HOT|COOL NO. 2/2020 - "Decarbonizing"

By: Claus A. Nielsen Business Development Director, DIN Forsyning

In 2018, the Danish parliament decided to phase out coal in Combined Heat and Power plants (CHP) by 2030. However, it was not fast enough for Ørsted, the owner of the CHP plant in Esbjerg. They wanted to phase out the coal in 2023 already – even though the CHP capacity was 300 MW district heating (DH) – equivalent to half the DH in Esbjerg, and two smaller villages. The other half of the DH was supplied by the local waste incinerator. In total, about 130,000 inhabitants are living in the distribution area. In Denmark CHP for DH was mandatory by law - for 30 years. - The mandatory CHP was introduced at a time when large amounts of heat from electricity generation was wasted. The cogeneration was a good idea then because it ensured the efficient use of coal and gas, needed for both electricity and heat production. Now we have good alternatives for renewable electricity generation. CHP production should not be mandatory anymore but planned separately, says business development manager Claus A. Nielsen from DIN Forsyning (DIN Utility). Smaller units create new opportunities Claus A. Nielsen and DIN have launched a plan for converting the coal based heat production to sustainable heat production. - We will combine many small and different solutions, linked to a central distribution network. It provides a flexible electricity- powered utilization of surplus heat from waste incineration, local industry, wastewater treatment, seawater, future data centers, and eFuel plants.

It is a modular solution, as each part is only used, when reason- able – economically and environmentally. When the wind blows and electricity is supplied from wind turbines, the heat pumps start, or when industrial production is high, surplus heat is utilised. As the electricity in Northern Europe becomes more based on wind, water, and solar, balancing power is even more important. The next generation must be modular and hybrid DIN believes "modular" is the right solution for the next DH generation. Instead of a few large units, Claus A. Nielsen believes the heat should be supplied by several smaller sustainable units. DIN's plan involves a new seawater heat pump too – the largest in Denmark with a capacity of 50 MW. The overall production system will include a new biomass heat plant, electric boilers, gas boilers, and surplus heat. The goal is the optimal utilization of surplus heat, perhaps containing new seasonal storage capacity and brand-new technologies. - The "modular" idea requires planning, but it allows us to implement sustainable energy easier - even if just small heat sources. To be ready when the coal fired CHP plant closes in 2023, we had to use well-known technologies, less sustainable than desired. But we will phase them out when possible following the changes in the entire energy system. An important design parameter is to have investment flexibility thus minimizing the risk of stranded costs. The next generation of DH will be hybrid and decentralized solutions.

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