There are a number of different revenue models. HRP is generally responsible for designing, construction and maintenance of the power plants. Ownership of the power plants then determines the revenue model:
The client owns the plant and operates the plant. HRP act as equipment supplier and is responsible for ongoing maintenance and support. Most common for Waste Heat Recovery
HRP owns the plant, and sells power back to the client at a competitive tariff
The system is owned by a Joint Venture between HRP and an investor (which could be the client itself). HRP receives a share of the JV revenue. Power is supplied on a power purchase agreement basis.