On a per capita basis, France and Sweden are by far the two countries with the highest electricity generation from nuclear power in the world. This is not the only similarity they share. Both France and Sweden have electricity generation mixes with very high shares of low-carbon electricity; roughly 90-95%. Historically this has been made possible thanks to hydro, then nuclear, and more recently thanks to expanding wind. In 2018 and 2019, France and Sweden were in the top 5 countries installing most new wind power capacity in Europe.1
In both countries’ electricity generation from fossil fuels (coal, gas, and oil) is small. As wind expands displacing all remaining fuel-based generation, nuclear is often the marginal source of power as both hydro and wind are cheaper providers of marginal electricity. This means nuclear power output is adjusted to match system conditions. Low demand and abundant supply from hydro and wind put downward pressure on electricity prices and reduce the capacity factors of nuclear, thus weakening reactors’ economics.
In this regard, the first quarter of 2020 was a case study. Between January and March in Europe, the winter has been mild, lowering electricity demand for heating, and weather conditions for electricity generation from hydro and wind have been favorable. Unsurprisingly in France and Sweden, electricity prices have been low, and electricity generation from nuclear has gone down. In France, day-ahead prices averaged below €30 per megawatt-hour (MWh), and electricity generation from nuclear has decreased by more than 10 terawatt-hours (TWh), or -10%.2 In Sweden, where the deployment of hydro and wind power is greater, day-ahead prices have been lower than in France; less than €20/MWh in average, and sometimes well below €10/MWh, and electricity generation from nuclear has decreased by almost 2 TWh, or -10%.3 These developments eventually led to the economic shutdown of the Swedish nuclear reactor Ringhals-1, scheduled to be permanently closed by the end of the year.4
The following charts illustrate specific situations when nuclear power output is adjusted to match system conditions in France and Sweden:
In France, between February 15 and 17, 2020, demand for electricity was relatively moderate, and hydro and wind outputs significant – combining for up to one-third of the country’s electricity production in the morning of February 16. At this time, spot market prices were negative and nuclear power bottomed out at 36 gigawatts (GW), against a maximum of 50 GW in these three days; a difference of about 30%.5
In Sweden, between February 14 and 20, 2020, demand for electricity was also relatively moderate, and hydro and wind outputs high – combining for up to three-quarters of the country’s electricity production during most of the day on February 17. At this time, spot market prices were just a little above €10/MWh and nuclear power hit a minimum of 5 gigawatts (GW), against a maximum of 8 GW in this week; a difference of approximately 35%.6
Instances when wind generates more electricity than nuclear come more often, and the 8th week of 2020 was the first full week when wind provided more electricity than nuclear in Sweden.7
In the future, this type of events will repeat more frequently as new cost competitive close to zero marginal cost renewable energy will be further expanded endangering nuclear power technology.
Thus, renewable energy displaces, and will ultimately replace nuclear power.