Renewable portfolio standards have required utilities to generate a portion of their electricity from renewable sources such as wind, the sun, or biomass (a fuel source comprising wood waste, municipal solid waste, grasses, and/or agricultural byproducts). Cofiring biomass and coal has been one way to harness a sustainable resource while continuing to provide energy at a low cost.
Wyandotte Municipal Services hired Barr to study cofiring coal with biomass at its power plant. We performed a test burn to uncover potential fatal flaws and determine how to best control the flow rate of biomass being fed to the boiler, which entailed temporarily using the plant’s limestone silo and feeders.
The project included three tests, a 25-ton material-handling test to determine whether the biomass would feed through the coal-handling system, and two eight-hour tests using 15 and 30 percent biomass, respectively. Barr evaluated the boiler capacity and thermal efficiency, as well as the approximate emission reductions gained from cofiring, and identified operational constraints. Although the utility ultimately decided to pursue other avenues for meeting the renewable portfolio standards, the test burn demonstrated that cofiring was a viable option for the facility.
The Wyandotte test burn was featured in an article titled “Biomass and Coal: A Powerful Combination,” in the August 2011 issue of Biomass Magazine.
A copy of the full test report is available from the state of Michigan's website.