Fuels: Biodiesels and E10

Fuels can be subject to a big debate. Both in terms of benefits, issues, and general opinions. Here, we intend to dispel the myths, reinforce the facts, and give you the knowledge to be confident in what you use.

Biodiesel

Lets start with Biodiesel, seeing as this is more commonly used in the UK boating world for inboard engines.

Back in 2011, a new piece of legislation was pushed which was called the European Directive EN 590 Ultra Low Sulphur Diesel. Since then, some minor changes have been added and adapted but is largely the same. The directive sets a requirement for the use of a more environmentally friendly diesel for Road going and inland waterway vessels.

All road diesel (DERV) that is now sold in the UK meets the EN 590 standards and has a compulsory 7% by volume biodiesel component blended into it, usually EN 14214 FAME (Fatty Acid Methyl Ester) biodiesel.

So now we know where the terms come from, why such a big deal? 7% seems comparatively low? Well, for a fuel tank of say 200 litres, yes, this would equate to just 14 Litres. But when you compare that to a busy fuel station on an average selling around 9,700 litres per day, that equates to 679 litres of Bio Diesel. There are over 8000 petrol stations in the UK, meaning 5,432,000 Litres, or simply put, Five and a half Million litres of biodiesel is purchased each day in just the UK, which would otherwise have been Diesel by itself. That’s less carbon being produced and more diesel availability in the long term giving us more breathing room to research alternatives.

The biggest issue with Biodiesels which only really affects vehicles, in particular boats, when they are stored up for periods of time with no activity. Cars, Trucks, Vans; they’re used on the daily and churn through the fuel before it ever really becomes a problem. But stick that fuel, which naturally has a slightly higher water content and lower sulphur content, and you begin to aid in the breeding grounds for the dreaded Diesel Bug.

The reduction in Sulphur has had a dramatic effect of also reducing air pollution by way of Nitrogen Oxide, whilst the Particulates can be highly corrosive to Exhaust parts. There is a drawback in that Sulphur does increase Lubricity somewhat, helping prolong High Pressure Fuel components for example. However, with fuel additives being commonly available, to not only deal with the aforementioned Diesel bug, you can also improve the overall cleaning capability of the fuel with products like RedEx or Wynns, as well as Marine16 or M68.

Going forwards, if you know you won’t be using your vessel for a while, for instance during Winterisation, ensure you treat your Diesel with preventatives to Diesel bug, fuel stabilisers and cleaning boosters, to give yourself every fighting change to prevent the drawbacks from ruining the start to your season and give your engine a nice healthy run.

HVO Fuels

Something that is becoming evermore commonplace, is the introduction of HVO Fuels. HVO, or Hydro-Treated Vegetable Oil, is a drop-in replacement to Diesel and is considered a more environmentally friendly and sustainable fuel source at this time. It is estimated that around 10 Million tonnes of green waste, manure and other organic substrates are lost from farms and the agricultural industry. By using this waste, and processing them to generate an Oil Byproduct, along with the growing of plants such as Rapeseed Oil, a greener process of manufacturing to power existing engines is possible. Again, as per the points raised in Biodiesel, there are the same drawbacks and considerations to think about. But in many cases, most engines will be able to take HVO’s without a modification or any issues being present. However, we’d recommend speaking to your engine manufacturer to confirm suitability. For instance, all of the Kubota series of engines from Nanni are absolutely fine to use with HVO. The larger Toyota models are still currently being tested and we hope to see the green light of approval in the near future.

E5 vs E10 Petrol

This is one of the more contentious subjects. From hearing rumours about E10 destroying someone’s engine, E10 having caused a fuel injector to explode and everything in between.

Lets have a very quick look at the history. What we know as E5, has been around since 2008, prior to this, you would have known it as 91 or 95 Octane or RON. For the same reasons as Biodiesel being introduced, E5 resulted in the introduction of Ethanol into Petrol, up to 5% volume. Going forwards in time, this then changed furthermore by the introduction of E10 in September of 2021. To note, this fuel was commonplace within European countries in 2011, a mere 3 years after the UK adopted E5.

To explain, E5 is the inclusion of no more than 5% Ethanol, whilst the E10, yep you guessed it; is up to 10% Ethanol. What does this mean?

Older components that use natural rubbers for sealing, such as some Carburettors and older fuel connection joints, can cause swelling, discolouration and cracking. Even some plastics can break down with the introduction of Ethanol. Whilst more modern introduction of seals where Silica content has been increased whilst we’ve moved away from natural rubbers and introduced petroleum-based rubbers such as Nitrile and Neoprene, for example, and plastics that have been specifically designed to be used in modern fuel systems, has resulted in a more versatile material that can be engineered to tolerate certain conditions, resulting in longer service life.

Ethanol in itself, is not bad for your petrol engine either, the by-product of Ethanol has the ability to clean surfaces, reducing deposits and build-ups. Granted, this can in fact pose another issue whereby your tank internals, fuel lines and components relating will get a bit more of a clean, as Ethanol itself is Now lets discuss the contentious ‘Water’ issue with Ethanol, and in particular what has been hitting the news in the last few years. Lets bust this Myth, Ethanol does not “grab water molecules out of the air” in the environment we’re talking about. Yes, it’s true that it is Hygroscopic, but that in itself doesn’t come into the equation as much when in a sealed tank. It is it’s hydrophilic properties that we are more concerned about, which means ethanol holds water. With regular Petrol, as well as E5 and E10, the primary cause of water collecting in tanks is condensation on tank walls. But unlike Ethanol-Free Petrol, which can absorb almost no moisture, E10 can hold up to half of one percent of water by volume, and the water molecules will dissolve in the fuel. The “solubilized” water will bypass the water separator and burn harmlessly through the engine. Only if phase separation were to occur would a water separator do its job, but by then the fuel itself would be the problem. Fuel/Water Separators cannot remove emulsified fuel.

And once water has saturated the fuel to such a degree, to cause what is known as phase separation, there is largely a greater danger of the fuel being ineffective for combustion and should be considered as a loss (engine knock or ‘pinking’ is a common issue on petrols that have degraded and begun to phase-separate), hence the importance of keeping the fuel in good shape to begin with.

So the take-away from this is:

1. Keep your fuel tank topped up. Less air, means less condensation on the tank walls.
2. If you have older components using natural rubbers, see if modern alternatives are available.
3. Although companies make E10 stabilisers and miracle cures, they do not solve any issues from long term storage, use the above methods to prolong the fuel and keep it stable.

A really good read is from Practical Boat Owners here. Well worth a read and goes into more depth.

In short, making sure your tank is topped up fully, the fuel is used and ensuring the integrity of your fuel tanks and connections are in good working order, will help in preventing future issues and keeping you going for the next time you wish to use your boat.