In many industrial processes, polluted air is generated as a waste product. A typical way to treat these gaseous exhausts is to enrich them in with mineral oil or natural gas in thermal waste air purification plants. Thus, harmful substances are turned into non-toxic combustion products. However, this is a very energy-intensive process, and the exhaust today is not used efficiently – in most cases there is simply no demand for the thermal energy. Conventional processes for electricity generation out of waste heat require very high investments; nevertheless the have a low energy efficiency. Therefore they are considered as rather uneconomical.
The team around professor Reinhold Altensen at the Giessen Institute hopes to change this to the better by utilising a micro turbine to turn the waste heat into electric power. In such turbines, the thermal energy typically is fed into the system after the working gas is compressed. For several reasons, in thermal exhaust air purification plants this is not possible. Therefore the scientists plan to generate electricity without high pressure. In what they call an “atmospheric gas turbine process”, they use a cost-effective turbo charger from automotive engineering. Their pilot plant serves to gather experience as to the dimensioning and operation of such a plant. “Our pilot installation will be a prototype helping us to clarify how marketable implementations could look like” says team coordinator Johannes Lang. Besides the dimensioning it is also important to find out in which cases noxious substances in the exhaust would rule out the utilisation of the process.
Reinhold Altensen sees excellent marketing opportunities for the new technology. “High energy efficiency, simple design and the use of standard products from automobile production translate into low investment cost and fast payback” Altensen explained. Rising standards as to the cleanliness of industrial exhausts have triggered a steep growth in the installation of thermal exhaust air purification plants, and the trend is continuing. In Germany alone, Altensen sees a market potential of at least 50 million euros over the 30 years ahead.
The project is being implemented along with industrial partners WK Anlagenbauand Ingenieurbüro Richarts & Schlitt. Results can be expected by mid-2017.