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Coal mines for sustainable heating? It’s not madness, it’s reuse!

2021. augusztus 31.

Justifiably, in people’s minds, coal mines are the number one catalyst for climate change. However, there is a way for these mines to give back a bit of what they took: at first, it might sound unbelievable, but mines can provide the perfect conditions for installing geothermal heat pump heating systems nearby.

 

It is not a new idea. As early as 1989, in Springhill, Canada, a company that produced packaging materials undertook the then-revolutionary attempt to obtain heat from abandoned coal mines.

The result is a year-round sustainable system that uses recycled heat only. In winter, the water is hot so, it can be used for heating, while in summer it is cool, so it acts as a nature-friendly air conditioner - many houses in the area use this technology, saying goodbye to polluting solutions.

The relatively simple method is based on the natural flooding of mines. Mines are filled with water from time to time, (this natural process can also be induced with human intervention) and towns on top of the resulting underground waterways can obtain energy via heat pumps from the naturally hot or cool water.

Adam Black, an energy project manager at Lanchester Wines, fell in love with the technology when he had to solve the heating supply for a 37,000-square-metre wine warehouse, cheaply and in an environmentally friendly way. He learned that underneath the warehouse was the tunnel system of an old coal mine, which could be turned into a free energy supply system, it just needed to be accessed.

With help of experts from Iceland, his team drilled into the old shafts beneath the company, from which 15-degree, pleasantly warm water burst. With some supplemental warmth from an electric heat pump, it was perfect for keeping the company's warehouse, and the wine bottles within, at the right temperature.

Geothermal energy is as old as human civilization: according to researchers the Paleoindians were the first to use hot springs, and natural heat sources for baking, cooking, or even ritual purposes. The movement of tectonic plates can generate heat, even close to the surface, so some countries, such as Iceland, can benefit from this.

Just to give you an idea of the proportions involved: an Icelandic company called Friðheimar, which produces about 40 percent of the country’s tomatoes in its 11,000-square-meter greenhouses, uses only environmental resources for heating and lighting. "Our plant needs as much energy as a settlement of seven thousand people" – Dóróthea Ármann said to BBC.

Although such efficient sub-surface geothermal energy is only available in few places, the use of former mines may significantly reduce air pollution in many countries. Abandoned mines have recently come into focus in the UK, as the last underground coal mine did not close until 2015. (Recently, another one would have been opened, but due to strong resistance, the project has been stalled for months.) The UK has committed itself to net-zero greenhouse gas emissions by 2050, with much focus on the nation’s heating needs, which account for around half of total energy usage.

The UK Coal Authority is currently exploring the feasibility of seventy projects addressing the heat generation potential of disused pits. It is estimated that one-quarter of British homes currently sit on a coalfield; the currently-untapped potential could give a huge boost to the British government’s ambitious plans.

According to Charlotte Adams, the UK Coal Authority's manager for mine energy, the heat produced in this way only generates 25 percent of the carbon emission of gas, even if the water obtained with this method needs to be purified, sometimes heated, or cooled, or even circulated. Moreover, it could be cheaper than gas, by about 10 percent, Adams estimates.

For a real success story, we should travel to the Netherlands, to the former mining town of Heerlen, which was transformed by geothermal energy experts in 2008. Today, it supplies five hundred buildings, homes and businesses with clean energy, reducing the settlement's carbon emissions by two-thirds. The Netherlands plans to say goodbye to gas production next year.

 

Cover: Getty Images