Qatar has ordered six liquefied natural gas ships from South Korea as it pushes ahead with a multi-billion dollar project to boost production of the fuel.

The world’s biggest LNG exporter is buying four vessels from Daewoo Shipbuilding & Marine Engineering and two from Samsung Heavy Industries, state producer Qatar Energy said Sunday. They’re the first batch of orders under a $19 billion deal signed between Qatar and Korean shipbuilders last year.

Daewoo, Hyundai Heavy Industries Co. and Samsung were selected to build more than 100 LNG vessels for Qatar by 2027. The Persian Gulf state is spending around $30 billion to increase LNG output by 50% by then.

Qatar also ordered four LNG tankers worth more than $760 million from China in October as it looks to expand its fleet. LNG is seen as an important substitute for dirtier fuels such as oil and coal and prices have soared in Europe and Japan in recent months.

Qatar Energy’s forecasts for global LNG demand are more bullish than those of some analysts. It expects demand to continue to grow until 2050, underscoring its investment. The International Energy Agency expects global gas demand to peak in the mid-2020s as consumers shift away from fossil fuels.