Heat networks, what are they and why does everyone talk about them?

In this newsletter, we always try to talk about current topics, one of which, without a doubt, is heat networks. Let's start at the beginning, what is a heat network, and what types exist?

A definition of heat networks, also known as district heating systems, are centralized systems that distribute heat to multiple buildings through a network of insulated pipes. This heat can be used for space heating, hot water, and cooling. Heat networks improve energy efficiency by using surplus heat from industrial processes, power stations, or renewable sources.

Generation of heat networks

First Generation: The first generation, also known as steam-based systems, utilized high-pressure steam to transfer heat.

Second Generation: The second generation introduced hot water distribution instead of steam, operating at temperatures around 120-150°C. These systems were developed post-World War II and provided improved safety and efficiency over the first generation. However, they still had relatively high heat losses and energy consumption.

Third Generation: Developed in the late 20th century, the third generation improved efficiency by lowering the distribution temperature to 70-90°C. This generation also incorporated better insulation for pipes and more sophisticated control systems.

Fourth Generation: The fourth generation, currently being developed and implemented, operates at even lower temperatures, around 40-60°C. This generation focuses on integrating renewable energy sources, enhancing energy efficiency, and facilitating the decarbonization of heat supply. It also aims to utilize smart grid technologies for better demand management and integration with other energy systems.

Fifth generation: heat networks represent the latest advancement in district heating technology, focusing on ultra-low temperature distribution and the maximization of renewable energy sources. These networks aim to create more sustainable and flexible energy systems with a range of innovative features.

The role of heat pumps

Heat pumps are a cornerstone of heat networks, playing a crucial role in enhancing efficiency, sustainability, and flexibility. The idea is simple, multiple heat pumps will be connected within a centralized or decentralized heat network to efficiently distribute thermal energy across a range of buildings or facilities.

Each heat pump extracts heat from a renewable source such as the ground, air, or water, and upgrades it to a usable temperature for heating or cooling purposes. This integration enables the entire system to operate at lower temperatures, reducing energy losses and maximizing the use of renewable energy sources. In case of one heat pump per flat, each heat pump can provide independent heating or DHW and have their own tariff plans.

A proven solution

If there is a country leading the promotion of such schemes, it is the UK. However, numerous projects in other countries are also embracing this innovative concept. Below are some examples showcasing these initiatives.

Enfield councils

Royal Alexander and Albert school

Networked geothermal project in Framingham

Another company that is also trying to take this solution to another level is the company Rendesco . I remember an interview on Net Hero Podcast, with its CEO, Alastair Murray where he explained very well how the idea is simple, the technology is there, and that the biggest handicap was the lack of infrastructure for each house to connect to one of these networks. that today are limited or do not exist. As he said, gas had that same problem, a hundred years ago, basically it is wanting to accept challenges.

Link to the interview

What will we see in the coming years?

In my opinion, we will see more projects of this nature in the future. When discussing decarbonization and increasing the use of heat pumps, we often focus on air-source heat pumps (ASHP). However, ASHP is not always a viable solution in many cases. Heat networks offer a wide range of possibilities, replicating the current gas infrastructure with heat pumps.

Manufacturers are also trending towards these projects in two opposite directions. On one hand, they are developing very large equipment for centralized systems. On the other hand, they are creating very small heat pumps, even wall-mounted units, that can be connected while occupying minimal space.