Coal: more than meets the eye

Under its five-year plan, the Coal Authority is managing its historic mining legacy issues in a way that is transforming them from challenges to opportunities, including for utilities, says Peter Thorn.

What has the Coal Authority, an executive non-departmental public body that manages around £3 billion worth of coal mining legacy issues, got to do with utilities?

Well for starters, it treats more than 120 billion litres of water a year – water that has the potential to supply around 63MW of heat energy per annum and generates iron-rich by-products.

The land it has, with grid connections and pumping flexibility, provides opportunities in the capacity and dynamic demand power markets.

Plus, its data holdings and mining expertise allow anyone working in a place that has seen mining activity in the past to gain assurances regarding risk and mitigation before embarking on any work, from major infrastructure to cable or pipe laying.

A five-year plan was developed for the Coal Authority that included commercial activities to generate income from sources other than the funding it receives from the Department of Energy and Climate Change (Decc), improving efficiency and reducing its carbon footprint. Three years into this plan, the Authority is on track but has even greater ambitions for the future.

Mine water treatment                                                                                            

The Authority operates 75 mine water treatment schemes, protecting more than 350km of rivers and several strategic aquifers from pollution caused by former coal and metal mining activities. The number of treatment schemes increases each year, which would increase operation and maintenance costs were it not for the savings achieved through innovation. To offset costs, with the eventual aim of achieving a carbon- and cost-neutral portfolio of schemes, it is working to develop further efficiency savings and commercial income from these sites.

The heat and water generated through the treatment process and the iron ochre by-product created, which were once discarded, are now valued. All these elements provide potential income streams, together with the land and grid access, which can offset the construction and operational cost of protecting the water environment.

Energy                                                                                                                     

Energy is a large part of the organisation’s operational costs. Renewable energy sources, such as solar cells and heat recovery systems, have been installed to reduce energy costs.

As well as self-generation and using more efficient machinery, the Authority is developing options to better manage energy across its portfolio and to make the most out of the capacity and demand response market. Many mine water treatment schemes are able to increase or decrease pumping to control mine water levels. Managing demand response is considered key to income generation and the sustainability of operations.

Working with developers, local authorities and Decc’s Heat Network Distribution Unit, sites with between 0.5 and 6MW of heat capacity are being mapped, with a view to getting the first of many heat networks ­running within the next 12 to 18 months.

Water company synergies                                                                                     

Some of the mine water sites provide water that is almost of potable standard, requiring little or no treatment before delivering into industry or agriculture, freeing up potable supplies for use elsewhere. This could be supplied privately or in partnership with a water company through the mains network. The Coal Authority is also looking at alternative end uses for water that is not potable.

The Authority’s Lamesley scheme near Newcastle has been co-treating mine water and secondary treated wastewater effluent together in constructed wetlands for more than ten years. This co-treatment process helps manage both iron and phosphate loading. A recent performance review of long-term monitoring data showed that the passive co-treatment scheme operates effectively all year round, which is attributed to the heat of the mine water maintaining ­biological processes throughout the year.

Another area of research being looked at is raw mine water discharging directly to mine water treatment works to reduce chemical coagulation in primary settlement tanks, or to watercourses in limited concentrations to reduce phosphate loading. These phosphate reduction opportunities are likely to be more relevant in AMP7, when stricter ­phosphate limits are likely to be required.

Data and expert services                                                                                       

When working in former mining areas it is essential to understand the risks involved. These can be related to shallow mine workings, mine entries such as shafts, and mine gas, among others. The Authority is able to provide expert advice as to whether there are mining hazards in an area; and if there are, how such hazards can be mitigated. These services are supported by the data sets it can provide for developments, standard mine hazard reports or bespoke advice.

Working with the Coal Authority can ­provide value to utility companies through:

• Managing mining risk on a land and ­infrastructure portfolio;
• Working in partnership in research, ­development and innovation;
• Partnering for heat or water sales, or grid access.

The future?                                                                                                             

With this ambitious five-year plan driving the Coal Authority’s innovation and commercialisation, the future is looking bright. Historic mining legacy issues will be there for decades to come, but the Authority is changing this legacy from challenges to opportunities.