HOT|COOL NO. 1/2023 "AI & Digitalization"

NO. 1 / 2023


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This year’s first issue of Hot Cool opens with an article about using Artificial Intelligence in District Heating. It goes in-depth with efficiency improvements in buildings and district heating systems and touches upon better wind and solar power inte- gration and cross-system solutions. Henrik Madsen, Professor and Section Head of DTU Compute and his team, has written the article. This tremendous technical article is followed by two exciting articles by Lars Gullev, Senior Consultant at VEKS – highlighting DH is Denmark – what it was, what it is and what it will be. The first provides a quick historical overview of the development of district heating in Greater Copenhagen from the beginning of 1903 until today. The second offers insight into the bench- marks for further development toward a CO2-neutral district heating system in Copenhagen in 2050. EBO Consult has made an article about Cooperative District Heating in the making, where we get inspiration from Den- mark and hear about the first achievements in the Nether- lands. In this article, Rie Christiansen Krabsen and Gerwin Ver- schuur discuss a Danish/Dutch comparative study and the first steps toward a Dutch district heating support organization. Finally, we present Fenagy, one of DBDH’s newest members, in the Member Company profile.



COOPERATIVE DISTRICT HEATING IN THE MAKING By Rie Christiansen Krabsen and Gerwin Verschuur 13


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DBDH Stæhr Johansens Vej 38 DK-2000 Frederiksberg Phone +45 8893 9150

Editor-in-Chief: Lars Gullev, VEKS

Total circulation: 5.000 copies in 74 countries 10 times per year

Grafisk layout Kåre Roager,

Coordinating Editor: Linda Bertelsen, DBDH

ISSN 0904 9681

Today there are many sensors in buildings and district heating/cooling systems with a high temporal resolution. Data from such sensors opens up for new AI and IoT-based solutions. Here we will describe the potential of some of such solutions for district heat- ing systems. However, we will also touch upon how such solutions potentially make the system more vulnerable and challenging with respect to privacy and GDPR. ARTIFICIAL INTELLIGENCE IN DISTRICT HEATING

By Henrik Madsen, Professor and Section Head on DTU Compute

Buildings and occupants The demand for smartness, trust, transparency, and versatility in managing heating, cooling, ventilation, lighting, and access control systems for a family home, public buildings like schools, and office buildings is growing. People want a comfortable, sustainable, cost-efficient, and safe place to live and work, and that's where sensors, AI, IoT, and automation jump in. GDPR and privacy Personal data are any information related to an identified or identifiable person. Only if the processing of data concerns personal data, the GDPR (General Data Protection Regulation) applies. This implies that the problem typically does not exist e.g., for a section of a district heating network, as well as for public buildings like schools and some office buildings. Today we are able to obtain electricity consumption data with a very high temporal resolution (e.g., every 15 seconds) also for single-family buildings. Given such data, it is often relative- ly easy to conclude which appliance has been used at which time. Likewise, most of us have hourly readings of water con- sumption online. We can see, for instance, that 2 liters have been used at 2 am, 3 am, and 5 am during a single night. This indicates frequent bathroom visits, which could lead to some privacy issues. Frequent and real-time data for district heating consumption can be used to better control heating and ven- tilation systems, but also to detect absence (e.g., holiday peri-

It will be argued that energy meter data and the use of AI in district heating provide the foundation for efficiency improve- ments in buildings and district heating systems. In addition, such data-driven methods give possibilities for CO2 and cost savings, better integration of wind and solar power, efficient in- tegration of the energy systems, and more satisfied end-users due to lower costs and a better indoor climate. One of the major problems today is that data and solutions often are linked to proprietary platforms. Consequently, it is challenging to implement cross-system solutions and harvest synergies from systems integration. Sadly, this often hinders the possibility of obtaining large savings and efficient imple- mentations. However, this cross-system functionality can be obtained using a non-profit data hub, like the national hub for smart energy and water systems at Center Denmark. For instance, Center Denmark is successfully used for cross-sys- tem optimization in the HEAT 4.0 project (see HOTCOOL no. 8, 2022). In the following we will start considering AI tools for individual buildings. Then we will consider the district heating networks, the plants, and conclude with remarks on district heating in re- lation to the energy system, the electricity/energy markets, and the society. The findings mentioned here are based on several district heating-related projects (CITIES, HEAT 4.0, FED, IDASC, ARV - please see the reference list).

Digital x-ray-based performance characterization Frequent energy meter data opens up for new inductive or data-driven tools. The tools act as a bit like a kind of x-ray vi- sion through the layers of the individual walls. Given this x-ray- based knowledge of the performance of the individual walls, the tool can provide evidence-based information about the performance of the separate buildings. This is useful, for in- stance, before deciding on a possible energy renovation. Similar AI tools and digital twin models can be used to obtain a better control of the indoor climate. This has been demon- strated, e.g., in the social housing Taastrupgaard in Høje-Taas- trup Municipality, where digital tools have been used to show that many radiators were misused. Sensors for the indoor CO2 levels, temperature, and humidity have also been installed in schools, e.g., in Hørsholm and Rudersdal, to monitor the indoor climate and obtain a better comfort and learning environment in the schools using the platform from Climify. Climify has also developed a FeedMe app, which can ensure individual and op- timized control of heating and ventilation of the classrooms, lowering the return temperature, minimizing mold risk, and obtaining energy savings. Forecasting Load forecasting obviously calls for data-driven tools. Lately, new methods for coherent forecasting of the heating load on all relevant time horizons from, say, 15 minutes to 96 hours ahead have proven to give considerable (15 - 30 pct) improve- ments in the accuracy of load forecasts at some of the largest DH operators in Denmark. These forecasting improvements lead to significant economic benefits in temperature control, production planning, and participation in the electricity mar- kets.

ods). Obviously, such data can be used to identify if the build- ing calls, e.g., for a renovation like replacing the windows.

Energy performance characterization of buildings Traditionally, energy performance characterization and labe- ling have mostly been based on deductive analysis, i.e., based on assumed theory for energy transfer and material proper- ties. Today the existence of frequent meter readings and, e.g., nearby meteorological observations data opens up for evi- dence-based inductive analysis, i.e., data-driven methods. The deductive approach used for buildings today Today the energy performance characterization and energy la- beling of buildings are based on rather simple calculations and a visit by an energy consultant. The cost of getting such a label is relatively high, around 700-1000 Euros. The methods used today are often criticized. The main problem is that two buildings, which in theory should be identical, might have a somewhat different energy performances in practice. This well-known performance gap between predicted and ac- tual building energy performance can be significant. Even after correcting for differences in user behavior and occupancy, the actual energy consumption can easily be 50-100 pct higher than the theoretical consumption. Generally, the technical sources for discrepancies between the theoretical performance and the measured performance can be broken into three baskets: The design and simulation phase (limitations, inaccuracies, and assumptions in the theory used to predict the performance); the construction and com- missioning phase (caused by the poor quality of workmanship and differences between assumed and actual materials, com- ponents and systems); and, the operation phase (poor-func- tioning of the systems and in particular the HVAC system).

Forecasting of PV and thermal solar energy production also calls for data-driven approaches for several reasons. By using

Simulation-Based vs Data-Driven Temperature Optimization Simulation-Based vs Data-Driven Temperature Optimazation

Simulation-based TO

Data-driven TO


Deductive (simulation/theoretical values)

Inductive (data-driven, self learning)

Optimal usage

• Simulation of new operational scenarios (where no data exists)

• Control of temperature and flow, reduction of heat loss, real time data

Temperature profile

• Temperature calculated using theoretical values for pipes, insulation, soil, etc.

• Temperature estimated using real life data and statistical/AI-based learning


Does NOT take into account: • Dirtiness, •

+ Take into account: • Dirtiness, •

Distribution net

Soil properties (temperature, humidity, ...)

Soil properties (temperature, humidity, …)



Wet or damaged insulation,

Wet or damaged insulation,

Deviations from design values / drawings

Deviations from design values / drawings



Constant parameters •

+ Self calibrating / automated learning •

Require recalibration, which can be difficult and time-consuming

Automatic recalibration for instance due to new costumers, heavy rainfall, damaged insulation, etc.

Production facilities

• New production facilities call for recalibration

• New production facilities call for recalibration

Figure 1: Differences between simulation-based and data-driven temperature optimization

Access to energy meter readings from individual households has proven to give further advantages. A simple sketch of the change of the setting is shown in Figure 2. Obviously, this calls for using advanced aggregation techniques to ensure that the aggregated temperature is representative, and to respect pri- vacy and GDPR. The use of meter data implies that it is rather easy to operate with zonal temperatures. This new solution for using meter data and the methods for zonal temperature con- trol leads to further savings and better options for integrating local heat pumps. Today electricity prices are high from time to time, so the con- trollers have a built-in balance between reduction in heat loss- es and the pumping costs. Finally, it is crucial to notice that the use of data and AI methods implies that the tools are auto-cal- ibrated continuously. This means that the system is much eas- ier to operate and maintain. Production and bidding optimization for DH systems Data-driven forecasting and temperature control methods are now also used in new tools developed at DTU for production

data-driven methods, the forecasting tool can automatically consider complex shading and the time-varying dirtiness of the panels. Some of the new forecasting methods are imple- mented in, e.g., HeatFor and SolarFor. Temperature optimization (TO) Historically, methods for temperature optimization have been based on simulations using theoretical models and detailed knowledge about the network. A prerequisite for using such approaches is that the model is carefully updated with infor- mation about the physics (pipes, ground temperature, the hu- midity of the soil, properties of the insulation of the pipes, etc.). First of all, this is a very time-consuming procedure, and sec- ondly, such methods lead to suboptimal descriptions of the dy- namical characteristics needed for control of the temperatures. Exactly like for the buildings mentioned above, data-driven methods can provide significant improvements in tempera- ture optimization, such as in zonal control of the network tem- perature. Again the AI technologies implemented, for instance, in HeatTO, give a sort of x-ray vision of the thermal properties of the pipes and their surroundings. The resulting data-driven digital twin models describe the time delay, heat losses, and dynamics. According to the experiences with HeatTO, heat loss is reduced by 10 to 20 pct (see, e.g., heatto/).

Figure 2: Use of meter data in temperature optimization (HeatTO).

For the future, weather-driven society district heating is already recognized to play a central role since these systems can pro- vide much of the needed flexibility at a low cost. Digitalization of district heating systems based on sensor data will further strengthen the position of district heating as a sustainable and low-cost energy supply technology capable of reducing car- bon emissions and contributing to climate change mitigation. In addition, we have proven that using data-driven tools has a huge economic potential. According to the so-called Damvad Report from 2019, the potential in Denmark alone is 240 to 790 mill DKK annually with state-of-the-art data-driven meth- ods for temperature optimization. On top of that, most of the methods for digitalization mentioned in this article will lead to considerable extra economic and operational benefits for dis- trict heating systems and their users. Reference to projects: IDASC: digitalized?fr=sM2FiMzQ4NjgwMg HEAT 4.0: CITIES: Flexible Energy Denmark: ARV:

optimization in DH systems. The tools can be used for different planning problems, such as operational planning under uncer- tainty, optimization of bids to the day-ahead electricity market, and long-term evaluations of DH system operations. The tools are able to take advantage of the uncertainty, for instance, in the production of thermal solar heat as well as forecasts of the electricity prices on markets with varying horizons. The general applicability and performance of the approach are evaluated based on real data from the three Danish DH systems of Brønderslev, Hillerød, and Middelfart with different characteristics. When considering bidding, the new tool reduc- es cost in all cases and can save up to 42.1%. Conclusion Development in sensor technology and the rapid develop- ment in AI and IoT have provided district heating operators with new opportunities. Using AI or data-driven models to pro- vide information from sensors, the operations in the building, at the plants, the network, and market participation can be optimized. The key is data-driven and auto-calibrated tools for the modern operator. Tools for coherent load forecasting are central. Knowing the future demand with reliable uncertainty intervals allows for setting the water temperature and flow optimally rather than operating with a large-than-necessary safety margin. Such state-of-the-art forecasts are also the prerequisite for smooth solutions for bidding on the electricity markets.

For further information please contact: Henrik Madsen,

HELLO, HOW CAN WE SUPPORT YOUR CITY? DBDH is the Go-To-Platform for district energy. We cooperate with all DH stake holders and support cities in their quest for a sustainable city transformation.

Use our strengths to help your city. We are the link to:  Achieving climate goals through fossil-free district energy  Strategic energy planning  Knowledge on district heating and cooling  A wide network of experts  Visiting green solutions in Denmark

We do not know everything about district heating, but we know who does :) Contact one of our team members. Our advice is free of charge.

Lars Hummelmose Contact for China and other Asian countries, North America, and the Middle East

Pia Zimmermann Contact for Eastern Europe, the Baltic States and CIS countries

Morten Jordt Duedahl Contact for Western Europe

Hanne Kortegaard Støchkel Sector integration and new heat sources


The background for Denmark's leading position in the world concerning the spread of district heating is that covering the heating needs of buildings by connecting to district heating has been part of Danish society for more than 100 years- indeed, for almost 120 years.

This article provides a quick historical overview of the development of district heating in Greater Copenhagen from the beginning of 1903 until today. Insight into the benchmarks for the further develop- ment toward a CO2-neutral district heating system in Copenhagen 2050 is shared in the article "District heat- ing in Greater Copenhagen - 2050."

By Lars Gullev, Senior Consultant, VEKS

100 years ago, daily waste was collected and transported by horse carriages to the city dump.


Starting point Once upon a time – more than 100 years ago -, the city council of Frederiksberg put both the environment and a future-orien- tated heat supply on the agenda. Frederiksberg is an independ- ent municipality situated in the western part of Copenhagen City. Heat production based on household waste incineration then became the starting signal for the development of district heating in the municipality. In the 19th century, Frederiksberg developed from being a village to a town with the nature of a big city. In 1857 – Fred- eriksberg became an independent municipality ranking as a market town. The city developed rapidly - industrial enterpris- es were built, and the factories attracted a workforce. The city grew bigger and bigger – the industry grew, and the popula- tion increased. A railway station was built, a fire service was established, schools and a library were built, and the city was provided with gas, running water, sewers, and electricity.

However, the busy activity had a natural – though problematic – "by-product": waste. Concurrently with the increase in popu- lation and the building of the outer area of Frederiksberg, the price of land increased, and it became even more expensive for the municipality to buy land for dumping grounds. At the same time, people were fully aware of the risk of, e.g., cholera by having dumping grounds placed too centrally. By the end of the 19th century, it was a cagey affair to walk around in the streets of Frederiksberg. Many of the free space areas were bursting with piled-up garbage with consequent odor problems. The municipality struggled with mountains of waste from the rapidly growing population. The lack of dumping grounds meant that the waste from the 75,000 inhabitants accumulated, and the fear arose that epidem- ics would break out. The municipality, therefore, had to come up with new thoughts – to build a waste incineration plant and utilize the surplus for district heating - a so-called Waste-to-Energy (WtE) plant.

Figure 1

The transmission network in Greater Copenhagen

district heating network. Herein lies a large part of the secret behind satisfaction with district heating in Denmark – the local commitment and ownership. The association Dansk Fjernvarme has organized 354 district heating companies that cover 99% of the district heating needs in Denmark. – the 58 companies are municipally owned and cover 50% of the district heating supply. Of the remain- der, 286 companies are consumer-owned, and the remaining ten are private and only cover a tiny part of the district heating market. The oil crises of 1973 and '79 – a wake-up call Until the beginning of 1973, there was no political interest in the district heating sector in Denmark. Still, with a shortage of imported oil - 92% of Denmark's energy consumption was based on imported oil - and rising oil prices as a consequence of the war between Israel and Egypt in 1973 did, it change. And the war between Iran and Iraq in 1979 – again with a shortage of imported oil and sharply rising oil prices – perma- nently changed the Danish energy scene. Heating Supply Act 1979 The Heating Supply Act in 1979, which was the first of its kind in the world, focused on the need for increased energy effi- ciency in Danish society. This meant, among other things, that where it made sense economically, electricity and heat had to be produced together by so-called combined heat and power production. This was the start of establishing the two district heating trans- mission companies - CTR and VEKS - to ensure the utilization of surplus heat from waste energy plants and cogeneration plants in the Copenhagen area. There were two transmission companies due to CTR having to use surplus heat from the waste-to-energy plant Amager Forbrænding and Amager CHP plant, respectively. On the other hand, VEKS had to use the sur-

In September 1903, the city of Frederiksberg received its first waste collection at the new waste incineration plant, and the plant was inaugurated. From December 1 of that same year, the district heating production was put into regular opera- tion. The heat produced by burning the waste was transported in the form of steam via a tunnel to the newly built Frederiksberg Hospital and an orphanage. With the new steam-based district heating supply, hospital standards were raised. Suddenly, mat- tresses and operating equipment could be disinfected, and in the large epidemic and tuberculosis department, it was essen- tial to have a sterile environment. In the following years up to the end of the 1940s, district heat- ing in the municipality of Copenhagen was quietly expanded to supply heat to public buildings - including public bathing fa- cilities. This development took place under the auspices of the company Københavns Belysningsvæsen, which later changed its name to Københavns Energi and today is called HOFOR. Organization of the district heating companies Until the end of the 1940s, all district heating companies had been municipally owned, but now the development of district heating in the Copenhagen area took off in earnest. In part, the increase in living standards had meant that more citizens could pay for installing water-borne heating systems in their homes - as a replacement for the stoves - which made the connection to district heating possible. In part, groups of citizens began to "join together" and establish district heating companies as con- sumer-owned, collectively owned companies. The driver for the latter development was the price difference between the expensive gas oil used in individual oil boilers and the cheaper fuel oil that could be used in large communal boilers. The price difference in oil could be used to finance in- vestments in boiler plants to produce district heating and the

plus heat partly from the waste energy plant ARGO in Roskilde and partly from the future Avedøre CHP plant.

• VEKS buys biomass-based district heating from the Avedøre CHP plant and from the waste-to-energy plants ARGO and Vestforbrændning. It also has its own biomass-based heat production from a CHP plant in Køge, a biogas engine in Solrød, and excess heat from the industrial company CP Kelco in Køge. VEKS delivers the heat to 19 local distribution companies in 12 municipalities. The development in the environmental declaration for district heating (kg CO2/MWh) delivered to an end-customer in VEKS' supply area shows a reduction in CO2 emissions of more than 76% in 2020 - the reduction is equivalent for an end-custom- er at HOFOR and CTR. So, in terms of environmental impact alone, the expansion of district heating in Greater Copenhagen has been a success. Varmelast Since January 7, 2008, Varmelast has handled the total load dispatching of the Copenhagen metropolitan area. In brief, load dispatching is an economic optimization of heat produc- tion hourly in proportion to the production costs and prices on the power market. Varmelast is a cooperation between HOFOR Varme, CTR, and VEKS. Before the power market liberalization, there were two large producers of district heating in the Copenhagen metropolitan area. The production companies had a joint load dispatching station. Back then, no confidential data were involved as they did not need to consider the liberalized power market. With the liberalization of the power market in the year 2000, the producers merged so that there was only one big produc- er of district heating in the Copenhagen metropolitan area, which handled the load dispatching of all the plants.

For outsiders, it may be surprising that two district heating transmission companies were established. It was a political de- cision that ensured the desired democratic influence among the companies' stakeholder municipalities. In the 1980s, Vestforbrænding had significantly greater heat production from burning waste than the company could sell to its district heating customers. Therefore, a pipe connection was established between Vestforbrænding and VEKS, so VEKS' supply area could use the excess heat instead of cooling it off in cooling towers. Subsequently, a line connection has also been established between Vestforbrænding and CTR, so that excess heat from Vestforbrænding can be delivered to CTR and/or VEKS depending on where the heat demand is most signifi- cant. What does the district heating system in Greater Co- penhagen look like today? The system today consists of four more or less linked systems: • Vestforbrænding, which supplies waste-based district heat- ing to five municipalities, is connected to the district heat- ing transmission networks of CTR and VEKS for excess heat supply. • HOFOR Varme covers a subset of its customers' heating needs by directly purchasing district heating from HOFOR Production - and the rest from CTR. • CTR, which buys biomass-based district heating from the CHP plants Amager and Avedøre - as well as the waste-to-en- ergy plants ARC and Vestforbrænding - sells the heat to five municipalities in the eastern part of Copenhagen.

For further information please contact: Lars Gullev,

Summary Today, the district heating system in Greater Copenhagen is characterized by heat production from large central produc- tion plants – three conventional CHP plants based on sustain- able biomass, three waste-to-energy plants, and peak and re- serve load units based on wood pellets, natural gas, and gas oil. Varmelast ensures that the total electricity and heat produc- tion in Greater Copenhagen area is optimized on an hourly basis, 24/7/365, so that the lowest total production costs are ensured for the benefit of the district heating customers. So, a concept – developed more than 100 years ago – remains viable in a world where competing heat producers deliver dis- trict heating into the same grid – competing with each other on costs.

In 2006, Amager CHP plant was sold off to the Swedish Vatten- fall. Out of consideration for the competitive situation of the power market between Ørsted (formerly named DONG) and Vattenfall, the producers could no longer perform the load dispatching for the heating and power production in the Co- penhagen metropolitan area on their own. Consequently, it was necessary to find a new solution to ensure the economic optimization of the production across the plants with different owners.

Facts about CTR • Founded in 1984 and owned by five municipalities in the eastern part of the Copenhagen area – Copenha- gen, Frederiksberg, Gentofte, Gladsaxe, and Tårnby. • Supplies local, municipally owned district heating companies in the five municipalities with heat – in- cluding HOFOR. The supplied heat corresponds to the consumption of 250,000 families. The heat is pur- chased primarily from the Amager CHP plant, owned by HOFOR Energiprocuktion and ARC's waste-to-en- ergy plant. • • VEKS owns Køge CHP plant, which produces electric- ity for the grid, steam for Junckers Industrier A/S, and sells (internally) district heating to VEKS Transmis- sion. It also owns a gas engine in Solrød, which pro- duces electricity for the grid and district heating for VEKS Transmission, based on biogas delivered from Solrød Biogas A/S. Køge District Heating Company handles the distribution of district heating to private consumers, business customers, and institutions in the city of Køge - Tranegilde District heating Com- pany handles the distribution of district heating to customers in the Tranegilde business area in the mu- nicipalities of Ishøj and Greve. For both Køge District Heating and Tranegilde District Heating, the heat is purchased internally from VEKS Transmission. • Facts about VEKS • Founded in 1984 and owned by 12 municipalities in the western part of Greater Copenhagen and along Køge Bay. • VEKS Transmission supplies 19 local district heating companies with heat in Vestegnen. The supplied heat corresponds to the consumption of 170,000 families. The heat is purchased primarily from Avedøre CHP plant, owned by Ørsted, and from waste-to-energy plants owned by ARGO.

For further information please contact: Lars Gullev,

Facts about HOFOR • Founded in 1857 for the production and distribution of town gas. • Today, the multi-supply company with activities within the drinking water, wastewater, production and distribution of district heating and cooling, dis- tribution of town gas, and production of district heat- ing and electricity. • Owns Amager CHP plant, and from here, HOFOR Varme directly buys some of the heat the company must deliver to its end customers. CTR buys the re- maining part. • Has 1,000,000 water customers, 700,000 wastewater customers, 500,000 heating customers, 300,000 town gas customers, and 39 district cooling customers. • Facts about Vestforbrænding • Founded in 1970 and owned by 19 municipalities in Zealand, Denmark – supplies district heating to Her- lev, Ballerup, Lyngby-Taarbæk, Furesø, and Gladsaxe municipalities – as well as surplus heat to CTR and VEKS. • Denmark's largest waste-to-energy company and Northern Europe's largest waste-based district heat- ing producer handles waste for 900,000 citizens and 60,000 companies. • In 2021, Vestforbrænding converted almost 500,000 tonnes of waste into heat (1.26 million MWh) and electricity (199,000 MWh). • www.vestforbræ

COOPERATIVE DISTRICT HEATING IN THE MAKING Inspirations from Denmark and first achievements in the Netherlands

By Rie Christiansen Krabsen, Marketing Manager, EBO Consult and Gerwin Verschuur, Program Manager Buurtwarmte in Cooperation Energie Samen

In the Netherlands, district heating has a market share of only 5% because Dutch citizens and industries are heavily depend- ent on natural gas, which is abundantly available in the Dutch underground. The extraction of natural gas has led to continu- ous high CO2 emissions and severe problems with earthquakes, forcing the Dutch government to stop the extraction in 2030.

lands must become an importer of natural gas. The war in Ukraine has worsened the situation. Like in many other Eu- ropean countries, citizens and industries suffer from extreme price levels for natural gas, and the urgency to find sustainable solutions for heating is now broadly felt. Therefore, Dutch so- ciety is searching for more knowledge about district heating, specifically cooperative district heating, where consumers own the district heating grid. Today, only one district heating co-

From a position as a net exporter of natural gas, the Nether-

in Denmark. In the Netherlands, district heating cooperatives are only partially accepted and need to be manifested in pol- icy or implemented in the heat law. In addition, it is possible to make a profit by delivering heat. The Dutch tariff regula- tion is founded on the NMDA principle, which means that the prices should not surpass the costs a natural gas user would have for the same amount of heat – in other words, "a cap." Every year, at the end of December, the ACM (national regu- latory authority) publishes the maximum prices that district heating companies can ask their customers for the heat and cold supply. This is just one of the many examples in the study where there are differences between the conditions for devel- oping cooperative district heating in Denmark and the Neth- erlands. From the Dutch perspective, the analysis works as an inspiration on how to expand cooperative district heating in the Netherlands. From the Danish perspective, the study can be read in the start-up phase of expanding and exporting district heating in the Netherlands because it gives an over- all picture of which differences and similarities between the two countries one can be aware of when working with district heating. First steps toward a Dutch district heating support organization Another aim of the project was to develop a Dutch district heating support structure similar to EBO Consult A/S that ena- bles cooperative initiatives to develop and operate district heat- ing projects. On the 22nd of September 2022, we arranged a meeting with ten cooperatives from across the Netherlands. Every cooperative signed a declaration to develop the support organization jointly, and the first steps toward its development and implementation are already moving ahead. On the following day, the 23rd of September 2022, we held a Dutch conference about how municipalities, public organ- izations, and cooperatives can collaborate to develop pub- lic-civil district heating enterprises. At the conference, there were representatives from Dutch municipalities, Klimaatver- bond, ministries of the Dutch state, and several district heat- ing cooperatives. Representatives from the Danish Embassy in Haag, EBO Consult A/S, and Hvidovre municipality joined the conference. The conference's outcome was a list of build- ing blocks to foster the development of cooperative district heating in the Netherlands. As a direct spin-off from the con-

operative exists, but around 80 initiatives are in the process of establishing a district heating cooperative. In Denmark, there exist about 323 district heating cooperatives. A grant from the Danish Energy Agency For many years EBO Consult A/S has held a lot of presentations about district heating at international seminars and confer- ences. Every time the focus has been on cooperative district heating– how consumers can manage and operate district heating and how the Danish regulations of district heating en- able cooperatives to exist under a not-for-profit regime. After the presentations, there have been numerous requests and questions about district heating, which has often resulted in sparring processes about implementing district heating in various countries. One of the ongoing collaborations has been with Cooperatie Energie Samen, a Dutch membership organi- zation that wishes to support the development of cooperative district heating. In 2020, The Cooperatie Energie Samen and EBO Consult A/S developed an application for the Danish "En- ergy Export Initiatives Grants program." At the end of 2020, we got the happy news that we received a grant. EBO Consult A/S has been sharing know-how with Cooperatie Energie Samen since then. Together, we have written a comparative study of the Danish and Dutch district heating markets focusing on cooperatives. We have taken significant steps to develop the beginning structures of a cooperative support organization that helps local district heating initiatives to grow and be im- plemented. Danish and Dutch comparative study The study investigates cooperative district heating in Den- mark and the Netherlands, where we focus on political, legal, financial, and organizational themes. But also about the roles of municipalities in the heat planning process, the available district heating technologies, the district heating marketing, the tendering process, the construction process of district heating, and the maintenance of district heating. We discov- ered several remarkable differences in cooperative district heating in the two countries during the writing process. In Denmark, district heating cooperatives have existed for many years. They are legally positioned as any other district heating company and are tariff regulated by the non-profit principle, where costs and revenues balance. The principle follows that it is impossible to profit from producing and supplying heat

ference in Groningen, the Dutch commission for the climate agreement invited Energie Samen and the Danish Embassy to organize a workshop of 75 minutes on the day of the Cli- mate Agreement in Utrecht on the 3rd of November 2022. This workshop centered around the cooperative model for the expansion of district heating in the Netherlands. Another spin-off from the conference in Groningen was a joint effort of municipalities and cooperatives to get the definition of en- ergy communities, as defined in European law, in the revised Dutch Heat Act that is under preparation. This definition is of great importance to get, similar to the Danish district heating

model, the non-profit principle established in the law for co- operative district heating.

In other words, Dutch cooperative district heating is in the making with inspiration from Denmark.

For further information please contact: Rie Christiansen Krabsen:

Denmark's background as a world leader concerning the expansion of district heating is that covering the heating needs of buildings by connecting to district heating has been part of Danish society for more than 100 years- indeed, for almost 120 years.

This article provides insight into the benchmarks for further development towards a CO2-neutral district heating system in Copenhagen by 2050. District heat- ing in Greater Copenhagen - history and status 2023" a historical overview of the development of district heating in Greater Copenhagen from the beginning of 1903 until today is shared.

By Lars Gullev, Senior Consultant, VEKS

Heat accumulators at Avedøre CHP Plant - 2*22,000 m3


What does the district heating system in Greater Copenhagen look like today? The capital's district heating system today covers a heat de- mand of 38 PJ (2020 figures) – of which heat production from waste energy plants covers approx. 32%. The heat demand of 38 PJ corresponds to about 25% of the total heating require- ment in Denmark. The heat production is dominated by large central cogenera- tion plants on waste and sustainable biomass, which account for around 2,150 MW of base load capacity. In addition, approx. 50 MW heat pumps were established recently, and surplus heat is utilized from the industry and sewage water systems. In addition to this, there is a peak and reserve load capacity of approx. 2,300 MW and two heat accumulators (2*22,000 m3 + 25,000 m3) of a total of 2,700 MWh. Peak and reserve loads are mainly based on natural gas and oil. However, in recent years, several electric boilers have been built for peak and reserve load heat production.

Briefly described - this is a district heating system based on large central production units - yet the future looks different.

Four years ago, the district heating companies HOFOR, CTR, Vestforbrænding, and VEKS decided to prepare scenarios - with associated analyses- to develop the district heating sy­ stem in Greater Copenhagen by 2050. Starting the analysis, it soon became clear that the future district heating system in the metropolitan area would be changed from being based on central production units to a system with more decentralized production units. It would also be characterized by a larger system integration with the electricity system than we know today. "Future District Heating Supply in the Greater Copen- hagen Area 2050". To ensure a shared vision for the future of DH in Copenhagen, the four district heating companies, HOFOR, CTR, Vestfor- brænding, and VEKS have for the fourth time completed a dy-

Figure 1 The transmission network in Greater Copenhagen

is an immature technology that must first be developed and tested in the Danish context. At the same time, heat pumps that use seawater will be challenged in efficiency during win- ter when the water temperature reaches 1-5 °C. Sewage water as a heat source and air-to-water heat pumps, which use outdoor air as a heat source, have excellent techni- cal potential. Still, for air-heat pumps, there are challenges in providing space for the physically large plants where the out- door equipment creates considerable noise.

namic development project "Heat Plan Greater Copenhagen." This phase is more ambitious is more ambitious than previous phases and it was given the name "Future District Heating in the Greater Copenhagen Area 2050." The primary purpose of the shared vision was: To build a unified vision-based frame narrative by 2050, supporting a future competitive and green district heat- ing supply - including searching for strategic challeng- es which could prevent the fulfillment of the vision and finding ways to deal with them. To develop shared ideas for options and ways of action by 2025 and 2030 concerning fulfilling the 2050 vision and frame story, thus ensuring a competitive and green future district heating supply To develop a common base that - across the four com- panies - should support the decisions to be faced in the coming years To ensure future decisions with stakeholders (owners, municipalities, customers, etc.) are made on a common base The analyzes of future technologies, therefore, included large heat pumps, low-temperature district heating, geothermal, CCSU (CO2 catch and storage), PTX, and heat storage. Large heat pumps The potential for large heat pumps in the district heating sy­ stem is considerable. It includes heat sources such as seawater, drinking water, wastewater, groundwater, air, industrial surplus heat, and geothermal. Based on the heat sources, the theoretical potential for large heat pumps in the metropolitan region's heat supply was esti- mated at 2,100 MW by 2050. However, when considering the available heat base in the individual distribution networks in the total supply area, the potential was closer to 1,200 MW.

HOFOR/CTR/VEKS has tested a 5 MW sea/sewage water heat pump established in Copenhagen Harbor for several years.

Surplus heat from the industry Industrial surplus heat, where the heat source usually has a higher temperature, such as 10-25 °C degrees, is often com- petitive, but the potential is relatively limited according to the analyses. However, there is great potential for using sur- plus heat from data centers, but it is unclear how many data centers will be established. With CP Kelco in Køge, VEKS has created a project to use sur- plus industrial heat by combining heat pumps and heat ex- changers - total utilized power amounts to 7 MW. Køge Power Plant, owned by VEKS, has established a 1 MW heat pump for using surplus heat from turbine oil cooling and a 13 MW heat pump to utilize surplus heat from flue gas con- densation. Low-temperature district heating Heat pumps are most efficient when they must deliver heat at relatively low temperatures, which is why it is an economic ad- vantage to place them as close to the distribution network as possible. As required in the transmission network, heat pumps that can deliver heat at higher temperatures are still relatively expensive and untested in Denmark.

Seawater would have great potential as a heat source, but it

Avedøre CHP Plant, unit 2

If the large heat pumps are to be used economically and technically in the best way, they must be placed close to the district heating network and a heat source (e.g., excess heat, groundwater, seawater, or sewage water). This requires reserved space in the metropolitan area and cooperation be- tween energy planning and physical planning in the munic- ipalities. The analysis has therefore investigated whether switching to low-temperature operation in both the transmission and distribution networks is possible. Today, flow temperature in winter is typically up to 115 °C in the transmission network and a maximum of 90 °C in the distribution network. In low-temperature operation, flow temperature is lowered to 90 °C in the transmission network and to 70 °C in the distri- bution network - in connection with new construction, flow temperature is reduced further. Return temperature must follow down. The analysis shows that it is technically possible to convert to a low-temperature level and to convert the transmission and distribution grids for relatively low costs. However, this requires a lot of additional technical and hydraulic analyzes as well as intensive cooperation between the district heating companies. Lowering the temperature is also estimated to provide signifi- cant savings in heat production costs - around 8% or DKK 250 million per year (€ 33 million/year). At the same time, lower Tf gives a smaller net loss; and the network's transport capacity is reduced by up to 25%. Therefore, it will be even more im- portant to see a temperature drop in connection with future decentralized production capacity placement. Geothermal Geothermal heat is a stable and suitable heat source for dist­ rict heating, and research indicates a sizeable geothermal po- tential in the underground area of Greater Copenhagen. The potential is limited by the quantities consumed in the distribu-

tion networks, which amounts to 6-700 MW. Since the plants utilize geothermal heat with heat pumps, they will primarily be able to supply heat to the distribution grid, as it will be too expensive to provide heat at the high temperature required in the transmission grid. In autumn 2022, HOFOR/CTR/VEKS started contract negoti- ations with the company Innargi regarding establishing geo- thermal energy in the capital area from around 2030. Capture and storage of CO2 In the metropolitan area, there are several large point sources for CO2 capture from the combustion of biomass and waste at large cogeneration plants. If CO2 from biomass - or the bio- genic part of the waste - is stored underground, this results in negative CO2 emissions. The capture process requires a lot of energy, a large part of which ends up as surplus heat that can be used in the district heating system. Together with five other companies, HOFOR/CTR/Vestfor- brænding/VEKS work together in the cluster collaboration C4 - Carbon Capture Cluster Copenhagen - with a vision to reduce CO2 emissions in the capital city area by 3 million tons annually through CO2 capture. Here, the heating companies' interest is to utilize the surplus heat that is a consequence of CO2 capture - and VEKS has entered the first LOI with a heat producer in this regard. CCS (Carbon Capture and Storage) is an investment-heavy technology, and the costs of establishing and operating CCS are uncertain. For CCS to become economically feasible, the process - either in the form of subsidies or by capturing CO2 from the biogenic part of waste and biomass - must be priced as "negative emission." Transport of CO2 to underground storage can be done by truck, ship, or in pipes, and the actual storage can be done offshore or on land-based coastal storage. In connection with the transport, there will be activities that generate surplus

PTES - Pit Thermal Energy Storage - Høje Taastrup under construction.

Copenhagen Hill Waste-to-energy Plant

heat, which may be interesting for the district heating com- panies to utilize.

In the spring of 2022, the "Cluster collaboration on CO2 trans- port and infrastructure in Greater Copenhagen" was estab- lished to initiate work on and make recommendations to the Parliament about what is needed to develop CO2 infrastructure in the capital area. In addition to HOFOR, CTR, Vestforbrænd- ing, and VEKS were 14 companies (behind the cluster coopera- tion), each of which has an interest in Denmark and the metro- politan area achieving the climate goals as cheaply as possible. In January 2023, the Cluster Collaboration submitted its report outlining the most important recommendations for CO2-trans- portation. Power-to-X As an alternative/supplement to storing CO2, this can be used in a Power-to-X (PtX) process to produce green fuels for heavy transport - trucks and ships - as well as aircraft. This process develops surplus heat, but the production of the excess heat can be highly fluctuating, which creates a need for huge heat stores and/or flexible backup heat capacity from, for example, biomass cogeneration/boilers with CO2 capture. The choice of PtX technology is decisive for the temperature of the surplus heat and whether or not the excess heat sup- ply is stable or fluctuating. The report also concludes that the district heating system in the capital can both deliver CO2 for collection and utilization and absorb and utilize up to 750 MW of surplus heat from PtX processes, provided that multi-string heat production is maintained. Heat storage A production mix based on multiple heat sources, as described above, necessitates the establishment of many more large heat storage facilities in the future - either as pit heat storage facilities or in pressurized steel tanks. With the future produc- tion mix, it is estimated that it will be profitable to increase the

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