BURGIN — Last week, Kentucky Utilities asked the state Public Service Commission for a rate hike that will increase customers’ bills by 12.2 percent over the next four years. KU says it needs the additional revenue to pay for the $2.5-billion in improvements to its coal-fired generating plants like the E.W. Brown facility near Burgin — improvements mandated by the federal Environmental Protection Agency in order to reduce harmful emissions.
“The money has to come from somewhere,” said KU spokesman Cliff Feltham. Thanks to a settlement reached with the EPA in 2009 after the federal agency found the Brown plant was in violation of the Clean Air Act, KU has already taken steps to significantly reduce the amount of sulphur dioxide — which causes acid rain, smog and other environmental hazards — coming from the massive smokestacks at Brown.And the electric company turned to a neighbor six miles down Burgin Road, Mercer Stone, to help solve its emissions troubles with limestone taken from the ground at Mercer Stone’s facility.
"It's certainly a fascinating way to resolve the situation," said Bobby Upchurch, vice president for Mago Construction Co. which owns Mercer Stone. "We're taking one of Kentucky’s most natural and abundant resources — limestone — to create a cleaner way to use another one of Kentucky’s most natural and plentiful resources — coal."
The 120-foot-deep limestone pit at Mercer Stone spans the length of 10 football fields. Until two years ago, the rock from there was mostly used in making concrete and blacktop. Now, ton after ton of the limestone is crushed into marble-sized chunks and delivered to E.W. Brown, where it undergoes further pulverizing and is mixed with water before being used to help the plant produce cleaner energy.“When I started 46 years ago, I never imagined for a second that limestone would eventually become be an ingredient that would filter out pollutants and result in cleaner air,” said Mercer Stone superintendent Jerry Thomas.
The process at Mercer Stone involves a series of large machines that remove the limestone, clean it of dirt and other unwanted rock, and then crush it into usable pieces. Eventually the process creates a product know as scrubber stone.“In order to become scrubber stone, we have to crush it three times and screen it four times,” Thomas explained.Even though the limestone is in tiny pieces at this point, there’s a lot more crushing to do when it arrives at Brown.
“Once the scrubber stone is delivered, we process it even further,” Feltham said. “We pummel the scrubber stone into an extremely fine powder at which point we add water to it.”That mixture is known as slurry and looks more like dirty water than any form of rock. “Slurry is injected into the flue gas chimney and what takes place is a chemical process in the chimney in which the sulfur dioxide of flue gas attaches to the slurry,” said Feltham, noting that 98.5 percent of the sulfur dioxide is eliminated in this process.“Moreover, it’s a combination of the slurry and the sulfur dioxide which falls to the bottom of the stack in the form of ash that creates a useful byproduct,” said Feltham. “The ash can be recycled into gypsum board, better know as drywall.”
Since the E.W. Brown plant has removed almost all of its sulfur dioxide emission, the facility is in good standing with the EPA in regards to that particular chemical byproduct. But KU is now in the process of addressing two additional EPA issues: reducing particulates and mercury control at E.W. Brown and it’s sister plant, Ghent, in Carroll County. The company is in the process of installing something called a “fabric-filter baghouse system” at each of the plants to address those issues.The cost of those improvements, according to KU, will cost approximately $1.1 billion.