DISTRICT HEATING AND COOLING SYSTEMS WITH HEAT PUMPS
District energy systems have the potential to decrease the CO2 emissions linked to heating, cooling, electricity and hot water. This is true in particular when considering the prospect of large polygeneration energy conversion technologies, allowing a more rational use of energy and a better sharing of resources between users. Significant improvements towards lower greenhouse gas emissions will however not be possible without rethinking the way heating and air-conditioning shall be met, namely changing from individual solutions to more rational solutions, including the consideration of networks when dealing with high energy density districts. Several alternatives of advanced networks exist. They range from relatively high temperature networks with local organic Rankine cycles or absorption cooling units, to low temperature networks with or without phase change fluids but with heat pumps. The paper presents a new network operated with CO2 and connected to a central plant with an open cycle CO2 heat pump. The system is discussed and compared with a double water network that would meet the same heating and cooling demands.