India, Nov. 1 -- Most of India's conversation on circularity in clean energy has gathered around batteries and solar panels, and with reason, since the country imports all its lithium, cobalt and nickel and holds both sectors to producer-responsibility rules. Wind has stayed at the edge of that conversation, partly because it is the most mature part of India's clean-tech economy, built over three decades into the world's third-largest wind manufacturing base, and partly because 80% to 94% of a turbine by mass is steel, copper, aluminium and iron that existing scrap markets recover.

Both facts have encouraged a belief that wind's end of life will look after itself, and for towers and nacelles it largely does. A blade, however, is glass or...