Billionaire Gautam Adani got rich off coal. Now his company is building a green energy plant the size of Chicago.

The sprawling solar and wind energy plant will generate enough electricity to power 16 million homes in India.

• Coal billionaire Gautam Adani is building the world's largest power plant, and it's all renewable.
• Adani's nephew, who's in charge of the project, says there's "no choice" but to go big on green energy.
• Still, the Adani Group makes 62% of its revenue from fossil fuel.

The largest power plant in the world is under construction, and it'll produce enough clean energy to fuel entire countries like Belgium, Chile, or Switzerland.

It will cover 200 square miles — nearly the size of Chicago.

Adani Green Energy Limited (AGEL) is building the solar and wind power plant in a salt desert in the western Indian state of Gujarat. AGEL is the clean energy unit of the Adani Group, the biggest coal miner and importer in India founded by billionaire Gautam Adani in 1988. Adani is currently the second richest person in Asia, according to Forbes.

The Adani Group has promised to dump $70 billion into clean energy by 2030 — including $20 billion on this project alone — as India tries to reduce its reliance on fossil fuels, CNN reported.

"There is no choice for India but to start doing things at a previously unimagined size and scale," Sagar Adani, the 30-year-old nephew of Gautum Adani and the executive director of AGEL, told CNN.

India — the third-largest energy consumer in the world, 73% of which comes from coal — has pledged to reach net-zero emissions by 2070, two decades later than the US has pledged. India also hopes to get half of its energy from renewable sources by 2030.

And AGEL's massive new plant could be a major step in making that happen.

The project, expected to be finished in five years, will create 15,200 green jobs and produce enough clean energy to power 16 million Indian homes, AGEL said in a press release on its website.

As India develops, Sagar Adani told CNN he hopes his country does not burn through as much fossil fuel as other countries did during their developments.

"If India does what China did, if India does what Europe did, if India does what the US did, then we are all in for a very, very bleak climatic future," Sagar Adani told the outlet.

However, AGEL's plant and green energy commitments are still built on profits from coal production.

The Adani Group's coal mining operations make up at least 3% of the world's coal-based carbon dioxide emissions, and the group makes 62% of its revenue from fossil fuel, Bloomberg reported.