Low Carbon Ready

Cleaner Engines

Project Data

Start date:

10/01/2020

End date:

10/31/2022

Budget:

£433,000

Summary

Cleaner Engines explored alternative temporary power solutions by converting diesel generators into hybrid units using biofuel (HVO), LPG, and glycerine. It assessed performance, efficiency and emissions, ultimately demonstrating the benefits of hybrid generators and supporting further evaluation of HVO as a viable fuel alternative.

What is the project about?

Cleaner Engines aimed to identify alternative temporary power solutions to reduce CO₂ and NOx emissions. It focused on converting diesel-powered mobile generators into hybrid units running on Hydrotreated Vegetable Oil (HVO) and developing hybrid generators powered by liquefied petroleum gas (LPG) and glycerine. Through testing a range of alternative fuels, the project compared performance, efficiency, reliability, customer feedback, and emissions to support informed decision-making at UK Power Networks in its journey toward Net Zero.

Hybrid generators offer a cost-effective, efficient, and environmentally friendly alternative to standard diesel units. Designed for use during planned and unplanned works, these generators are deployed to maintain power supply to customers during outages.

The solution included hybrid units equipped with remote monitoring, enabling several advantages over traditional diesel generators: reduced fuel consumption, real-time status and fuel level tracking, lower emissions, and an improved customer experience through quieter operation—particularly at night.

How we’re doing it

The project involved emissions testing, performance analysis, and customer feedback to assess the suitability of various alternative fuel options. Traditional diesel generators are often oversized and underloaded, resulting in inefficient operation, higher fuel consumption, increased emissions, and more frequent maintenance.

Hybrid generators address these issues by using a combustion engine that operates intermittently and at optimal efficiency to charge a battery pack. Under normal conditions, power is supplied silently from the battery, while during periods of high demand, both the battery and engine work together to deliver peak output. This setup ensures the combustion engine runs only when necessary, significantly improving overall efficiency and reducing emissions.

In collaboration with suppliers, the project successfully designed and built hybrid mobile generation units. A training and awareness pack was also developed and rolled out to field engineers to familiarise them with the operation of the new system. Feedback from operators and the public has been positive, highlighting the reduced noise and improved environmental performance.

Emissions testing of generators running on LPG, HVO, and glycerine was carried out through controlled trials led by Imperial College London’s Centre for Low Emission Construction, contributing robust data to support future deployment decisions.

What makes it innovative

Cleaner Engines was innovative in its focus on converting traditional diesel generators into hybrid units powered by alternative fuels such as Hydrotreated Vegetable Oil (HVO), liquefied petroleum gas (LPG), and glycerine. This approach aimed to significantly reduce CO₂ and NOx emissions, supporting environmental sustainability goals. By evaluating multiple alternative fuel options, the project compared performance, efficiency, reliability, and emissions to determine the most viable solutions for temporary power generation.

The use of HVO as a biofuel proved especially promising. When combined with a battery pack in a hybrid setup, HVO generators delivered lower emissions and improved customer satisfaction, particularly due to their silent operation during typical use. HVO was also found to be the most straightforward fuel to adopt, requiring minimal changes from existing diesel infrastructure.

LPG hybrid generators, however, encountered operational issues that rendered them unsuitable for field deployment. In contrast, glycerine-fuelled generators showed strong environmental benefits, with emissions testing revealing substantial reductions in CO₂, NOx, and particulates compared to diesel and HVO. Despite these gains, glycerine posed practical challenges—its high viscosity and density required specialised high-pressure pumps for refuelling, and supply chains were not yet mature, complicating logistics.

Through this project, UK Power Networks gained critical insights into the viability and challenges of various alternative fuels, helping inform future strategies to decarbonise temporary power generation and support progress toward Net Zero.

What we’re learning

Lessons Learned from the Cleaner Engines Project:

Reduced Noise Well Received by Customers:
The significantly lower noise levels during operation—especially overnight when running from the battery pack—were positively received by customers, improving satisfaction and reducing disturbance.
Need for Operational Warning Lights:
The silent operation of hybrid units while supplying power via battery led to the installation of operational warning lights. These were necessary to alert field operatives that the unit was active, even in the absence of sound.
Remote Monitoring via Online Portal:
The use of an online portal to monitor generator status, GPS location, and fuel levels remotely proved to be a highly valuable feature, improving operational efficiency and oversight.
Importance of Trailer Certification:
Trailer approval was identified as a key requirement for deploying mobile generators. Future projects should involve transport departments early in the process to ensure trailer compliance and avoid delays.
Configurable Charging Settings:
Battery charging parameters—such as the minimum state of charge before recharging begins and scheduled charging times (e.g., evening charging for overnight use)—can be adjusted through the online portal, offering flexibility to suit different operational needs.
Hybrid Design Reduces Generator Size Requirements:
The hybrid setup, with the generator and battery operating in parallel, effectively handles high inrush currents at startup. This eliminates the need for oversized diesel generators, allowing for smaller, more efficient units to be specified without compromising performance.

Reports & Documents

View project reports on the Energy Network Association’s Smarter Networks PortalProject Registration Document

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Project Data