The first large-scale power plant in the U.S. that removes and stores carbon dioxide from coal combustion is now fully operating near Houston, Texas, capturing more than 1 million tons of CO2 annually.

Operated by NRG Energy and JX Nippon Oil & Gas Exploration Corp., the Petra Nova plant — which cost more than $1 billion — extracts carbon dioxide from flue gases and then pipes them to the West Ranch oil field 80 miles away, where the CO2 helps extract additional oil from the ground. The U.S. Department of Energy, which provided $190 million in grants to the plant, called the facility “the world’s largest post-combustion carbon-capture system.” A second large carbon-capture plant is set to become operational in Mississippi by the end of the month. The Kemper Power Plant is designed to turn lignite, a type of coal, into a gas called syngas, removing some of the CO2 before the syngas is burned to generate electricity.