Wind, solar, and other new sources of renewable energy make up a small fraction of the global energy mix, but they are expanding rapidly. Since 1990, worldwide renewable electricity generation has grown an average of 2.8 percent per year, according to the International Energy Agency (IEA). Solar, in particular, seems poised for a boom. Global capacity has jumped an average 50 percent every year since 2006, according to McKinsey & Company, a global consulting firm. Prices continue to drop, making the technologies competitive with traditional forms of generation in many markets.
Still, the rapid expansion of carbon-heavy coal in developing economies has largely offset clean energy’s gains. The average unit of energy produced today is basically as dirty as it was 20 years ago, according to the IEA.
