Are District Steam Systems a Decarbonization Strategy?
I will look at the annual delivery efficiency of medium pressure steam distribution systems (100 to 175 PSI). District energy systems typically do not have any condensate return systems and the host site must cool condensate from 170° to 140 °F before dumping it into the sewer. Most of the hosts utilize the steam at low pressure (15 PSI or lower) or as hot water for heating or domestic use. This results in 50% to 66% instantaneous efficiency of fuel input to useful thermal energy delivered to the building for heating or DHW loads. When accounting for the standby losses during the summer and night set back periods, the efficiencies are much lower due to standby losses from year-round hot infrastructure. An important question we should ask ourselves is “Can we afford to use valuable future renewable energy sources at these poor delivery efficiencies, or do we need to find better answers?” I will present some alternative solutions for the decarbonized all-electric carbon free future rather than utilizing this early 19th century distribution system. Open discussion at the end of the presentation.
Scott Greenbaum PE, CEM, CPHC, CBCP, GBE - I graduated from the United States Merchant Marine Academy with a BS in Engineering (1977) and from New York University with a MS in Energetics (energy production technologies and efficiency) in 1981. I have been involved in the building energy business since 1980. I have worked in the commercial, institutional, & industrial building sectors in many capacities from energy auditor, MEP engineer for developer, HVAC design engineer, commissioning agent for both new and existing buildings, central plant design and evaluation, and decarbonization engineer. I recently obtained Passive House (PHIUS) certification as a consultant (CPHC). District Energy Systems I have worked with include Vicinity (Baltimore, Boston, Cambridge, Philadelphia), MATEP, Con Edison Steam, Vicinity (Philadelphia), University of Hartford, and Clark University.