ScotAsh was set-up in 1999 as a joint venture between LaFarge cement and Scottish Power. In the financial year 2003/4 ScotAsh marketed nearly 500,000 tonnes of pulverised fly ash and fly bottom ash, from approximately 800,000 tonnes. The remainder of the ash goes to nearby, long term storage for potential future use. ScotAsh continues to develop markets for the ash, which is currently utilised in cement, concrete addition, waste stabilisation and land regeneration.
Prior to 1999, Scottish Power sold a lower quality ash to a smaller market, primarily the local cement works. There were two key barriers to increasing market sales. Firstly, most ash is produced in the winter, whilst most construction is in the summer. Secondly, the carbon content of ash for cement must be less than 7%, whilst the carbon content from the power station can vary from 5% to 20%. These were both overcome in 2003 with an £8 million investment in storage silos (to increase stockholding capacity), new blending and packaging facilities, and an ash beneficiation plant. The ash beneficiation plant utilises electrostatic technology to separate carbon (unburnt coal) from the ash. This can reduce the carbon content to as low as 1.5% and produces another valuable by-product, unburnt coal.
Using pulverised fly ash in cement, and as an addition to concrete mixes, can result in CO2 reductions of around 30% per tonne of cement produced, while each tonne of PFA re-used in cementitious products saves on average 900kg of CO2 emissions (ScotAsh, 2005a). Due to its low density, reusing ash in this way saves a greater weight of natural aggregates and reduces transportation impacts and costs. In the two years to March 2005, ScotAsh saved around one million tonnes of virgin aggregates (ScotAsh, 2005b).
| Industry Sector | Specific Industry |
|---|---|
| power utility sector |
|
| cement industry |
|
| raw material / ash recovery |
|
Forth Valley, Scotland, United Kingdom
Economic |
|
|---|---|
Environment |
|
Social |
|
None.
20 July 2010