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Renewable Energy

Wind of discontent

by Lea Sibbel 18 Jul 2011
Wind of discontent

The downside of the world's energy solution

An environmentalist observing the steady rotation of the hundreds offshore wind turbines at the coast of Germany's North Sea, stretching from the Dutch border all the way up to the islands of Fohr and Sylt, gets a sense of a peaceful tranquility and hopeful enthusiasm: This could be the future of green energy, one possible way to help fight climate change.

Meanwhile, the troubles under the surface of the water usually go unnoticed.

Recent developments only strengthen the hope of those concerned about climate change. At the end of May, the German government decided to take a turn in its energy policy: By 2022, nuclear power will be completely abandoned - which will inevitably lead to a greater reliance on renewable energy, not least wind power.

Environmentalists could not be happier about the push for renewable forces in the political arena. The latest decisions state that by 2020, 35 percent of Germany's energy will come from renewable sources. According to the German Federal Ministry of the Environment, this plan is ambitious, but feasible, if the expansion rate of the previous years is retained. Between 2006 and 2010, the amount of current from renewable sources has risen 40 percent, from 11,6 percent of the total electricity generation in 2006 to 16,8 percent in 2010. With an output of about 27 GW in 2010, wind energy is one of the most efficient suppliers for alternative energy.

Regarding climate change, this development is welcome news, particularly because renewable energy goes hand in hand with a reduction of greenhouse gases. A task force of the Ministry calculated that thanks to these alternative solutions, 120 million tons of CO2-equivalent (a figure for global warming potential measuring how much of a certain greenhouse gas contributes to the greenhouse effect) was eliminated in 2010. The share of energy gained from windparks amounts to 23,7 percent of this figure. And there is more to come: The emission of 117 million tons of CO2 was avoided, with windparks yet again taking on a huge share (22,3 percent).

These numbers make Kyoto-supporters giddy. But it seems that when it comes to environmental issues, there is always a trade-off. So while the Dutch and inhabitants from the Maldives tentatively start to hope once more, the ecosystem of the ocean suddenly encounters new challenges.

Trouble below the surface

Building windparks offshore is argued to have many advantages. First, there is the obvious: Turbines in the sea do not disturb human settlements. More economic reasoning takes the efficiency of offshore parks into consideration: Out in the sea, the wind blows stronger and more consistent. But often forgotten is that while a windpark is erected, the noise can disturb the sonic system of whales, a species that is already endangered.

Whales make use of that sonic system for communicating, navigating, feeding and nursing. Already, ocean noise pollution, as created by engines of huge industrial vessels, restricts the communication network of whales increasingly, points out bioacoustician Lindy Weilgart in a New York Times article. But with the erection of windparks, the noise level is only being augmented.

Underwater, sound is highly intensified. According to a research by several environmental organisations, such as NABU, Deepwave and BUND, sounds from diverse sources start to interact under water, creating a high level of noise. The most common technique employed to build windparks is the pile-driving process, which creates repeated impulses of noise that accumulate easily and can reach an intensity of 200 decibels. In the North Sea and the Baltic Sea, where most offshore windparks are situated, the native porpoise is particularly threatened by this process, potentially becoming a victim of serious hearing impairment, says Hans-Ulrich Rosner, director of the tideland-department of WWF Germany.

And the period of installation is not only a matter of a few weeks. For the offshore windpark "Bard I", situated northwest of the North Sea island Borkum, it took one year alone to build the first 24 foundations, but an average offshore windpark compasses 80 wind turbines. The installation of 100 turbines at the Thanet offshore windfarm at the English coast lasted 100 days. At Vestas, the largest manufacturer of wind turbines in the world and producer of Thanet, one is proud of that time frame: "It is a record for the industry", says Rikke Tikjob Christiansen, vice president of the offshore communication department at Vestas. But it still means more than three months of increased underwater noise.

Environmentalists have long been concerned about the whales' acoustic well-being. A few years ago, several environmental organisations went to court against the government of George W. Bush, provoked by the US Navy's plan to employ a sonar program to locate submarines, operating on a low frequency with a volume of 230 decibels, an amount that could seriously harm marine mammals. In the end, nature won: The federal court blocked the Navy's sonar system. (Ever since, the Navy has sought to find loopholes and exemptions. But that's a different story.)

Now, however, nature is in a match against itself, with lines of tension stretching beyond the problematic impacts on the sonic system of whales, as offshore windparks also endanger birds. WWF's Hans-Ulrich Rosner warns that the millions of migratory birds (in particular songbirds) crossing the North Sea and Baltic Sea every year are now at risk to collide with the wind turbines. The danger intensifies in bad weather conditions, when the birds are hardly able to spot obstacles in advance.

A study conducted in 2008 by the University of Hamburg and BioConsult showed varied results. While some migratory birds actively change their route, avoiding windfarms if the weather allows for it, other resident species, such as sea gulls and non-migrating cormorants, enter the areas nonetheless, exploring them as a potential new food source. This behaviour increases the danger of collision. For other resident species, the erection of offshore windparks coincides with a loss of habitat and barrier effects. One such species is the loon, which loses its basis for foraging, resting and molting. In extreme cases, these barrier effects can lead to a fragmentation of the species' vital biotope-composition of resting and breeding grounds, states the Federal Office for Nature Conservation in Germany.

Yet another peril could stem from the cables leading off the wind turbines. "The cables might cause a deviation of fish routes, because of the electric fields they create, but we are not certain about this yet", says Rosner. "What is causing us more distress is the temperature rise around the big cables in the tidelands" - originating from their electric activtiy. The tidelands in the North Sea are extremely sensitive and dynamic ecosystems, which call for very careful treatment.

All these problems are not unknown. The Federal Office for Maritime Shipping and Hydropraphy (BSH) in Hamburg, which is responsible for authorizing offshore windparks, has issued guidelines of what to do environmentally if a new windpark awaits approval. Thus, surveys must be conducted not only about the pertinency of the territory, but also about the impact of the wind turbines on sea dwellers and birds.

However, what must be considered is the enormous economic momentum of wind power sweeping through the Republic, with the latest turn of policy now stronger than ever. Christian Dahlke, head of the division "organisation of the ocean" of the BSH does a quick counting: "We have so far approved 23 windparks in the North Sea and 3 in the Baltic Sea. Sixty-eight more projects wait for our authorization." These figures have increased the ambition of environmentalists and engineers alike to find a solution that benefits both the fight against climate change and the ecosystems affected by offshore windparks.

Floating towards a solution?

In the Norwegian Sea, within eyeshot of the small municipality of Karmoy, a new technique is currently being explored, which experts hope to address marine concerns. "Hywind", the first full-scale floating wind turbine, has been tested in the sea since 2009. The concept was developed by Statoil, the Stavanger-based oil titan, which now pursues alternatives to its main source of energy. Financial support came from the government enterprise Enova, which promotes green energy.

Unlike the wind turbines planted in the seabed, Hywind floats in the water, balanced by from a steel cylinder filled with water and rocks, extending up to 100 meters under the surface. Its position is secured with a three-point mooring spread which is attached to the seabed. A submarine cable leads the electricity generated to the mainland.

With the two-year trial period coming to an end, Lyndsey Corrigan, communication manager at Statoil, draws a realistic conclusion: "The design of floating wind turbines is challenging, given the need to combine the effects of environmental loads (from wind, waves, currents) and the loads from the turbine itself." Plans to adapt the design to rough sea conditions with storms and extremely high waves are on their way, including reduced steel weights, a higher capacity turbine and a more efficient floater that can be installed in shallower waters. Only then can the next step be taken: Installing a multi-turbine offshore demo windpark. And then: Commercializing the floating turbines.

If the floating design really does get commercialized, it could potentially help reduce the problem of noise pollution, because there is no longer a need to pile the turbines into the seabed. Corrigan is also optimistic about avoiding a clash with birds, as locations could be chosen more flexible, with regard to habitats and migratory routes.

But the future of large-scale windparks is complicated by more than just engineering difficulties. Up to this moment, their financial viability is also hotly debated. Hywind has guzzled 370 million Norwegian Kroner (about 47 million Euros) - for one turbine. Yet Statoil is sure that the floating design will eventually be able to compete with bottom fixed developments.

The New York Times expressed a more pessimistic view in one of its articles, doubting the financial feasibilty of such projects because the costs for installation, maintenance and repair would be very high. Then again, Christian Dahlke of the BSH argues the complete opposite: "We were once told that the costs of floating windparks would be about one third of the ones with fixed foundations."

If that proved to be true, the new kind of offshore-wind turbines could actually compete with onshore windparks, which are two to three times cheaper than the offshore model, estimates Rosner. What is more, the capacity of the two offshore versions is comparable, with Hywind creating 2,3 MW and regular offshore wind turbines supplying between 2,0 and 3,0 MW. With the German government planning to gain no less than 25.000 MW from offshore windparks by 2030 - which equates to more than 8000 3,0 MW offshore wind turbines - floating windparks could be not only environmentally, but also economically advisable.

But time is running. While the technique for floating windparks is not mature yet, pressure to keep up with international agreements to reduce greenhouse gas emissions, coupled with the eradication of nuclear power, will lead Germany to a greater amount of renewable energy, not least from offshore windparks. Yet they will not be floating: All of the 68 projects awaiting approval at the BSH employ turbines with a fixed foundation in the seabed.

Ultimately, the turn towards renewable energy is prioritzed, even by organisations like the WWF. "Windparks need to be especially supported", says Rosner. For the porpoise, long years of being exposed to the pile-driver thus lie ahead.

Top Image Credit: Â © TebNad

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