“Many are sceptic to entirely or partly removing nuclear power and fossil fuels, since there can be large fluctuations in how much electricity can be produced with renewable energy. But our study shows that this does not have to be a large problem. It’s all about finding a good mix of energy sources,” says Jon Olauson, researcher at the Department of Engineering Sciences at Uppsala University.
The difficulty with electricity production is that it happens in real time. The electricity needed right now must be produced right now. This places great demands on flexible regulation of hydroelectric power, which is the simplest way of storing energy. In the study, the researchers have looked at the Nordic countries’ energy demands and what would happen if the countries entirely relied on renewable energy sources.
“With only wind, solar, hydroelectric, wave and tidal power we become more dependent on nature and changes in weather. If the wind dies down for a few weeks, wind and wave power plants won’t produce the electricity needed. The system we have today is primarily designed to handle variation in electricity production over a day, or over a whole season,” says Jon Olauson.
The research team, which is based at Uppsala University’s Ångström Laboratory, have based their calculations on the electricity consumption of the Nordic countries. By then deducting the renewable energy that is already being produced they calculated who much more renewable energy is needed. They have studied different mixes of energy sources, where expansions would be possible and what potential is available.
People and society have clear consumption patterns. We consume more electricity in the winter than in summer, and more during the day then at night.
“Today, hydroelectric power is used to balance out seasonal variations, but we need more knowledge about how it could be used to balance semi-long-term variations. An alternative would be to import electricity or use gas turbines. You could also pay major electricity consumers such as manufacturing industries to close down their operations at certain hours to save electricity. This is already being done, but could perhaps be expanded,” says Jon Olauson.
The study has not taken into account the current limitations in distributing electricity across the Nordic countries. With the current distribution system it would be tough to manage electricity delivery everywhere with only renewable electricity sources. In Sweden for instance we have a lot of production in the north but most of the consumption in the south. The next step is to model the entire power system to find the bottlenecks.
“Whichever way we mix the renewable sources we get quite large variations between semi-long-term periods. So further studies should focus on how hydroelectric power can help balance these variations. Another way to reduce the need for balancing could be to produce slightly more electricity than needed and then cut off production at times of low consumption,” says Jon Olauson.