Fan heaters and similar power-driven radiators are booming in Germany. The sales figures are increasing rapidly. The federal government is now testing whether their use could endanger the entire power grid. Fan heaters are only of limited use as a substitute for natural gas anyway.

Fear is spreading in Germany. While toilet paper, pasta and tin cans were hoarded in previous years, this year it’s fan heaters. The Hornbach hardware store chain reported a 100 percent increase in sales by the end of June, and 50 percent for other chains. There are no nationwide sales figures, but it is clear that the demand for electricity-powered alternatives to gas heating has increased significantly.

Anyone who buys such devices wants to be prepared for the worst case, the failure of the natural gas supply in winter. The gas storage tanks will hardly be full before the cold snap. Should Russia then stop deliveries to Germany completely, the industry would first be turned off the gas tap. Private households, hospitals and other institutions and authorities are considered protected consumers. If the winter gets colder than usual, gas could also become scarce for all private households – in the worst case.

It is extremely unlikely that such an emergency will occur, but after the events of this year it cannot be completely ruled out. Fan heaters may appear to be a patent alternative, as they are not operated with gas but with electricity. But that brings with it other problems. If all households that now heat with gas wanted to cover the same amount of heat with fan heaters, the German power grid would certainly collapse.

But it will not come close to that. Fan heaters are not designed for continuous operation throughout the home. It is possible, but it would be very expensive. For example, to completely heat a 50 square meter apartment, you would need four to five fan heaters, each with an output of 2000 watts. The purchase costs between 150 and 200 euros. To heat the entire heating period from October to March would cost around 3400 euros at the current electricity price. This is unaffordable for most households.

A scenario in which fan heaters are only used selectively and intermittently, for example to keep children’s rooms warm overnight, is therefore realistic. But even that can put a strain on the power grid. The analysis company Prognos, which also prepares forecasts for the Federal Ministry of Economics, calculates in the FAZ that 8 gigawatts of additional output would be required, even if only 10 percent of the gas heating systems were replaced by fan heaters at peak load times. The normal maximum load is 85 gigawatts, so fan heaters would increase it by almost ten percent.

It is questionable whether the German power grid can withstand such an additional load. It would probably not collapse nationwide, but maybe locally. Regions in which gas is currently used to heat a great deal are at risk. Here, too, the proportion of heaters would probably be higher in an emergency. However, this is only a rough assumption. Nobody knows how the fan heater purchases are distributed geographically in Germany and who would turn them on when and for how long. Local operators such as Stadtwerke München only warn that the “large-scale and intensive use of fan heaters would lead to an extreme load on the power grids.” Will this happen? Unlikely.

Nevertheless, the power grid must be prepared for the worst case. The federal government has therefore commissioned a new stress test. The energy suppliers should check to what extent their networks can withstand an increase in maximum load. Fan heaters that may have been switched on millions of times are not an explicit scenario, but are of course also tested with them. A first stress test under different conditions showed that there is no danger to the power grid in winter.

Many factors would have to come together for the network to collapse. A first would be the collapse of the gas supply for private households or a situation in which there is no longer enough natural gas for power plants, which could then produce less electricity.

A second would be a so-called “dark lull”, i.e. a condition in which both wind turbines and solar systems deliver little or no electricity. And thirdly, there would also have to be problems with the nuclear power plants in France. Many reactors there are currently shut down due to problems with the cooling system or maintenance work. It is unclear how many will be back online by autumn.

The problem is not that the French nuclear power plants could supply too little electricity to Germany, but that Germany has to help France with electricity so that the lights and heating don’t go out there. Since September 2021, this has been happening every month to some extent. Since then, the export rates of electricity to France have consistently exceeded imports from the neighboring country.

The second stress test should run for several weeks. Only then will it become clear what conclusions will have to be drawn from it. In the case of negative results, a stronger integration of coal-fired power plants in the heating period would be conceivable, and the discussion about the continued operation of nuclear power plants until the end of March should then flare up again – also because they fuel opposition politicians like Markus Söder (CSU), who made it this year, only to approve four wind turbines in his state of Bavaria. Because Bavaria has been lagging behind in these statistics for years, the federal state would be one of the first to be affected by an electricity shortage.

However, it is quite possible that the stress test will certify that the German power grid has good resilience. Then there would be one less reason to be afraid of cold rooms in winter. However, it is doubtful whether this will slow down sales of fan heaters.

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