Rudolf Diesel was a visionary. As far back as 1893, he carried out trials at our company headquarters in Augsburg on the engine that later bore his name, operated by pure peanut oil. However it was not until a good 100 years later that bio-fuels were to make a comeback for use in diesel engines at MAN Diesel & Turbo. Our engineers recognised the sign of the times back in 1994 and, for research purposes, started operating modern, large-bore diesel engines with vegetable oil, old fat and tallow from animal carcass processing. In the meantime, many of the systems that have been optimised to the specific requirements of the various bio-fuels are successfully generating electricity and heat – including from rapeseed, soya bean and palm oil. Our customers are also even using old frying fat or animal fats.
 
Our diesel engines, which are primarily designed for heavy fuel oil, a fuel that is certainly cheaper but which is very demanding in terms of the engine’s technical capacity, can also be operated with bio-fuels with just a few modifications. The injection components in particular will however require adaptation: fatty acids can have a negative impact on the service life of the injection systems and oil pumps – a fact that our specialists take into account when selecting materials for these components. The higher oxygen content of bio-oils also affects the combustion temperature in the cylinder. The result is an up to 30 per cent higher nitric oxide content in the exhaust gas. However, this drawback can be countered with an SCR system. A further disadvantage lies in the fact that the lower thermal value of bio-fuel reduces the  output of an four-stroke engine compared to operation with heavy fuel oil by around five per cent. Clear advantages include sulphur-free exhaust and the significantly lower particle emissions.
 
For ethical reasons, thermal and electrical energy generation should use sustainable raw materials that do not compete directly with food production. Research and development work is currently focusing on jatropha, African palms and special algae. In relation to climate change, the overall CO2 balance sheet of bio-fuels also has to be taken into account. This does not necessarily need to be better for every bio-fuel than the clean burning of natural gas, for instance.