The Capitol Area System, or CAS, is a district heating and cooling loop that serves both State and private users in the Capitol area. It consists of two main components: the “loop,” which is made up of over three miles of underground piping, and the central plant. The plant produces hot water and chilled water, which are pumped into the “loop.”
The plant was originally constructed in 1988 as a combined-cycle cogeneration merchant plant with a nameplate capacity of 62.1 MW capable of dual fuel use. Steam was a by-product of power generation and was used to heat the buildings on the loop or drive an absorption chiller to produce chilled water. As time went on and larger power plants came online, the CAS plant was used less frequently, and eventually, the turbines were shut down and decommissioned. Dual-fuel steam boilers were installed to provide hot water to the loop when the turbines were not running.