The utilisation of excess heat from industrial companies has been made easier. This constitutes a considerable sustainable contribution to the production of district heating. We contribute to the development, and the CO2-reducing sector coupling.

1 January 2022 marked an important turning point that most Danes probably missed. New rules for taxes took effect making it profitable for companies to utilise their excess heat. Excess heat even from small projects might now be profitable and could contribute to a more sustainable production of district heating. This sector coupling allows for the utilisation of a resource that is otherwise wasted. Senior Project Manager, Knud Erik Nielsen elaborates:

The new law adjustment has kickstarted several new ideas. We possess the relevant technical knowledge and are currently contributing to several excess heat projects  where we clarify the green and socioeconomic benefits of utilising the heat. In one of our projects, industrial excess heat will make up half of the heat demand of an entire district heating company allowing it to forgo the use of fossil fuels. Companies can reduce their energy consumption and contribute to the green transition while consumers get price competitive district heating. It is a win-win  situation for everybody involved, not least the climate.
Knud Erik Nielsen
Knud Erik NielsenSenior Project Director
District Heating
Aalborg

The role of heat pumps
As Knud explains, heat pumps are a wellknown and efficient way to transform excess heat into district heating. To illustrate, an industrial production might produce excess 30-degree wastewater containing a lot of energy that can be  utilised by a heat pump. At this temperature, the heat pump will have an efficiency (COP value) that is 1.5-2 times higher than facilities that use outdoor  air as their source of energy. The COP value is an expression of how much kWh-heat you get when the heat pump uses 1 kWh electric energy. This shows how the electricity consumption is significantly lower when using industrial wastewater which in turn makes the price of district heating less sensitive to fluctuating prices of electricity.

Combining knowledge from two sectors
Artelia has extensive experience with excess heat projects in terms of heat pumps and integration into the district heating network. The production and  distribution of district heating is a central business area at Artelia, and we can
also draw on our knowledge from various industrial projects. In terms of sector coupling, it is a great advantage to us that we already have specialists who consult companies on energy consumption. One of them is Pia Clausen who possesses detailed knowledge of the complicated array of laws, fees, CO2-quotas and sustainability requirements.

By entering an agreement with the Danish Energy Agency concerning energy efficiency, companies can avoid paying excess heat taxes altogether. Otherwise, the taxes have been cut in half compared to 2021. Companies can save energy and,  potentially, water used for cooling the excess heat. Excess heat supplied by a quota  company also benefits the quotas the company is allocated. The utilisation of excess heat results in a lot of advantages for industrial companies.
Pia Clausen
Pia ClausenProject Manager
Energy & Industry
Aarhus

Research in sector coupling

We are expanding DTU Elektro’s laboratory SYSLAB at Risø Campus with a facility for tests and analyses of sector coupling between electricity, district heating and gas. Artelia oversees design management, and we supply the basic and detailed designs of district heating, installations, electricity and SCADA.

Environmental declarations
As Pia points out, the emission factor (CO2/kWh) of district heating companies will improve when utilising excess heat. The CO2 has already been attributed to the industrial company that produces it, rendering the heat CO2-neutral once it reaches the district heating company. The heat simultaneously allows the district heating company to reduce their use of bio and fossil fuels. The new and
complicated EU regulations that include heavy reporting of and verification requirements for the level of sustainability of biofuels might also help push forward the utilisation of excess heat and electricity. We assist district heating companies prepare their environmental declarations.

Electrification of district heating
Generally speaking, the use of heat pumps and excess heat is connected to the national strategy for using more electricity in the supply of district heating. The electrification would allow the district heating system to also utilise excess electricity from wind turbines. According to the Heat Plan 2021 from Aalborg
University, about one-third of the district heating supply will stem from electricity in 2045. It will consist of a mix of heat pumps and electric boilers which, according to Knud, is a good combination:

It is important to remember that electric boilers have several advantages while they
are cheap to install and maintain. They are good at stabilising the electric grid as they can react and regulate immediately. In the future, large electric boilers will replace supplementary oil boilers in many places. This might be necessary to achieve a completely CO2-neutral district heating capacity which is already a market demand. To illustrate, we are currently involved in a project concerning a 30 MW electric boiler for Vordingborg Forsyning, and we expect to take on a lot of similar projects soon.
Knud Erik Nielsen
Knud Erik NielsenSenior Project Director
District Heating
Aalborg

Lastly, Knud mentions the interrelated issue of the increasing need for energy storage:

It is important to remember that electric boilers have several advantages while they
are cheap to install and maintain. They are good at stabilising the electric grid as they can react and regulate immediately. In the future, large electric boilers will replace supplementary oil boilers in many places. This might be necessary to achieve a completely CO2-neutral district heating capacity which is already a market demand. To illustrate, we are currently involved in a project concerning a 30 MW electric boiler for Vordingborg Forsyning, and we expect to take on a lot of similar projects soon.
3D-model of an electric boiler