RAS LAFFAN INDUSTRIAL CITY, Qatar — The compact assembly of towers, tubes and tanks that make up the Oryx natural gas processing plant is almost lost in a vast petrochemical complex that rises here like a hazy mirage from a vast ocean of sand.

But what is occurring at Oryx is a particular kind of alchemy that has tantalized scientists for nearly a century with prospects of transforming the energy landscape. Sasol, a chemical and synthetic fuels company based in South Africa, is converting natural gas to diesel fuel using a variation of a technology developed by German scientists in the 1920s.

Performing such chemical wizardry is exceedingly costly. But executives at Sasol and a partner, Qatar’s state-owned oil company, are betting that natural gas, which is abundant here, will become the dominant global fuel source over the next 50 years, oil will become scarcer and more expensive and global demand for transport fuels will grow.

Sasol executives say the company believes so strongly in the promise of this technology that this month, it announced plans to spend up to $14 billion to build the first gas-to-liquids plant in the United States, in Louisiana, supported by more than $2 billion in state incentives. A shale drilling boom in that region in the last five years has produced a glut of cheap gas, and the executives say Sasol can tap that supply to make diesel and other refined products at competitive prices.