What is agora in the dark web

Climate protection activists had good reasons to celebrate at the beginning of the year: Vattenfall switched off its coal-fired power plant in Hamburg's Moorburg district, and some power plant units in the Rhineland also went offline. But just then, of all days, many other coal-fired power plants in the country were running at full speed - as if they wanted to once again show what they can do with all their might. Power plant operator Leag, for example, reported that its large-scale systems in Lusatia are working at full capacity. Together with the gas-fired power plants, the coal piles secured the power supply in Germany these days.

Because the wind turbines and photovoltaic systems weakened a lot at the beginning of January. There was a lull in the whole of Germany and off the coasts, and the sun was barely visible. In the period between the morning of January 6th and the morning of January 10th, for example, wind energy on land and at sea together with photovoltaics did not exceed ten gigawatts of output - but the electricity consumption during these hours was between 51 and 74 gigawatts. A similar picture emerged between January 15th and 17th.

What does this mean for the coal phase-out? Does the risk of blackouts increase with every power plant that goes offline? After all, it is not that rare that so-called dark doldrums occur - that is, that wind and sun are largely absent for several days and as a result hardly any green electricity is produced. For example, the German Weather Service (DWD) calculated on the basis of weather data from 1995 to 2015 that the domestic wind turbines on land and at sea can only use a maximum of ten percent of their installed capacity on average 13 times a year for at least 48 hours. If you add photovoltaics, there are still two at least two-day periods a year in which the systems hardly supply any electricity.

"We need additional gas-fired power plants that can deliver electricity over a longer period of time."

"Up to now we always had enough energy storage that we could call up when we needed electricity - coal heaps and uranium fuel rods, for example," says Albert Moser, holder of the chair for transmission networks and energy economics at RWTH Aachen University. With the phase-out of coal and nuclear power, these stores will be lost. His conclusion: "We need additional gas-fired power plants that can deliver electricity over a longer period of time if renewable energies are unable to do so." This is not a contradiction in terms of the energy transition and climate protection, because instead of fossil natural gas, CO₂-neutral gases can gradually be used there. By this he means above all hydrogen, which is generated by electrolysis with green electricity.

A study by Prognos, Öko-Institut and Wuppertal-Institut, commissioned by the Berlin think tank Agora Energiewende, shows how many gas-fired power plants are necessary to ensure security of supply after the coal phase-out. It comes to the conclusion that the installed capacity must grow to 43 gigawatts by 2030 and to 73 gigawatts by 2050. According to the Federal Network Agency, almost 32 gigawatts are currently installed. The authors based their study on the fact that by the end of this decade almost all coal-fired power plants will be taken off the grid - a thoroughly realistic scenario in view of the EU's increased climate targets. Philipp Litz, project manager at Agora Energiewende, is convinced that there will be enough time to build the necessary systems. "We are assuming that, above all, many small, decentralized gas engines and turbines will be installed. This is much faster than building large power plants."

But who should build new systems if they are only needed as a safety net for renewable energies in the long term? The electricity exchange provides an incentive: if gas-fired power plants are in demand, prices there will be high because of the electricity shortage. If it becomes apparent that these market signals are insufficient, the state must provide additional support - with a premium so that the operators can supply electricity at any time. "If you look at the energy transition as a whole, the costs for the backup capacities are manageable," says Christoph Kost from the Fraunhofer Institute for Solar Energy Systems (ISE). He also points out that, even without the energy transition, significant investments would have to be made in the power plant park, as many coal-fired power plants are outdated.

There are always good conditions somewhere in Europe for producing green electricity

Closer European cooperation creates additional security. After all, the weather conditions within Europe differ considerably. For example, if the wind is weak in the North Sea region, it often blows strongly in the Balkans. To take advantage of this, the EU is pushing ahead with the European network expansion so that more electricity can flow across borders. The exchange of electricity between the European countries will increase sharply, predicts Kost. "That strengthens the security of supply, even in dark doldrums."

Battery storage systems, on the other hand, do not help in the dark, as they are exhausted very quickly. On the other hand, the so-called load management is different: industrial companies can postpone some processes in times when a lot of energy is available and the price on the electricity exchange is therefore low. Agora expert Litz warns against underestimating the potential of load management in dark doldrums. However, the incentive to operate the systems based on the electricity supply is still too low, because electricity is subject to many taxes and surcharges. "Consumers hardly notice fluctuations in prices on the electricity exchange," says Litz. "That has to be reformed."