Fred Pearce, New Scientist 21 Apr 09;
YOU can understand the frustration on both sides. Environmentalists worldwide are clamouring for bold action to end the burning of fossil fuels and plug the world into renewables. Politicians throw their weight behind a $14 billion scheme that would replace the equivalent of eight coal-fired power stations with tidal power. What do they get for their pains? Green outrage.
"This massively damaging proposal cannot be justified," said Graham Wynne, chief of the UK's normally staid Royal Society for the Protection of Birds (RSPB). Friends of the Earth said it was "not the answer". What is going on here? Have greens lost the plot? Has environmentalism been hijacked by big construction companies? Or do we simply have to learn that even environmental energy comes at an environmental cost?
The project causing all the controversy is the Severn barrage on the west coast of Britain, but similar stories are playing out across the world. As greens gradually win the argument for switching to renewable energy, they are finding that they don't always like the look of the new world they are creating.
The problem is one of scale. Bigness is often an issue for greens, many of whom grew up reading one of the movement's key texts: E. F. Schumacher's Small Is Beautiful. They liked biofuel while it was about recycling cooking fat, but not when it became growing millions of hectares of palm oil in former Borneo rainforest. Solar panels on roofs are good, but covering entire deserts with them is another matter. They like small wind turbines and even small wind farms, but get very jumpy as wind power reaches industrial scale.
Small may be beautiful, but it won't change the world. You can't generate vast amounts of green energy without large-scale engineering projects, which inevitably do some damage to the natural environment.
Greens have been here before, to some extent. Once, long ago, they loved large dams. From the 1930s to the 1960s, hydroelectricity was regarded as the new, clean and cheap source of electricity. Nobody cared about climate change then, but they did care about the killer smogs from burning coal. From the Rockies to the Alps, from Scandinavia to the Tennessee valley, nature would be harnessed to provide clean power for the masses. Woody Guthrie once wrote a song about the splendours of the Grand Coulee dam on the Columbia river: Roll along, Columbia, you can ramble to the sea, but river, while you're rambling, you can do some work for me he sang in 1941.
All that started to change in the 1960s after engineers tried to dam the Grand Canyon on the Colorado river and hikers rebelled. By the mid-1990s opposition to large dams had grown so intense that the World Bank stopped funding them for several years. Even after green projects became a major priority for most government aid agencies, none of them would touch China's Three Gorges dam on the Yangtze river, even though it replaces some 20 large coal-fired power stations. Projects like the Severn barrage are now provoking similar opposition.
The Severn estuary is a natural marvel. The British coastline has some of the highest tidal ranges (the difference between high and low tides) in the world, and the long funnel shape of the estuary gives it a tidal range that peaks at more than 13 metres, the largest in the world apart from the Bay of Fundy on the east coast of Canada. The tidal surge is so strong that spring tides create a wave running upriver, known as the Severn bore.
In January, the UK government announced its intention to go ahead with a major project to extract energy from the Severn's tidal range. The most likely option is a giant 16-kilometre barrage across the estuary, though the shortlist includes four smaller projects (see map and diagram).
First proposed 35 years ago, the full barrage would trap more than 400 square kilometres of tidal estuary behind a wall of concrete and sand. As the tide rises, sluice gates would be opened to let water in. At high tide the sluices would be slammed shut and the outrushing water forced through turbines. The barrage's theoretical peak generating capacity would be 8.6 gigawatts, enough to supply 5 per cent of the UK's electricity and 35 times as much as the largest existing tidal power plant, on the Rance estuary in France. Its lifetime might be more than a century, several times that of a conventional power station.
Ironically, the estuary's enormous tidal range is also key to what the RSPB calls its "truly exceptional ecological value" - hundreds of square kilometres of intertidal mud flats, sand banks and salt marshes, around half of which the barrage would obliterate.
In the parts of the estuary enclosed by the barrage, low tide would be about 5 metres higher than before, meaning that much of the intertidal zone would be permanently flooded, including 190 square kilometres of treasured wildlife habitat that is home to 70,000 birds in winter. The surviving flats might compensate by hosting more wildlife, but nobody can be sure. The barrage would also be a barrier to migrating eels and salmon. Even the famous bore might disappear. Friends of the Earth says the barrage will "wreck one of the most important wildlife sites in Europe".
Unfortunately there is nowhere like it for a tidal barrage. Engineers have identified other potential sites to tap the UK's exceptional tidal range, including Morecambe Bay, the Solway Firth and the Wash. But because the electricity-generating potential of tides is equivalent to the square of the tidal range, the exceptional range of the Severn estuary means it has about 80 per cent of the potential national resource.
One alternative is to ditch the full barrage and replace it with lagoons along the estuary's coasts, which would generate electricity while saving some habitats. Lagoons are on the shortlist, but engineers advising the government say they would deliver less.
Or how about directly tapping tides for their strong currents? The idea is to create an underwater version of a wind farm, with turbines attached to the sea bed in areas where strong currents flow, such as through channels and around headlands. The engineering company Metoc has identified 20 coastal areas where this could be done around Britain, the best sites being the Pentland Firth between mainland Scotland and Orkney, and around the Channel Islands.
Jewel in the crown
The problem is, nobody knows for sure how much power might be generated from tidal currents. The upper theoretical limit from all 20 sites combined is about the same as from the Severn barrage alone, but the technology is at a much earlier stage of development, and the most promising sites are remote from the transmission grids that carry power to customers. Nonetheless, the Scottish government has singled out the Pentland Firth as the "jewel in the crown" for its plans to exploit renewable energy.
There appears to be no getting away from the fact that only big projects can deliver big quantities of renewable energy, and this inconvenient fact is dividing green opinion. The UK government's Sustainable Development Commission, chaired by the former director of Friends of the Earth Jonathon Porritt, has come out in favour of the barrage. It concluded at the end of 2007 that, provided alternative habitat could be created for the birds, the barrage should be built. Porritt said "the enormous potential to reduce our carbon emissions" outweighed the environmental harm. He made some enemies that day.
Wind power is another front line. Studies of the windiness of onshore Europe have showed that most of the wind is in upland regions loved for their scenic beauty. This is particularly true in the UK, which has an estimated 40 per cent of Europe's exploitable wind and could make a big contribution to European Union targets for generating a fifth of its power from renewables by 2020. But most of this wind blasts into the Scottish Highlands, and tapping it means putting big turbines on highly visible hilltops.
Many say the solution for wind is to put it offshore. The winds are stronger, there are no neighbours, and turbines can be bigger. One bit of sea usually looks much like another. But even then the issues don't go away.
Again the UK exemplifies the problem. Plans for 10 wind farms off the coast of Scotland received a preliminary go-ahead this year. But Scottish waters have 45 per cent of Europe's breeding seabirds, many living around the reefs and shallows favoured for wind farm sites. Another concern is noise. There is good evidence that piledriving during turbine construction frightens away marine mammals and maybe fish too.
In the US, too, offshore wind farms are creating dilemmas. The 130-turbine Cape Wind project for Nantucket Sound, off the coast of Massachusetts, promises to be the US's first offshore wind farm - as soon as an already decade-long permit process is completed. The delay has been caused largely by objections from influential residents, including the Kennedy family, who say their view of the ocean will be spoiled. The battle has split the local environmental movement, culminating in Greenpeace organising street protests against Robert Kennedy Jr, an environmental lawyer and prominent opponent of the project.
Another emerging battleground is transmission. Scotland is debating whether to build a £300 million high-voltage power line linking the wind farms of the Highlands to the population centres of lowland Scotland and England. The cheapest way to do this would be to run overhead cables through the Cairngorms National Park. Undersea cables would be aesthetically preferable but would cost much more.
Scotland's dilemma will soon be writ large elsewhere. Most renewable sources of energy are intermittent. The wind is a byword for variability. The tides are predictable, but they ebb and flow to their own rhythm. Solar too comes and goes: the sun's rise and fall may be predictable, but clouds are not. If renewables are to be more than a niche source of power, this variability will have to be evened out to meet patterns of demand.
The only real solution is monumental transmission systems that link up renewable energy sources so they can substitute for one another. To work well, these systems need to be built on a continental scale.
One idea on the table is a European supergrid linking big population and industrial centres in countries such as Germany, France and the UK with the continent's great potential sources of green energy, which are mostly on the periphery. They include geothermal energy from Iceland, hydroelectricity from Scandinavia, wind power from the North Sea, and solar energy from the Iberian peninsula and even the Sahara desert (New Scientist, 14 March, p 42).
Such a network could guarantee renewable electricity for most, if not all, Europe's needs. When the sun goes down in the Sahara, Germany could switch to geothermal from Iceland. If the wind was blowing fiercely in the North Sea, spare power could be used to pump water uphill between reservoirs on Norwegian rivers, ready for release to generate energy when the winds dropped. But there could be huge battles ahead if local environmentalists object to the power lines passing through, and watch out for a "save the deserts" campaign when the solar power people get serious.
"This could be a blueprint for India, too, or north-east Asia, southern Africa or North America," says Nick Dunlop, founder of e-Parliament, an online global network of parliamentarians that is backing the plan. In the US, President Barack Obama is already on the case. He has promised to devote tens of billions of dollars to a national electricity grid. The idea is to link up desert states like Nevada, with their huge potential for solar power, and the Midwest states with their wind, to the power-hungry markets of the east. Again, though, battles lie around the corner.
Green schism
All these recurring disputes have to do with scaling up cuddly green technology to the point where it makes a real difference to the climate. They expose an emerging schism in the environmental movement. On the one side are the "sustainable developers", for whom nature is a resource to be managed. On the other are the "preservationists", who hold nature sacrosanct and for whom any damage by mankind to natural ecosystems is a defeat. Radical British environmentalist Paul Kingsnorth, who cut his teeth opposing road construction in the 1990s, now says: "To me, a wind farm on a mountain, a tidal barrage that turns a great river into a glorified millstream, or carpeting the Sahara with giant solar panels... are a similar desecration." For the preservationists, trade-offs are impossible. For sustainable developers, they are the essence of environmentalism.
There are many more disputes ahead. If more and more of the world decides to opt for renewable sources of electricity, the drive to do it faster and cheaper will grow. More large corporations with their eyes on the bottom line will get involved. More corners will be cut. Environmentalists will inevitably find themselves on the barricades defending the natural world from other environmentalists intent on generating clean energy.
The bottom line for greens is that these dilemmas and contradictions are the fruits of success. And the more successful their arguments for cutting greenhouse gas emissions are, the greater and more frequent will be the dilemmas. Rarely will there be a right or wrong answer. All visionaries imagine that once they get their way, it will be plain sailing. It rarely is.
Fred Pearce is New Scientist's environment correspondent
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