15 January 2025
Achtergrondartikelen
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Heerlen's fifth-generation heat and cold grid is regularly seen by technocrats as a model project. What makes this heat grid so special? And can the technology be applied elsewhere in the Netherlands? Ria Doedel is general manager at Mijnwater, which provides sustainable heating and cooling for homes and businesses in Parkstad. She explains why this system can be seen as an exemplary model.
"Our heat and cold network is a fifth generation exchange network. This means that heat and cold is exchanged within and between buildings. Only when the demand exceeds the supply available from the exchange do we make use of our hot and cold sources. These sources are located in the mining galleries.
Since people stopped pumping water out of the mines, the corridors have refilled and the water takes on the temperature of the surrounding rock. This means that at different depths the water has different temperatures. At 700 meters depth it is 28 to 30 degrees Celsius, this is used as a heat source. The water at 200 meters depth is used as a cold source. So we are a very low-temperature heat network," Doedel explains.
What makes the heat and cold network so interesting technically?
"Especially the exchange of heat and cold. With a regular heat grid, you have a heat source and a heat demand and the heat is simply transported from A to B. With the heat and cold grid, you have a heat source and a heat demand. With Mijnwater's heat and cold network, software checks where the nearest heat or cold is available. That's a big difference from other heat networks."
Doedel explains this using an example: "When you cool somewhere you always produce heat as a byproduct. For example, we supply cooling to a local supermarket. The resulting heat is used to heat apartments."
"In addition, our grid has high energy efficiency. The temperature of the hot springs is 28 to 30 degrees Celsius. We keep this low until the place where the heat or cold is delivered to the customer. As a result, we have hardly any temperature loss due to transportation. The temperature jump to 40 or 65 degrees Celsius is smaller because of this, so you need less energy to heat it further than if you were to use an air-water heat pump."
The grid provides cold as well as heat, how does this work?
"The need for cooling is increasing all the time. A well-insulated new home is less likely to lose heat in the summer. The grid can supply cold to buildings that also have a delivery system for cold. If there are only radio towers, we cannot supply cold, but if there is floor or air heating, we can. This avoids having to install air conditioners everywhere, which can be unsightly.
In addition, we capture the heat that remains after cooling and then store it in the mine galleries. One advantage of this is that the outside temperature does not heat up even more because of all the air conditioners blowing heat outside. Especially in cities, this system helps reduce heat stress."
In Heerlen, mining galleries are used as a heat and cold source. Is this technique translatable to other places in the Netherlands where there are no mine galleries? "The mine galleries are a unique feature in South Limburg, but you can exchange heat and cold anywhere where a source is available. If you develop the right software, you can exchange heat and cold between users anywhere you have sources of heat and cold. You have to look at the available sources in an area. Aquathermy or heat released from cooling data centers are a good option."
What is the current state of the system and what does the business case look like?
"The infrastructure consists of the heat and cold sources, the backbone connecting areas and the transmission network for supplying customers. We are currently expanding further in Heerlen. Last year we drilled a new hot well. The expansion of the backbone should be ready in April. Then we will have the capacity to roll out further.
In Heerlen we are going to grow quite a bit more. Currently we have about a thousand customers including 25 large users. Once the infrastructure expansion is finished in the spring, we can connect new customers. We also want to roll out in Kerkrade, where there are also mining operations. We hope to start delivery there in 2027. Mijnwater has no short-term ambition to roll out the technology in other places. We have our hands full with the rollout in Heerlen and Kerkrade.
With this plan, we can also start writing black figures. As part of that plan, we have made clear choices about the balance between large and small consumers. Connecting ground-level homes in particular does not break even, because you have to build an extensive distribution network to get to every front door. That creates an unprofitable top. So you need that balance with wholesale customers to be able to write black numbers at the corporate level.
As part of the energy transition, we do see it as our responsibility to get homes off the gas. But also to help residents in energy poverty by offering stable energy costs. With a heat grid, you don't run into fluctuating prices throughout the year, as you do with gas prices."
What challenges will you face in the near future?
"One challenge is the large number of permitting processes and their long lead times. The deep hot wells fall under the Mining Act. As a result, we face procedures that take a year or more, and we have quite a few of those to go through. The lead time is often uncertain; it can sometimes take much longer than is prudently justified. That entails a financial risk, because then you can sometimes start delivering later than you had envisioned."
The second challenge is the unprofitable top on connecting ground-level homes. You'd prefer to connect as many homes as possible but you can't do that indefinitely because that puts pressure on the company's financial result.
In addition, there is a challenge in connecting housing owned by corporations. We have to connect to the schedule with which corporations are making their property more sustainable. Often we are dealing with neighborhoods with multiple corporations, so then you have to align all the schedules. That's not easily done yet."
What are Mijnwater's expectations toward the future?
"We are going to implement our plan, but there are a number of uncertainties. A lot is unclear about the Collective Heat Act, there are a number of elements in there that could have quite an impact. For example, the municipality's choices regarding lots can affect the rollout of the grid. We have to prepare for that by talking to the municipality. You'll figure that out together, but it's good to talk about it before the law goes into effect.
In addition, there is currently quite a bit of fuss about the fixed costs of a heat network, following the situation in Amsterdam. We try to keep the costs for consumers as low as possible, because we realize that heat is one of the basic necessities of life. That is why we invest in the standardization of our installations. Standardization allows us to keep future maintenance costs low during the operating phase, and it makes it possible to connect new customers with a shorter lead time.
To that end, Mijnwater believes it is important to draw the right comparison. "We always compare ourselves to the cost of a sustainable alternative rather than heating with gas. Ultimately, we all want to say goodbye to fossil fuels. Then you shouldn't just look at rates."
Source: Heat365.co.uk