| Abstract |
District Heating (DH) service is a system for distributing heat generated in a centralized location for residential and commercial heating requirements such as space heating and water heating. Heat is distributed to the customers by means of a network of underground insulated pipes. The A2A District Heating in Milan started in the early 90s, mainly based on heat production from Waste to Energy plants and from natural gas fuelled Combined Heat and Power (CHP) plants. Currently, a plan to strongly expand the district heating service in the city is under development according with the ‘fundamental idea’ behind modern DH systems: use local renewable energy sources, local heat and energy sources that under normal circumstances would be lost or remain unused. The main goal of the plan is to improve the air quality in the city enhancing at the same time energy saving. Milan area is plentiful of underground water which allows the exploitation of geothermal renewable energy for DH from groundwater. Groundwater, at a temperature of about 288 K, is not directly channelling to DH network but heat pump can be used to extract low temperature heat from the groundwater and transfer it to DH network hot water at 363 K. The first applications of heat pump fed by groundwater in Milan DH systems have been realized in Canavese and Famagosta plants where the heat pump is integrated with a high efficiency natural gas fuelled CHP plant. The heat pumps of Canavese and Famagosta have started operating respectively in 2010 and 2011, and they showed high performance, reliability and operative flexibility. The DH systems are still under development, mainly by mean of network extensions. At their maximum capacity production, heat pumps will product about 216 TJ/year of thermal energy which involves an estimated energy saving of about 72 TJ/year of primary energy and avoids the emission of about 3,200 Mg/year of CO2. Locally, will be also avoided the emission in the urban area of about 12 Mg/year of NOx, 3 Mg/year of SOx and 0.3 Mg/year of particulate matter (PM10). |