Futuristic engine with clean energy streams

Future Fuels: How Biodiesel and Diethyl Ether are Rewriting the Rules of Engine Performance

Nico Varela in Climate & Environment June 2025 • 4 min read.

"Explore the potential of rapeseed methyl ester and diethyl ether blends to revolutionize low heat rejection engines, paving the way for cleaner and more efficient combustion."

As the world grapples with dwindling fuel resources and increasingly strict emission standards, the search for alternative fuels has intensified. Among the frontrunners in this quest are methyl ester fuels, particularly biodiesel derived from rapeseed oil. These fuels have shown promise, especially when used in low heat rejection (LHR) engines, which employ thermal barrier coatings to increase combustion temperature and efficiency.

The primary goal is to mitigate engine exhaust emissions, specifically hydrocarbons (HC) and carbon monoxide (CO). One innovative approach involves incorporating diethyl ether into the fuel blend within LHR engines. This combination seeks to harness the benefits of both biodiesel and diethyl ether to achieve a cleaner, more efficient combustion process.

The heart of this exploration lies in modifying engine components with ceramic coatings. Pistons, cylinder heads, liners, and valves are treated with lanthanum zirconate using a plasma spray technique. By studying the effects of rapeseed methyl ester (biodiesel) and its blends with diethyl ether (at 10% and 20% volume concentrations), researchers aim to unlock the full potential of LHR engines for a sustainable future.

Unlocking Efficiency and Reducing Emissions

Futuristic engine with clean energy streams

The investigation reveals that while diesel and biodiesel generally exhibit higher thermal efficiency in LHR engines, the addition of diethyl ether impacts this performance. Specifically, blends containing 10% (B10) and 20% (B20) diethyl ether show slightly lower thermal efficiency compared to pure biodiesel when used in an LHR engine. This highlights the nuanced relationship between fuel composition and engine performance, indicating that the optimal blend may depend on specific operational parameters.

However, the real triumph lies in the significant improvements observed in exhaust emissions. All diethyl ether blended biodiesel fuels demonstrated notable reductions in CO and HC emissions within the LHR engine. The higher oxygen content inherent in the blended fuel plays a crucial role, promoting more complete combustion and thereby reducing harmful pollutants.

CO Reduction: Diethyl ether blends reduce carbon monoxide emissions.
HC Reduction: Hydrocarbon emissions see a significant decrease.
Oxygen Content: Higher oxygen levels in the fuel promote cleaner burning.
LHR Engine Benefits: Low heat rejection engines enhance these emission reductions.

Compared to pure biodiesel, the diethyl ether blends achieve a 10% reduction in CO emissions and an impressive 18% reduction in HC emissions. This underscores the potential of diethyl ether as an effective additive for enhancing the environmental performance of biodiesel in LHR engines. These results suggests a promising avenue for achieving cleaner combustion in internal combustion engines, addressing critical environmental concerns.

A Step Towards Sustainable Fuel Technology

The exploration into the use of rapeseed methyl ester and diethyl ether in low heat rejection engines offers valuable insights into the future of fuel technology. The improvements in emissions—specifically the reduction of CO and HC—demonstrate a promising path towards cleaner and more sustainable engine performance. Continuous innovation and refinement of these fuel blends could pave the way for a new generation of engines that balance efficiency with environmental responsibility, contributing to a greener future.

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This article is based on research published under:

DOI-LINK: 10.17485/ijst/2016/v9i15/87322, Alternate LINK

Title: Experimental Investigation On Performance, Combustion And Emission Characteristics Of A Low Heat Rejection Engine Using Rapeseed Methyl Ester And Diethyl Ether

Subject: Multidisciplinary

Journal: Indian Journal of Science and Technology

Publisher: Indian Society for Education and Environment

Authors: S. Krishnamani, T. Mohanraj, K. Murugumohan Kumar

Published: 2016-05-04

Everything You Need To Know

What modifications are made to engine components in low heat rejection engines, and how do these changes improve engine performance?

Low heat rejection (LHR) engines utilize thermal barrier coatings, like lanthanum zirconate applied via plasma spray to components such as pistons, cylinder heads, liners, and valves. These coatings increase combustion temperature, leading to higher thermal efficiency and reduced heat loss. This modification allows engines to operate more effectively with alternative fuels like rapeseed methyl ester and diethyl ether blends.

How does the addition of diethyl ether to rapeseed methyl ester impact exhaust emissions, particularly carbon monoxide and hydrocarbons, in low heat rejection engines?

The use of diethyl ether blended with rapeseed methyl ester leads to a noteworthy reduction in carbon monoxide (CO) and hydrocarbon (HC) emissions. Specifically, compared to pure rapeseed methyl ester, diethyl ether blends can achieve up to a 10% reduction in CO emissions and an 18% reduction in HC emissions within low heat rejection engines. This makes it a promising strategy for cleaner combustion.

Why are rapeseed methyl ester and diethyl ether used together in low heat rejection engines, and what specific advantages does this fuel combination offer?

Rapeseed methyl ester, also known as biodiesel, is used in conjunction with diethyl ether to leverage the benefits of both fuels. Rapeseed methyl ester serves as the base fuel, offering a renewable alternative to traditional diesel. Diethyl ether is added to enhance combustion properties, particularly in low heat rejection engines, leading to reduced emissions and improved engine performance. The combination aims to optimize efficiency and environmental impact.

How does the thermal efficiency of low heat rejection engines change when using diethyl ether blended with rapeseed methyl ester, compared to using pure rapeseed methyl ester or diesel?

While both diesel and rapeseed methyl ester generally show higher thermal efficiency in low heat rejection engines, adding diethyl ether can slightly lower the thermal efficiency compared to pure rapeseed methyl ester. Blends containing 10% (B10) and 20% (B20) diethyl ether have demonstrated this effect. Despite this, the emission benefits—specifically reduced carbon monoxide and hydrocarbon emissions—often outweigh the slight reduction in thermal efficiency, making the trade-off worthwhile for environmental considerations.

What specific materials and techniques are employed to modify engine components, and how might future research expand upon these methods to optimize the performance of low heat rejection engines with alternative fuels?

The investigation focused on applying lanthanum zirconate via plasma spray to engine components such as pistons, cylinder heads, liners, and valves in low heat rejection engines. The goal of this modification is to enhance the performance of these engines when using rapeseed methyl ester and diethyl ether blends. This ceramic coating helps to retain heat within the combustion chamber, leading to more complete combustion and reduced emissions. Further research could explore different ceramic materials or coating techniques to further improve engine performance and durability with these alternative fuel blends.