India is on track to become the most populous nation in the world by 2022, according to United Nations estimates. And that scale, coupled with extreme poverty, make India particularly challenging for energy policies aimed at reducing climate change.

Bill Gates has been grappling with this question, and his conclusion is that India is “big enough that you can’t give them a pass on greenhouse gas emissions.” As the world’s richest man acknowledges in the video above, ”it’s a dilemma” because “when you get to electrification, you get this huge health benefit, you get lights at night, refrigeration.”

On the one hand, a large proportion of India’s citizens is very poor, with many millions of families living hand-to-mouth on subsistence farming. Better access to cheap energy from coal could bring significant gains in standards of living, education, health, and life expectancy.

“And who’s the rich world, that’s done all this emission, to say ‘Oh no India, don’t electrify,’ because right now their direct path would be to take coal and burn a lot of coal,” says Gates. In general, his belief is that ”the very poor countries should be unconstrained.” He adds that ”if they can figure out how to get power with coal or natural gas, they should go ahead because they are so poor and they have not emitted any of the greenhouse gases that are up there.”

But at the scale of India, a significant expansion of coal burning could make it very difficult, if not impossible, for the world to achieve the carbon-dioxide-emissions reductions scientists say are needed to prevent the worst impacts from climate change.

“Who’s the rich world, that’s done all this emission, to say ‘Oh no India, don’t electrify’?”

Gates’s hope is that new technology for producing clean energy at very low cost will resolve this extremely thorny problem. He has announced he’s investing $1 billion of his own money in clean energy projects over the next five years, and has helped rally other billionaires and governments to provide funding as well.

Gates cites technology that captures the carbon dioxide produced by burning coal and prevents it from entering the atmosphere as one possibility: “The question is how much of it could you capture and does it raise the cost by the time you’ve used up the energy and capital equipment and liquefied it and put it in the ground and made sure it’s going to stay there.”

Whatever the exact technology breakthrough, Gates believes ”innovation has to surprise India and say, “No, that coal, which you are looking at as the straightforward path, here’s another approach that can meet the twin objectives of lots of electrification but with India not being a huge contributor to missing this incredible goal of getting to zero emissions.’”