Consider the crucial cases of China and India. Renewables have long enjoyed must-run status in both places, meaning that their curtailment is only permitted on grounds of grid security, with generators being instructed to lower output when transmission lines reach safe loading limits. But, in both countries, the past five to ten years have nonetheless seen curtailment rates reach unprecedented levels – of as high as 40 or even 50 per cent – in some regions, such as Xinjiang in north-western China and Tamil Nadu in southern India.39
