There are significant challenges, which include:
– ORC is a waste heat energy solution, and if you have to pay for the fuel, or to harvest it, it does not have a payback (i.e. solar thermal energy)
– ORC is designed for 24/7 heat supply. Any fractional time heat supply sources have no payback
– Most residential waste heat sources are time limited (i.e. hot water heaters only operate a small amount of time, solar energy is only part of the day, etc.)
– Most residential applications for CHP have no payback, and required significant amounts of support. All result in no profit to the equipment supplier. A good example is the recent attempt of the residential sterling engine by Dean Kaman.