WiDE: Extending the Lifespan of Diesel in a Decarbonizing World

Transport accounts for approximately one-fifth of global CO2 emissions, with road transport alone responsible for three-quarters of these emissions.

Most of these road transport emissions come from passenger vehicles such as cars and buses, followed by freight trucks. While gasoline is the most common fuel for light-duty vehicles, diesel is the primary fuel for commercial vehicles such as trucks and buses.

That’s because this mixture of hydrocarbons obtained by the distillation of crude oil has higher engine efficiency.

Diesel actually has a 25% to 35% better fuel efficiency than gasoline, making it the best option for commercial vehicles. Besides offering better fuel economy, diesel engines deliver better acceleration and towing and hauling potential, require less maintenance, and offer greater durability.

But at the same time, diesel is one of the biggest contributors to air pollution through pollutants like soot, carbon monoxide (CO), nitrogen oxides (NOx), sulfur oxides (SOx), hydrocarbons (HCs), and particulate matter (PM).

Diesel engines also emit carbon dioxide (CO2), which, while notectly toxic like other gases, is a significant greenhouse gas. Data show that diesel fuel consumption accounted for about 25% of total US transportation-sector CO2 emissions in 2022.

To help reduce the negative effects of diesel fuel on our health and the environment, researchers from the Federal University of Technology Owerri (FTO) in Nigeria turned to Water-in-Diesel Emulsion (WiDE) technology and identified it as a promising strategy for reducing pollution from diesel engines¹ while maintaining, or even improving, their performance.

Diesel Emissions: Why They Remain a Major Pollution Challenge

As a major source of harmful emissions, diesel engines pose serious health risks, such as respiratory issues and cardiovascular problems. They also contribute to environmental problems like smog, acid rain, and global warming.

To mitigate the environmental impact of compression-ignition engines, modern diesel engines use various emission-control technologies, such as Diesel Oxidation Catalysts (DOCs), Selective Catalytic Reduction (SCR), Exhaust Gas Recirculation (EGR), and Diesel Particulate Filters (DPFs).

While these technologies can help reduce emissions, they don’t do that entirely, and on top of that, they increase the cost and complexity of engines.

For instance, DOC effectively reduces CO and HC but has minimal effect on particulate and NOx emissions, while DPF is effective for reducing particulate emissions but doesn’t address CO or NOx, which can be effectively reduced by the cost-effective EGR, but it may slightly increase particulate emissions.

There are other alternatives, such as biodiesel, which is derived from biomass and has been successful at significantly reducing PM, CO, and HC, but again, it may increase NOx emissions.

NOx and PM formation, as FTO researchers noted in their study, are temperature-dependent and exhibit an inverse relationship, meaning reducing one often increases the other.

A solution to this problem is to introduce water into the combustion chamber, which substantially reduces both NOx and PM emissions. Now, there are a few different ways to introduce water into diesel engines. This includes Fumigating Water into the Inlet Manifold (FWIM) andect Water Injection (DWI), which reduce NOx and PM emissions but may increase HC and CO emissions.

There’s yet another easy but effective way to cut diesel engine pollution, and that’s Water-in-Diesel Emulsion (WiDE).

WiDE: Extending the Lifespan of Diesel in a Decarbonizing World

Blending water into diesel, facilitated by surfactants, shows positive effects on emissions reduction, engine performance, and combustion efficiency. This technique can actually slash sport and NOx emissions by over 60% while keeping performance strong, or even enhancing engine efficiency sometimes.

This cleaner option, which lowers combustion temperature, reduces high-temperature combustion duration, increases jet momentum, and enhances fuel economy, works in existing diesel engines without modification.

WiDE Technology: How Water-in-Diesel Reduces Emissions and Improves Performance

When mixedectly, diesel tends to float at the top because it is lighter than water. An emulsion fuel, however, is a mix of two immiscible liquids that can’t blend completely, with one substance distributed throughout the other. So, the emulsion is created using high-energy techniques with the help of surfactants.

For the diesel engine to operate on emulsion fuel, WiDE stability time is critical, as declining emulsion stability while the engine is running will negatively impact the combustion system and cause the engine to fail prematurely.

Special chemicals called surfactants play an essential in keeping diesel and water mixed evenly. They create stable emulsions by reducing the surface tension between the two, effectively binding them together.

So, in WiDE technology, very small water droplets are mixed into diesel fuel, and surfactants are added to keep them evenly blended, allowing the emulsion to stay stable for as long as 60 days. When this combination burns inside the engine, the water droplets rapidly vaporize, triggering a phenomenon known as a “micro-explosion” that breaks the fuel into finer particles.

This improves mixing of air and fuel during combustion, lowering peak combustion temperatures and reducing the formation of nitrogen oxides. The complete combustion also reduces soot and PM emissions.

Given the potential of this simple technique to significantly reduce diesel engine pollution, without requiring engine redesign, researchers at FUTO took a deeper look at the technology and its promise as a quick path to cleaner diesel use by analyzing studies from around the world.

According to studies reviewed in the WiDE analysis, running diesel engines on WiDE can drastically reduce harmful emissions. Notably, NOx emissions declined by 67% and PM dropped by 68% compared with standard diesel fuel, “positioning it as a cleaner alternative fuel for diesel engines.”

In addition to environmental advantages, several experiments also reported performance benefits. This includes improvements in brake thermal efficiency (BTE), which measures a system’s effectiveness in converting fuel into useful work output. Furthermore, studies on other engine performance characteristics, such as brake power, BSFC, and torque, also show promising results with WiDE.

So, not only do WiDE engines produce cleaner exhaust, but they also utilize fuel more efficiently.

“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.”

Meanwhile, a look into the significance of surfactants revealed that choosing the right surfactant and its concentration is key to emulsion stability, which affects both the performance and safety of the fuel.

The researchers found that multiple surfactants provide the best results, improving both the stability of the fuel blend and the quality of combustion inside the engine.

Despite the encouraging results, the researchers highlighted the need for additional work, focusing on refining surfactant combinations and assessing the emulsion’s long-term effects on engine components.

More importantly, WiDE can offer a practical way to reduce pollution from currently operational engines and contribute to other clean technologies rather than replace cleaner, long-term solutions. Combining this fuel approach with biodiesel and advanced emission-control systems, according to the team, can help support broader 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.”

Alternatives to Diesel: Low-Emission Fuels and Clean Transport Solutions

WiDE technology is just one of the many ways the transportation sector can address diesel’s limitations. The search for cleaner alternatives has led to a range of fuels and propulsion technologies that can help the industry achieve long-term decarbonization. One promising pathway to reduce emissions is biodiesel and renewable diesel, which are derived from biomass.

Biodiesel is produced by transesterification of vegetable oils like soybean oil, sunflower oil, rapeseed oil, and palm oil, animal fats from meat processing plants, and recycled cooking oil from restaurants. Algae is yet another promising source of biomass feedstock.

Renewable diesel is similar to biodiesel but is a hydrocarbon chemically equivalent to petroleum diesel.

Hydrogen is yet another solution to limit greenhouse gas emissions from motor vehicles through hydrogen internal combustion engines (H2ICE) and hydrogen fuel cells (FCEVs). Both can power vehicles using the zero-carbon fuel.

When it comes to H2-ICE, the regular internal combustion engines use hydrogen instead of diesel or gasoline.

FCEVs generate electricity from hydrogen using a device called a fuel cell, where hydrogen is combined with oxygen to produce electricity that powers the electric motor, much like an electric vehicle.

While internal combustion engines are most efficient under high load, making H2-ICE the most suitable choice for heavy trucks, FCEVs are more efficient at lower loads, making them ideal for tow trucks or concrete mixer trucks.

Both H2-ICE and FCEVs have similar emissions profiles, but while the former can produce NOx and trace amounts of CO2, the latter produces only water vapor.

As a result, several automakers are actively pursuing FCEV plans, which include BMW Group, Toyota, and Hyundai Motor. Recently, Alpine also unveiled its hydrogen-powered concept supercar, the Alpine Alpenglow, which produces 740 bhp at 7,600rpm, reaches a 9,000rpm redline, and tops out at 205mph.

But as recently shared, hydrogen comes with its own cost and infrastructure hurdles that need to be tackled with policy support, investments, and public-private partnerships to drive adoption.

Then there are synthetic fuels, or e-fuels, produced using captured carbon and green hydrogen. This alternative fuel is created through chemical processing. Most synthetic fuels have been produced by treating existing fossil fuel sources, such as converting natural gas into fuel oils, liquefying coal and turning it into diesel and gasoline, and lately converting wood or animal waste into fuel oils.

These options, however, make use of solid or sequestered carbon, which means they release CO2 into the atmosphere. e-fuels eliminate this problem by removing dependence on fossil fuels, enabling decarbonization of energy-intensive sectors.

These fuels are made by extracting CO2 from the atmosphere, and if emissions released during the combustion are equivalent to the CO2 used to produce them, then this method is considered carbon neutral.

To synthesise e-fuel, CO2 is sourced through either air capture, which sucks CO2 directly from the ambient atmosphere using liquid solvents or solid sorbents, or by capturing CO2 emitted from other industrial processes. The captured CO2 is then combined with hydrogen and subjected to high temperatures and pressures that convert it into hydrocarbons.

Together, these solutions are helping address the environmental impact of diesel and paving the way for a cleaner, more sustainable transport future.

Investing in Cleaner Technology

Cummins Inc (CMI -1.28%) is one of the world’s leading manufacturers of diesel and natural gas engines, especially for heavy-duty trucks and industrial applications.

The company is actively investing in decarbonization technologies, including hydrogen engines, fuel cells, and advanced after-treatment systems. Through its “Destination Zero” strategy, Cummins is working on improving diesel efficiency and emissions in the short term while scaling zero-emission solutions for the long term.

The global power solutions company operates through a few key segments.

The Components segment designs and manufactures axles, brakes, drivelines, and suspension systems, while the Power Systems segment focuses on alternators and prime power generator sets. Its Accelera segment manufactures and supports electrified power systems, including battery, fuel cell, and electric powertrain technologies, as well as hydrogen production technologies. Then there’s the Engine segment, which manufactures a range of natural gas and diesel-powered engines, while the Distribution segment supports power generation systems, high-horsepower engines, and heavy- and medium-duty engines.

Balancing diesel innovation with long-term energy transition goals has helped CMI shares rally 6.65% YTD and 68.78% over the past year, now trading at $543.42. With that, the $75 billion market cap Cummins has an EPS (TTM) of 20.51 and a P/E (TTM) of 26.54. It pays a dividend yield of 1.47%.

When it comes to the company’s financial position, Cummins posted $33.7 billion in revenue for the entire 2025. Its Distribution and Power Systems segments achieved record sales and profitability last year, driven by “robust demand for data center backup power.” Its GAAP net income for the period was $2.8 billion, and diluted EPS was $20.50.

Cash dividend was increased for the 16th straight year, with Cummins returning just over $1 billion to shareholders through dividends.

These “strong operational results” came “despite continued weakness in North America truck markets,” with CEO Jennifer Rumsey stating, “2025 marked a historic year for Cummins as we made significant progress in advancing key strategic priorities while continuing to raise performance cycle over cycle.”

For the full year 2025, Cummins also reported $458 million, or $3.28 per diluted share, in charges related to the Electrolyzer business within Accelera. This action was taken as part of a strategic review initiated in response to shifts in expectations for hydrogen adoption, to streamline operations, and to reduce ongoing costs in light of the weaker demand outlook.

Meanwhile, for Q4 of 2025, Cummins recorded a revenue of $8.5 billion, GAAP net income of $593 million, and diluted EPS of $4.27.

Segment-wise, Accelera sales increased the most, by 31% to $131 million, due to the timing of electrolyzer installations, followed by Power Systems, which increased 11% to $1.9 billion, driven by increased power generation demand, particularly in data center markets in North America, China, and the Asia Pacific.

Demand for power generation products, especially for data center applications, also helped increase sales in the distribution segment by 7% to $3.3 billion. In contrast, the components segment’s sales dropped by 7% to $2.4 billion due to lower demand for medium- and heavy-duty trucks in the US, but reported stronger demand in Europe and China. Meanwhile, lower demand for medium-duty and heavy-duty trucks in the US and Mexico led to a 4% decline in engine segment sales.

Now, for the current year, the company is forecasting revenue to increase between 3% and 8%, with plans to continue generating strong operating cash flow and to return 50% of operating cash flow to shareholders in the long term.

“In 2026, we anticipate that demand will be slightly better in the North America on-highway truck markets, particularly in the second half of the year, paired with continued strength in data center power generation markets. Cummins remains well-positioned to invest in future growth, deliver strong financial results, and return cash to shareholders in 2026.”

– Rumsey

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Conclusion

While integral to numerous industries thanks to their durability, high efficiency, and significant torque, diesel engines are also a major source of harmful emissions, including NOx, PM, CO, HC, and SO2, which pose serious health risks and are incompatible with global climate and air quality goals.

Water-in-Diesel Emulsion (WiDE) technology presents a compelling solution here. By significantly reducing harmful emissions without requiring engine redesign, it offers a practical and cost-effective pathway to cleaner combustion.

While not a permanent substitute for zero-emission technologies, WiDE can play a crucial transitional. When combined with other innovations such as biodiesel blends and emerging clean fuels, it helps bridge the gap between legacy diesel dependence and a sustainable energy future.

References

^{1. Nnadozie, C. F., Onuoha, C. P., Oguzie, E. E., & Emereibeole, E. I. (2025). Advancements in diesel emission reduction strategies: a focus on water-in-diesel emulsion technology. Carbon Research, 4, 45. https://doi.org/10.1007/s44246-025-00210-y}