Silo addition changes by-product from waste to profit
An engineering firm specifies a bolted steel tank to solve a power station's fly ash storage problem.
Every year, US power companies burn more than 1 billion tons of coal, resulting in more than 100 million tons of by-products, including some 70 million tons of fly ash, a glassy, powdery material. For decades, many power plants disposed of fly ash by sluicing it to closely regulated disposal ponds. But as land and water have become less plentiful and environmental regulations more stringent, it's become less practical for power plants to use this solution. Other power plants dispose of their fly ash by trucking it to landfills. Here, they have the advantage of being able to compact the material more thoroughly (thus disposing of more material per cubic foot) and of piling the fly ash upward, above the ground.