LONDON, Sept 22 (Reuters Breakingviews) - The green energy boom is facing new headwinds. Falling costs, cheap capital and supportive politicians helped propel a headlong rush into renewable power. Now fracturing supply chains and higher interest rates are pushing up prices – and testing the resolve of consumers and governments. It took a while for the world to wake up to the need to replace fossil fuels. Yet in the past five years or so, the push to replace electricity generated by burning coal and oil with solar and wind power turned into a headlong rush. Global investment in clean...