Nuclear Power & Climate Change

Load-following has an important role in the maintenance of the national grid. Base load power should be produced using methods in which stability and reliability are key. Photo: Istock

Why do we need different sources of electricity?

The demand for electricity varies widely at different times of the day and from one season to the next. It makes sense to use nuclear power to produce base load power that satisfies a steady basic demand. Load-following flexibly adjusts the supply to fluctuations in consumption.

Winters in Finland are cold and dark, whereas summers are quite the opposite. That alone causes extensive fluctuations in the demand for electricity. Demand also varies widely between daytime and nighttime.

During the Finnish winter, the demand for electricity is as much as 12,000–14,000 megawatts. Electricity is consumed by lighting, household appliances and heating as well as by offices and factories. Finnish industrial facilities consume approximately 50 percent of all electricity. Demand is at its highest during weekdays in temperatures well below zero.

In the middle of summer, the need for electricity is nearly half of the need in the winter, in other words, approximately 7,500–8,000 megawatts. This is the year-round basic need; the minimum demand. It is reasonable for the production of base load power to be fairly close to that figure for security of supply and cost efficiency reasons.

Nuclear power and hydropower provide affordable base load power

Base load power should be produced using methods that are affordable and in which stability and reliability are key.

“Nuclear power and hydropower are excellent methods of producing base load power. A nuclear power plant should thus always be operated at full capacity. This is usually the case, with the exception of shutdowns for maintenance and refueling,” says Tuomo Huttunen, a specialist at Finnish Energy.

“Hydropower can generate base load power and perform load-following. Producing base load power with hydropower is economical, but what makes it specifically useful is that it allows for flexibly addressing fluctuations in demand.”

Hydroelectricity is both produced in our own hydropower plants and imported from plants in Sweden and Norway. Opportunities to build additional hydropower plants in Finland are fairly limited. That is why increasing the construction of additional nuclear power is justifiable here.

Part of the electricity comes from combined production plants, which produce both electricity and heat. This is efficient and sensible, since in the winter, the need for both heating and electricity is high. In the summer, heat and electricity production in the combined production plants is considerably reduced, as fairly little heating is needed in sectors other than industry.

Load-following and weather-dependent electricity production

Load-following includes part of the hydropower capacity, the combined production plants and electricity imported from abroad, as well as steam-electric power stations, which generate only electricity from biomass or coal, for example.

Load-following power covers that portion of our demand for electricity that fluctuates. Load-following has a very important role in the maintenance of the national grid.

Load-following is mainly produced by hydropower plants. The volume of electricity in the grid is, to a certain extent, also controlled by means of imports. There are also other methods to carry out adjustments in a very short time. In winter, when demand is at its highest, electricity is also produced in combined production plants and, to a lesser extent, in separate electrical power plants.

Wind turbines and solar panels do not generate load-following, since their electricity production volume is not adjusted by people but by weather. Thus, we can talk about weather-dependent or variable electricity production methods, which need to be accompanied by load-following.

Self-sufficiency should be increased

Finland imports an exceptionally large portion of the electricity it needs. The volume of imported electricity is twice that of the planned electricity production of Fennovoima's Hanhikivi 1 nuclear power plant.

“Today, the proportion of imported electricity in Finland is too high. Transfer cables crossing national borders are operating at high capacity. In order to increase flexibility, Finland’s own production capacity should be increased so that, if needed, the transfer cables could accommodate additional imports.”

“That is why building new nuclear power plants in Finland is a good thing,” Huttunen emphasizes.

Illustrations: Antti Pihlajaniemi

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