Wisconsin Electric Power Co. (WEPCO) told the Wisconsin Public Service Commission on July 7 that it and Madison Gas and Electric Co. (MGE) and WPPI Energy are making progress in adding the ability to fire Powder River Basin coal at Elm Road Generating Station Units 1 and 2.
The new units, located at the existing Oak Creek power plant, were built several years ago to fire primarily Pittsburgh-seam coal out of Northern Appalachia. But it was found that PRB coal has become a more cost-effective option. On a delivered Btu basis, PRB coal is now about 35% cheaper than bituminous coal.
“The overall Fuel Flexibility Project (‘Project’) is to utilize sub-bituminous coals in the Unit 1 and Unit 2 boilers by blending sub-bituminous and bituminous coals at various blend rates, from 0% (i.e., 100% bituminous coal), to 100% sub-bituminous coal (i.e., 0% bituminous coal),” the filing said. “This Application requests authority to fund the next steps, Stage 2 of the Project, to upgrade ERGS equipment to enable use of up to a 60% blend, by weight, of PRB coal and enable testing up to 100% PRB.”
During Stage 1, extensive demonstration testing and several modifications, including boiler modifications, were completed at ERGS to prove project feasibility. Completion of Stage 1 resulted in the units reliably operating at a sustained 20% PRB blend.
Given the current coal storage capacity at the site the ERGS units have a limited ability to operate at levels above 20% PRB blend on a sustained basis. Stage 2 does not include an increase in the coal storage capacity or modification of the fuel handling equipment and thus sustained operation on blends of more than 20% PRB will continue to be limited even after the completion of Stage 2. Expansion of the coal storage capacity and modification of the fuel handling equipment may be included in future applications.
The ERGS units each having a net capacity of about 634 MWe. Unit 1 went into service in 2010 and Unit 2 in 2011. The ERGS facilities are operated by WEPCO and are majority-owned by Elm Road Generating Station Supercritical LLC. MGE and WPPI each have 8.33% part-ownership of ERGS.
Gradual process underway to ramp up PRB coal in blends
At each incremental step of the PRB coal content ramp up, the test data is closely monitored and evaluated for both immediate limitations (e.g., control systems and logic, fan capacity, pulverizer capacity, etc.) and long term effects (e.g., boiler slagging and fouling, ash and gypsum quality, waste water treatment system effects, etc.). In an effort to minimize operational risk, testing is confined to one unit until confidence is gained with operational performance at various sub-bituminous coal blends.
During the Stage 2 work, the goals are to achieve usage of a 60% PRB coal blend, by weight, while maintaining current net generating capacity, and to test at higher blend rates up to 100% PRB.
Testing began in May 2013 on Unit 2. Testing began by blending 20% PRB with 80% bituminous coal. In January 2014, the blend was increased to a 40% PRB and 60% bituminous coal mix. In May 2014 the blend was increased to a 60% PRB and 40% bituminous coal blend. The 40% PRB and 60% PRB test burns were limited, short duration tests to evaluate the short term impacts to define possible activities and modifications that may be addressed during the upcoming 2014 Fall outage for Unit 2. Long-term effects of using a 40% PRB blend will be evaluated over the Summer/Fall of 2014.
Approximately $100,000-200,000 per unit per week has been saved by WEPCO, MG&E and WPPI in fuel costs associated with using more sub-bituminous coal since beginning the project, the application noted.
Commission approval of Stage 2 costs is requested by December 2014. That timing will provide the ability to complete identified modifications on Unit 2 during the 2015 Fall outage, enabling testing of the next incremental blend following the unit’s return to service. Under the current Air Pollution Control Construction Permit for these units, all modifications would have to be completed and placed into service on both units by July 11, 2016, unless an extension is granted.
U.S. Energy Information Administration data shows coal deliveries to Elm Road earlier this year of Pittsburgh-seam coal out of the Federal No. 2 mine of Patriot Coal, the Emerald mine of Alpha Natural Resources and the Bailey complex of CONSOL Energy, with PRB deliveries out of the North Antelope Rochelle mine in Wyoming of Peabody Energy.