Minewater Project

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Short description

Reuse of flooded mine shafts for district heating and cooling.


Minewater is a clean, renewable source of energy. The warm (28°C) and cold (17°C) water is pumped out of the mine shafts and piped to Weller’s minewater power station. This produces hot and cold water that is transported to the buildings.




Starting date:




Qualitative Analysis

Description of the Process

Warm and cool water from the abandoned mine galleries is pumped up to the city of Heerlen where it is used to pre-heat and pre-cool climate control systems in new office buildings and a new neighborhood. A seven kilometer distribution network with hot, cold, and return pipes connect the various users in the city. In the future, the municipality, which initiated the project and owns the infrastructure, aims to expand the network and interconnect new users and new heat sources.

Situation before

Before the project, heating and cooling in Heerlen was typical of any other Dutch city. However, there was the untapped resource of geothermal energy from within the old mine galleries.


In 2000, a local woman, Iliana Demonen, realized that the old mines could be a source of sustainable energy. In 2007, calculations indicated that minewater would be a long term economically viable source of heat and cooling as the rate of energy prices increases. In 2008, the first stage was completed, with a energy central in the new Heerlenheide neighborhood redevelopment.

Result of project

By using the minewater to pre-heat and pre-cool buildings' climate control systems, an approximate 55% saving on CO2 has been achieved by reducing the amount of fossil fuels needed. In addition, the legacy of the city's mining history has been kept alive through the adaptive resuse of the old galleries.

Problems during the the realization of the project and how they were approached

In the practical development of the project, there was a technical challenge to hit a 2.5 meter wide gallery 700 meters beneath the surface. Proudly, experienced drillers of Heerlen succeed in hitting the galleries every time. Knowing which galleries were still open or which had been collapsed was also unrecorded, but was able to be ascertained by interviews with the old miners.

Policy and legal context

In terms of extraction, two levels were considered. The groundwater law from the Province of Limburg applies to the top 500 meters of the ground. Under that, it is regulated by the national government. To solve the problem, a unique solution was made where the governor is the concession holder for the entire project. Subsidies and grants were used in the establishment of the project. Furthermore, it is unusual for a municipality to operate such a company, as energy provision is not its core business. However, with such large investment with such a long return time, it is uninteresting from a purely business perspective. As such, the municipality took it on itself. Eventually, it would like to shift the ownership to a private company. Regarding the distribution of heat and cold, the legality in terms of the European competition law needed to be confirmed. They needed to prove that the minewater program did not constitute a restriction of trade and a restriction of choice for the consumers. In this case, the trade-related and environmental concerns balanced each other. Furthermore, because it is only a small area, the future inhabitants are not obligated to live in a house warmed by minewater, and no significant international impacts are made on trade of energy sources.

Factors that contributed to the success of the project

The miners were enthusiastic about the project from the very start. A large amount of investment came from subsidies from the Netherlands and the European Union.

Challenges that the project must overcome

The project has not been as successful in terms of cost recovery as was imagined. The Municipality of Heerlen accumulated a a debt of almost 4 million euros in the realization of the project. The cost-effectiveness of the program was questioned by accountants from the very beginning, but the project was carried out anyway, for social and environmental reasons. The pay-back-time is a gamble that energy prices will continue to rise, though there is a risk that they could stabilize with other new forms of energy. There were several other technical risks, including the contamination of the mine water and collapse of the mine galleries. The cost of supplying heat or cold with the minewater has 70% fixed costs and 30% variable costs that fluctuate with the cost of energy. This is contrary to conventional fuels, such as natural gas, which has a low fixed cost and a high variable cost. Prospective users of the minewater have to balance the additional expenses occurred for investing in the building technology that allows them to utilize the minewater with the risk that the minewater may be more expensive than other fuels in the future, if the cost of energy remains constant and does not increase in the next fifty years. For the minewater company, expanding the transportation infrastructure is very expensive, about 600 euros per meter to connect another client to the wells, and buildings that wish to use the minewater must pay higher upfront costs to utilize the minewater than they would to use conventional energy sources.

Role of different stakeholders in the system during the realization and maintenance of the project

The Weller Housing Association was the first committed partner for utilization of the minewater infrastructure. The urban redevelopment in the neighborhood of Heeerlerheide has been optimized for using minewater, for example with radiant floor heating in all of the new dwellings and an impressive community center. The redevelopment includes new dwellings, parking facilities, a community center, a school, a library, retail space, and new green spaces.

Spatial quality

While most of the infrastructure is underground, the new community center built by the Weller Housing Association is a celebration of the minewater project. The hyperboloid shape of the building echoes a cooling tower, and inside the minewater is utilized for heating and cooling. An information area was also constructed to show and teach about the project.

Ease-of-use compared to conventional processor

Utilizing the minewater requires a low-temperature heating a cooling system, which is possible for newly built buildings, but not feasible for existing structures. Choosing for the minewater requires a long-term commitment and is more expensive up-front. Minewater energy is provided for 15-17 euros per gigajoule, compared to the fossil fuel market price of 18 euros per gigajoule. However, this gap is unpredictable and companies feel that there is some risk that the minewater project will not be reliable in decades to come.

Contribution of the project to the design practice

The Heerlen minewater project was the World's first minewater power station. It has created a splash that inspired several later projects, including in Oviedo, Spain. Successive projects have been able to achieve similar results for far less investment, as some of the kinks were worked out already by Heerlen. Awareness was spread via the Minewater08 conference, held in Heerlen.

Advice for future developments to futher develop the trend

There are ways to do it very easily, there is an example in Northern Spain, they build the same system for 52,000 euros. They had an open shaft, so they didn't have to drill. Oviedo, Spain. Jean Weijers said, “We did it on the hard way. In this kind of project there is a lot of research. The Spainsih project found us by Google, and they did it on a simple way what Heerlen had investigated. In Spain, they had to pump because otherwise they would flood, so the pump energy was not an added expense." In the case of Heerlen, the temperature gradient of the minewater is not unlimited or quickly renewed. To overcome this challenge, the minewater project is looking to use the galleries as seasonal heat storage as well. They are pursuing heat producers in the area, including an iron works company, to have a source of energy to be stored in the minewater.

Description of the built ecolgy niche that the cyclifier inhabits

There were several enabling conditions for this project. The demand for heat and cold is taken as a starting point, as well as the presence of warm and cool water in the abandoned mine galleries - over 4000 km worth in South Limburg. Alternative energies concern local sources. However, the buildings need to be prepared for using the heat, so it is only feasible in new buildings. Conventional heating systems are relatively cheap to install but expensive to operation, whereas using minewater is expensive to install and only slightly cheaper to operate.

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