Replacing Red Diesel with DiMethyl Ether (DME) in Heavy Duty Vehicles: Red Diesel Replacement Phase 1 - summary report. Project number: RDR/P1/L2/5868

Executive Summary: The UK Government has a legal target to achieve net zero carbon dioxide emissions by 2050. This will require over an 85% reduction (from 2019 levels) in UK industrial sector CO2 emissions by 2050. The off-highway machine sector, while a relatively small overall CO2 contributor, will need to develop lower carbon products to allow this reduction target to be met. Energy suppliers will also need to provide alternative energy sources. Opportunities remain for off-highway machine CO2 reduction at the engine, machine, and work site levels but they will be insufficient to achieve the required CO2 reduction. This will drive the need for fundamental power systems changes. The off highway machine sector contains a diverse range of applications that vary widely in power, duty factor, transient requirements, ambient conditions, and location. There is not likely to be a single power solution to deliver the required CO2 reduction that can meet every off-highway industrial OEM’s specific requirements and sustainability goals while delivering an optimal balance of owning and operating costs. To support customers in achieving the required CO2 reduction, Perkins Engines Company is developing a range of solutions including batteries, hybrid powertrains, and renewable fuels. Renewable Dimethyl Ether (rDME) is one of the low carbon renewable alternative fuel options seen as having potential due to its good compression ignition properties, extremely low soot emissions, relative ease of liquified storage relative to LNG, and reduced well-to-wheel GHG intensity. rDME does have several challenges compared to diesel however (lower energy density, material compatibility, lower lubricity, and higher compressibility). Perkins Engines Company Limited, Flogas Britain Limited and Loughborough University were granted Red Diesel Replacement Phase 1 competition funding to accelerate development of renewable DME as a potential low carbon alternative fuel option for the off-highway sector by demonstrating a DME-fuelled industrial engine. To allow testing of the engine, Loughborough University upgraded one of their engine test cells with DME-compatible fuel handling equipment. Perkins modified the high and low-pressure fuel systems of a 3.6 litre, four-cylinder Perkins® 904 Series diesel engine. A bespoke DME fuel injection system could not be obtained within the timeframe of the project leading to the use of modified production fuel injectors and an off-board air-driven fuel pump. The modified engine was successfully tested at Loughborough and matched the diesel engine power. The testing demonstrated a significant soot emissions reduction for the same level of NOx (oxides of nitrogen) emissions. DME fuel injector spray rate and visualisation measurements were obtained and used to develop DME combustion simulation capability. Flogas provided the DME test fuel and carried out a study on the rDME supply chain to support their development of low carbon off-grid energy sources. Key obstacles to the adoption of rDME for off-highway equipment that were identified include the current lack of DME compatible fuel injection equipment, the lack of RTFO “Development Fuel” status for rDME, and competition from other sectors for the available rDME.