Yeah, the way the article is worded further down strongly suggests that they are using the aluminium as an energy source: "Using the production process as a vi

Yeah, the way the article is worded further down strongly suggests that they are using the aluminium as an energy source: "Using the production process as a virtual battery is “an interesting option” for the industry, said Marian Klobasa, who heads the demand response and smart grids unit at Germany’s Fraunhofer Institute for System and Innovation Research ISI, an applied science researcher. If the volatility of the power market increases, Klobasa said by phone from Karlsruhe, “then it may make commercial sense and be economically worthwhile.” Trimet’s Hauck estimates the full costs 70 euros to 150 euros to store one megawatt-hour based on 1,000 hours of use per year. That would make supply competitive at some periods of peak demand during the winter." Aluminium plants in the UK already do demand shedding at time of peak load on the UK power grid - I'm sure German plants do much the same thing.