When the ten per cent saved equals ten billion
Where will the electricity from offshore wind turbines be transported to? How will the electric power requirements be met when there is no wind? Which shore approaches should be selected for the cables? How can they be connected? Is direct current the only alternative?
Text and photo: Albert H. Collett
Europe faces formidable challenges if it is achieve its climatic goals. One of them is to build a rational power transmission network in the North Sea. The investments will be in the hundreds of billions. Good solutions are important.
North Sea network
One of those who is looking for good solutions is Magnus Korpås, research director in Energy Systems at SINTEF Energy. Through NOWITECH* and the "Role of North Sea power transmission in realizing the 2020 renewable energy targets" project, he and his colleagues are trying to create an optimization model for what is referred to as the North Sea network. A clear definition of what the North Sea network is does not exist, but it is all about transporting electricity in the most rational way to solve both the climate and energy challenges Europe faces. There are at least three key elements: Strengthening the link to Northern Europe, the landfall of offshore wind power, and the electrification of the Norwegian continental shelf.
The optimization model that Korpås Magnus and his colleagues are working on is new. Many have made sketches of it, many wise words have been said and written, but no structured methodology for the overall design of the North Sea network has been produced until now. A fundamental approach is of course the realistic one. But it does not help creating promising visions if they prove to be wishful thinking. The optimization model is designed as decision support for power utilities and wind power developers. In the efforts to assess the financial consequences of the different varieties of the North Sea network, EMPS has been adopted. This is SINTEF Energy Research's proprietary power market simulator that is used by many large power companies in the Nordic countries.
Radial and meshed
Energy networks are primarily characterized by two models, radial and meshed. The former have a node that the lines radiate from. They are vulnerable. If a line is severed, there is a power outage. This is one of several reasons why a meshed network is necessary to ensure a reliable supply of power. The North Sea network will be a combination. The search for the best combination involves billions of kroner. Just as important as the combination is the location of the components. Where should the meshes be? How fine should they be? And not least, what capacity should the network have?
Many people involved
For the EU, the challenge is to look outside its borders, says Korpås' colleagues at SINTEF; Knut Samdal in Electric Power Systems and Petter Røkke in Electric Power Technology.
Research directors Petter Røkke, Knut Samdal and Magnus Korpås explain that the North Sea Network is all about the efficient transport of electric power.
Hydroelectric power from Norway and the Alps and solar power from the Sahara are being considered for a possible future European "super highway" which in principle can range from the Sahara in the south to Finnmark in the high north.
While Samdal is particularly involved in systems analysis, Røkke is working primarily with "harder components." There are many researchers in their respective fields that are engaged in issues related to North Sea network. Hallvard Faremo is for example in the process of completing work that has focused on the special dynamic requirements of the cables to be used for offshore wind farms.
Another SINTEF researcher is Bjørn Gustavsen who is a capacity in deciding between direct current and alternating current. Many believe that the choice of direct current is made because of the low power losses, but the important technological issues are unresolved.
*NOWITECH, Norwegian Research Centre for Offshore Wind Technology, is an FME led by SINTEF Energy Research with SINTEF, NTNU, and IFE as the main partners.