Published online 3 June 2011 | Nature | doi:10.1038/news.2011.348

News: Explainer

Policy change promises more renewable energy and electricity price hike.

Activists have campaigned against nuclear power in Germany. F. DOTT/GREENPEACE/AP PHOTO

Germany announced on 30 May that it will shut down all of its nuclear power stations by 2022. This leaves the country looking for ways to keep the lights on while meeting targets to cut carbon emissions. Nature explains the impact of the nuclear phase-out.

How much nuclear power will Germany lose?

Germany's 17 nuclear plants generated 140 terawatt-hours (1 terawatt is 1012 watts), or 22.5% of its electricity last year. By shutting them, the country is reverting to a nuclear phase-out plan that has been the status quo since 2002, before Chancellor Angela Merkel announced plans to extend nuclear power's lifespan last September.

Of course, 140 terawatt-hours won't disappear all at once. Seven nuclear plants that were shut after the Fukushima disaster — and another, shutdown since 2009 — will not re-open. Those supplied around 50 terawatt-hours, says László Varró, head of gas and electricity markets at the International Energy Agency in Paris. The remaining nuclear plants are likely to run until 2021 or 2022.

How will Germany fill the energy gap?

In the short term, Germany has ramped up spare capacity at existing coal-fired plants, and has also started importing electricity from France and central Europe, says Dietmar Lindenberger of the Institute of Energy Economics at the University of Cologne, Germany. His group is currently performing an energy analysis for the German government.

In the longer term, the government wants to raise Germany's use of renewable sources from the current 17% of electricity generation, or 100 terawatt-hours, to 35% by 2020. As part of the same energy policy, adopted in October 2010, the government also wants electricity consumption to fall by 10%.

“Without nuclear power, decarbonization is more difficult and more expensive.” Laszlo Varró

International Energy Agency

The idea of reducing demand by 10% is 'very ambitious', Varró, Lindenberger and market analysts agree.

On the renewable-energy plan, however: "If anyone can do it, Germany can," says Varró. "Germany is currently adding about 11 terawatt-hours of new renewable electricity generation a year. If they keep this pace up for a decade, they will get there." Germany's cabinet is due to approve a series of laws this month to boost the prospects for renewable energy, involving such measures as expanding the electricity network to cope with larger amounts of intermittent power.

Put the targets together, and renewable energy sources still won't quite fill the gap created by nuclear's absence. This means that Germany will probably need to buy in electricity and build new gas or coal plants. The country already has enough gas and coal plants under construction to provide 10 gigawatts for 2015, but this is merely to replace old plants, says Lindenberger.

What does building coal and gas power plants mean for carbon emissions?

If Germany doesn't import electricity, its domestic carbon emissions are likely to increase — because even a doubling of power from renewable sources combined with a 10% cut in demand can't quite replace the low-carbon nuclear power that will be lost. Analysts put the increase between 170 million and 400 million tonnes of carbon dioxide between 2011 and 2020 (depending on different assumptions about the country's shifting power mix).

Germany has national targets to cut carbon emissions to 40% below 1990 levels for 2020. That means that by 2020 it needs to slash 70 million tonnes a year from its electricity sector's carbon emissions, says Varró. "Without nuclear power, decarbonization is more difficult and more expensive," he says — predicting that the nuclear phase-out will lead to a surge in lower-carbon gas plants replacing coal plants.

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Europe's carbon emissions from electricity are capped under the European Union Emissions Trading Scheme (ETS). If Germany imports electricity from elsewhere — to avoid increasing domestic carbon emissions — then other countries will have to buy more ETS credits to emit carbon dioxide. Because the supply of these carbon credits is limited, their cost will go up. Electricity suppliers will charge their consumers more. The final result is that everyone will pay more for their electricity.

How much more will people pay for electricity?

In Germany, consumers are likely to have to pay 1 or 1.5 Euro cents (1.5–2 US cents) more per kilowatt-hour of electricity — about a 5% increase on electricity bills, says Matthias Kleiner, head of the DFG, Germany's national research agency. Industry, which pays lower rates for its electricity, will feel a greater effect.

Ultimately, the effects of Germany's nuclear phase-out decision will spread around Europe. Other countries may have to replace coal plants with gas plants, and electricity will become a little more expensive for everyone.

There will be a greater need for networks to transmit the cheapest sources of renewable electricity (such as northern European wind power or southern European solar power) across many European countries. "The power system needs to change substantially from a national to a supranational system," says Lindenberger.