IIT Roorkee alumnus Shantanu Agarwal-led Mati Carbon has won the $50 million grand prize in the XPRIZE Carbon Removal competition. The startup uses an enhanced rock weathering model, which captures carbon dioxide while boosting crop yields for farmers. Mati, which works with farmers in India, Tanzania and Zambia, spreads crushed basalt on farmers' fields to accelerate a natural weathering process.