Coastal energy: the tides
If you want controversy, if you want environmentalists’ mutually-spilt blood on the organic cotton carpet, talk about tidal power, a topic on which I made myself extremely unpopular with large numbers of eco-friends twenty years ago. I suggested (to paraphrase) that as the proposed (eternally proposed) Severn barrage could produce as much electricity as several nuclear power stations, and as the emissions would be nil, after construction, and as the cost per kilowatt hour over its 125-year life (ignoring the crazy financial conventions which make it seem expensive for the first 25 years), would be negligible, I was not so bothered about the dangers to a few birds. Now, I know that was a simplification of the ecological price for that potential lunch, but Friends of the Earth was split down the middle, and I do wonder what the balance of environmentalist opinion would be if, by some chance, the economics of the project were massaged such that it were realistically offered as an option today.

Luckily, there are other ways of harnessing the enormous potential of the tides around Britain, with much less ecological or physical impact on the coastline. Tidal lagoons are enclosed, stand-alone structures which use essentially the same principle as the barrage: allow the tide in, hold it, then release the water through turbines. So, if you put them in an estuary (they can also be offshore), they are argued to be much less damaging than the barrage, as the tide can flow past them and the upstream mudflats are unaffected. Tidal Electric have a proposed scheme in Swansea Bay, and a Friends of the Earth report in 2004 was extremely favourable, emphasizing the advantages of the lagoon over the barrage, especially the fact that, although the lagoon would enclose less water, its much higher capacity factor (the proportion of its potential capacity which it can actually produce) means that its output per year would be greater. It has one large disadvantage, in that it would require a lot more aggregate in its construction: it is far from clear both where this would come from, and what the overall environmental costs would be.

Even more luckily, a third way of harnessing tidal energy offers itself. ‘Tidal stream’ technology is a device placed underwater, offshore – it can be in an estuary or off a coastline – where it extracts energy from the tidal stream passing over it. This can be like a vertical axis wind turbine, as with Blue Energy’s tidal fence devices in the Philippines, or like a conventional horizontal axis turbine, as with the Marine Current Turbines Ltd Seaflow, which has been operating off the coast of Devon for two years. Even more exciting (to this awe-struck observer) is the Engineering Business Group’s Stingray, tested in the Shetlands in 2002 and 2003. Its monster-from-outer-space-like structure sits on the sea bed, holding out large hydroplanes, like horizontal paddles, which oscillate up and down with the tidal flow.

Coastal energy: the wind
Offshore wind power is the most developed of the coastline energy technologies, with several ‘farms’ either up and running, in construction, or planned. AMEC Border Wind demonstrated, in a study in 1998 that we could supply 40% of our electricity from 4800 km. To put it another way: twenty blocks of sea, each 15 km square – given our coastline stretches for nearly 19,000 km, that’s just 0.03% of the UK controlled seabed. In 2003, the DTI published phase one of the new Strategic Environmental Assessment, which concluded that although there are potential problems they are not serious enough to halt development. It has commissioned long-term studies, and imposed strict environmental criteria to be applied in the case of each proposed wind farm.

Two of the most controversial issues for the public are the danger to birds and the visual impact of windfarms. You don’t need to be looking all that closely to notice quite contradictory reports about birds. “Wind farms pose low risk to birds” was the headline from the BBC on 8 June 2005, quoting research in the Royal Society’s journal. “World's biggest wind farm plan 'threatens seabirds’ ” was the headline in the Guardian, on the same day, quoting an RSPB spokesman referring to fears about the Kentish Flats project. The Danish National Environmental Research Institute found that the Tunø Knob offshore wind farm had ‘no significant impact’ and their latest research, using radar at the Nysted wind farm, shows that birds are adept at avoiding the windfarm: they just fly round it!

For excellent background reading, if you’d like to pursue this, start with the Birdlife International report, written for the Council of Europe in September 2003. This, and all substantial reports, emphasise that continuing research is advisable in this area, and also about the underwater ecology.

On the visual impact, too, it is easy to find contradictory evidence. At Porthcawl in South Wales, the Scarweather Sands offshore wind farm is vehemently opposed by ‘SOS Porthcawl’, but Greenpeace’s opinion survey in the area found that of 650 visitors polled, 83% said that it would make no difference to them, while only 4% said the siting of the wind farm would make them less likely to return to Porthcawl and 13% said it would make them more likely to return.

There are other environmental impacts of offshore wind power, both at installation and in operation. A good source for a detailed discussion on this is the report prepared for Greenpeace by the German Windpower Institute. During the construction phase, there will be damage to the benthos (sea bed flora and fauna) which may be serious if disturbed material settles on feeding grounds, to fish, and to mammals (for example through denial of feeding areas and the noise and vibration from pile-driving) which is impossible to quantify exactly. There will also be discharges of (probably small) levels of pollutants from ships and machinery.

During windfarm operations, in addition to the potential problems with birds, there will again be some disturbance of fish and mammals from vibration, as yet unquantified, some pollution from maintenance equipment, and some effect on fish from the electromagnetic effect of the transmission cables, again difficult to quantify. The general consensus is at present that all these impacts are either known to be, or expected to be, not large enough to prevent development.

One ecological species which may be more difficult to convince is human: the fishermen. The government is drafting a new Marine Bill which will share out power over, and access to, the inshore waters. It is suspected by the fishermen of being about to give far too much weight to the wind power interests. Barry Deas, chief executive of the National Federation of Fishermen's Organisations, was quoted in The Guardian as calling the dispute "a turf war". Since they are also in an uneasy stand-off with the sea-anglers and the dredging companies, we can perhaps assume that the government already knows not to look for free lunches on the coastline.

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