Coal power is on borrowed time. Its exit from the U.S. mix is accelerating. In the U.K., records for consecutive days without any coal power being used have been tumbling. Later this month, Germany will hold a reverse auction that will see the country paying hard coal generators not to operate.

A new report by the think tank Ember finds that the global fleet of coal power plants is now running at a utilization rate of 47 percent. Phase-out dates for coal power are fast approaching across Europe. Most of the continent's major economies have targets this side of 2025; Germany's 2038 goal makes it the exception. 

So the writing for coal power itself is on the wall. But some of the infrastructure associated with the coal economy — mines and power stations alike — should not be so hastily scuttled.

Across Europe, a host of projects will use coal’s legacy to contribute to the energy transition. Some are still in the conceptual phase, but some are fully financed and ready to scale.

All in all, coal infrastructure could still play a role not just in power, but heat, energy storage, and carbon capture and storage.

1. From coal power to plastic power?

Edinburgh-headquartered Simec Atlantis Energy, better known for its MeyGen tidal generator, acquired the Uskmouth coal plant in Wales back in late 2017.

The 220-megawatt power station is to be converted from running on coal to burning a proprietary waste-derived fuel developed by Simec Atlantis. The pellets are a mix of paper, cardboard and non-recyclable plastic, plastic that in the past would either have been shipped overseas or sent to landfill, both incurring not unsubstantial costs. Tim Cornelius, Simec Atlantis’ CEO, estimates that there is sufficient plastic waste of this kind to support 1 gigawatt of power generation in the U.K.

Trials of the pellets and the milling process to make them have been successfully completed, and the technology is garnering interest, Cornelius said. 

“We've had coal-fired power station owners from China, India, the U.S., Australia and across continental Europe all visiting, desperate to understand the results of the trials,” said Cornelius in an interview earlier this year. The conversion of each 110-megawatt generator will happen one at a time. A tender for engineering, procurement and construction contractors is expected to conclude in Q1 2021 with financial close following shortly after.

2. Flooding mines for district heating

The thing about mines is that they are very hot. By pumping water through flooded mines, where it warms up, you have the bones of a district heating system. If the water temperatures aren't that high, you just need to make sure the end users are located in close proximity.

In February, the U.K. approved the first district heating scheme to use water from a coal mine. The Seaham Garden Village development is being built next to a drinking water treatment plant owned by the government’s Coal Authority. The water reaches the surface at temperatures up to 20 degrees Celsius and will have an output of 6 megawatts.

In total, 1,500 homes will be warmed by the flooded mine below.

The U.K. Coal Authority believes every community above Britain’s coalfields — which run from southern Scotland through large parts of England and into Wales — could get its space heating using this method. That equates to a quarter of all the country’s houses.

A smaller 2-megawatt system in Spain is already operating on a similar basis, with plans to scale it up to 6 megawatts.

Heat is the single-largest source of emissions in the U.K. With progress on decarbonizing heat slow across Europe, and heat networks in far too limited a supply, distributed heat centers, like mines or waste heat from industrial processes, are likely to be utilized in greater numbers.

3. Exploring carbon capture and storage potential

Last month, academics from Wales, Germany and Poland launched a pilot project to inject CO2 into a test site in Mikołów, Poland. 

The test mine, ‘Barbara’, will have a horizontal well drilled at a depth of 50 meters using the existing mineshafts to avoid any vertical drilling. The researchers hope to improve the volume of gas that can be stored inside the coal seam itself. They’ll also conduct a real-world environment risk assessment before choosing a location for a commercial-scale project.

“As many European regions have significant, rich coal deposits, partnerships such as this can play a pivotal role in meeting the EU’s carbon emission reduction targets,” said the project’s lead, Professor Hywel Thomas, in a statement.

Most European carbon-capture-and-storage projects focus on pumping CO2 into the seabed in the North Sea, but that option isn't available across the continent. Large-scale projects are few and far between thus far, despite years of hype. In May this year, oil majors Shell, Equinor and Total made the final investment decision on the Northern Lights project, which will pump CO2 into the seabed of the North Sea. It is the first project licensed to do so in Norwegian waters.

The ETES demonstration plant in Hamburg offers life beyond coal. (Credit: Siemens Gamesa)

4. Energy storage via hot rocks, dropped rocks and compressed air

Better known for its wind turbines, Siemens Gamesa might seem an unlikely candidate to convert old coal power plants. But the wind giant recognizes what longer-duration storage can do for renewables on the system, as well as for its own customers.

Siemens Gamesa's Electric Thermal Energy Storage technology can be used as a standalone technology, but it really comes into its own when used as a drop-in replacement at a coal power plant. The ETES system uses electricity and any spare waste heat that's available to raise the temperature of a vast pile of volcanic rocks to temperatures beyond 800 degrees Celsius. The heat can generate steam for a turbine to produce power or dispatch the heat itself.

Hasan Özdem, head of technology management and projects for Siemens Gamesa, told GTM earlier this year that ETES changes the narrative for the power sector. “It was wind and solar versus coal and gas power plants. What we are saying is no: ETES can give those conventional power plants a space in the energy future by turning them into green storage facilities.”

A 30-megawatt/130-megawatt-hour demonstration plant in Hamburg, Germany has already been running for a year. The company has held talks with 10 potential customers and is ready to scale a modular system up into the gigawatt-hour range.

There is also research to use coal mines for a variety of other energy storage methods. Flooded mines could use chambers at different depths to create underground pumped hydro. Gravity-based storage concepts, like Gravitricity, could make use of existing mine shafts. Coal mines are also considered good candidates for compressed air storage projects, according to early research efforts.