WarmtelinQ and Vattenfall reach new milestone in construction of heat transfer station in Leiden

You might notice them when you’re driving along: technical buildings whose function is not immediately visible. They sometimes make you wonder what’s going on inside. Some of these installations play a key role in energy supply, for things like heating houses and buildings. Vattenfall’s ‘De Sleutel’ heat transfer station along the A44 motorway near Leiden is such a building. But what goes on inside? Project Manager Roelof Zeijlemaker knows everything about this. He works on the construction of these stations for WarmtelinQ: key links in the system that will soon be using waste heat from the port of Rotterdam to heat 120,000 houses and businesses in the province of Zuid-Holland.

Rather than coming from the city of Leiden itself, the heat that will soon be heating houses comes from the port of Rotterdam. A lot of waste heat is generated there during industrial processes, which would otherwise be lost in the air or water. This heat is used to heat water in WarmtelinQ’s closed system. Large pipes are used to transport this hot water to cities like The Hague and Leiden.

“You cannot get this hot water straight into the houses. There’s another key step in between,” explains Roelof. “The hot water runs through our pipes and into the heat transfer station, where it is transferred to Leiden's local heat network. It is similar to your central heating boiler at home, which transfers heat to the water that heats your home. It's just done on a much larger scale here.” This makes the heat transfer station the link between the source, infrastructure and end users.

The heat transfer station makes use of a smart system. Two water streams come together there: hot water from WarmtelinQ and cold water from the local heat network. These water streams don’t mix. “The heat is transferred by means of a heat exchanger,” says Roelof. “This contains metal plates through which the heat flows.”

The purpose of this system is clear: to use less gas and to use energy in a more sustainable way. “Using heat from the port will reduce the need for natural gas. It will save 110 million m³ of natural gas per year. It will also reduce carbon emissions by around 180,000 tonnes.”

Not much will change for users. Roelof: “You won’t really notice anything; your house will be heated like before.” But there’s a big difference behind the scenes. Heat that would otherwise be lost is now given a new lease of life. “That’s the great thing about it. We’re using waste heat that would otherwise not be used. It’s an important step towards a more sustainable future.”

The system is designed to ensure that there’s always enough heat, even when it’s very cold outside. This safeguards energy security. “WarmtelinQ provides the basis,” explains Roelof. “And in case of extra high demand, an outage or maintenance, Vattenfall’s peak and backup installation is used. It consists of a boiler house and a large heat storage tank.”

According to Roelof, the real strength mainly lies in the system as a whole. A heat transfer station is not an isolated installation; it is part of a value chain that goes from the heat source in the port, through the pipes to the station and afterwards to the heat network in the city. “Everything needs to work together,” he says. It’s a complex, but efficient system.

Most of the satisfaction Roelof gets stems from seeing this system take shape. “I help to convert plans on paper into an actual installation,” he says. “Building a heat transfer system of this size doesn’t happen very often. That’s what makes this project unique, which is why I like working on it so much.”