With energy trends resulting in a move away from coal-fired plants, fly ash availability has been significantly reduced. This has presented a challenge for precasters that manufacture utility structures. In most cases, producers are required to use a pozzolan for resisting conditions that could negatively impact a structure’s integrity.
Varying degrees of this situation exist from coast-to-coast – as outlined below – and solutions to the shortage vary by location. But with the fly ash supply continuing to dwindle, now is an opportune time to examine alternative solutions, including slag, silica fume and silicon dioxide. Adding these materials to limestone could be part of the long-term solution. No matter which option proves to be the most fruitful, now is the time to find it – before the coal-fired power plant and its byproducts become outdated.
Members of the NPCA Utility Structures Product Committee offered their current experiences with the fly ash shortage, highlighting the various effects for precasters across the U.S.
Bruce Blackledge – Shea Concrete Products – Wilmington, Mass.
Even with the power plant in Somerset, Mass., running for about the last month, fly ash has been difficult to obtain on a consistent basis. For the most part, the situation has been, “Get in line and wait your turn.” We have primarily been using fly ash only when required (DOT-type work or if mandated by specifications). Many of us have supplemented with slag and are using it regularly. Many of us have and/or will run slag/cement mixes with testing to submit to the DOTs for review and acceptance as a fallback when Somerset ultimately shuts down again.
Chris Fitzpatrick – Oldcastle Precast – Westminster, Colo.
Fly ash in the West and Midwest has been the most reliable. There has been talk of allocation in California but to date it has not happened. The central U.S. region has a strong supply of fly ash thanks to production out of Texas and the Dakotas. The majority of the issues have been logistical challenges with the terminal and occasionally with the rail cars not making it to the terminal.
The East has had the biggest issue with fly ash supply. Many regions such as New England, the Virginias and the Carolinas have experienced allocation or lost their supply. As a result, New England and the Virginias switched from fly ash to slag this year.
Regardless of the current supply status, the days of having an affordable, reliable source of fly ash are nearly over. A decade ago, fly ash was largely viewed as a supplement to cement and was used because it was half the cost of cement. The durability conversation wasn’t the reason many people used fly ash.
It’s time for suppliers and DOTs to get ahead of the game. We need to work together to find alternate sources and open up the specifications. Let suppliers be creative in meeting durability needs, rather than prescribing the methods in which the DOT’s needs are met.
Tyler Haack – Jensen Precast – Fontana, Calif.
Fly ash suppliers on the West Coast have stated that they do not see any supply issues for this year. So at this moment, we feel satisfied with our supply, but will be keeping a close eye on it for our forecasted future.
Asher Kazmann – Locke Solutions – Houston, Texas
In summer 2016, we experienced a shortage of both Class C and Class F fly ash in Texas due to the shutdown of coal power plants resulting from low energy demand. Some concrete manufacturers had their fly ash supplies cut off completely during these summer months, but the fly ash supply did come back online at the end of the season.
Alternative materials have been used in place of fly ash, and at least one slag material has now been approved for TxDOT paving projects. In general, project engineers tend to allow the slag material in lieu of fly ash, but these discussions do not usually take place until after projects have been bid out.
To promote and maintain fair competition among concrete manufacturers, it’s imperative that specifiers and DOTs recognize the fly ash shortage and clearly allow for alternative materials in the project specifications.
Timothy Burke, P.E. – Headwaters Resources
Dynegy closed operations at Wood River this year and has begun shutting down units at other plants in Illinois. These changes remove approximately 80,000 tons of material from the St. Louis and southern Illinois markets.
But it’s not all doom and gloom for the industry. The Labadie and Rush Island plants are operational and have stabilized their materials in the face of new EPA regulations. The Illinois market has been ahead of the curve on this, as most plants were in compliance before the end of 2015. In Missouri, the market was slower to react as the state challenged regulations set forth by the EPA. There was a material shortage in the state due to poor quality in the first half of this year, which was the result of large plants testing different products to meet the EPA regulations. Now that testing is complete, these plants should continue to produce quality material suitable for use in all concrete applications.
Additionally, the Prairie State plant in Marissa, Ill., continues to roll along, producing material from coal harvested directly adjacent to the facility. Estimates indicate it will take at least 15 more years to mine all this coal. This means the plant is set to continue operations for at least ten more years and will also be able to continue production from the same, continuous source. The plant produces a Class F fly ash and has the capacity to produce several million tons of ash each year, which would be more than enough to supply the entire concrete industry in southern Illinois and eastern Missouri.
Now that all of the plants have settled in with emissions regulations, I believe the Illinois and Missouri region is in a strong position with the continuous availability of fly ash.
Outlook for the future
The following points, courtesy of the American Coal Ash Association, paint a picture of what to expect in the future:
- Despite coal plant retirements, coal usage is expected to grow 3.4% over the next two decades.
- Fly ash production is expected to increase 2.6% through 2033.
- Technologies to improve ash quality will increase the volume of ash available for beneficial use.
- Reclaiming fly ash from disposal facilities will increase supply.
While the availability of fly ash varies across the U.S., trends indicate that this once widely used resource is becoming increasingly scarce. As a result, professionals in the precast industry should not only monitor this downward trend, but also continue to research products to serve as a replacement.