U.S. coal producer Peabody Energy has signed a deal with SSA Marine to export coal from the Powder River Basin from a proposed export terminal in Washington state.

The companies agreed to ship up to 24 million tonnes of coal a year through the proposed terminal, called Gateway Pacific, near Bellingham, Wash. just south of the U.S.-Canadian border.

The terminal would serve as the U.S. West Coast hub for exporting Peabody's coal from Wyoming to China, South Korea, Japan, India and other Asian countries, the company said.

Coal from Wyoming and Montana, which traditionally stays within U.S. borders, is now profitable to export, thanks to rapidly industrializing nations such as China, where coal is the most common power-plant fuel.

The company said demand for seaborne coal demand is expected to top 1 billion tonnes this year, amid fast-growing demand in Asia.