LONDON—Greek shipowners, closely followed in the shipping industry for their investment choices, have splashed a record $1.8 billion this year to buy 11 new LNG carriers.

The owners are betting that falling energy prices will spur demand for such vessels as European countries move to became less dependent on Russian gas pipelines. The U.S. is also expected to start exporting liquefied natural gas in substantial volumes in 2018.

At around $200 million apiece, LNG carriers cost at least three times as much as other types of vessels of similar size. But while the market for ships such as container vessels, tankers and dry-bulk carriers is marred by overcapacity reaching up to 25% above demand, leading to unsustainable freight rates, LNG carriers are usually linked to lucrative contracts that stretch to more than 10 years, racking in substantial earnings for their owners.

The Greeks are the world’s biggest shipowners, controlling 12% of all ships in the water, and rank second behind Japan with 12% of LNG carriers, according to shipping-data provider VesselsValue.com. They were among the first to move into the LNG market over the past decade, and the combination of the global quest for cleaner energy sources along with natural disasters and political crises has conspired to their benefit.

“The first big boom in demand came with the 2011 Japanese tsunami, which knocked out a huge number of power stations, and demand for LNG in Japan went through the roof,” said James Allan, a gas ship broker at London-based Galbraith. “Up until mid-2012, daily charter rates hit $140,000, and with a break-even point of $40,000 to $50,000, it was party time for owners.”