The Wisconsin Powerhouse is the electricity and heating hub for all Kohler processes on the Wisconsin campus. To generate heat, large boilers produce steam at over 200 pounds per square inch (PSI) which is then reduced to 5 PSI to provide heat for processes and buildings across campus. Historically, this reduction was accomplished by passing the steam through a pressure-reducing valve that throttled down the steam for distribution to Kohler's heating systems.
A new steam turbine generator (STG) performs the same necessary pressure reduction as the valve but with the added benefit of generating electricity for the plant. Steam passes through the STG and spins an impeller, or rotor, and is reduced in pressure. The steam is exhausted from the turbine and used for heating. As the turbine impeller spins, it is connected to a generator that produces electricity at 2300 volts. The STG generates 650 kW of energy. This not only offsets a portion of Kohler's purchase of electric power but also reduces greenhouse gas emissions by 1,297 metric tons per year.
"The steam turbine generator was a good fit for the Wisconsin Powerhouse because we generate steam at a high pressure and then reduce a large portion of the steam to 5 PSI for heating," said Ken Baker, Staff Engineer – Utility Systems. "A key component to this system is having a use for the thermal energy, which we do for at least half the year in Wisconsin."
The STG is an example of a Combined Heat and Power (CHP) system. CHP systems use a single source of energy, high pressure steam in this case, to produce thermal and electrical power. The combined efficiency of these systems is much greater than traditional separate heat and power systems and provide environmental and economic benefits.