2.2 Efficiency TargetsThe generation efficiency of the unit must be high for the system to provide an attractive investment for a steam user. The use of the downstream steam by a process means that the outlet steam is not a loss from the system, giving more efficient electricity generation than a condensing turbine. Generating efficiency is the electricity generated, divided by the energy input that is used to perform this generation, and figures in excess of 70% are expected from the steam microturbine. To realise this, any losses of steam from the system must be minimised as they significantly affect efficiency making effective sealing paramount. A maximum steam loss of 2% of the mass flow rate through the microturbine was specified. Losses in the conversion process through the generator and inverters must also be minimised along with loads from ancillary equipment in the package, for example cooling fans and pumps.