India, May 29 -- Anyone who can afford air-conditioning is now going to want it. Many who can't will try to scrape together the means for at least a few days or weeks of cooling a year.

It's easy to shrug this off as expected growth, of the kind every hot country has seen as incomes rise.

This isn't just that.

It is also one of the century's great electricity-demand stories.

The International Energy Agency (IEA) has warned that, without strong action, indoor cooling energy demand globally could more than triple by 2050. Key drivers of this demand will be the massive and under-served emerging economies of India, Indonesia and Brazil.

We worry about the power demands of artificial intelligence, as we should. But an equally significant ...