Design and Model Based Performance Analysis of a District Energy Supply System

A district energy supply system for Almono, Pittsburgh has been studied by the Center for Building Performance and Diagnostics, Carnegie Mellon University. Almono is a mixed residential/commercial redevelopment proposed for a 178 acre brown field site on the banks of the Monongahela River in Pittsburgh, PA. The district energy supply system would provide electric power, cooling, and heating for the occupants and the buildings of the site and for possible additional energy based developments. The various energy requirements of Almono’s proposed residential and commercial buildings for power, cooling, heating, and hot water have been estimated first based on Energy Information Administration data (1993), and then again on the advanced building code of the International Energy Conservation Code 2006 (IECC 2006). A comparison of these estimates highlights the importance of building envelopes on the energy requirements of the Almono development. The daily and seasonal load profiles for power, cooling, and heating that challenge efficient and economic operation of district energy supply have been developed. Various prime mover technologies for combined cooling/heating/power, CCHP, systems have been considered: gas turbine, internal combustion engine, and steam turbine. These technologies affect the choice of fuel, and the fractions of power and heat provided. The paper estimates loads of the Almono site based on the operation and performance of both conventional and advanced residential and commercial office buildings, suggests additional energy loads that would provide for improved technical and economic performance of system, and considers the selection of a fuel and the use of solar energy as the energy sources. It presents preliminary overall flow diagrams for various district energy supplies that include various possible fuel and solar energy inputs, and use of the river as a heat source/sink. It also comments on operation of the district energy supply to meet the hourly and seasonal energy loads of the Almono site.