Diesel Fuel on UK Canals

In the UK we’ve traditionally had two types of diesel; unmarked (white) diesel primarily for use by vehicles on public roads which attracts the full fuel duty rate of 20%, and red diesel (marked with a dye) which is sold at a reduced duty rate of 5%, used for ‘offroad’ purposes, including agricultural vehicles, commercial craft, trains and heating.

‘Red’ diesel has also been used by ‘pleasure boats’ on UK canals. 


Current Red Diesel plus Biofuel (FAME)

Since 2010 private owners had been expected to self declare the proportion of diesel used for heating and propulsion when purchasing fuel so that the propulsion element could be taxed at the higher 20% rate. That situation looked likely to change after a 2018 European court ruling decreed that, for equalisation of EU taxation regimes, UK private pleasure craft would no longer be able to use any reduced rate red diesel on UK waterways and must use ‘white’ diesel. However in 2021 following Brexit the UK government decided that red diesel could continue to be used with self reporting.

In 2011, because of increasing environmental concerns about the effects of diesel fuels, the EU decreed that all fuel for “off road” equipment should now, like road diesel, also be low sulphur and this included the fuel used by leisure boaters in the UK. UK fuel suppliers have met this obligation by supplying dyed EN590 DERV, the very same fuel used in diesel road vehicles, but with a red dye. This means red diesel now also contains 7% bio-fuel with plans to gradually increase this proportion over coming years. We now call this ‘First Generation Biofuel’.

The inclusion of biofuel in current diesels has led to the common problem known as Diesel Bug. It was found that a selection of yeasts, moulds and microbes breed at the interface between this biofuel and water. Any boat will collect water in the bottom of the fuel tank, and this will encourage growth, especially during winter inactivity. Over recent years it has become apparent that leisure boaters in particular suffer this growth of microbes, yeasts and moulds, which if left untreated will eventually get into the fuel system and block water traps, filters and eventually pipes and pumps. Fuel additives and filters are available to treat the problem and we list companies offering Fuel Cleaning (Polishing) Services and Equipment.

Beyond Diesel?

Electric canal boats are usually seen as the future, especially when electricity comes from renewable sources. The heavy weight of batteries is probably not a problem for canal craft, actually reducing ballast requirements. Fully electric cruising would require hundreds of mains charging stations around the network. Hybrid boats with diesel generators charging batteries to power electric propulsion are already afloat, promising quieter cruising and more efficient performance. However they would still be burning diesel, even if it were the ecologically friendly HVO. Solar panels could help charge batteries but currently not enough for daily cruising.


HVO, Less Economically Damaging and Polluting Diesel

Hydrotreated Vegetable Oil (HVO) is a 2nd generation biofuel that is gradually becoming readily available for regular commercial marine use. It is made by converting waste vegetable oils and animal fats into diesel fuel using hydrogen.

The environmental impact of HVO is consequently much reduced, being made from waste oils so not directly produced on land otherwise reserved for growing food.

It mixes with all other diesel fuels, has full approval from current engine manufacturers and does not attract water or promote the development and growth of diesel bug, being completely stable when stored.

The Inland Waterways Association has been investigating and reports that “feedback from IWA members who are trialling this new fuel has been overwhelmingly positive. HVO is indeed a viable alternative to diesel fuel and is in fact potentially a straight drop-in replacement compatible with fuel that is already in a boat’s tank.

As well as being 90%+ carbon neutral, there is no need to change the boat’s method of propulsion or to modify the existing engine with any kind of upgrade or trade-in. This means that all diesel engines powering today’s inland waterways craft can easily become nearly carbon neutral overnight, simply by changing their fuel to HVO.

HVO can also be used on-board for domestic use such as cooking and heating. In the trials, boaters discovered that diesel-fuelled domestic devices could efficiently operate on HVO and demonstrated a cleaner burn with reduced fumes and smoke … and less cleaning required!

With air pollution being another crucial issue that needs to be tackled, the lack of smoke is a particularly welcome benefit. Quieter running noise has also been reported.

Thanks to Inland Waterways Association for information about HVO and image of trad boat Skylark running on HVO! For more information on IWA’s Green Boating Guide and its Vision for Sustainable Propulsion visit https://waterways.org.uk/green-boating.

So what is the catch? At this time, the two main issues with HVO are a lack of availability and taxation issues affecting the price. The first of these will hopefully be resolved as demand increases. Once the market has been established, supply will inevitably increase and in turn, the price may drop. However, IWA will call on the Government to introduce tax cuts on HVO in order to make it more affordable and appealing for boaters to switch their fuel source. Another potential third issue is that of sustainability. HVO, like all biodiesels, is manufactured from vegetable oils. Currently, the HVO being supplied to the inland waterways is made exclusively from waste and recycled oils and does not adversely affect the world supply of food and food oils. However, IWA recognises that as demand increases, there may be a risk that this could change. The charity will work to ensure this does not happen.

All materials and images © Canal Junction Ltd. No unauthorised reproduction. Page last updated: 08/03/2022.

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