Climate-friendly Cement? California Takes on a High-Carbon Industry
Dust swirls in the air at a cement factory on the outskirts of Redding as mud-caked tires travel along a wide conveyor belt. The tires are carried up 90 feet into a smoldering-hot incinerator, where they’re used as fuel for firing a kiln. The massive, 2,700-degree kiln at the Martin Marietta, Inc. plant churns more than 2,500 metric tons of pulverized limestone and other materials daily to produce clinker, the jagged lumps of rock that are used to make cement. The factory needs a constant and steady supply of fuel to sustain its 24-hour operations. Although the burning tires supply some fuel to fire up the kiln, about 80 percent still comes from fossil fuels, including high-polluting coal. As a high-carbon and energy-intensive product, manufacturing cement, the key ingredient in concrete, takes a heavy toll on the climate. The Redding factory emitted about 282,000 tons of carbon dioxide in 2020 — equivalent to about 55,000 gas-powered cars. Under pressure from state lawmakers, California’s cement industry is gradually taking steps to reduce its carbon footprint. But experts say the industry is one of the most difficult