Water-In-Diesel Emulsions with Surfactants Can Improve Combustion Efficiency, Reduce NOx and Particulate Emissions, and Improve Brake Thermal Efficiency, According to Review of Studies

  

      In 2025, A group of Nigerian researchers published a review of studies on diesel emissions reduction technologies, focusing on water-in-diesel emulsions. The research team from the Federal University of Technology Owerri, examined evidence on Water-in-Diesel Emulsion (WiDE) technology, an approach that blends tiny water droplets into diesel fuel. The technology could be used to decrease pollution, such as nitrogen oxides (NOx) from diesel fuel, without the problems associated with current methods, such as catalytic converters.

     According to Good News Network:

“The key is that the water is not simply poured into the fuel tank. Instead, tiny droplets of water are evenly dispersed throughout the diesel using compounds known as surfactants. Surfactants act like stabilizers, helping the water remain suspended in the fuel and preventing the mixture from separating. According to the review, properly formulated emulsions can remain stable for up to 60 days.”

“When the fuel is injected into the engine and ignites, something unusual happens. The trapped water rapidly turns into vapor. This sudden expansion creates what researchers call a “micro-explosion,” breaking the fuel into finer droplets and improving the way it mixes with air.”

“Better mixing leads to more complete combustion. At the same time, the presence of water helps lower peak combustion temperatures inside the engine. This combination delivers two important benefits. Lower temperatures reduce the formation of nitrogen oxides, while more complete combustion reduces soot and particulate emissions.”

     The researchers found that nitrogen oxide emissions could be reduced by as much as 67% and particulate matter emissions by up to 68%. An additional benefit of the technology is that it can increase thermal brake efficiency, a measure of how effectively an engine converts fuel energy into useful mechanical power. With better thermal brake efficiency, more of the power in braking is used to do work, and less is lost as heat.

“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 researchers tried different combinations of surfactants, looking for combinations that produced the most stable fuel mixtures and the best combustion performance. Thus, selecting the right surfactant formulation is believed to be the most important part of further developing this technology. Another issue to be determined is the long-term effects of WiDE on engine components.

“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.”

     Below are the abstract and highlights of the paper, followed by its recommendations for future studies.

 

 

 

References:

 

Simply Add Water to Diesel Fuel to Cut Engine Pollution by 67%–with No Loss in Efficiency. Andy Corbley. Good News Network. July 3, 2026. Simply Add Water to Diesel Fuel to Cut Engine Pollution by 67%–with No Loss in Efficiency - Good News Network

Advancements in diesel emission reduction strategies: a focus on water-in-diesel emulsion technology. Chukwuemeka Fortunatus Nnadozie, Chiamaka Prisca Onuoha, Emeka Emmanuel Oguzie & Enos Ihediohamma Emereibeole. Carbon Research. Volume 4, article number 45 (May 28, 2025). Advancements in diesel emission reduction strategies: a focus on water-in-diesel emulsion technology | Carbon Research | Springer Nature Link