Bill Gates’ Breakthrough Energy Ventures has announced a new investment in a biofuels company, in spite of the ExxonMobil algae biofuel exit late last year But critics say the technology has long featured in oil industry greenwashing campaigns and is far from a commercial reality.

Biofuels in India are being pushed by the Modi government but experts say its plan to substitute 20 percent of gasoline with ethanol could be a shortsighted approach to energy security in the water-scarce nation.