(Reuters) - U.S. energy infrastructure company Glenfarne said on Wednesday its unit struck a 20-year deal to sell liquefied natural gas to trading firm Gunvor, moving its planned Brownsville export project in Texas closer to a final investment decision. The deal covers 0.5 million tonnes per annum of LNG on a free-on-board basis and converts a previous preliminary agreement between the two firms. Global demand for LNG has surged since Russia's invasion of Ukraine upended gas markets in 2022, driving buye ...