Coal Combustion By-Products (CCBs)
What does the future hold for CCBs?
It is difficult to predict what the future will hold, but several likely scenarios will emerge:
More CCBs Produced: Coal plays a very important role in the production of electricity in the US, and will continue to do so for the foreseeable future. Using more coal will result in the production of more CCBs. Even if we do not use more coal, reducing emission levels at current utilities will inevitably result in poorer quality CCBs that cannot be used in traditional markets and must therefore be disposed. We have a choice, either use more of the CCBs or dispose of increasing quantities in landfills.
Existing markets for ash cannot possibly use all of the ash that will be produced. We currently use less than half of the CCB's produced and as ash quality decreases, it will be increasingly difficult to even maintain this level, let alone increase it.
Different Types of CCBs: As new coal fired utilities are built, they will utilize technologies specifically focused on reducing emissions, such as gasification and clean coal technologies (CCT). While these technologies do an exceptional job at reducing emissions, they generate large quantities of by-products. Since CCT is quite different from conventional pulverized coal combustion (PCC), it is not surprising that CCT by-products are very different from PCC by-products. Many industries use PCC by-products because they have been available for many years and their uses are well understood. Uses for CCT by-products are not nearly as well understood, and it will take time to generate the knowledge as well as the utilization markets.
More Ash Beneficiation: This is already being done at many utilities in order to provide a consistent quality product, but should become more commonplace in the future. Most of the beneficiation now practiced is to reduce the amount of unburned carbon in ash to below specification levels. As more utilities convert to low NOx burners, there will be less high-quality ash available for traditional uses and it will be necessary to beneficiate simply to preserve existing markets. It is possible that ash may be reclaimed from old landfills and beneficiated, particularly if the stored ash is of marginal quality and the current ash quality is very poor.
Development of Consumer Markets: Most of the current CCBs are utilized as commodity components by large industries and very little is marketed directly to consumers. Consumer products represent a significant marketing opportunity for CCBs since most consumers have already demonstrated a preference for recycled products. CCBs are not readily available in most consumer products, but that is changing.
Prepackaged concrete containing processed CCBs is now being produced by Quickcrete in limited market areas. Instead of using aggregate from local quarries, they are using processed bottom ash. There is no difference in the performance of the concrete and the product has the added benefit of offering customers the opportunity to use a product containing a high proportion of recycled material.
Coal Combustion By-products (CCBs) are used in some of today's products which are used in the construction and transportation industries. Check out what some of these current uses are in a typical suburban home ...
| Animated (Flash) Movies* | Web pages with Graphics |
| Today's House - use of CCB-based products | |
| Today's House |
Another consumer product that contains CCBs is synthetic lumber, frequently used for deck construction. Decks made with this recycled product are less prone to splintering and will last much longer than decks made with pressure-treated lumber. Again, the consumer has the choice of using a product that is comprised primarily of recycled material.
Other home products containing CCBs such as siding, roofing shingles, paving bricks, tiles and blocks are already available, and it is likely that many more will soon find their way to the store shelf.
With additional appropriate regulatory and economic incentives, the future for these recyclable materials could be bright. Additional research will yield yet more products and uses in the "house of tomorrow" ...
| Animated (Flash) Movies* | Web pages with Graphics |
| Future House - potential uses of CCB-based products | |
| Future House |
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- Current CCB-based Products include:
(as seen in the above "Today's House" movie) - Road base (from fly ash)
- Additives for flowable fills (from fly ash)
- Foundation (footers/basement walls from fly ash)
- Driveway (concrete additive from PCC fly ash)
- Wallboard (from flue gas scrubbers)
- Roofing granules (From cyclone combustors)
- Garden, agriculture and soil modification (from fly ash)
- Potential CCB-based Products include:
(as seen in the above "Future House" movie) - Driveway (concrete from FBC ash-based low energy cements)
- Sewer pipes from super pozzolans
- Masonry blocks (from PCC bottom ash)
- Bricks for fireplaces (from fly ash)
- PVC water pipes (from fly ash)
- Rot-resistant concrete back board for tub/shower area (from bottom ash)
- Ceramic wall & floor tiles and grout (from fly ash)
- Roofing granules (from cyclone combustors)
- Bricks for siding (from fly ash)
- Ash-filled plastic lumber for decks and siding