Alternative "Drop-in" fuels


Why seek alternatives to diesel?

As many industries are looking to reduce their reliance on fossil fuels, alternatives to dino-diesel are gaining traction.

Fossil fuel diesel although a very convenient energy carrying fuel, also has a number of drawbacks which are gaining notoriety with users, customers and increasingly government legislation.  The adverse effects on air quality are well-documented and the drive to decarbonise transport also adds to the desire to move away from traditional diesel where possible. 

What alternatives to diesel are there?

Hydrotreated vegetable oil (HVO) and gas-to-liquid (GTL) ‘engineered’ fuels are options many are considering as a stop on their decarbonisation journey.

  • HVO is obtained from growing and harvesting vegetable crops and treating the oil obtained from the crop to turn it into a biofuel.
  • GTL is obtained by processing natural gas into a synthetic liquid fuel. 

Both HVO and GTL can be used as a substitute fuel in diesel engines requiring few or no modifications

Both of these fuels still have carbon emissions although HVO is in theory a renewable fuel source and has generally lower carbon intensity than GTL fuels. The reduction in carbon emissions, particularly when using HVO fuels makes it an attractive option for decarbonisation of diesel traction particularly where fleet assets may many years of usable service left to give. Replacing fleets before they are life-expired has both significant cost and carbon implications, whilst re-tractioning existing vehicles poses availability challenges where vehicles are highly utilised.

The wind of change in air-quality

The UK Government announcement that it would scrap diesel fuel duty tax break for construction and logistics firms from 2023 has led many in this segment in the UK to look toward alternative fuels that can be utilised in existing heavy-duty diesel engine applications. Alternative "Drop-In" fuels are attractive as switching to these fuels does not require significant adaptation or replacement of existing equipment or incur added maintenance and installation costs.

Read on to see the Ricardo testing results

Testing emissions and efficiency of alternative fuels

Ricardo has worked to assess and independently test hydrotreated vegetable oil (HVO) and gas-to-liquid (GTL) ‘engineered’ fuel as a replacement for traditional fossil fuel diesel in heavy duty diesel engines. 

To measure the green credentials of HVO and GTL, Ricardo has carried out testing of diesel-powered generator sets from 30 to 500 kVA using engines certified at EU Stage IIIA emissions.  Each unit was tested to relevant international standards and cycles for the class of equipment. 

The emissions comparisons were made between a standard pump-grade EN590 diesel, HVO and GTL. By measuring emissions and the chemical analysis of each fuel, testers could determine a ‘carbon-balance’ fuel consumption for each fuel option, an essential part of making a fair comparison of the fuel options. 

In this testing the results have demonstrated significant emissions improvements when operating on both HVO and GTL fuels, compared to pump-grade diesel. Particulate matter emissions were reduced by up to 42 percent, carbon monoxide by 14-35 percent, and hydrocarbons and NOx by 6-25 percent. These improvements to air quality are a welcome benefit which has the potential to improve station and depot air quality for both passengers and staff.

When comparing fuels, it vital to compare the fuel consumption for each. HVO showed a fuel consumption increase of 0.1 to 1.7%, with GTL fuels having a 2.0-3.9% higher fuel consumption which for most is an acceptable trade-off for the reduction in both carbon intensity and exhaust emissions.

Drop-in fuels allow reductions in both exhaust and carbon emissions and so are an attractive option for asset owners seeking to avoid early fleet replacement costs. 

If you'd like to explore alternative fuels for your rollingstock then get in touch

Further details on testing of alternative fuels for our client Aggreko can be found here

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