New fuel technology offers cleaner, more efficient diesel engines
image: Advancements in diesel emission reduction strategies: a focus on water-in-diesel emulsion technology
Credit: Chukwuemeka Fortunatus Nnadozie, Chiamaka Prisca Onuoha, Emeka Emmanuel Oguzie & Enos Ihediohamma Emereibeole
A team of researchers from the Federal University of Technology Owerri in Nigeria has highlighted a promising new way to cut diesel engine pollution without sacrificing performance. Their review of global research on Water-in-Diesel Emulsion (WiDE) technology shows that blending small amounts of water into diesel fuel can dramatically reduce harmful emissions while maintaining or even improving engine efficiency.
Diesel engines are widely used in transportation, agriculture, and industry because they are durable and powerful. However, they are also major sources of air pollutants such as nitrogen oxides and particulate matter, which contribute to smog, respiratory illnesses, and climate change. While devices such as catalytic converters and particulate filters help to control these emissions, they add cost and complexity to engines. The new study presents WiDE as a simpler, cleaner alternative that can be used in existing engines without modification.
WiDE technology involves mixing tiny droplets of water with diesel fuel using surfactants that keep the mixture stable for up to sixty days. During combustion, the water inside the emulsion vaporizes rapidly, causing a “micro-explosion” that improves the mixing of air and fuel. This process lowers peak combustion temperatures, which in turn reduces nitrogen oxide formation. At the same time, the improved air–fuel mixing helps burn fuel more completely, cutting soot and particulate emissions.
Studies reviewed by the researchers showed that using WiDE can reduce nitrogen oxides by up to sixty-seven percent and particulate matter by as much as sixty-eight percent compared to regular diesel fuel. In addition to cleaner emissions, many experiments also found that engines running on WiDE achieved higher brake thermal efficiency, meaning they converted fuel into useful work more effectively.
“Water-in-diesel emulsions are a practical and cost-effective way to make diesel engines cleaner,” said lead author Dr. Chukwuemeka Fortunatus Nnadozie. “Because the technology does not require redesigning the engine, it offers an immediate path toward lower emissions in developing and developed countries alike.”
The study also examined the role of surfactants, chemicals that allow water and diesel to remain uniformly mixed. The right choice and concentration of surfactant are crucial to maintaining emulsion stability, which affects both performance and safety. Researchers found that formulations using a combination of surfactants achieved the best stability and combustion results.
While WiDE shows great promise, the authors recommend further work to optimize surfactant selection and to study the long-term effects of the emulsions on engine components. They also emphasize that WiDE could complement other clean technologies, such as biodiesel and advanced emission control systems, in achieving global climate and air quality goals.
“This technology can bridge the gap between conventional diesel use and a cleaner energy future,” said co-author Professor Emeka Emmanuel Oguzie. “With proper formulation and testing, it could become an important part of sustainable transportation and industrial power systems.”
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Journal reference: Nnadozie, C.F., Onuoha, C.P., Oguzie, E.E. et al. Advancements in diesel emission reduction strategies: a focus on water-in-diesel emulsion technology. Carbon Res. 4, 45 (2025). https://link.springer.com/article/10.1007/s44246-025-00210-y
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About Carbon Research
The journal Carbon Research is an international multidisciplinary platform for communicating advances in fundamental and applied research on natural and engineered carbonaceous materials that are associated with ecological and environmental functions, energy generation, and global change. It is a fully Open Access (OA) journal and the Article Publishing Charges (APC) are waived until Dec 31, 2025. It is dedicated to serving as an innovative, efficient and professional platform for researchers in the field of carbon functions around the world to deliver findings from this rapidly expanding field of science. The journal is currently indexed by Scopus and Ei Compendex, and as of June 2025, the dynamic CiteScore value is 15.4.