Natural gas prices could reach $50 per million British thermal units in 2018, up from $28 a year earlier, according to research firm IHS.

The forecast is based on the assumption that the cost of natural gas will rise over the next several years.

Natural gas is also projected to become the third-most-used fuel in the U.S. by 2030, up almost 4 percent from 2014, according the National Association of Manufacturers.

Natural-gas prices have been driven up by a surge in demand from China, which has expanded its use of shale gas to the point that it is producing a third of the country’s output.

Natural Gas for Home Use, which tracks the prices of gas in the United States, predicts natural gas could hit $40 per million BTUs in 2019, up 1 percent from last year.

The forecasts come as U.N. climate negotiators in New York have pushed for global action to curb greenhouse gas emissions.