German energy plan under pressure

In order to facilitate an Energiewende from nuclear power towards wind and solar energy, Germany must invest tens of billions in new high voltage lines. Meanwhile power companies are trying to slow the transition down.

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Wind turbines and solar panels instead of nuclear power plants. That was the German message after the nuclear disaster in Fukushima (Japan), caused by an earthquake. All nuclear power plants will close down before 2020 and be replaced in part by renewable energy.

But this transition is not without flaws. The Dutch newspaper NRC Handelsblad ran a story about the difficulties of this ‘Energiewende’. Two weeks ago, German electricity transmission system operators presented a plan: 4400 kilometres of new high voltage direct current (HVDC) overhead power lines are necessary to expand the interconnector capacity between north and south. North Germany has large wind parks. The largest load centres are located in the south.

The technology has been proven. “In China, they have these kind of interconnectors covering thousands of kilometres,” says professor of process and energy systems engineering, Margot Weijnen (TPM).
But it seems that permits and money are the biggest hurdles. An investment of at least 20 billion euros is necessary. Prof. Weijnen: “It certainly is a lot of money. But this kind of investment in HVDC lines will also be needed in other parts of Europe in the near future, especially if we want to incorporate more large scale renewable energy and energy source without endangering the stability of the European electricity grid.”
The supply of renewable energy is irregular; therefore, it is necessary to connect different parts of the country in order to fill up any gaps that could exist when the sun isn’t shining or wind isn’t blowing in a particular region.

“One can work on it in two ways: by creating local smart grids with the possibility to store electricity and manage electricity demand. Or to aim at a large grid in Europe with connections to Asia and Africa. But probably both options will be combined,” says associate professor Karel Mulder (TPM, section Technology Dynamics and Sustainable Development).

Prof. Weijnen stresses that it is a smart move to build high voltage DC power lines: “They will have less transmission losses than high voltage AC. An additional benefit is that flows can be steered over DC lines. In the interconnected AV network, loop flows occur in neighbouring countries whenever Germany has more wind power than it can handle. In other words, the internal German congestion problem is exported to the Netherlands and Poland.”

The transition sets off a battle between the defenders of the old way of producing electricity and the supporters of renewable energy. “The old way was to invest in power plants that will supply electricity on demand on the spot. The power plants are expensive and the money paid for it is amortised over a long period of time, for example 30 years. After that period it is financially very rewarding to keep the power plants open, because the investment is paid off. Therefore the electricity companies with these kinds of plants want to keep them open over a longer time,” says professor of wind energy, Gerard van Bussel (Aerospace Engineering).

Prof. Van Bussel, Prof. Weijnen and Mulder expect the electricity companies to try to delay the Energiewende. “But the transition will probably not be cancelled,” says Prof. Van Bussel. “In order to make renewable energy work, these kinds of changes are necessary.


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