Carsten Østergård Pedersen, Senior Manager, District Energy, Grundfos (Group)

What makes the District Energy schemes in Denmark so successful? Could you elaborate on the structure and mechanism that paved the way for their high penetration?
Carsten Pedersen: The main principle is that District Heating is owned by the consumers. That means profit is returned as lower prices, giving them the incentive to continuously improve the network, making it effective and efficient in projects. There is a high degree of support from the inhabitants of Denmark. District Heating here is almost 100% in big cities and 70% in total. And it makes sense on top; really, the government is supporting and incentivising environmentally friendly energy solutions, if it financially and socially makes sense. This is why energy efficiency is often the number one criterion when choosing equipment for installation in District Energy in Denmark.
At Grundfos, we are also placing a great deal of focus on operating instead of capital investment, which makes sense in the long term. We focus on calibrating the equipment correctly, which we recommend to our customers. Furthermore, we offer services, such as energy audits and checks on components. We can go to a District Cooling facility and test the pumps to see what energy is being distributed and compare it with alternative pumps, as it could be oversized and not running efficiently. We see that in most cases pumps are 20% oversized, sometimes a lot more. Everyone wants to be on the safe side, and they want to calculate for possible extensions to the network, but that hurts the efficiency. Once the system in place has been running for maybe 10 years, or even before it reaches that period, then you should look at replacing it with smaller and newer pumps and at the same time, if you size it right, it will be even more efficient.
We are developing system expertise in Grundfos, and we need to prevent breakdowns. In my opinion, what really matters is to optimise the systems to make them run better and more efficiently. We are currently developing solutions for District Heating, where we lower the supply temperature, which means we are significantly reducing the heat loss we have out of the pipes. When you distribute hot water, you lose energy out of the pipes.
This is reduced by lowering the temperature. This can also be applied in District Cooling, if you increase the temperature from the normal five degrees C to maybe 15-20 degrees C. It’s about having the temperature as close to the surrounding temperature, because you lose the temperature to the surrounding environment, even in well-insulated pipes. When we lower temperatures in District Heating, you can also utilise a lot more renewable energy sources. You could have surplus heat from industry and geothermal, where you can get “free” hot water of 20 and 40 degrees C and just have to add heat pumps to effectively boost the temperature to a certain level. We have a lot of renewable energy from windmills and solar that’s electricity-based. When the sun is shining a lot and wind blows, there is a lot more electricity than we need, so by coupling the electricity grid and District Heating, we actually store the electricity. If we go to the Middle East, you could use solar. Instead of heating up the water, you could cool down the water and have ice storage, instead.
In District Heating, a temperature of 65 degrees C is enough for a majority of the buildings, but due to just a few buildings, it is often kept at 100 degrees C. By reducing it, for example, using our temperature [zoning technology], we not only reduce the energy loss and the carbon emission, but we can also use more renewable energy sources much more effectively.

Could you elaborate on the temperature zoning technology?

Ronak Monga,
Business Development Manager – HVAC, Grundfos – Greater Middle East

Ronak Monga: Temperature zoning technology was the pilot for the District Heating plants undertaken in Denmark. District Energy networks can be very widespread and, therefore, to ensure that heating water is reaching at a high enough temperature to even the farthest end-users, is critical in maintaining comfort for those users. As a result, the hot water is produced at a very high temperature, which consumes a high amount of energy.
Not only that, it also means that buildings/users connected closer to the District Heating plant, get this high temperature of water and high pressure, which is also bad for the equipment, such as heat exchangers and radiators within the building and households. Also, the higher the difference of the temperature between the supply hot water for heating and the surrounding ambient temperature, higher is the heat loss from the pipe network, wasting even more energy.
Therefore, Grundfos developed and introduced District Heating providers with Temperature Optimisation Units that increase system efficiency with low-temperature zoning and demand-driven supply for District Heating. This ties in directly with reducing the energy consumption and lower emissions from District Energy plants. The temperature optimisation units work based on decentralised mixing loop concept, where the return hot water, which is at lower temperature than supply, is allowed to mix with the supply hot water in controlled amounts by use of a temperature sensor and a pump adjusting its speed via VFD, based on the signal from that temperature sensor. This, combined with remote monitoring and control technologies, allows the District Energy company to constantly monitor the energy and heat consumption, as well as the end-user supply temperature, so that they ensure the highest comfort with the lowest energy consumption – providing great savings for the District Energy company.

Do you see the same solution gaining traction in the Middle East for District Cooling projects?
Monga: In Denmark, the ownership model of District Energy plants is quite different from the Middle East. Most District Energy plants are owned under joint ownership by building and home owners connected to the plant. It is, therefore, in the high interest of the owners in the connected buildings/homes to be more efficient within the District Energy plant, as well as on the consumption side, to reduce the low delta-T issues and, hence, save money and generate high revenue. That model is a fantastic motivation for all involved stakeholders to focus on efficiency and could be tried out in the Middle East. We are working on employing technologies like temperature zoning, as pilot feasibility studies in the Middle East, to try and present District Cooling stakeholders in the Middle East with two or three new technologies. One of these is focused for District Cooling providers and two of them will be focused on the buildings connected to the network.

Pedersen: One thing I would challenge in the Middle East is the traditional way of designing based on American standards, where you do District Cooling at five degrees C. I simply believe if you increase temperature in District Cooling, there will be lower loss in the system. I know that District Cooling is used in very densely populated areas, so the energy loss out of the pipes is less in percentage than in urban areas in Denmark, but it is still a very big loss that could be reduced significantly.

Monga: Density makes a huge impact on the success and return of investment that goes into producing District Cooling. In the Middle East, populations are more concentrated in major cities, like in the United Arab Emirates and in Saudi Arabia, where we can see three major cities – Riyadh, Dammam and Jeddah – using District Cooling. It’s motivating for us, as it allows us to participate in making a positive contribution to sustainability, which is what we strive to do in every aspect of our business.
The supply and production temperature of most District Cooling plants in the region is 4.5-5.5 degrees C, whereas the ambient temperature can be very high, especially during summer months, which is also when we need the most amount of cooling. Due to this high ambient temperature, the amount of heat absorbed by the supplied chilled water can also be higher, which can reduce efficiency. By introducing the temperature optimisation zone concept, not only can the District Cooling optimise the supply temperature to the nearest users/connected buildings but also provide an opportunity for excellent savings.
Within the buildings connected to the District Cooling applications, mixing loop technology can also provide significant savings. The concept of mixing loops within a building also works on a very similar technology to the decentralised mixing loops in the temperature optimisation zone concept, discussed earlier. Returned chilled water from the cooling loads within the building can be mixed in controlled amounts to the chilled water supply from the heat exchanger within the ETS (energy transfer station). This can improve the Delta T within the building, bringing large energy savings.

Pedersen: If I should recommend two things, it is increasing temperature for District Cooling. We have seen data centres, very critical applications, where they are doing cooling with 20 degrees C, very different from what you see in Middle East with five degrees, so we know it’s possible. The normal argument is that the temperatures are designated based on how the chiller runs more effectively and again that is five degrees C. But you can get other chillers, I don’t think that’s a big problem, and you could create zones with a higher temperature. The other thing is getting rid of the Low Delta T issue – it’s a control and a sizing mater. For District Cooling, the good thing is really to optimise the temperature set, for the Low Delta T syndrome.