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

All over the world, politicians try to solve the big question: How to decarbonize the world, their country, region, or city. Some answers have more political than real value. For reducing CO2 emissions on a scale significant to the climate, it is not enough to encourage people to eat vegetarian food on Wednesdays or to dry their laundry outdoors. CO2 reductions, at scale, are achieved by integrating the entire energy system. Here the district heating grid is the backbone. In this issue, you can read about solutions reducing CO2 emissions - all linked to the district heating network utilizing excess electricity from wind turbines and solar cells, surplus heat from data-centers, eFuel production, and heat pumps absorbing energy from the ocean.

NO.2 / 2020



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FLY GREEN! By Henrik Søndergaard

LARGE SCALE HEAT PUMPS By Lars Hansen, Morten Stobbe, Sannah Grüner







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Decarbonizing is a big issue

All over the world, politicians try to solve the big question: How to decarbonize the world, their country, region, or city. Some answers have more political than real value. For reducing CO 2 emissions on a scale significant to the climate, it is not enough to encourage people to eat vegetarian food on Wednesdays or to dry their laundry outdoors.

CO 2 reductions, at scale, are achieved by integrating the entire energy system. Here the district heating grid is the backbone.

In this issue, you can read about solutions reducing CO 2 emissions - all linked to the district heating network utilizing excess electricity fromwind turbines and solar cells, surplus heat from data-centers, eFuel production, and heat pumps absorbing energy from the ocean. When so many opportunities, how do you find the right solution for your area? DBDH publishes Hot Cool, but the main business is helping cities or regions in their green transition. We help to find specific answers for a sustainable district heating solution or integrating green technology into an existing district heating system. Any city, or utility in the world, can call DBDH and get help to find a green district heating solution suitable for their city. Very often, a similar system is in operation in Denmark, being the most advanced district heating country in the world. DBDH then organizes visits to Danish reference utilities or expert delegations from Denmark to the city.

DBDH is a non-profit organization - so guiding by DBDH is free of charge.

Just give us a call.

We’ll love to help you decarbonize your city!

Best regards

Lars Hummelmose Managing Director, DBDH +45 2990 0080

Airplanes, trucks, and cargo ships that do not emit CO 2 . Does that sound like future music to your ears? The Jumbo jet Denmark is in the air and is on its way to the green future where DISTRICT HEATING can tie it all together. District heating can ensure that the sustainable future becomes financially sustainable too! Here you see a little of the HUGE plan that will make Denmark, a pioneer in green energy conversion, become CO 2 neutral in 2050 – with district heating as the backbone of it all!

We start in the theory classroom: The energy is constant. New energy cannot enter the universe, and energy cannot disappear. Energy cannot be used. But energy can change from one form to another. Chemical energy can e.g. change to motion energy and heat (as it does in a combustion engine car). Or when waste burns, becoming heat, producing steam, that drives a turbine, running a generator, making electricity, and so on. We have become adept at directing the transformation from one form of energy to another. To convert energy into the form of energy we need to meet our goals. But every time the energy changes its form, we say, there is a loss of energy. Of course, that is not true. But we perceive it this way, e.g. when the car uses gasoline and most of the energy turns into heat we can't use for anything.

The principle of green conversion of aircraft, trucks, and cargo ships:

1. POWER FROM WIND TURBINES TO PRODUCE HYDROGEN - Conversion from electrical energy to hydrogen happens via electrolysis - and a part of the converted energy turns into heat energy. Either, wasted energy, or energy used for DH. - Then the hydrogen is compressed to 700 bar to become liquid. Electricity is required here too, and again, much of the electrical energy becomes heat - either wasted or used for DH. 2. CO 2 CAPTURE - Carbon capture technology is to wash the smoke to remove the CO 2 , before leaving the chimney - from e.g. a waste incineration plant or biomass-fired plant. The process requires electricity and heat energy - obtained by burning more waste. Again, the excess heat is either wasted energy or energy for DH. 3. HYDROGEN AND CO 2 TURN INTO LIQUID FUEL - By mixing hydrogen (produced by wind turbines) and CO 2 (captured from, e.g., waste incineration), environmentally friendly liquid fuel for ships, trucks, or aircraft, can be produced. CO 2 and hydrogen are the basics ingredients in the hydrocarbons we currently are pumping up from the underground as oil and gas. To produce liquid fuel, such as eFuel, an energy conversion developing heat energy – is either wasted or utilized for DH.

Here is where the district heating comes into the picture. District heating is brilliant when large energy transformations happen. The largest transformations today are combustion - with CO 2 emissions as a negative side benefit. The district heating (DH) has so far reduced the energy waste from e.g. electricity generation by using surplus heat for another purpose: heating homes, institutions, offices, and everything else. But right now, new winds are blowing over Denmark to reduce CO 2 emissions. Tailwinds for wind turbines and solar cells, and headwinds for the combustion, from which district heating has been so good at utilizing the excess heat. But with the new winds blowing, new opportunities arise too, when surplus heat from data centers, today emitting as much CO 2 as air transport, is to be utilized. Or when the wind energy transformed from electricity to liquid sustainable fuel to be used by airplanes, trucks, and cargo ships! Again, DH becomes the key to utilizing the heat energy from the energy transformation otherwise wasted.

Energy is money. Wasted energy is money wasted. With the district heating, the energy waste in the inefficient energy conversion processes can reduce. District heating can make sustainable energy economically sustainable!

Figure: – post edited by DBDH

This far so good – enough about the theory. Here are a few high- profile examples of green transition planning, being launched in Denmark, and where sectoral integrating and district heating are to ensure it all becomes cheaper and greener.

Giant plant in Copenhagen to produce 250,000 tons of eFuel

Some of the largest Danish energy and transport companies are now joining forces to develop a plant to produce sustainable fuels, based on wind power.

1. The first stage is a 10 MW electrolysis plant, to produce hydrogen for buses and trucks, in 2023 already.

3. The final stage is to be ready in 2030 and exploit the full potential of the new offshore wind farm. The electrolysis capa- city increases to 1.3 GW and enough captured CO 2 to produce 250,000 tons of fuel annually. This can replace 30% of the fossil fuels used at Copenhagen Airport. Full completed, the plant will replace 250,000 tons of fossil fuels for road, sea, and air transport, saving the environment for 850,000 tons of CO 2 annually.

2. The second stage, ready by 2027, is a 250 MW plant, expected to be powered by a new wind farm offshore Bornholm in the Baltic Sea. Hydrogen will be produced at the plant, combining CO 2 , captured from point sources in Copenhagen, e.g., from the ARC waste incinerator you can read about below. The aim is to produce methanol for maritime transport and jet fuel, so-called e-kerosene.

Denmark kills two climate birds with one stone

Population growth is exploding, cities are turning into metropoles, and waste in ever-increasing quantities is being dumped in a landfill to harm the local environment and global warming. Estimated the amount of waste worldwide will increase from 1.3 billion tons per year discarded in 2012 to 2.2 billion tons in 2025, but that figure may prove much higher. The vast majority will end up in a landfill. But not in Denmark. Talking about waste, Denmark is - with good reason - regarded as a small light in the dark, in an ocean of garbage. Particularly, concerning sorting the waste and utilizing the energy resource, in the combustion of the non- recyclable part, Denmark stands out to the rest of the world. Through waste incineration, Denmark has killed two climate birds with one stone. Denmark has taken out landfills from the equation and can now, with new technology, capture CO 2 from waste incineration plants, and use it as a resource for producing sustainable fuel.

Waste incineration emits a large amount of CO 2 . And from the political debate, one could very well get the impression waste incineration is the greatest environmental sins of all. But that picture is misleading. At a modern waste cogeneration plant, the energy in the non- recyclable waste is utilized while protecting the environment. Spreading the modern incineration method globally, hence waste not thrown in a landfill, will represent a global environ- mental and climate quantum leap. One of the world's major environmental culprits is waste in landfills. Waste landfill leads to methane emissions, a green- house gas 23 times more powerful than CO 2 . In 15 of the EU's 28 member states, more than 50% of the waste is landfilled. And the picture only gets worse in a global perspective.

Peter Blinksbjerg, chemical engineer and quality manager, Amager Ressource Center

Illustration: BIG

Carbon Capture at a waste incineration plant in Copenhagen

ARC is currently actively working on constructing a carbon capture plant within the next five years, cleansing the smoke from at least 160,000 tons of CO 2 .

Amager Resource Center (ARC), the owner of CopenHill (the cover image), burns the non-recyclable waste to produce electricity and heat for the capital region. The smoke is cleansed from more than 99% of the harmful particles, so the smoke is mostly water vapor - and a lot of CO 2 . The ARC emits 480,000 tons of CO 2 annually, of which 160,000 tons are so-called fossil CO 2 , resulting from the burning of plastic. In collaboration with the five owner-municipalities, ARC has investigated the possibilities to capture CO 2 and recycling it. The conclusion is that it is possible - both technologically and economically. The energy to operate the carbon capture plant comes from CopenHill's production, and the CO 2 can be sold - e.g., to the upcoming eFuel giant plant in Copenhagen (see above).

The final decision to build a carbon capture plant is up to the politicians in the ARC's owner municipalities.

For further information please contact: Henrik Søndergaard, Editor at Hot Cool,

Source material: Ørsted Ingeniøren Ingeniøren Siemens Audi


Although there are several tools for project feasibility studies, few software programs provide data and scientific calculation methods to perform strategic energy planning at a city or regional scale. That is why a group of research institutes and cities have developed the Hotmaps toolbox in the framework of a European project. City planners, consultancies and utilities can nowaccess data and calculationmodules for the entire European Union. The application of the toolbox in seven pilot areas has already brought some results and advanced their transition towards a greener future.

By Sara Giovannini, Policy and Communication Officer at Energy Cities; Lukas Kranzl, Senior Scientist at TU Wien; Marcus Hummel, Managing Director at e-think – energy research

An urgent need to support strategic planning of cities According to the European Commission, 1) “Becoming the world’s first climate-neutral continent by 2050 is the greatest challenge and opportunity of our times”. The European Union, but also its national and local governments are setting up ambitious plans to reach this goal. However, if we want to succeed, we should look at the heating and cooling (H&C) sector more carefully. Heating and cooling accounts for the largest share of energy consumption in cities (where 75 % of the EU population live): new technical, regulatory and governance frameworks are necessary to transition to a more sustainable and green system.

In most European cities and regions, there is a need to better identify, analyze and map resources and solutions to decrease energy demand on one hand and to meet the remaining demand with green, efficient, and cost-effective energy sources on the other hand. Thanks to strategic energy planning, including H&C, we can promote the transition to a more flexible integrated energy system with a focus on energy efficiency and renewable energy. However, knowledge, access to data, and resources for cities to perform this analysis are often lacking.

Hotmaps dataset is good, but using local data is always better

A toolbox and a large data set for Europe is now available for free for city planners The Hotmaps project addresses this challenge. Leading research institutions in Europe 2) developed a GIS-based website that allows you to have in just 5 minutes an estimate of H&C demand in your region and the potential of local renewable energy to cover this demand. By performing more detailed analyses, the tool supports the development of fully- fledged heating and cooling strategies. The Hotmaps software is • Fast: it provides a quick indication about which direction to go, to kick-start detailed technical planning. • Free and open-source: it is available online, with no fees. You don’t need to install additional tools. • Easy to use: no need to be a GIS expert, the software combines web-based visualization of GIS data with a flexible selection tool. Data are visualized directly on the website. • Adaptable: You can retrieve indicators at various geographical and administrative levels. Moreover, you can upload your data to your account and use it to elaborate comprehensive heating and cooling strategies for your area of interest.

Hotmaps especially provides open GIS data on the distribution of heat demand (HD) in buildings, based on gross floor area (GFA) data. Researchers broke down energy demand data from the national level to the local level using several other (open) data sets. The data collected with a top-down approach was compared with other sources for 20 selected areas across Europe. The average difference of all compared values was 12% (median 8%), with a standard deviation of 10%. A comparison of the developed maps with maps based on municipal building stock datasets (bottom-up approach) for three cities shows that, for these locations, the overall tendency of the distribution of gross floor areas and heat density is similar in both approaches. In figure 2, you can see the difference between bottom-up and top-down dataset. The blue dots indicate that the Hotmaps’ top-down data assign a lower share of energy or gross floor area to a specific hectare cell compared to the bottom-up data (and vice versa for the red dots). Therefore, the developed datasets seem to systematically overestimate the GFA and HD in low-density areas and underestimate the GFA and HD in high-density areas.

Figure 1 a screenshot from the website.

Figure 2 : Difference between the top-down and bottom-up values for each hectare element in three cities: (a) gross floor area (GFA) of all buildings (including industrial and non-energy relevant buildings) in the bottom-up data vs. heated area (HA) in the top-down data (left column), (b) HA in the bottom-up data vs. HA in the top-down data (middle column), and (c) heat demand in the bottom-up and the top-down data (right column). (Müller et al., 2019) Therefore, we believe that the Hotmaps dataset allows performing the first analysis for strategic heat planning, including the identification of areas that might be suitable for district heating. For the detailed planning of supply infrastructure, however, users can upload their own data in the toolbox to get results

Hotmaps provides a large array of data sets with detailed resolution: from NUTS0 data down to LAU2 and even Hectare- level. Default data is available for the entire EU27 area, UK, and Switzerland, intending to support local, regional, and national H&C planning. 3) Hotmaps open-source data sets provide information on: • Building stock; • Space heating, cooling, and domestic hot water demand; • Climate context; • Industrial processes; • Heating and cooling supply; • Renewable energy sources data collection and potential review; • Hourly load profiles.

Quantitative results are key to prioritize long-term scenarios

Strategic heating planning is the unavoidable step towards decarbonization Cities are not the only potential user of Hotmaps. The tool can support consultancy companies advising local authorities in the development of their sustainable energy and climate action plans, and utilities willing to identify new potential geographical areas to be supplied by district heating. The elaboration of spatially differentiated strategic plans for different districts of a city will avoid uncoordinated projects, harmonizing energy, and urban planning. The ultimate goal is to decarbonize the building stock, which would be beneficial for the entire heating and cooling sector and the economies of cities. Utilities and consultancy companies have thus interest in collaborating with cities to build shared local visions. The tool can also be used to support strategic macro-planning processes on a national level, such as the update of the comprehensive assessment of efficiency in H&C. According to article 14 of the Energy Efficiency Directive, the EU Member States have to perform this exercise by the end of 2020. Several governments have already expressed their interest in using Hotmaps. “The Hotmaps toolbox has been useful to identify and verify additional resources in our area, not just for heating/cooling networks, but other sources of locally generated energy.” Jeremy Draper, Senior Practitioner Milton Keynes

The Hotmaps toolbox was developed together with cities, to make it useful for local/regional/national authorities, and urban planners. Seven European pilot areas have been successfully testing it, to develop their heating or cooling strategies: Aalborg (Denmark), Bistrita (Romania), Frankfurt (Germany), Geneva (Switzerland), Kerry County (Ireland), Milton Keynes (UK) and San Sebastián (Spain). These strategies have identified promising scenarios for a decarbonized H&C sector in 2050 with a mix of building renovation, district heating, and decentralized renewable systems. They resulted from qualitative and quantitative analyses as well as discussions with stakeholders and revealed interesting opportunities on the way forward. Thanks to the Hotmaps toolbox, cities could identify the cheapest supply areas for different types of district heating grids systems. For example, it turned out that investing in a district heating grid connected to a waste incineration plant together with using excess heat in the wastewater treatment plant could be an economically interesting option for the City of Bistrita, and should be further explored. In Geneva, there are great opportunities for using the ambient heat of lake water in a low-temperature district heating grid. For Frankfurt, the exploitation of heat sources using different types of heat pumps feeding into district heating grids will be one of the pillars of a decarbonized heating system. Industrial excess heat, excess heat from data centers, river water, and ground heat will play a key role in this context. However, due to the high heat density in the city and the limitations for renewable energy and excess heat sources to provide peak power, a strong focus will also lie in reducing energy demand. A reduction of the space and water heating demand of around 50% by the year 2050 might be needed to meet CO 2 emission reduction targets. Thanks to Hotmaps, users can obtain a large-scale vision of the whole city, allowing them to identify energy-related issues very easily. Hotmaps helps gather all the information required to identify planning priorities for the future and can be used as a decision-making tool, to create different energy scenarios. It helped cities to bring together all the actors of the energy sector, to refine their knowledge of the territory, and to share data and analysis.

For further information please contact: Lukas Kranzl,

“Thanks to Hotmaps, we have a quick overview of where the heat demand is high enough to invest in district heating pipelines. This enables us to easily identify hot spots, which our energy utility can then investigate in more detail. A strategy across city boundaries is also made easy with the default data.” Paul Fay, Deputy Head of the Energy Office of Frankfurt

1) 2) 1 TU Wien Energy Economics Group - Technical University Vienna; – University of Applied Sciences and Arts Western Switzerland; Fraunhofer Institute for System and Innovation Research; CREM - Centre de Recherches Energétiques et Municipales; EURAC – Institute for Renewable Energy; eThink – Energy Research; 3) More information on Hotmaps data collection process is available at https:// and

120TWh additional annual primary energy savings*

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120TWh additional annual primary energy savings*









Decarbonized, sustainable and resilient District Heating with Danfoss Enspire® and Energis® *A new report from Aalborg University, Denmark, outlines the directions and solutions towards further decarbonizing of the European heating and cooling sector by 2050. A key takeaway form the report shows us that a modern 4th generation low-temperature district heating will signicantly increase energy eciency and could lead to 120TWh additional annual primary energy savings. Ahead of the technical challenges linked to the constant expansion of the heating networks as well as the new EU legislation, the District Heating utilities need new tools and software to plan projects and optimize costs. Danfoss Enspire® is our new and improved SCADA solution which helps you to achieve more control of the district energy system with less eort. While with Danfoss Energis® you can better plan, control and optimize existing and future district heating networks. Those two advanced software from Danfoss allows you to have an improved and sustainable network operation as well as stable energy distribution. Optimal, sustainable and digitalized district heating means decreased cost, reduced CO2 emissions and resilient operations. *A new report from Aalborg University, Denmark, outlines the directions and solutions towards further decarbonizing of the European heating and cooling sector by 2050. A key takeaway form the report shows us that a modern 4th generation low-temperature district heating will signicantly increase energy eciency and could lead o 120TWh additional annual primary e ergy savings. Ahead of the technical challenges linked to the constant expansion of the heating networks as well as the new EU legislation, the District Heating utilities eed new t ols and software to plan proj cts and optimize costs. Danfoss Enspire® is our new and improved SCADA solution which helps you to achieve more control of the district energy system with less eort. While with Danf ss Energis® you ca better pla , control and optimize existing and future district heating networks. Those two advanced software from Danfoss allows you to have an improved and sustain ble n twork operation as well as stable energy distribution. Optimal, sustainable and digitalized district heating means decreased cost, reduced CO2 emissions and resilient operations. Decarbonized, sustainable and resilient District Heating with Danfoss Enspire® and Energis®

Read more about the Aalborg University report on

Read more about the Aalborg University report on


Investing in electric kettles – or electrical driven boilers as they are called this size – are an important part of the CTR’s CO 2 neutral strategy combining heat and electricity systems using wind turbines. Read this article and find out why! By Jan Hindsbo, Vice Director, CTR (The Metropolitan Copenhagen Heating Transmission Company)

Once upon a time… In 1984 the municipalities of Frederiksberg, Gentofte, Gladsaxe, Copenhagen, and Taarnby, in the Greater Copenhagen Area, joined forces to implement and operate a united district heating system: The Metropolitan Copenhagen Heating Transmission Company known as CTR - now aiming to be CO 2 neutral in 2025.

The main part of the 18.000 TJ/year of heat from CTR is delivered by Combined Heat and Power plants (CHP), and waste-to-energy plants characterized by low variable cost but relatively large investments.

Today the large CHP plants are converted from coal to biomass (via long-term capacity contracts with Ørsted, and HOFOR Energy Production).

THE TOTAL CAPACITY IN CTR IS 2100 MJ/S In a case of a shutdown, or in peak load situations, CTR has 1040 MJ/s of peak load and reserve capacity (ultimo 2020): • 450 MJ/s of gas-fired boilers • 470 MJ/s of oil-fired boilers • 120 MJ/s electrical boilers

Next step… Integrating more green and sustainable energy sources, without increasing prices, is the next step. This is where the electric kettle comes in the picture – or electrical driven boilers as they are called this size. They are placed in Peak Load Stations (PLS) smoothen out peaks in energy

supply and demand. They absorb electrical energy from wind turbines when the wind is blowing and too much electricity in the net, and they supply energy to the DH network when it is cold, and the heat demand is too high. This is very important for stabilizing a DH net. Today PLS boilers in the CTR system are gas-fired, oil-fired or electrical. The PLS has low operation hours and fast response time in case of a CHP plant shutdown. Even though they only deliver 5 % of the heat, they contribute significantly to the CO 2 emission. Thus, converting PLS from fossil fuels as gas and oil is important for reducing CO 2 emissions and CTR is converting PLS stations to be CO 2 neutral in 2025. But the lifecycle of a PLS is 30 -50 years. Many things must be considered!

The future Peak Load Stations The future PLS must be CO 2 neutral, fast response, cheap in investment, and, as the full-load operation hours are low, the variable production cost is of minor interest.

Yearly cost pr. MJ/s installed


















Operation hours on max. capacity

Electrical drivenboiler

Biomass CHP

Oil boiles on rape based biooil

Electrical driven heatpumpe heat source Sewage water Electrical driven heatpumpe heat source sea water

Gas boiler on Bio natural gas

Local heatpumps of air

Fuel plant situated in central areas - uncertain

Gas boiler on Bio LPG

Oil boiles on straw based biooil

Geothermal energy incl. Heatpump

Graphical presentations of the technologies are shown in the diagram - they are all possible CO 2 neutral solutions. The horizontal axis shows the estimated operations hours on full load and the vertical axis the estimated total expenses pr. installed capacity. As peak load stations in CTR’s system typically operate below 500 hours pr. year, electrical driven boilers and bio-gas boilers will be the cheapest solutions. More energy-efficient heat pumps need more operating hours to be economical

THE LIFECYCLE OF A PLS IS 30-50 YEARS AND CTR ARE CONVERTING STATIONS TO BE CO 2 NEUTRAL IN 2025 Since 2018 CTR has a 40 MJ/S electrical boiler in operation in Gentofte. By the end 2020 another electrical boiler station, containing

two 40 MJ/s heaters, will be in operation in Gladsaxe. INVESTMENT SHARE OF COST IN THE GLADSAXE PLS: • Electrical heaters: 25% • Electrical connections: 40% • District heating connections: 35%

1) Transmission System Operator: Energinet; 2) Distribution System Operator: Ørsted

Planning the location of the PLS The shortest possible distance between the power grid and the district heating system is essential.

This year two electrical 40 MJ/s boilers, will be connected to Energinet’s 132 kV system in Gladsaxe, only competitive as the old PLS was located just beside an Energinet power transformer station.

Transmission and Operation Management To ensure operability and minimizing costs it is vital to involve a Transmission System Operator 1) (TSO), and a Distribution System Operator 2) (DSO) in the planning process. In this case, CTR and the TSO (Energinet) identified and planned the optimal place for the PLS together, considering the shortest possible distance between the power grid and the DH network. The electric boilers/heat pumps are only a small part of the investment. The electrical transmission installations (cable and transformers) and connections to the district heating systems represent significant costs too. CTR’s primary PLS strategy is to deliver CO 2 neutral fast operational peak load energy to the DH system. Secondary it is balancing the electrical system using excess electrical energy production and adjusting the frequency. As CTR does not operate in the electrical market an external partner was necessary in this case. In Gentofte, it is Lyngby Kraftvarme (Former Danish Commodities) buying electricity and operating the boiler based on agreed prioritization. The priority is electrical heat available for peak load and reserve load in the DH system. The second priority is Lyngby Kraftvarme using the boiler as an ‘energy accumulation tank’ in the reserve-power market. The success of integrating the DH system and the electrical system depends on partners cooperation and using each partner’s strengths and flexibilities.

The DH system can accumulate energy big time. This project is realizing a fine solution for the future excess power in the grid balancing it out via the DH system – using a very big electrical kettle :-)

For further information please contact: Jan Hindsbo, JAH@CTR.DK

A new heat pump center, next door to Facebook's data center, is an important part of District Heating Funen's (Fjernvarme Fyn) plan to phase out coal in 2022. Surplus heat from two Facebook server buildings is connected to a large heat pump system – heating up district heating (DH) water before it is fed back into the DH network.

By: KimWinther, Head of Business Development

‘We get surplus heat from Facebook as 27 degrees hot cooling water from their servers. Our nine heat pumps, chill the server building cooling water before sending it back to the servers. He points out a massive blue pipe in the corner of the large room where other pastel-colored pipes of various shades blend with the blue DH pipe: 'In the blue pipe, 35-40 degrees return water from the DH network comes in. The heat pumps bring up the temperature to 75 degrees, using the surplus energy from the servers. And then we send the DH water back to the DH net'. Kenneth Jensen points on a large hall with nine giant heat pumps in a row and says: ‘They upgrade the energy from Facebooks' cooling water to the DH water’.

In 2017 DHF and Facebook signed an agreement on the utilization of surplus heat for approximately 7,000 households. This was the beginning of Denmark's largest and one of the world's most advanced heat pump systems. The plant was in operation in the spring this year, and an expansion is already decided. When increased 45 MW heat pumps, using surplus heat and energy from the air, will heat about 10,000 more households in the future. The total investment will be € 30M.

Project manager Kenneth Jensen from DHF shows off the ‘Tietgen Heat Center’ opposite side the road from Facebook.

Coal represents 30% of the heat in DHF – in two years, it’s zero!

Today, coal represents 30-40 percent of the heat production for the 100,000 households by DHF.

‘The collaboration with Facebook fits super well into our DNA’, says Jan Strømvig. ‘DHF set an ambitious plan to phase out the coal by 2025 but will advance the timeline to 2022, saving the environment almost 400,000 tons CO2 per year. The Tietgen Heat Central and other heat pump systems utilizing heat from wastewater, electric boilers, bio boilers, large energy stores, and a bit of natural gas are solutions displacing the coal in 2022’. Wind-power to pumps and servers The large heat pumps use a lot of electricity to upgrade the surplus heat from the Facebook servers to the DH net explains Lauren Edelman, energy consultant from Facebook. ‘This is why Facebook is investing in wind turbines, and green power from Norway to operate our data center and the heat pumps here’ she says. She emphasizes that Odense was chosen because green power was accessible and so was an opportunity to utilize the surplus heat for DH.

For further information please contact: Kim Winther,

By: Jakob Zinck Thellufsen & Henrik Lund , Department of Planning, Aalborg University

District heating and cooling infrastructures are essential for a green transition. To make it happen cities andmunicipalities play a crucial role as they govern the local activities needed to implement renewable energy sources and facilitate reductions in energy demands. To force the local green transition in the 4th biggest city in Denmark, the Aalborg City Council asked the local university to write a plan for a 100% renewable energy system for the municipality – more efficient and at the lower socio-economic cost compared to the status-quo reference scenario, still relying on fossil fuels in power plants, engines, boilers, etc.

The plan is called The Smart Energy System for Aalborg. It shows how wind, solar, and renewable energy can supply all local demands – not only for electricity consumption but also for transportation, heating, and industry. The target is to achieve a 100% renewable energy system in 2050. The study is carried out by researchers from Aalborg University on the request of Aalborg Municpality. The project started in March 2018 and was finalized in 2020. Throughout the study, the municipality has been included in discussions and the work is used for their continuous planning of renewable energy sources, district heating grid development and other local energy planning issues.

Aalborg District Heating Other District Heating Buildings Roads Aalborg Municipality

Mapping ‘supply and demand’ Aalborg is no independent island dispatched from the rest of Denmark – but is balancing an energy system in a national and global context. This requires mapping all energy sectors nationally and all consumptions and future energy demand locally. So this was the first step.



10 15 20

Kilometers Map of the current heat sources in Aalborg Municipality, used for investigating the heat demand reductions in different supply areas.

Identifying energy demands now - and for the future For identifying heating demands, a local geographic analysis mapping district heating, individual boilers, and heat pumps were made. The analysis included energy efficiency measures and the costs of implementing energy savings in buildings. For identifying the future energy demands for industry, transportation, and electricity the consumption of today was mapped. Then it was scaled based on the Danish expectation for future energy demands identified in the IDA Energy Vision 2050.

Wind and solar Aalborg Municipality has several possible locations for wind turbines, as well as rooftops and land areas to support local solar PV installations. Most of the electricity can be sustainable and locally produced. This meaning more of Denmarks' large offshore wind capacity can be used in the Copenhagen area, with no space for land turbines. The benefits of system integration and energy storage The Smart Energy System for Aalborg is a cost-efficient renewable energy system integrating all energy sectors. The electricity produced on the wind turbines and solar cells are directed towards not only the electricity sector but also to transportation, heating and fuel demands in industry and heavy-duty transport. By doing this, it is possible to use the variable electricity more flexible due to various demand profiles and the accessibility to cheap storage. Storing energy as hot water, gas or liquid fuel is much cheaper than storing it as electricity. However, to gain this cost-benefit it is necessary to utilize the hot water in district heating, the gas in industry and thermal plants, and the liquid fuel in heavyduty transport, shipping, and aviation. As the Sankey diagram illustrates, all these couplings are used in the Aalborg Energy Vision. Electricity is converted to hot water through heat pumps and electric boilers to be utilized in the district heating network. Here thermal storages are utilized so more heat can be produced when the sun is shining and the wind is blowing – to be used later.

Identifying energy supply now and green energy for the future

Balancing energy supply and demand for electricity, industry, and transportation on a national scale is of course a national matter. But Aalborg has to level local industry demands with local supply as local industries may be unproportional in size and energy consumption. For Aalborg, to balance the local and national energy supply, the next step was to identify and qualify local and national energy supply sources. Biomass For green transition biomass is very relevant. Under the right circumstances, biomass for incineration is CO 2 neutral. But it is a limited resource too. Overutilization of biomass in Aalborg can set a limit for other cities to begin an easy renewable energy transition by biomass incineration. The Smart Energy System for Aalborg suggests 25 GJ/person energy supply from biomass similar to the level identified in The Danish Society of Engineers, IDA Energy Vision.

Sankey diagram illustrating the energy flows from supply to demand in the smart energy vision for Aalborg Municipality in 2050.

In the Aalborg Energy Vision, the total excess heat from industry increases from 340 GWh to 640 GWh, supplying almost half the heating demand in Aalborg Municipality. Furthermore, the electrolyzers and electrofuels production also produce excess heat, bringing the total up to 850 GWh. To utilize surplus heat in this scale, season storage is implemented, for accumulating surplus heat in the summer period to be used during the winter period with larger heat demands. By combining surplus heat from the industry, using heat pumps and storages, it is possible to supply 1100 GWh heat, which is 70% of the demand. The rest is covered by CHP (combined heat and power) running on green gas. The green gas is either biogas or synthetic methane produced from a carbon source and hydrogen. Comparison of the fuel consumption and total annual costs in ‘the business as usual scenario’ versus ‘the 2050 smart energy vision’ for Aalborg Municpality.

For fuel production, electrolyzers produce hydrogen which can be stored short term in hydrogen storage, but else is converted into fuel or gas to be used in industry, peak load power plants, or the transport sector. Finally, the wind is also integrated into the transportation sector through electric vehicles. These are smart charged so it better fits with low demand hours from other electricity demands and hours with large wind and solar energy production.

Low-temperature district heating and excess heat utilization

A low-temperature fourth generation district heating grid is implemented in the Aalborg Energy Vision, reducing supply and return temperatures. This way it is possible to increase efficiency on the district heating heat pumps and utilize more waste heat. In Aalborg, a large cement industry, Aalborg Portland, already delivers a substantial amount of excess heat to the district heating grid.

Fuel comsumption [TWh]

Total annual costs [M €]













Solar PV




Onshore wind




Offshore wind



Total annual costs



2050 BAU



For further information please contact: Henrik Lund,

J. Z. Thellufsen, H. Lund, P. Sorknæs, P. A. Østergaard, M. Chang, D. Drysdale, S. Nielsen, S. R. Djørup, K. Sperling, Smart energy cities in a 100% renewable energy context, Renewable and Sustainable Energy Reviews, Volume 129, May 2020, S. Djørup, K. Sperling, S. Nielsen, P. A. Østergaard, J. Z. Thellufsen, P. Sorknæs, H. Lund, D. Drysdale: District Heating Tariffs, Economic Optimisation and Local Strategies during Radical Technological Change, Energies, Vol 13, Issue 5, March 2020, S. Nielsen, J. Z. Thellufsen, P. Sorknæs, S. R. Djørup, K. Sperling, P. A. Østergaard, H. Lund: Smart Energy Aalborg: Matching End-Use Heat Saving Measures and Heat Supply Costs to Achieve Least Cost Heat Supply, International Journal of Sustainable Energy Planning and Management, January 2020.

Europe has the ambition to utilize district heating (DH) as the backbone of the energy transition because it can store energy from unstable renewable energy sources like wind and sun, necessary for reducing the CO 2 -emissions by 40% in 2030. But todoso the temperatures inDHgridsmustbe loweredwithout letting people freeze. This article tells you how the municipalities of Gentofte and Gladsaxe in Denmark did it by zoning the grid!

By: Carsten Østergård Pedersen Head of District Energy, Business Development

The municipalities of Gentofte and Gladsaxe in Denmark have a fast-growing district heating network. Situated north of Copenhagen the municipalities have a mix of commercial buildings, multi-storage residential buildings, and single-family homes. During cold winters, all supply temperatures were 110°C for meeting the heat demand for every customer. But single-family houses do not need that high temperature so lowering the supply temperature in parts of the distribution network seemed like a good idea. Comfort for everybody “We wanted to turn down the temperature to save energy without affecting negatively on the comfort for those living in critical points of the distribution network. So, wemade some experiments in collaboration with installers and consultants. But we did not find the ideal solution” says Magnus Justesen, Technical Manager, at Gentofte and Gladsaxe District Heating Co. (GGF). “What we needed was a pre-fabricated turnkey solution meeting our demands for temperature reduction, simple installation, and operation.”

The solution was Grundfos iGRID. It lowers the supply temperature locally in specific zones of the grid. To do so a local mixing loop pumps water from the return pipe into the local supply pipe.

By monitoring the critical parts of the network with pit measure points, the mixing loop can adjust temperature and pressure to meet the exact consumer need in real-time. This reduces heat losses and improves comfort.

Installing a mixing loop in a pit

Finished work

27% heat loss reduction The first zoning solution was developed in cooperation between Grundfos and GGF for a zone supplying 300 large villas consuming 9,000 MWh/year.

From 2018 to 2019 supply temperature in the zone was lowered from 90 to 67°C during winter and from 72 to 62°C during summer.

By working with selected house owners optimizing their return temperatures, GGF expects to lower supply and return temperatures in the zone even further, leading to a 27% heat loss reduction in 2020 compared to 2018.

T-ZONE in Gentofte, Copenhagen




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Supply/Return temperatures, summer [°C]



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Heat loss reduction [MWh/year]




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* The zone is continuously adding new houses, as it is an area converting from natural gas to district heating.

Benefitting the pipe lifetime and the green energy transition Lowering the supply temperature brings additional benefits. According to Magnus Justesen, it reduces the risk of pipe damage and leakage and it paves the way for utilizing wind and solar energy as well as surplus heat from industries to the DH network. “We are very satisfied with the solution and the energy savings it offers, and we will install similar solutions in other residential areas in the future,” says Magnus Justesen.

How do you locate heat loss in your district? Imagine if you could use smart meter data to unlock the distribution network black box, locate leaks and heat loss and see what happens in the pipes below your feet. The solution is ready. It’s up to you to take the next step.

iGRID is an end-to-end solution reducing heat losses in district heating zones through real-time temperature optimisation. The next versions include heat pumps (HP) for the low-temperature zones enabling surplus energy connected to the DH locally. HP can increase capacity and lower carbon emissions too.

For further information please contact: Carsten Østergård Pedersen,

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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