The joint project funded by the Sächsische Aufbaubank (SAB) to develop an after-treatment system to minimize pollutant emissions from micro and nano CHP units was launched at the beginning of 2020. In addition to the Professorship for Reaction Engineering at the IEC, the project partners are Argomotive GmbH (Dresden) and Autotechnik GmbH from Johanngeorgenstadt.

Combined heat and power units (CHP units) are modular systems for the simultaneous generation of electrical energy and heat which are preferably operated at the point of heat consumption. CHP units use the principle of combined heat and power (CHP). The advantage of CHP plants is the high degree of utilization (up to 90%) of the fuel used. CHP units are classified according to their electrical output as nano (up to 2.5kW), micro (up to 20kW), mini (up to 50kW) and large CHP units. Modules in the nano and micro CHP class are used in single and multi-family homes or to supply several properties via a local heating network.

CHP systems in the nano and micro range have become increasingly important in recent years. A large number of manufacturers with different CHP unit types (fuel, engines) have established themselves on the market, partly due to numerous subsidy programs.

Combined heat and power plants with an output of 1MW or more are generally subject to the Technical Instructions on Air Quality Control ("TA Luft"), which specify the emission limit values. The "TA-Luft" does not apply to combined heat and power plants with an output of less than 1MW, but general requirements for combined heat and power plants not subject to licensing apply. Accordingly, all measures must be taken that are possible according to the state of the art in order to avoid air pollution caused by pollutant emissions. For this reason, subsidy programmes often require that emissions must be minimized in accordance with the state of the art in order to receive state subsidies. Special bonus payments for CHP plants with particularly low pollutant emissions are based on the 50% value of the "TA Luft" specifications for NO_x and CO.

One possible way of reducing pollutant emissions and thus improving the immission situation at the CHP unit's operating site is to use efficient exhaust gas aftertreatment systems. As a rule, current CHP units are equipped with a diesel oxidation catalyst (DOC) as a maximum. With the general tightening of emission limits, it can be assumed that even micro and nano CHP units will not be able to comply with the required limits in future without efficient four-stage exhaust gas aftertreatment. The applicants want to break new ground here and achieve an innovation in the form of a combined cleaning system for the simultaneous reduction of the pollutants CO, HC, NO_x and particulates (4-way system). The innovative character is based in particular on the development of a denitrification technology (SCR) coupled with particle reduction through filters, which has not previously existed in the CHP classes under consideration. A key focus is the research, development and testing of a new type of SCR coating, which is preferably to be applied to a filter substrate.