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District Heating: Not a hottie, but I’d still do it

When it comes to the energy transition of Leiden, it is vital to explore new ways to heat the city without gas, the good old gas that has been something oh so convenient, but also deceptive. It has betrayed Leiden, and many others. Now it tries to explain things for the better: “Come on, carbon capture and storage will fix this. And how about condensing boilers?! Hey, at least I am not as bad as oil and coal!”

But Leiden has started to realise that it needs to look for a new source of warmth. Now it seems that the best bet for Leiden is to opt for―no matter how unsexy it sounds―an extensive district heating network. Others, like many cities in Denmark, have already fallen in love with it.

Simply put, in a district heating system heat is distributed in the form of water or steam from the site(s) of production to a wide range of users. The system, like any other, has its pros and cons. A top-down imposed centralized system might raise objection, and the initial changes needed in the infrastructure will be costly. Nonetheless, a district heating system would offer substantial long-term benefits for Leiden.

District heating systems are energy efficient and highly flexible as they can utilize various sources of heat for optimal energy use.

To start with, surplus or waste heat from different processes could be pumped in the network. For instance, cogeneration plants that produce both electricity and heat (for a network) are significantly more energy efficient than conventional thermal power plants that merely waste the by-produced heat. Surplus heat can be connected to the district heating network from various local, or more distant sources, such as the Rotterdam harbour. Using waste or surplus heat would result in significant total energy savings, which is positive for the environment, and perhaps even for the wallets of the Leidenaars.

Apart from waste heat sources, the system can be fed by almost any current (and likely future) heat production forms. Some of the renewable examples are geothermal heating, biomass, central solar heating, and various types of heat pumps that can harvest heat from air, ground and water. In Duindorp, for instance, the district heating is fed by warmth harvested from seawater.

District heating system’s flexibility and compatibility with different forms of heat production makes sure that Leiden will not be dependent on only specific sources of energy. This, in turn, provides energy security. In order to make the district heating system even more flexible, it is recommended to pair it with (seasonal) thermal energy storages that act as a buffer and solve the intermittency problem of certain renewable energy sources. The storages can also help to optimize the energy efficiency of the system and its financial returns.

In short, it is time for Leiden to leave its smelly old gas system and move on. District heating—even if it remains unsexy—is a perfect fit for Leiden in its longevity and adaptability. It will open endless possibilities to keep the city warm and cosy—now, and in the future.


Photo: Bill Ebbesen

Sources and further reading:

State of Green: New White Paper on District Energy

The Guardian: Lessons from Denmark: How District Heating Could Improve Energy Security

Sustainable Cities Collective: The Heat is On for Sustainable District Heating and Cooling

UNEP: District Energy in Cities

The Energy Collective: Holland: Pioneering Sustainable District Heating Innovations

Review of District Heating and Cooling Systems for a Sustainable Future

Towards Next-Generation District Heating in Finland

The ADE: What is District Heating?