Dead lakes, dry holes: RWE’s post-mining plans threatened by climate change

RWE is digging the biggest hole in Europe for dirty lignite – and they don’t have a working plan to deal with the consequences, says L. Michael Buchsbaum.

RWE’s plans for land cleanup after mining are shockingly irresponsible

RWE’s plans for land cleanup after mining are shockingly irresponsible (Photo by Ende Gelände, CC BY-SA 2.0)

Last year’s record reduced water flowing through Germany’s Rhine River should be setting off alarm bells for myriad reasons. Ever-worsening climate change is reducing precipitation in its Swiss headwaters, suggesting that this year’s “low water event” will not be uncommon going forward.

This water scarcity will also have a major impact on the future of the three giant open pit lignite mines in the Rhineland coalfields west of Cologne. The pits are owned by RWE, which must now realize how preposterous its long-term recultivation plans are when faced with climate change-induced droughts.

Impacts of lignite mining

Put together, the Hambach, Garzweiler and Inden mines produce around 100 million tons of filthy lignite annually, which is fed into three nearby RWE owned power plant complexes. These plants are some of the most toxic emitters in Europe, the source of some 75 million tons of annual CO2 emissions.

While opposition to coal mining and burning has increased, international media has mainly focused on the continuing clashes around the embattled Hambach Forest or the looming destruction of several villages dotted around the growing surface mines. Most people don’t know that RWE’s plans for land cleanup after mining are shockingly irresponsible.

Producing over 40 million tons of lignite per year, the Hambach is the largest mine in Germany. Uncovering all that lignite requires miners to displace another 220 to 250 million square meters of “overburden” or soil, most of which is dumped nearby. Over 85 square kilometers in size and with mining operations in the pit over 500 meters (1,640 feet) below the surface, the Hambach is both the deepest and largest hole in Europe.

The German Great Lakes

But what’s to be done with the giant Hambach hole once mining is complete? RWE plans to turn it into a vast lake over 4200 hectares in size and up to 400 meters deep.

To fill it, the company will require a volume of over 3.6 billion cubic meters of water to be diverted from rivers over a period of at least 40 years, most likely through 2100.

However, the future artificial lake may be further enlarged if officials permit RWE to also flood the nearby Inden open pit mine as well as the older Bergheim pit. Either way, the planned “Lake Hambach” would become the deepest and, after Lake Constance, the second largest lake in Germany.

It won’t be the only mammoth new water body in the area.

Several kilometers away sits the currently expanding Garzweiler mine. When production there ends, also in the 2040s, RWE is planning to create Garzweiler Lake stretching across a 2,300 hectare surface area with waters over 200 meters deep. For this, the company plans to fill it up with another 60 million cubic meters of water per year, also over a 40-year period (roughly 2.4 billion cubic meters).

Beyond then, even after the lake reaches a planned water level of 65 meters above sea level, it will still need to be topped up annually with another 25 million cubic meters more of Rhine water in order to offset outgoing flow losses from years of RWE’s drilling into the Earth and disturbing the natural ground water table in the area.

RWE has no idea what they’re doing

Since the 1980s, RWE has “recultivated” much of the area by planting millions of trees, many of which populate the otherwise desert-like slopes of the largest artificial hill in Germany, the Sophienhöhe, sitting adjacent to and comprised of soil and dirt that was once inside the Hambach mine. However, polluted water run-off from this and other spoil heaps located directly beside the envisioned lakes will likely acidify them, fouling the diverted Rhine water and rendering the new lakes lifeless for decades to come as well as unsafe for most recreational activities. Though RWE and other companies proudly show off similar (albeit much smaller) artificial lakes–the largest only being only around 100 hectares–as positive post-mining land uses, experts admit that much of the “lake” water is unhealthy and humans should limit their recreational activities.

In addition, it’s not even clear if RWE will be able to get the water to fill the holes: diversions of this size have never been attempted before. And given that the Rhine River is now regularly flowing lower than usual, it’s also unsure where this water will even come from. It sounds almost like a cruel joke: the water needed to fill in these enormous pits is getting scarcer, due to climate change exacerbated by the reckless burning of lignite.

Finally, by flooding the mines, any potential for “standard” renewable energy to be built within these vast spaces will be eliminated unless expensive floating wind or solar farms are constructed. But even if RWE simply back-fills them with the removed earth, that’s not enough to allow renewable energy redevelopment. Once excavated and replaced, the uncompacted soil “swells” the land, rendering future wind-farming challenging as turbines cannot be safely anchored. That requires more expensive additional steps—as we will discuss in another post.

As ludicrous as these schemes are, beyond filling the pits with Rhine water, there doesn’t seem to be a Plan B. Nevertheless, RWE and the state government of North Rhine-Westphalia insists that the mines should continue to be expanded for decades to come, seemingly unconcerned with what to do with the gaping holes once all that coal is removed.


L. Michael Buchsbaum is an energy and mining journalist and industrial photographer based in Germany. Since the mid-1990s, he has covered the social, environmental, economic and political impacts of the transition from fossil fuels towards renewables for dozens of industry magazines, journals, institutions and corporate clients. Born in the U.S., he emigrated to Germany and Europe to better document the Energiewende. He is also the host of The Global Energy Transition Podcast.

1 Comment

  1. James Wimberley says

    The World Bank, a pretty reliable source, says (link) :

    “While up-front costs are slightly higher, the costs over time of floating solar are at par with traditional solar, because of floating solar’s higher energy yield – due to the cooling effect of water.”

    Since the lakes will be pretty useless for other activities for a long time, floating solar farms are quite an attractive option.

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