Micro combined heat and power units (mCHP) are efficient energy systems for residential applications. With biogas as renewable energy source, the full potential of this technology would be released. Especially in rural areas, where centralized heating systems are rare, biogas is most likely available. However, there are disadvantages compared to natural gas that inhibited the usage of biogas in mCHP until now. First of all biogas is not as clean as natural gas and comprises various components according to its production conditions and raw material input. This leads to a higher rate of soot particles and pollutants in the exhaust gas. Consequently, fouling in the downstream heat exchanger (HE) is a serious issue when operating biogas in mCHPs. One approach to solve this problem is the identification of a fouling resistant coating for the HE surface in contact with the flue gas. This is complemented with a redesign of the HE to improve coatability and cleanability. This work presents the proceeding to evolve a fouling resistant HE for operating biogas in mCHPs.