Metro trains generate excess heat when operating. The electric motors create heat due to their electrical and mechanical functioning at acceleration, at constant speed and at deceleration. About half of the heat in an underground system is produced when trains slow down: waste heat is produced by the brakes when a train approaches a station. The ventilation system of the trains also generates excess heat. For citys it is interesting to use this excess heat for their district heating network. In Berline the ReUseHeat project worked on an interesting example.
Waste water management systems exist in every city and could be exploited to heat buildings. They promise major heat recovery potential. The temperature of waste water ranges from 10 to 15°C on average, and can go even up to 20°C during summertime. This guarantees an adequate heat source for the operation of heat pumps throughout the whole year. The ReUseHeat project worked on an example of this application in the “Gran Arenas” project (Nice).
In 2010, data centres world-wide used about 350 TWh of electricity. It is just over 1% of the world’s total electricity use and it is constantly growing. Most of the power consumed by the Information Technology (IT) equipment is converted into waste heat, which must be removed to avoid damage to the equipment. The energy requirement of the cooling system represents up to 40% of the overall data centre energy consumption. The ReUseHeat project worked in Brunswick on the use of datacentre’s excess heat in the district heating network.
Southern European hospitals have high cooling and heating needs during the whole year. Combined district heating and cooling networks are, therefore, an interesting application. There are approximately 7,154 hospitals in Europe. Every hospital has considerable cooling needs and the excess heat from the cooling system can be captured and used in heat networks. Considering a conservative potential waste heat recovery tertiary buildings, up to 10 TWh year of heat could be supplied from this low-carbon source. The ReUseHeat project worked on an interesting application in hospitals in Madrid.
Arcelor Mittal Ghent has a lot of residual heat, which is currently cooled down in order to discharge it in a canal or into the air. Local authorities and the company are investigating whether the residual heat could be used for a heat network towards Zelzate and Terneuzen. The Province of East Flanders acts as an energy broker that brings stakeholders together, to create support and to support actions towards realization.
In 1984 the first geothermal plant has been established in Denmark, Thisted. In combination with two absorption heat pumps, excess heat from a waste incineration plant and a straw fired boiler it is part of a district heating network. This heat network delivers a total of 7 700 kW to 5 117 consumers in the area.
Gram Fjernvarme is consumer owned and was until 2009 based on natural gas with a CHP unit and two boilers. In 2009 a solar field is established to provide solar thermal power to the heat network. The solar field is expanded in 2015 to a total area of 44 800 m2 of solar collectors providing 60% of the total heat demand. From 2016 onward excess heat from a neighbouring carpet factory is added to the district heating network.
The ENTRAIN project aims at improving the capacities of public authorities to develop and implement local strategies and action plans for enhancing the use of endogenous renewable energy sources (RES) in small district heating (DH) networks. As part of the project there have been set up five initial surveys and local action plans for a specific region. The outcomes of the Regional Action Plan for Friuli Venezia Giulia are briefly described.