Suzhou | On a baking hot day on the factory floor of the third-largest battery manufacturer in China, one of the increasingly rare human employees circles a giant container, or module, that houses a 3.7MWh battery.

Water sprays from hoses fixed to the ceiling, soaking the steel structure in a stress test designed to mimic the bruising journey it’s about to make across the Pacific bound for a clean energy project in the United States, Australia or Europe.