Battery storage to make reserve coal plants redundant

Renewables International

This week, the future of “operating reserves” may have just begun in Berlin. A new battery storage unit connected to the grid has gone into full operation; we described the system a few months ago here.

In a way, this battery is not really about storage the way we generally think about it – power saved for several hours or days; rather, it will be rapidly and frequently charged and discharged. Operating reserves – the German is “Regelenergie” – are essentially plant capacity used to accommodate short-term fluctuations. Sometimes, a bit of power is quickly needed to stabilize grid frequency; this power is needed within a second. At other times, power is needed within a minute.

The Germans break down this market roughly into “second reserves” and “minute reserves,” though the former is also further broken down into primary and secondary. Indeed, even if you don’t speak German the Wikipedia entry for Regelleistung (synonymous with Regelenergie) shows how big the discussion is in Germany, especially compared to the stub of an entry at Wikipedia for operating reserves (which also covers a wider range of ancillary services including longer-term backup energy).

The new battery reacts within a fraction of a second, far faster than conventional plants can with their rotating masses. In other words, this option provides more grid stability than conventional plants can. And it also appears to be cheaper than the conventional option, according to one insider who spoke with me off the record yesterday in Berlin. Indeed, he added that the sale price of this system could be a third lower than this pilot project already based on the prices being negotiated for further sales.

While wholesale prices are making conventional power unprofitable, the market for operating reserves remains quite healthy. North German power provider Wemag, which contracted the storage system, has probably made a wise business decision to expand more into lucrative future market – away from wholesale power and towards operating reserves.

The system is a real-world example of the kind of battery storage recently described in the recent study for a 100 percent supply of renewable power. If you speak German and want to see a good summary from German television, there is a recommendable video here.

Source: Renewables International. Reproduced with permission.