Nevada–Texas–Utah retort
Shale oil extraction technology
The Nevada–Texas–Utah retort process (also known as NTU, Dundas–Howes or Rexco process) was an above-ground shale oil extraction technology to produce shale oil, a type of synthetic crude oil. It heated oil shale in a sealed vessel (retort) causing its decomposition into shale oil, oil shale gas and spent residue. The process was developed in the 1920s and used for shale oil production in the United States and in Australia. The process was simple to operate; however, it was ceased from the operation because of a small capacity and labor extensiveness.
History
The NTU retort was a successor of the 19th-century coal gasification retorts and it is considered as a predecessor of the gas combustion retort and the Paraho processes. It was invented and patented by Roy C. Dundas and Raymond T. Howes in 1923. The process was improved by David Davis and George Wightman Wallace, a consulting engineer of the NTU Company. In 1925, the NTU Company built a test plant at Sherman Cut near Casmalia, California.
In 1925–1929, the process was tested by the United States Bureau of Mines in the Oil Shale Experiment Station at Anvil Point in Rifle, Colorado. Retorting was carried out from 17 January to 28 June 1927.
The public source identifies “Nevada–Texas–Utah retort” as shale oil extraction technology. This brief keeps that definition visible, then builds a research path around Nevada, Texas and Utah.
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Datasets, specimens, observations and peer-reviewed methods provide the appropriate test for the technical claims summarized here. The source revision retrieved here is dated Jul 16, 2026. The linked authority identifier is Q7003687. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1923, 1925, 1929 and 1927.
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This entry incorporates text from “Nevada–Texas–Utah retort” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.