Mine water could heat schools, but officers urge caution

Heat from underground mine water could potentially be used to warm schools in north Wales according to a report by the Coal Authority.

Flintshire County Council’s Environment and Economy Overview and Scrutiny Committee will consider the report next Tuesday which suggests drawing water used for heating from disused mines.

But council officers have advised members that more research is needed into the effectiveness of the idea and the long term costs and savings before they consider implementing the system.

According to the Coal Authority report ground source heat pumps, using either gravity or a borehole, draw water from abandoned coal and metal mines – which typically sits at a temperature of around 21°C – compress it to increase the temperature and use it to provide heating for buildings.

The system would be designed to offer a low-carbon alternative to gas boilers and, while maintenance costs for the heat pumps would be higher, the scheme could represent an overall saving while reducing the carbon impact of school water use.

Two potentially viable areas and one more complicated option have been identified in the report.

According to the report the most promising site for implementation is Hawarden High School. This would use gravity to pipe mine water downhill into the system from the Prescott Level drainage tunnel which channels water from underneath private land owned by Hawarden Estate.

This would be difficult to implement however as it would require laying a 380m pipe through Grade II listed woodland to reach the school.

In Buckley a potential mine water network has been identified including the Elfed High School, Mountain Lane CP School, Southdown CP School, Westwood CP School, and Westwood Centre (early years).

There is also a potentially viable cluster in Mold covering Mold Alun, Ysgol Maes Garmon, Ysgol Glanrafon and Ysgol Bryn Coch.

Effectiveness 

In their advice to members however, officers said it was too early to adopt the new technology, stating more evidence was needed to prove its long-term effectiveness and value.

“As a new technology, many risks are difficult to assess, including long-term financial affordability of operation and maintenance,” they stated in the report.

“Risks and unknowns prevent a definite case for progressing development at this stage. The case for progressing with a specialist feasibility study must be weighed against the time and resource implications in relation to the potential benefits and outcomes of the project.

“Decarbonisation will inevitably mean transitioning from gas boilers. Air source heat pumps have significantly lower capital costs, but potentially higher running costs.

“The question is whether investing in a mine water ground-sourced system will offer a more efficient and affordable system in the long-term, or whether the complexity of maintenance will cause great problems that draw upon  disproportionate time resource.

“The most promising site in this study so far is Hawarden, which is still expected to require a secondary source of energy to cover the full heat demand.

“Ultimately, an efficient transition from gas boilers must take into account the complete process. A ground-source heat pump system may theoretically be more efficient in operation, but using mine water will increase maintenance costs, requires multiple heating systems for Hawarden High School and causes significant negative impact on habitat and road disruption through installation.

“There is currently not a case to proceed due to disproportionate time resource compared to other readily accessible technologies.”

Committee members will consider the report on Tuesday, January 13.