• Pure oils pressed from plants, largely untreated. 
• Mostly rapeseed; also soya, corn and sunflowers.
• Oils are pressed directly from the plants. 
• They are also extracted from the remaining press cake with solvent. 
• This is followed by filtering and cleaning, which reduces solids and also components such as calcium, magnesium and phosphorus.

• Not available at conventional filling stations. 
• Usually only available from the producer (farmer). Manageable logistics.

• Vegetable oils are much more viscous (thicker) than diesel and are not suitable as a petrol substitute.
• They are harder to ignite and deliver slightly less energy per litre than diesel.
• They must be preheated in winter. Up to 10% fossil diesel is often added to improve viscosity and ignition characteristics.
• DIN 51623 Fuels for vegetable oil compatible combustion engines.

• In tractor and agricultural machinery engines, in stationary CHP plants, rarely in truck engines.

• Almost all types of diesel engines have to be “converted” (other seals, filters, injection system, etc.).
• Manufacturer approval for running on vegetable oil should be available.
• Operated with SAE 10W-40 engine oils - as for diesel engines. 
• Significantly reduced oil change intervals. Oil service life only 25-30% (up to about 250 hours) compared to using diesel.
• Vegetable oil does not fully burn, especially when the engine is cold. Highly viscous components condense and contaminate the engine oil as uncombusted vegetable oil. 
• Engine oil may be mixed with a maximum of 5% vegetable oil. Otherwise there is a risk of piston ring sticking and deposits.
• Oil analysis to determine vegetable oil content and oxidation characteristics are absolutely essential.

• Biodiesel is often referred to as fatty acid methyl ester (FAME) or RME (rapeseed methyl ester).
• Based on oils and greases of vegetable or animal origin. 
• These are “transesterified” into biodiesel in refineries specially designed for this purpose with the aid of methanol. 

• B100 (pure biodiesel with 100% biodiesel) is available at many truck filling stations and service stations as it can be transported in tankers without intermediate cleaning.
• Only a few refineries specialise in production, so availability is not unlimited.
• Also sold at special pumps as an admixture to diesel, where it is usually called B7 or, depending on the concentration, also B5, B10 or B15.

• Slightly higher viscosity and lower cold stability than diesel.
• Reduces mileage slightly, but is usually somewhat cheaper (mainly due to different taxation).
• Largely carbon-neutral (up to 68%), as combustion only releases the amount of carbon dioxide that plants or animals remove from the atmosphere as they grow.
• DIN EN 590 applies to B0 to B7 diesel; DIN EN 14214 applies to admixtures for B0 to B7 and B100.
• B100 is often subject to additional quality requirements from operators for viscosity, combustibility, water content, cold stability, density and solid foreign substances.

• Predominantly as a standard additive to fossil diesel (B7).
• Also in pure form (B100) for truck use (freight forwarders, municipalities).

• No conversion of the diesel engines is required up to B10.
• B100 should be approved by the engine manufacturer.
• Mixed operation using B100 and diesel fuel is also usually possible without problems.
• Both types of fuel can be refuelled alternately, subject to OEM approval. 
• Any residues in the fuel system may be dissolved due to ester residues remaining in the RME/FAME (B100) from the refining process. Plastics, rubber and seals may also swell and non-ferrous metals in the fuel system can be attacked. 
• As a precautionary measure, replace the fuel filter more frequently. Perform accompanying fuel and engine oil analyses. 
• SAE 5W-30 to 10W-40 diesel engine oils approved by engine manufacturers can still be used.
• When B100 is used, oil-change intervals in truck engine manufacturers’ specifications are often reduced to 30,000km instead of 120,000km.

• Bioethanol, less commonly referred to as agro-ethanol, is made from residues of plants that still have residual sugar or starch content.
• Alcohol is produced by fermenting these raw materials, which are usually not suitable for use in foodstuffs.
• The starting materials are prepared as a mash to which yeast is added. The components result in a fermentation, which produces alcohol.
• The alcohol content is then distilled from the fermented mass. The end-result is bioethanol with an alcohol content of up to 99.9%.

• Produced on a relatively large scale, but pure bioethanol is not freely available.
• Bioethanol can be used in petrol engines. E10 super petrol at filling stations contains 10% bioethanol.
• Bioethanol is unsuitable for addition to diesel fuel. 

• Pure bioethanol has a higher octane rating than petrol and a different ignition point.
• Ethanol makes rubber (seals and hoses) and plastics softer or more brittle. 
• Unlike petrol, it does not vaporise at temperatures below 13°C (preheating may be necessary in winter).
• DIN EN 228 permits the addition of ethanol to petrol in Germany up to 10% by volume (E10). 
• However, E10 must meet the quality requirements of DIN EN 15376 for super petrol.

• Pure bioethanol or gasoline-ethanol mixtures containing more than 10% ethanol are no longer used as fuel. 
• Bioethanol is usually added to the petrol. In accordance with DIN EN 228, this may contain up to 5% bioethanol (E5) without it having to be declared.
• A higher concentration of 10% admixture is possible in super petrol (E10), but this has to be declared.
• Bioethanol is also often used as a basis for producing fuel additives.

• For years, petrol engines have been able to operate without problems with E5 and E10.
• All engine oils listed in vehicle manufacturers’ approval lists can be used.
• E10 can increasingly condense in the engine oil at low engine temperatures in short-haul transport. Its viscosity and lubricity are reduced as a result, and wear and tear occurs. 
• An engine oil analysis in the OELCHECK laboratory may indicate mixing with unburned bioethanol. 

• Like petroleum, natural gas is produced from fossil components.
• It is extracted from underground deposits and consists predominantly of highly flammable methane.
• In some cases it has to be cleaned of corrosive, toxic and/or non-combustible foreign gases.
• Water is removed in a drying process.
• For use as fuel it is compressed and stored or marketed in overpressure gas tanks.

• Relatively well-developed filling station network.
• Available at almost all motorway filling stations. 

• Natural gas burns cleanly without harmful hydrogen sulphide (no acid rain). 
• Neither nitrogen oxides, particulate matter nor soot are produced in any significant quantities.
• The energy content of 1kg of natural gas is equal to that of 1.5l of petrol or 1.4l of diesel - hence it offers higher performance than other fuels. 
• The octane rating is 125 (petrol is roughly 95). 
• Due to the high knock resistance, the fuel-air mixture can be highly compressed. High efficiency is achieved with low consumption.
• DIN EN 16723-2:2017-10 specifies natural gas for use in transport and biomethane for feeding into the natural gas network.

• In principle, any petrol engine can be run on natural gas. Steel pressure tanks have to be installed. 
• Can also be used in buses or suitably designed new vehicles. 
• It is important to distinguish between bivalent vehicles that run on CNG and petrol, and monovalent vehicles that run purely on gas.
• Internal combustion engines of vehicles powered by natural gas may also be used indoors (e.g. forklifts).
• Natural gas-powered engines are used on a large scale for alternative generation of electrical energy, especially where waste heat can be used.

Biogas in natural gas quality: 

• Biogas is produced by fermenting any kind of biomass. Its methane content is significantly lower than that of natural gas. It may contain a large proportion of carbon dioxide.
• For biogas to be used like natural gas, it must be purified of harmful gases and its methane content increased to at least 96%.
• Unpurified/unprocessed biogas can only be burned in specially designed engines (usually CHP). 

LNG (liquefied natural gas): 

• Natural gas becomes liquid when cooled to temperatures below -162°C. This reduces its volume by a factor of 600. Natural gas that has been liquefied by refrigeration compressors is called LNG. It is predominantly used in ships and special commercial vehicles.
   

• Significantly higher combustion temperatures occur in gas-powered engines than in petrol engines. The engine and its oil are subjected to extreme thermal loads. 
• Unlike petrol, natural gas does not contain additives which have an active cleaning effect, among other things.
• There is an increased tendency to oxidation, with the risk of ash containing hard deposits forming.
• Engine manufacturers generally require the use of low/mid-SAPS engine oils, which have a limited sulphate ash content.
• Some engine oils have been specially developed for natural gas and biogas engines.
• Regular checks on the oxidation tendency and initial pH (i-pH) are recommended.

• Liquefied petroleum gas is primarily obtained as a by-product when extracting natural gas and crude oil, and when distilling crude oil.
• It may consist of propane, butane or a mixture of the two. 
• As a fossil fuel, it can also be used in petrol engines to generate energy.

• Filling station network is very limited. 

• LPG is gaseous at ambient temperature and pressure. However, it can be liquefied at low pressure, usually 6 bar at room temperature. Once condensed, the volume is reduced by 260 times. 
• It has a high knock resistance of over 100 octane.
• LPG burns almost sulphur-free, no soot is produced. Emission values are lower than those of petrol. 
• DIN EN 589 defines the quality requirements.

• As fuel for petrol vehicles equipped with a gas tank for LPG operation. This is why it is also known as “autogas”.
• Internal combustion engines powered by LPG or natural gas may also be used indoors (e.g. forklifts).
• Also versatile use for heating, cooking or as a heat transfer medium in trade and industry.

• The engine oil can become increasingly diluted by condensed LPG gas fractions, especially with many cold starts, such as in short-haul transport. 
• LPG, like natural gas, contains no additives or active cleaning agents such as are added to petrol. 
• The engine oil has to neutralise the oxidation products that arise when running on LPG, which lead to deposits.
• Usually low-or mid-SAPS engine oils are used, which tend to have a low sulphate ash content.

• Raw materials are solid biomass (straw, wood, plant waste) or specially cultivated crops.
• Thermochemical combustion of biomass produces synthesis gas.
• This is converted into liquid hydrocarbons in a synthesis (usually using the Fischer-Tropsch process*). 
• The synthetic fuel produced can be converted into diesel or petrol by applying distillation processes used in petroleum refining.

• Not available in all countries.
• Are added to conventional fuels.

• BtL fuels are chemically only slightly different from fossil petrol or diesel fuels. 
• They usually have a higher cetane rating (around 70) than diesel (50-60).
• Special properties can be tailored during distillation.
• EN 15940:2016 Paraffinic fuels.

• Currently not used in pure form.
• DIN EN 228 or DIN EN 590 allow undeclared addition of BtL to specified petrol and diesel fuels.

• No conversion of engines is necessary (also for exclusive use).
• The products recommended by manufacturers can be used as engine oil.
• Oil analysis depends on the load and mileage, as for operation with fossil fuels.

• With the help of steam, adding pure oxygen to natural gas produces a synthesis gas. 
• Conversion to hydrocarbons takes place by means of Fischer-Tropsch synthesis*. 
• This produces long-chain paraffins that are converted into liquid fuels, primarily diesel, by cracking and distillation (fractionation). 

• Permanently available in many countries because gaseous natural gas is more difficult to transport and store than GTL.

• Burns cleaner than fossil diesel and produces significantly fewer emissions.
• Almost sulphur-free and contains no aromatic compounds.
• Easier to ignite than fossil diesel (higher cetane rating).
• Cold behaviour similar to fossil diesel.
• EN15940:2016 standard for paraffinic diesel fuels.

• Pure GTL is used in diesel engines on commercial vehicles or mobile machines and devices (construction machinery).
• Low-emission inland waterway vessels are other major users.
• GTL is added to diesel fuels such as Shell V-Power Diesel.
• Leading diesel engine manufacturers have given approval for operation only with GTL.

• No conversion of diesel engines necessary.
• Engine oil analyses to monitor the oil change interval, as for operation with fossil diesel fuel.