Standard diesel, B7 or B10
B7 or B10 fuel is usually offered at onshore petrol stations. This is a mixture of fossil diesel and up to seven or ten per cent biogenic components such as RME (rapeseed methyl ester) and FAME (fatty acid methyl ester). This fuel complies with the DIN EN 590 standard and is suitable for all diesel engines. However, B7 and B10 are less durable. If the fuel contains water, which is often unavoidable on board, bacteria can grow and clog the fuel filter. The biogenic content favours water absorption, which increases the risk of diesel pest. This fuel is therefore less suitable for yachts, but is often sold at boat petrol stations.
More about diesel:
B0, white diesel, Aral Ultimate
White diesel, or white diesel as it is often called, is pure fossil diesel of the MK1 type, which is often sold at boat fuelling stations in Denmark and Sweden and should not contain RME or other renewable raw materials. It has a long shelf life. In Germany it is called B0 and is only available at very few petrol stations. The easiest way to fill up with fossil fuel is to use Aral Ultimate Diesel.
As press spokeswoman Eva Klem confirms, the fuel does not contain any FAME additives. "FAME is not added during the production of Aral Ultimate Diesel. Aral Ultimate-Diesel is suitable for all diesel engines and fulfils the requirements of EN 590 in all respects; in some cases it even far exceeds them. As Ultimate-Diesel may contain up to 7 per cent biodiesel by volume in accordance with the above-mentioned standard, we are obliged under the 10th BImSchV to clearly display the notice "Contains up to 7 per cent biodiesel" on the petrol pump. This notice is also required if a diesel fuel - such as Ultimate Diesel - does not contain biodiesel."
The premium diesel fuels from other manufacturers generally contain biodiesel components and are therefore no more stable in storage than standard fuel.
GtL
The abbreviation stands for Gas to Liquid and refers to a process in which natural gas is converted into a liquid fuel. This complies with the DIN EN 590 standard applicable to diesel and can be used without hesitation or conversion. GtL is low-odour and transparent. The great advantage is the long shelf life of the fuel. It does not decompose and absorbs practically no water, so diesel pest bacteria do not find good living conditions and there are hardly any problems. In addition, synthetically produced diesel burns cleaner than fossil fuel; the engine produces visibly less soot. GtL is mainly offered by Shell and is readily available in the Netherlands and Denmark. As the hydrocarbon comes from natural gas and therefore from a fossil source, GtL is no more climate-friendly than fossil diesel.
HVO100, climate control diesel:
Like GTL, this fuel is produced synthetically, but hydrogenated vegetable oil is used as a carbon source. The CO₂ released during combustion was therefore previously removed from the atmosphere by plants. If the energy required for synthesis comes from renewable sources, the fuel is actually climate-neutral. The technical properties correspond to those of GtL; HVO100 is colourless, practically odourless and burns almost soot-free. It also does not absorb water and can be stored for many years. There is therefore a much lower risk of problems with diesel pest. It is not one hundred per cent protection, so you should continue to pay attention to tank hygiene and above all avoid condensation. The risk of bacterial growth corresponds to that of fossil B0 diesel.
The fuel is mainly produced by the Finnish manufacturer Neste OY and used to be called C.A.R.E diesel. HVO100 has been available at some Swedish boat petrol stations for several years. In Germany, its distribution is still limited. However, since the fuel has also been approved for road use since the end of May this year, it can be filled up at an increasing number of land-based petrol stations. But you should take a close look. Sometimes HVO is only offered as an admixture to fossil diesel; these fuels are then called, for example, Klimadiesel 25. Although this combination reduces the diesel plague problem, it is not climate-neutral and also produces more soot than HVO100. HVO100 can be refuelled with canisters here.
XtL
This is a collective term for synthetically produced fuels. The "X" is merely a placeholder for the underlying carbon source. It can therefore be GTL, HVO100 or so-called e-fuels. Another technical term for these fuels is "paraffinic diesel"; they comply with the EN15940 standard.
E-Fuels, PtL
If surplus green electricity is produced, water can be converted into hydrogen by electrolysis. This hydrogen can either be burnt directly in a special engine or further processed and enriched with carbon and used as a synthetic fuel. This is also referred to as Power to Liquid PtL. The trick here is that the carbon is removed from the atmosphere and released again as CO₂. This means the fuel remains climate-neutral. It is also liquid and can be stored in the tank as usual. Its use is therefore comparable to refuelling with GtL or HVO 100 - an ideal solution, you might think. But the process is very complex and inefficient. Only 15 per cent of the energy used can actually be used in the combustion engine. At the moment, e-fuels are not yet available at petrol stations and are more of a pipe dream. However, car manufacturers such as Porsche are working intensively on the further development of industrial production. E-fuels could also make air travel more environmentally friendly.
Green or coloured diesel
At Scandinavian boat petrol stations you can sometimes find pumps with "grön diesel" or "färgad diesel". In German: green or coloured diesel. This is a low-taxed fuel that is sometimes also sold in marinas. It is intended for commercial use, but can also be sold to private individuals. However, operating pleasure craft with green diesel is illegal and can lead to a fine or even imprisonment if discovered during an inspection. Technically speaking, green diesel is generally the same as so-called MK1 diesel, without the addition of the renewable fuels RME or HVO100. Incidentally, green diesel has recently become blue in Sweden, as the previous colourant is no longer permitted.
The best solution is HVO100
One of the disadvantages of HVO100 is the slightly higher price compared to normal marine diesel. However, the 20 cents per litre that usually has to be paid more is disproportionate to a machine breakdown due to diesel pest or the costs of tank cleaning. Another disadvantage is that sealing materials and hoses that have previously swollen on contact with FAME/RME can shrink on contact with HVO100, leading to leaks. However, Volvo as well as Yanmar and Vetus have now approved HVO100 for their engines. The sealing problem is therefore more of a theoretical problem. Otherwise, this diesel has several advantages: HVO100 has a much lower air conditioning load and is even better for the engine with fewer particulate emissions. Some users report that the engine runs more smoothly than with conventional diesel.
HVO100 is currently the best diesel fuel for boat engines.
