De-Carbonizing Heat Supplies in Urban Areas

Keynote Lecture District Heating systems are considered to be one of the most effective heat supply systems in urban areas. District Heating systems are commonly supplied by a set of different heat production plants. In mature systems, heat production technologies have evolved over time. To-date, District heating systems are mostly supplied from large boilers or Combined Heat and Power systems, commonly fired with fossil fuels such as coal, oil or natural gas. In the transition to de-carbonise European Heat Supply, interventions are being held in District Heating Systems to introduce large scale solar heat production plants, large scale thermal storage and intensify the use of industrial and commercial waste heat. In the long term, operation temperature is expected to be reduced to favour integration of renewables and mitigate local heat losses. With limited space available in consolidated urban environments, the hierarchized structure of District Heating Systems needs to be re-thought. Users, taking profit of their roofs to generate solar heat shall inject excess heat into the district, thus allowing for optimal use of excess heat in domestic solar systems during summer. In this paper, a comprehensive review to heat production systems is presented, with particular focus on District Heating Systems, their transition to low energy systems, and the potentialities of distrit heating connection of de-centralised Solar Thermal Systems