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PFA and the circular economy

Matthew Eynon* says the decline in coal-fired electricity production will have a knock-on effect on mine-works stabilisation.

kjhIt was announced recently that Aberthaw Power Station in the Vale of Glamorgan is to downgrade operations due to ‘challenging market conditions’1 and from April 2017 will only generate electricity when needed (i.e. predominantly during winter).  The last few days in South Wales has also seen climate protesters occupying the coal mine at Ffos Y Fran under the #EndCoal banner2.

It is obvious that huge pressures are bearing down on the coal and energy industry in the UK due to global commercial, environmental and social realities.  These are unlikely to change significantly in the short term.  But a major by-product from coal-fired power stations is Pulverised Fuel Ash (PFA), a key recycled aggregate in the construction industry, with large environmental and economic benefits. 


Given its pozzolanic nature, PFA is used in low carbon cement, concrete and as a major component in the grout mixture used for stabilising historical coal mine-workings; typically for new developments where there is a risk of subsidence at the surface, utilising the WRAP protocol to meet the ‘End of Waste’ criteria3.

We have seen an increase in PFA costs through 2016 so far and, based on the forecast restriction of supply, can expect this cost increase to accelerate - as has been experienced in Scotland recently since the closure of Cockenzie power station in 2013.

What likely overall impact is restricted supply of PFA going to have on the construction industry in South Wales and other local coalfields?  Will it perhaps drive research into suitable alternatives (virgin and recycled)?

It may be that the circular economy cannot immediately provide suitable recycled aggregates; so virgin products could become necessary until materials research catches up and produces a practical reality.  So, for the short-medium term at least, you can probably expect an increase in the project costs of mine-works stabilisation, until the supply and demand balance is restored.


At my company we foresee that contract terms for mine-works stabilisation projects will become an important issue over coming months, as predicting and providing certainty on PFA costs may be challenging to those unaware of this issue.  We are currently reviewing contracts for a range of live projects and implementing cost-sensitivity assessments linked to this matter.

Planning mine-works stabilisation projects during the cold months, as one possible means of addressing peaks and troughs of supply/demand,may become a reality for large or marginal sites.  Some developments may become unviable through a difficult period of austerity, until land values or other commercial factors, including new aggregate sources, redress the balance.



*Matt Eynon CGeol is a UK Registered Ground Engineering Specialist with Earth Science Partnership Ltd