It has some features that are similar to a conventional CHP power station and the SP4:
- it uses a hot gas to drive a turbine
- It collects and uses the hot by-products rather than wasting them.
However, the hot gas is not steam. Instead, the COGEN uses gas turbines. These are rather like jet engines. As the gas burns, it expands and drives the rubine blades around. Instead of using steam to drive the turbines, the COGEN uses the exploding, hot exhaust gases to do the work.
As before, these gases are cooled in heat exchangers. This brings their pressure down and ensures that there is a good, fast flow across the turbine blades.
The water in the heat exchanger boils into steam which can be used on the site.