Minewater in Parkstad
Overview
In the heart of Heerlen, a city once bustling with coal mining activity, a remarkable transformation is taking place. Where once coal was extracted from the depths of the earth, now lies an example of sustainability and innovation. The Mijnwater project is not just a heating initiative; it's a symbol of the Netherlands' commitment to a greener future.
As the energy transition gains momentum, the project is rewriting the narrative of energy consumption in Heerlen. Coal, once synonymous with industrialization, has been replaced by renewable heat and cold, marking a significant milestone in the city's history.
As the first 5th Generation District Heating and Cooling Grid (5GDHC) in the Netherlands, this initiative towards a fossil-free future is made possible through the collaborative efforts of Enexis Holding, the Province of Limburg, local municipalities, housing associations, and building owners.
Mijnwater doesn't just provide warmth; it represents a smart, forward-thinking approach to energy consumption. By leveraging old mine tunnels as renewable heat and cold sources, the plant is not only reducing CO2 emissions but also honouring the industrial heritage of the region in a sustainable manner.
History
Once the second-largest city in South Limburg, Heerlen flourished in the first half of the 20th century due to its thriving coal mining industry. When the government made the decision to phase out coal mining in 1965, the city faced the challenge of redefining its identity and adapting to a new era.
Hidden beneath the city and its surroundings, the legacy of the mines lives on in the form of an extensive network of tunnels, serving now as the foundation for the innovative heating and cooling system carried out within the Mijnwater project.
Launched as a pilot initiative in March of 2004, the project aimed to utilize the underground tunnel system to supply heat or cold directly to a small number of customers. Four years of research culminated in the inauguration of the world's first mine waterpower plant on October 1 of 2008. In the summer of 2020, Mijnwater expanded its energy network with the construction of a pipeline route of approximately 1,750 meters, consisting of 2 pipelines through the center of Heerlen.
Today, Mijnwater boasts the first 5th generation heating and cooling network in Europe.
The project's impact is felt across various sectors, with offices, shops, social real estate, and homes all benefiting from its sustainable heating and cooling solutions. Existing buildings have been retrofitted to achieve energy label A/B, making them eligible for 100% heat and cold supply by Mijnwater.
Successful stories
Before connecting APG to the Mijnwater system, the data center's constant heat output was wasted, expelled into the atmosphere. However, with the implementation of emission and ventilation enhancements, coupled with the utilization of heat pumps, approximately 21,000 GJ of heat is now recovered annually - around 6,000 GJ is used to heat 32,000 m² of office space, while the remaining 15,000 GJ is directed back into the mine water infrastructure for utilization in other connections.
This residual heat supply is particularly noteworthy for an office building constructed in the seventies, resulting in an impressive CO2 reduction ranging from 118% to 130%.
Center plan Heerlerheide Gen Coel
The Gen Coel center plan, a dynamic hub of activity housing various facilities, including shops, a supermarket, school, childcare, library, and 194 apartments and care facilities, was connected to Mijnwater in October 2008, marking a significant step towards sustainability and energy efficiency. In the first quarter of 2014, the mine water connection and power plant underwent further improvements to incorporate two state-of-the-art heat pumps. These pumps maximize efficiency in harnessing energy from mine water, one focusing on heating tap water and the other ensuring comfortable warmth for residents and users. The installation basement is equipped with cutting-edge digital controls, seamlessly regulating the flow of energy.
Technical details
Mijnwater 1.0 represented a significant advancement in District Heating or Cooling networks, known as 4th generation District Heating or Cooling (4DH, 4DHC). During winter, the grid distributed warm water at 28°C from the mine to provide heating, while in summer, cooler water at 16°C from a shallower source was circulated for cooling purposes. This pioneering system, categorized as a '4th Generation' grid, utilized a low-temperature heat source (or high-temperature cooling) and centralized the distribution of warmth or cooling to customers. Initially, there was no simultaneous energy exchange between customers, and the grid served a single large office building (national statistics bureau CBS) and a social housing project. However, it became evident that this setup was gradually depleting the geothermal source, limiting scalability.
In 2013, a significant enhancement was introduced with the transition to 'Mijnwater 2.0', representing a fully operational 5th Generation Heating and Cooling grid (5GDHC). Unlike traditional DHC systems, which typically operate based on supply-side management, the entire framework, operation, and enhancement of the Mijnwater grid are centered around demand-driven principles. The main improvement consisted indeed in the capability for the grid to facilitate simultaneous exchange of heat and cooling among all customers, while storing any excess energy for future use. This circular reuse mechanism significantly reduces energy demand and eliminates wasteful heat, directing it back into the grid. By cooling buildings during summer months, the storage system accumulates heat for winter use, ensuring a sustainable and efficient energy cycle.
The core principle of this system lies in its utilization of a conventional two-pipe spine, with one pipe conveying warm water and the other transporting cold water. However, unlike traditional systems, the direction of flow within these pipes is not fixed, being initiated only at points of demand. Heat can be extracted from the warm water using a heat pump, returning cooled water to the cold pipe, while coolth is extracted in the reverse manner. This innovative approach ensures that customers requiring cooling inadvertently provide waste heat to neighboring users in need of warmth. At one end of the spine, the pipes are interconnected via a heat exchanger, facilitating the conversion of residual flows of cold water into warm water, and vice versa. The exchanged heat is further utilized or stored, potentially in thermal storage units, allowing for energy sharing across time. This integrated thermal storage system stores heat and coolth from the past for future use, thereby significantly reducing overall energy consumption. Thermal energy is stored across various mediums, including buildings, hot water boilers for short-term storage, the water grid for intermediate storage, and the mine water for long-term storage. Through this dynamic exchange and storage mechanism, energy consumption is effectively minimized while optimizing the utilization of heat and coolth within the local area and across different time frames.
The Mijnwater grid operates across three distinct levels, each governed by independent controls. Formerly known as the Mijnwater 1.0 pipe system, now serving as the 'backbone', it channels water from the mine through its infrastructure. This backbone connects to the mine via two warm and two cool wells, engineered to allow bidirectional flow, facilitating both extraction and infiltration of water, which equates to energy. Primarily, the backbone serves two key functions: linking cluster grids together and acting as a substantial heat exchanger that connects the warm and cool wells, serving as the thermal interface with the long-term thermal storage of mine water. As of spring 2019, the backbone connected to four cluster grids, each interfacing with it via a large heat exchanger housed within a dedicated cluster installation. These cluster grids function as two-pipe spines, facilitating thermal energy exchange within the local area and with the backbone.
Future perspectives
With Enexis Holding NV and the Province of Limburg joining forces to booster their previous investments in Mijnwater, this collaborative effort aims to propel the project to the next phase of development. Enexis Holding NV has decided to further invest in the heating network of Mijnwater with almost EUR 80 million in 2023. The Province of Limburg will also invest EUR 40 million in the heating network of Mijnwater in Heerlen via the Limburg Energy Fund (LEF) in the coming years. Through a joint investment program, phase 1 financing totaling €120 million has been secured, paving the way for the expansion of Mijnwater's sustainable heating network.
The expansion of Mijnwater is part of a comprehensive master plan aimed at developing the company into a future-proof energy provider that significantly contributes to the sustainability of the Parkstad region. This expansion will unfold in multiple phases, starting in Heerlen before extending to Kerkrade-West and Kerkrade-Centrum. The project's infrastructure backbone, represented by the Backbone pipelines, is currently under construction and is expected to be completed by May 2024, heralding a new era of sustainable energy delivery in the region.
Summary
Depth of drilling: 700 metres
Geothermal power: 20 TJ/a heating, and 20 TJ/a of cooling
Units covered: 250000 m2 of floor space in large office buildings, shops, supermarkets, educational institutions, and homes
Total amount of investments: EUR 3 billion for 2040
CO2 emissions avoided: reducing CO2 emissions by 65%