Combined Heat & Power
Think of our current technological combinations for heat & power on any particular site as "recipes"; We must work with available ingredients. Providing too much heat or electricity on site, for example, may be a bad investment and an over-use of natural resources.
Available technology dictates functional and efficient combinations of systems. For example, if you don't have a pool on site, then it is very hard to justify a microturbine or fuel cell.
If you don't have a large thermal demand, then a small fuel cell may be an alternative if it can be integrated with a heat pump for heating and cooling. Small scale fuel cells are still emerging internationally. With the loss of ClearEdge's 5kW system a few years ago, we're waiting for another manufacturer to fill the void.