In India as in many other countries, political and economic considerations have yielded an energy strategy of simultaneously pursuing clean energy and burning fossil fuels, an approach that ultimately puts security ahead of climate.

The investments have boggled advocates of green energy, but officials say India's ambitious economic growth targets - reaching annual gross domestic product of $5 trillion before the end of the decade, up from $3.2 trillion in 2021 - can be met only by sharply increasing dirty and cleaner energy sources alike.

"India is pivotal to the future of global energy and climate policy," said Amy Myers Jaffe, an energy and climate expert at the New York University School of Professional Studies.

Renewable energy in India rose to 163 gigawatts in August from a few megawatts in 2010, according to the Institute for Energy Economics and Financial Analysis, a research group in Cleveland.

India's pledge to achieve carbon neutrality by 2070 leaves ample space for coal-powered generation to increase even as cleaner energy sources gradually take up a larger share of the energy mix.

India's national oil company, ONGC, is adding renewable energy to its portfolio, and Coal India has proposed setting up solar parks in reclaimed mining areas.

India has taken advantage of Moscow's supply of heavily discounted crude oil - now supplying about a quarter of its daily needs - to shield India's state refiners from losses.