Sounds impossible, but our large-bore diesel engines can produce valuable energy from almost anything; even from used cooking fat. We’ve proven it – in the small Austrian town of Fritzens. Here, the fast food joints, pub landlords and even households save their old cooking fat in plastic containers. 1,800 tons of it each year. And our 1,120 kW large-bore diesel engine converts it into energy for 3,500 households.
In the cogeneration plant at the sewage treatment plant in the Austrian town of Fritzens, engineers from MAN Diesel & Turbo have found an unusual fuel: used cooking fat. The local gastronomy establishments and private households collect their waste fat in plastic containers and bring it to the recycling sites. These fats and oils that were once poured down the drain and then had to be separated in the treatment plant at high cost have now proven themselves as environmentally friendly sources of energy. Environmentally friendly because the incineration of plant oils and biogases that are formed through the decomposition of organic materials add only as much CO2 to the atmosphere as the plants remove from the atmosphere in the course of their growth. It’s a CO2-neutral form of energy generation.
For the cogeneration plant in Fritzens, using the old plant fat as fuel isn’t a problem. The plant’s power generator is driven by an MAN six-cylinder inline type 21/31 diesel engine (Piston diameter 210 millimeter, stroke 310 millimeter). The electrical output of the engine is 1,130 kilowatts, the heat output around 1,350 kilowatts. What makes this large-bore MAN engine highly effective in energy generation is the simultaneous use of the engine power and heat generated – the cogeneration. The efficiency is 88%.
In addition to engine power that produces electricity via the generator, the engine heat is used to keep the treatment plant’s digestion towers at working temperature and dry the sludge. The dried sludge is granulated or pelleted and can be used as fuel for the boiler or process heat furnaces. Some is delivered to a cement plant, which saves tons of fossil fuel as a result.
Before the old fat is burnt in the engine, the particulates are allowed to settle, which further increases the energy efficiency of the waste disposal plant. Because around 10% of the deposits react with waste water in the plant, generating biogas, which fuels an associated gas engine heating plant.
To ensure that the plant is not just CO2-neutral, but also operates as emission neutrally as possible, there is an exhaust treatment system including selective catalytic reduction system. Here, nitrogen oxides (NOx) and unburned fuel are removed. In addition, a downstream oxidation catalytic convertor removes unburned fuel, carbon dioxide, carbon monoxide and residual ammonia from the NOx reduction process.
The nine gigawatt hours of electricity generated each year by the generator covers the requirements of the entire facility and feeds six million kilowatt hours of ecological electricity into the public network – enough for 3,500 households. That makes the facility completely self sufficient in energy and the entire value created remains in the region.
As a result, the Fritzens facility is, in every respect, a model for how MAN intelligent technology can create environmentally friendly energy even from problem substances.
MAN. Engineering the Future — since 1758.