Coal to liquids (CTL) is a technology used to convert coal into liquid fuels, such as diesel and gasoline. The process involves heating fine coal particles in the absence of oxygen (a process known as pyrolysis) to produce a coal-derived synthetic crude oil. This synthetic crude oil can then be further refined into transportation fuels using traditional refining processes.

The efficiency of CTL depends on various factors, including the type and quality of the coal used, the technology employed, and the overall process design. In general, CTL plants have lower overall efficiencies compared to conventional crude oil refining, as the process requires additional steps and energy inputs to convert the solid coal into a liquid fuel.

According to estimates from the U.S. Department of Energy, the overall energy efficiency of CTL plants can range from approximately 45% to 65%. This means that for every unit of energy input in the form of coal, around 45% to 65% can be converted into liquid fuel products. However, it is essential to note that these efficiency figures are highly plant-specific and can vary significantly based on the specific technology used and the operating conditions.

In comparison, gasoline, a petroleum-based fuel, is relatively more efficient to produce from crude oil. Modern refineries can achieve energy efficiencies of around 85% to 90% in converting crude oil into gasoline, as the refining processes are optimized for efficient hydrocarbon conversion.

When considering the efficiency of CTL versus gasoline, it is also vital to consider the environmental implications. CTL processes can be more carbon-intensive than gasoline production, as they involve additional energy inputs and the release of greenhouse gases. Therefore, the overall environmental impact of CTL should be carefully considered when evaluating its efficiency compared to gasoline.