In a remote corner of west Texas, in the shadow of a sprawling wind farm, one of the world's largest batteries was switched on last week. Deep in oil country, the battery is at the vanguard of efforts to help renewable energy sources realise their potential and, ultimately, oust fossil fuels in the US.

For many in India, when the largest blackout the world has ever seen struck last week, it didn't come as a surprise. Smaller, scheduled blackouts are a common way that the country copes with its explosive growth in demand for electricity.