Technology Committee
report, Renewable Energy: Practicalities. Both AEA Technology
and Friends of the Earth have also backed the tidal lagoon scheme,
with AEA Technology concluding that tidal lagoon technology is
"mechanically feasible, environmentally benign and economically
4.4 Once the Swansea Bay scheme is established,
we would like to develop further lagoons in Newport and Rhyl.
There are 22 further sites around the UK with tidal ranges high
enough to support tidal lagoonswe believe that there is
the potential to supply up to 20% of the UK's electricity needs
from tidal lagoon technology.