Underground Railway Energy for Sustainable Cities

Underground Heat: How Urban Railways Can Power Greener Cities

Rhea Morgan in Climate & Environment June 2025 • 4 min read.

"Unlock the potential of urban railways with ground source heat pumps for sustainable energy and reduced carbon emissions."

Cities around the world are under increasing pressure to reduce their carbon footprint. Traditional methods of heating and cooling buildings contribute significantly to greenhouse gas emissions, compelling urban planners and engineers to seek innovative, sustainable alternatives. Underground railways, often overlooked, present a unique opportunity to tap into a consistent source of thermal energy.

Imagine a scenario where the constant activity of trains running through underground tunnels isn't just a transportation solution but also a power source for heating homes and businesses. This concept is becoming increasingly viable through the implementation of ground source heat pumps (GSHPs). These systems can extract heat generated by trains, infrastructure, and even the earth itself, providing a renewable energy source right in the heart of the city.

This article explores the potential of using urban railways as a source of renewable energy, focusing on how ground source heat pumps can be strategically integrated to create more sustainable urban environments. From the pioneering research in this field to real-world applications, we'll delve into the science, technology, and benefits of this innovative approach.

Unlocking the Potential: How Ground Source Heat Pumps Work with Urban Railways

Underground Railway Energy for Sustainable Cities

Ground source heat pumps (GSHPs) are highly efficient systems that transfer heat between the ground and buildings. Unlike traditional heating and cooling systems that generate heat or cold, GSHPs simply move it. This makes them far more energy-efficient and environmentally friendly. When paired with the thermal energy generated within underground railway systems, the benefits are amplified.

The basic principle involves extracting heat from the ground near railway tunnels and using it to heat buildings in the winter. In the summer, the process is reversed, with heat from buildings being transferred back into the cooler ground. Here’s a breakdown of how this works:

Heat Absorption: Pipes filled with a heat transfer fluid are buried in the ground near railway tunnels. These pipes absorb heat generated by the trains, equipment, and surrounding earth.
Heat Transfer to the Heat Pump: The heat transfer fluid circulates to a heat pump system located in a nearby building or energy distribution center.
Amplification: The heat pump concentrates the heat and transfers it to the building's heating system, providing warmth to homes, offices, and other facilities.
Reversal for Cooling: In the summer, the heat pump reverses the process, extracting heat from buildings and transferring it back into the cooler ground near the railway tunnels.

This symbiotic relationship not only reduces reliance on fossil fuels but also helps to maintain a more stable temperature in the underground tunnels, potentially reducing the need for extensive air conditioning.

The Future is Underground: Embracing Sustainable Urban Energy

The integration of ground source heat pumps with urban railway systems represents a significant step toward creating more sustainable and resilient cities. By harnessing the untapped thermal energy beneath our feet, we can reduce our reliance on fossil fuels, lower carbon emissions, and create healthier, more livable urban environments. As cities continue to grow and evolve, innovative solutions like this will be crucial in building a greener future for all.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.applthermaleng.2018.10.118, Alternate LINK

Title: Modelling Of Heat Energy Recovery Potential From Underground Railways With Nearby Vertical Ground Heat Exchangers In An Urban Environment

Subject: Industrial and Manufacturing Engineering

Journal: Applied Thermal Engineering

Publisher: Elsevier BV

Authors: Akos Revesz, Issa Chaer, Jolyon Thompson, Maria Mavroulidou, Mike Gunn, Graeme Maidment

Published: 2019-01-01

Everything You Need To Know

What is the primary benefit of using ground source heat pumps (GSHPs) with urban railways?

The primary benefit is the creation of a renewable energy source by harnessing the waste heat from trains, equipment, and the surrounding earth within the railway system. This reduces reliance on fossil fuels, lowers carbon emissions, and contributes to more sustainable urban environments. Ground source heat pumps (GSHPs) are highly efficient at transferring heat, making them ideal for this application.

How do ground source heat pumps (GSHPs) work in conjunction with urban railways to provide heating and cooling?

Ground source heat pumps (GSHPs) utilize a heat transfer fluid circulating through pipes buried near railway tunnels. In winter, these pipes absorb heat generated by trains and the earth, transferring it to a heat pump. The heat pump concentrates the heat and delivers it to buildings. In summer, the process reverses, with the heat pump extracting heat from buildings and transferring it back into the cooler ground near the railway tunnels. This symbiotic relationship provides both heating and cooling while reducing energy consumption and environmental impact.

What are the key components involved in integrating ground source heat pumps (GSHPs) with urban railways?

The key components include pipes containing a heat transfer fluid, buried near the railway tunnels to absorb heat. This fluid then circulates to a ground source heat pump (GSHP) system. The heat pump concentrates the thermal energy and transfers it to building heating systems in the winter and reverses the process in the summer for cooling. This integration involves infrastructure near the railway tunnels and within buildings or energy distribution centers.

What are the environmental and sustainability implications of using urban railways for renewable energy via ground source heat pumps (GSHPs)?

Integrating ground source heat pumps (GSHPs) with urban railways significantly reduces reliance on fossil fuels, leading to lower carbon emissions and a smaller carbon footprint. This directly contributes to creating healthier and more livable urban environments. It allows cities to move towards greater energy independence and sustainability by tapping into a readily available, renewable energy source, helping mitigate the impacts of climate change and promoting a greener future.

Beyond heating and cooling, are there other benefits to integrating ground source heat pumps (GSHPs) with urban railways?

Yes, besides providing heating and cooling, the integration of ground source heat pumps (GSHPs) with urban railways can help stabilize temperatures in underground tunnels. This can potentially reduce the need for extensive air conditioning in these areas. Furthermore, this technology promotes a more efficient use of existing infrastructure by converting waste heat into a valuable resource, enhancing overall energy efficiency in urban environments.