China’s ENN is expected to make a profit of between $110 million and $130 million on a single liquified natural gas shipment to Europe. SINGAPORE—The economic slowdown in China, a Trump-era trade deal and Europe’s desperate hunt for natural gas are creating a windfall for some Chinese energy companies. The unusual alignment is helping Europe stock up for the winter. With demand down, Chinese companies that signed long-term contracts to buy U.S. liquefied natural gas are selling the excess and making hundreds of millions of dollars per cargo. Buyers include Europe, Japan and South Korea. Just 19 LNG vessels from the U.S. docked in China in the first eight months of the year, compared with 133 for the same period last year.