7 questions about heat grids

A heat grid is a system of insulated pipes. The system consists of two pipelines: one for hot water and one for cold. Hot water is transported from a heat source to the customer through the hot water pipeline. That customer can be the operator of a district heating network that supplies the hot water in the same way to a home, for example. At the end destination the heat is released via a heat exchanger, after which the water cools down. The now cooled water returns through the second pipeline to the source where it is heated once more. So, it’s a closed cycle. There are different types of heat sources, like geothermal, solar heat or industrial waste heat, for example. Gas boilers are also used to handle peak demand in the winter. The water temperature in the pipes varies greatly depending on the grid, going as high as 120°C. There are already quite a few heat grids in the Netherlands, and about 450,000 homes are connected to these. Until recently, these have been installed by the large energy companies, but increasingly a variety of parties are joining in, from network operators to local heating cooperatives.  

When we talk about energy needs, the discussion is often about electricity, despite the fact that about 40% of the energy we collectively use goes to heating. In many cases, a heat grid is the cheapest way to increase sustainability, like in older residential areas with a low energy label, for example, and in commercial greenhouses. Here, solutions for each individual location, such as a heat pump in combination with insulation, are often more expensive. 

One concrete project is WarmtelinQ in the province of Zuid-Holland. There is great opportunity there. There is a lot of industry generating waste heat in and around the Port of Rotterdam, while this region, with its numerous buildings and vast commercial greenhouse operations, has a very high demand for heat. The Dutch government recognised the social importance of putting that waste heat to good use and so commissioned Gasunie to transport heat in that region. Gasunie will transfer the heat to the district heating networks using a main transport pipeline. This task is in keeping with the contribution we make to the energy transition by providing energy infrastructure on a large scale. As an independent network operator, we transport heat from all sources and to all customers, and under equal conditions.

In the first phase of WarmtelinQ – the route between Vlaardingen and The Hague – the pipes are now being laid and we expect to supply the first heat to energy company Eneco in The Hague in the autumn of 2025. At the same time, we are laying the pipeline leading to the port. The third route is from Rijswijk to Leiden. The investment decision has been made for this and we hope to be able to supply energy company Vattenfall from 2027. WarmtelinQ works regionally with local initiatives, municipalities, the province and district heating network operators. There is intensive contact with local residents, neighbourhood organisations and businesses, and we actively invite them to contribute ideas and talk with us. 

This differs per municipality or region. In the case of WarmtelinQ, energy companies Eneco and Vattenfall already operate heat grids that can distribute the heat supplied. Besides this, Gasunie is also involved in a new project, Warmtenet Eemsdelta-Groningen, where it is being investigated whether heat can be transported from Eemshaven or Delfzijl to Groningen. Such projects involve numerous parties, like provincial authorities, municipalities, the local district heating company and the regional network operator. Housing associations are an example of a major end user of district heating, given all the homes they are responsible for heating.

Work has been going on for some time on drafting the new Dutch law on district heating, formally called the Wet collectieve warmtevoorziening, and more commonly the Warmtewet (Heating Act). The aim of this law is to ensure, among other things, growth and sustainability of heat grids and district heating systems. The law sets out which parties will be given a key role in these. The discussion mainly centres on whether these should be public parties, private parties, or a combination of these, and about the responsibilities the parties will be given. This law also regulates Gasunie’s role as a heat transporter. Our role is not in question. The law was originally set to be implemented at the start of this year; however, the implementation date has been repeatedly set back due to the ongoing discussion.  

Absolutely. Industry will always need high temperatures. And even once natural gas has been replaced by hydrogen or electric boilers, waste heat from high-temperature processes will still be generated. What’s more, the expectation is that ‘new heat’ will become available through the hydrogen production process. Although this will not be as hot, it will be released in large quantities. This, too, offers opportunities.