Night Storage Heater

Stuttgarter Zeitung reports about a new experiment to revive old technology for helping to solve the problem of storing excess energy from wind and solar. Thanks to this Tweet by Heiko Stubner for the link.

That old technology is called “Nachtspeicherofen” in German, and “storage heater” in English.

The difference is that in German the part “Nacht”, meaning “night”, indicates that these devices historically were used to store heat from cheap electricity at night. They have a long history in Germany, going back to the 1950s. At the time, utilities wanted to generate more electricity demand at night so as to avoid costs for regulating down coal and nuclear power plants.

For the last couple of years, there has been some controversy over these devices in Germany. The government decided in 2009 to phase their use out since heating with electricity is less effective than burning fossil fuel directly at the building to be heated.

The Bundestag (Parliament) reversed that decision in 2013. The reason for that was that having these storage options would help to deal with fluctuations in electricity supply resulting from a larger renewable market share.

Like with every good idea, SPIEGEL was strongly opposed.

Let’s discuss the reasons for their opposition.

For one, they seem to think that it costs a lot of money to integrate these devices into the smart grid. They don’t give any reasons for that. And there is not much reason. Obviously, all German households are already integrated into the Internet. And all you need is a device which tells the storage heater to switch itself on. That can’t cost much.

And SPIEGEL’s “most important” argument: If we have storage, that means that coal power plants will get switched off less often.

That is correct, as far as it goes.

But on the other hand, if we don’t have storage, we need to just switch off low CO2 power sources just because demand can’t keep up with supply. And then fire coal in time slots where supply from renewable is insufficient.

Obviously, with renewable expected to go to 80 percent by 2050, this latter problem will be much more serious than the former. And having more storage is obviously good news for the energy transition.

Eventually, all energy needs to be sourced from renewable electricity sources. That includes heating. Just like cars, heating needs to transit to electricity as well. Removing one of the few already existing and working solutions to store electric energy would be a step in the wrong direction.

Published by kflenz

Professor at Aoyama Gakuin University, Tokyo. Author of Lenz Blog (since 2003,

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