Abandoned coal mines contain large volumes of water at constant temperatures (increasing with depth by 1-3 °C per 100 m), thanks to their networks of flooded galleries and shafts lying at depths of up to several hundred metres below the surface. Heat pumps can take this geothermal energy and uplift it to a more useful temperature.
In Lund there is a high activity to demonstrate the latest solutions in many fields. One such field is to construct the largest LTDH network based on fossil fuel free waste energy. Kraftringen Energi (Lund’s energy and utility company) and its partners develop concepts for energy, mobility and lighting for the infrastructure. The construction will start in 2018 in the district of Brunnshög to become Europe’s largest LTDH facility and test field for LTDH solutions. The total development will cover 100 ha over time. This way, the city can keep growing without increasing the GHG emissions. The biomass presently used in the DH system can be used elsewhere to replace fossil fuels.
In Høje-Taastrup (Copenhagen) a project is established that will innovate, demonstrate, evaluate and disseminate technological solutions
needed to exploit and use sources of very low-grade “waste” heat for heating of energy efficient
buildings via Low Temperature District Heating (LTDH) and show how the District Heating (DH)
systems can be more resource efficient and more energy efficient. The demonstration covers both
new developments and stepwise transition of existing areas with district heating and energy
retrofitting of buildings.
The GRENOBLE-ALPES-METROPOLIS district heating, with its 170 km of liquid pressurized
water distribution pipes, is the second largest District Heating System in France (900 GWh). The
district heating is a strong part of the energy strategy of the city. The integration of renewable and recovery energy accelerates and solutions are deployed to achieve
a 100% RE District Heating in 2033. State of the art solutions (biomass, waste heat from incineration
plant, geothermal energy) are combined with innovative solution (storage, CO2 capture, smart control) .
The municipality of Windsbach has planned a new residential housing project, heated by district
heating (DH). In total approximately 100 low energy consumption houses are planned. The total heat demand is estimated with 1000 MWh. The
peak load will be about 800 kW. The aim is to supply as many houses as possible with the provided
district heating. The complete heat is produced with renewable energy. Therefore biogas CHPs and
one peak load biogas boiler are installed.
Odense wants to phase out the remaining 30% coal consumption in the heat
production for the district heating network by 2025. In 2018, the coal consumption was already reduced from ~900.000 t/y in 2010 to 2-300.000 t/y but the goal is to substitute this completely. To realize this purpose, electric heat pumps, large heat storages, biomass boilers, and electric boilers are constructed. The challenge is
to carry this out without price increases for the consumers, especially the greenhouse industry where
heat price is an important competition faction.
Drammen wished to upgrade their existing district heating which was a mixture of electric, biomass
and gas/oil. They recognised the need to move from fossil and combustion fuels and so decided to
utilize seawater as a heat source for an industrial heat pump. Also recognizing the danger of
HydroFluoroCarbons (HFCs) and other synthetic working fluids they began to explore the use of
ammonia.
The network in Ferrara has already achieved significant results, but represents a perfect field to test advanced improvement strategies. As of 2014 the network is 56 km long, with 591 users’ substations, delivering approximately 143 GWht/a. The energy mix is a combination of geothermal source (14 MWt), WTE (30 MWt) and gas boilers, including a significant storage system (1,200 m3). The average temperature levels are 90°C on the supply line and 60°C on the return line.