Elon Musk is secretly building a giant battery in Texas. Ultimately, though, it’s the other part of Tesla Inc. that could have a bigger impact there.

The scoop on Tesla’s hush-hush project near Houston, courtesy of my colleagues at Bloomberg News, landed soon after February’s ice-induced blackouts across Texas. Tesla’s effort is part of a small but growing stationary energy-storage capability in the state. Bloomberg NEF counts less than 500 megawatt-hours of capacity currently installed but more than 2,000 announced or in progress. With the right chemistry and configuration, batteries can send power to the grid rapidly — which is relevant in light of February’s debacle.

Power grids run at a certain frequency. There is very little tolerance for deviating from that; a little too high or low and you risk serious damage to generating plants and other equipment.