In this issue
		Energy Services Bulletin home page
		Innovative ownership makes wind farm a good neighbor
		Arizona co-op cleans up with fly ash sales
		California utilities test peak-shifting cooling technology
		BPU helps Kansas City's biotech industry grow
		Updated cooling rebate program targets commercial customers
		Air Force leads Federal agencies in green power purchases
		Resort area utilities grapple with price of popularity
		Energy organizations make plan to encourage efficiency
		EPTC wind farm simulator answers interconnection questions
		Seminar prepares public utilities for Colorado RPS
		Topics from the Power Line: Select the right heat pump for residential heating and cooling
		Energy shorts
		Technology Spotlight: The rising cost of steam
		Calendar of events

Arizona co-op cleans up with fly ash sales

The Apache Station coal-fired powerplant produces thousands of tons of fly ash annually that AEPCO markets to concrete manufacturers. (Photo by Boral Material Technologies)

Fly ash, a byproduct of burning coal to produce energy, can pose an expensive disposal problem for utilities with coal-fired plants, unless the utility is Arizona Electric Power Cooperative, which considers fly ash a marketable commodity with positive impact on its bottom line.

Years ago, the Benson, Ariz., co-op sluiced the fly ash from its Apache Generating Station into a landfill, the standard method for handling the waste material. But there are many costs associated with ash ponds, as the sites are called, said AEPCO Regulatory Affairs Manager Jim Andrew. "There's the cost of water for sluicing, and when a pond reaches the end of its life, you have to close the old one and build a new one," he said. "With the necessary environmental safeguards, closure and construction are very expensive."

Fly ash needed for concrete

Boral Material Technologies, a coal-combustion-product marketer approached AEPCO with a better idea: sell the fly ash to concrete manufacturers. Fly ash that meets the ASTM standard C-618, as AEPCO's does, makes concrete more durable, said Rick Hoelscher, utility services director for Boral's western and southwestern regions. "The spherical structure of fly ash causes little bubbles to form in the concrete," he explained. "Those air pockets keep hardened concrete from cracking when temperature causes it to expand or contract."

Boral pays AEPCO for fly ash, turning the former waste material into a source of income for AEPCO. "We enjoy the royalties, but the cost savings from eliminating disposal costs are bigger," observed Andrew. Finding a beneficial use for a byproduct is good for public relations, he added, and, "our customer-owners see how the royalties contribute to the bottom line."

AEPCO's contract requires Boral to take 80 percent of the fly ash Apache Station produces. "We still keep a landfill for off-quality ash, but very little fly ash goes into it," said Andrew.

Maintaining quality to maintain value

Several factors affect the quality of fly ash, said Hoelscher, starting with the collection method. "Once fly ash gets wet, the structure starts to change and it's no good for concrete," said Hoelscher.

Like most coal plants more than 30 years old, Apache vacuumed up its fly ash and sluiced it out to the holding pond. Boral had to change Apache's collection system from wet to dry.

Different types of coal produce different quantities, as well as quality of ash. High carbon content will ruin concrete, so the combustion process must burn as much carbon as possible. This presents a challenge, since running a cooler flame reduces the amount of nitrous oxide, a greenhouse gas, in plant emissions. "We work with our customers to minimize NOx while ensuring the quality of the fly ash," said Hoelscher.

Getting feedback from utilities on loss of ignition is critical, as is maintaining the coal-grinding equipment. "The finer the grind, the more complete the combustion," Hoelscher stated. "Over time, the ball mill wears down and the grind gets coarser, so it has to be regularly checked and adjusted."

Fly ash uses, demand growing

When Boral retrofitted the Apache Station's ash collection system, the company added a silo to hold the byproduct, too. AEPCO produces more fly ash during winter heating season, but the peak demand for concrete is during summer construction season.

Arizona is experiencing a construction boom, so there is plenty of demand for the concrete additive. "We can sell as much as we produce," said Andrew. "Our peak year was 2002 when we produced 146,000 tons of fly ash, and Boral took it all."

The growing interest in green building practices promises to keep the market healthy. "The fly ash content in concrete counts toward the recycled content credit for LEED certification," said Hoelscher.

The building industry has discovered that fly ash improves the performance and cuts costs of other construction materials besides concrete. Fly ash is a component in roofing tiles, carpet backing, wall board, siding and paver bricks. Different grades of ash are also finding use in road construction and even plastic piping.

The list of utilities turning waste into profit is getting longer, too. Boral currently markets fly ash for more 30 electric utilities, including Tri-State Generation and Transmission's Craig and Laramie River stations. Fly ash from Great River Energy's Coal Creek Station is a key component in Flexcrete aerated concrete.

Utilities interested in moving fly ash out of their waste stream and into the growing market place can contact the American Coal Ash Association. As AEPCO has shown, it's hard to find a better win-win solution for a utility, its customers and the environment.