Saving Energy in Hospitals with CCHP

Abstract

The combined production of electrical, heating, and cooling energy, referred to as combined cooling, heating, and power (CCHP), is becoming an increasingly important technology. It offers several advantages, including lower consumption of primary energy, reduction of air pollution, and reduced cost. The simultaneous production of electrical, heating, and cooling energy provides higher system efficiency; this combined system can be the most economical solution for a building if the system is located where there is high consumption of electrical, heating, and cooling energy throughout the year. A good example of this type of consumer is a hospital. This paper starts with an analysis of typical energy demand profiles in a hospital and technical criteria to assess the feasibility of using CCHP plants. A case study of a non-optimized CCHP system predicted a large potential for energy savings. CCHP of a planned hospital in future will be an autonomous system for the combined generation of electrical, heating, and cooling energy. The driving cogeneration units were two high-efficiency gas engines that produced electrical and heat energy. A Miller cycle gas engine was used as a driving unit because of a high demand for electrical and heating energy. A natural gas-fuelled reciprocating engine was used to produce 735 kW of power; electrical energy was used only in the hospital. A deficit in electricity could be met by purchasing power from the public network. The generated steam used to drives three steamabsorption chillers is delivered to individual heat consumers. An additional peak-time wasteheat boiler provides additional heat during the winter. We thus affirmed that in large hospitals, major opportunities exist for CCHP applications because of the high required capacity and regular demand profiles. This system could provide simultaneous heating and cooling. No technical obstacles were identified for implementing the CCHP system. Typical patterns for the CCHP driving units were determined from the hourly energy demand over several seasons, and the average ratio between electric and thermal loads in the hospital was suitable for CCHP system operation. An analysis performed for a non-optimized CCHP system predicted a large potential for energy saving and CO2 reduction.