Aberthaw Ash Should Be Treated as a National Resource

There are some industrial materials which would be treated very differently if they were discovered today, detached from the history that produced them. The pulverised fuel ash at Aberthaw is one of them.

Pulverised fuel ash, or PFA, is the fine ash produced when pulverised coal is burned in a power station. At the former Aberthaw Power Station, CCR Energy estimates that there are around 18 million tonnes of it, held in a mound some 50 metres high across the site. Because it is associated with coal-fired generation, it is easy for people to see it only as a legacy issue. In my view, that is the wrong starting point.

If a geologist found a finite deposit of predominantly aluminosilicate material with proven cementitious potential, we would be talking about safeguarding it. We would recognise it as a resource. We would ask how to use it properly and how to make sure it was not wasted. The fact that this material came from a power station should not prevent us from taking the same view.

I have worked with fly ash for many years, including in the cement industry and through the UK Quality Ash Association. Over that time, I have seen fly ash processed, commercialised and used successfully in cementitious and non-cementitious markets. That experience makes me cautious about claims which are not proven at scale, but it also makes me very clear about the opportunity that exists when the material is understood and handled properly.

For me, Aberthaw should be seen as part of a national resource. Once this material is gone, it is gone. Coal-fired power stations are no longer going to produce significant quantities of fly ash in the UK. That means decisions about its future should not be made as though it were simply something to clear away. It has to be assessed as a finite material with potential value for construction, carbon reduction and UK resource security.

The UK has only a limited number of major single-site legacy fly ash deposits of this scale. Aberthaw is one of the few that could make a meaningful contribution to the cementitious market for many years. That is significant because there is potential demand for several million tonnes/year of supplementary cementitious materials in the UK. Aberthaw cannot meet all of that demand, but it could make a valuable contribution.

This is becoming increasingly important because the UK is moving from a position where fly ash was continuously produced by coal-fired power stations to one where future indigenous supply must increasingly come from legacy deposits. At the same time, the cement and concrete industries need increasing quantities of lower-carbon supplementary cementitious materials. That changes the way we should think about deposits such as Aberthaw. There is also a resource-security argument: making greater use of indigenous legacy fly ash can reduce dependence on imported cementitious materials while retaining more of the economic value within the UK.

The reason this matters commercially is that the underlying cementitious market is established rather than speculative. Fly ash has been used for many decades as a supplementary cementitious material, and proven technologies exist to dry, classify and, where necessary, remove excess carbon from stockpiled material. There are also markets in blocks and other construction products, from simpler applications through to more sophisticated products such as autoclaved aerated concrete blocks.

That does not mean every question has been answered. At Aberthaw, one of the key technical issues I would particularly want to understand is chloride content, alongside the normal characterisation of variability, moisture, fineness, carbon content and other relevant chemical properties.

We know from previous experience that the ash has the potential to work well. We know the broad mineral content and we know processing technologies are available. But chlorides can affect where material can be used, particularly in reinforced concrete and related applications.

Getting that result would allow much more informed conversations with potential partners and investors.

That is an important distinction. There is no shortage of interesting ideas around fly ash, including rare earth extraction, geopolymers and other novel uses. Some may prove valuable, and it is right that CCR Energy is looking broadly at the options rather than becoming fixed on one route too early. But there is also value in momentum. A clear technical result, followed by focused discussions with credible partners, can turn a general opportunity into something much more practical.

The carbon case is also strong. Work we have done, albeit at benchtop level, indicates that every tonne of cement replaced by using processed coal-derived fly ash from legacy stockpiles saves some 760kg of CO₂. Processing has its own footprint, particularly drying, but if renewable energy can be used for that stage, the overall benefit becomes even more significant. That creates both a commercial and a societal argument for making good use of the material.

There is also a wider discussion about the best commercial model. If the public sector simply sells the material too cheaply, it may lose long-term value. If it prices it too high, it may limit the market. A partnership or equity-based approach could allow value to be shared over time, particularly if the material increases in importance as demand for supplementary cementitious materials grows.

I am not dismissive of the more innovative possibilities. Rare earth elements are clearly of strategic interest, and other countries have looked at fly ash through that lens. But any extraction route has to be judged carefully. Some processes use strong acids, and if they render the remaining material unusable, then one potential value stream may be gained at the expense of another. The best approach is to look at all options, but to test them against what is commercially proven, scalable and capable of preserving value.

That is why I keep returning to the idea of Aberthaw as a national resource. It is not only a site issue for South Wales, nor only a legacy of coal-fired generation. It is a finite material which could support the UK’s need for lower-carbon construction products, improve domestic resource security, reduce reliance on primary and imported materials, and create a platform for further innovation.

The next step should be practical. Establish the key technical facts, particularly around chloride content. Use those facts to engage serious partners. Build momentum through routes that can generate cash flow, while allowing more innovative work to continue in parallel.

Aberthaw’s ash should not be treated as a liability to be disposed of, but as a resource whose value needs to be protected, proven and put to use.