Minnesota Power’s construction of new air emissions controls at the coal-fired Boswell Unit 4 is going along on schedule and actually below budget.
The utility updated the Minnesota Public Utilities Commission on the project in a Nov. 26 application for approval of a rate rider for the project.
The utility is installing Alstom’s circulating dry scrubber (CDS) technology, referred to as the NID system, for the removal of particulate matter (PM), SO2, acid gases including hydrochloric acid and trace metals, and other hazardous air pollutants being addressed by EPA regulations, while also reducing plant wastewater. In addition to the NID system, Minnesota Power is installing a powdered activated carbon (PAC) system to capture flue gas mercury, in combination with the fabric filter integral to the NID to control PM.
“Construction activities have been proceeding well,” Minnesota Power wrote. “Erection of the NID building is underway, as well as fabrication of the fabric filter components. The NID equipment is nearly all on site. The elevator foundation, silo foundation, and compressor building foundation and floor slab are complete. Overall, construction is approximately 37 percent complete, engineering is more than 96 percent complete and the project stands at more than 54 percent complete. Construction activities were halted in late November 2013 until spring 2014, while engineering and purchasing efforts continued through the winter. Construction activities resumed at the site in April 2014.”
Minnesota Power reported that the BEC4 Project’s total anticipated project cost has decreased to a current estimate of about $260m from an originally estimated $350m. The total project cost reflects Minnesota Power’s 80% ownership interest in the equipment and facilities that comprise the BEC4 Project.
Reasons for the cost reduction include that the initial project cost estimates from April 2012 were based upon the design and footprint for a recent installation of a specific CDS technology at another utility’s facility similar to BEC4. Through the request for proposal process that took place in the first half of 2012, it was determined that Alstom’s NID layout fit the BEC4 site much better, with the constraints created by the location of Blackwater Lake, than the CDS technology used in the initial estimate.
Also, over the past two-plus years Minnesota Power was able to refine its engineering of the project as the company has progressed from the initial design stage through the planning, procurement and initial construction stages.
Incidentally, the Minnesota Court of Appeals on Nov. 3 rejected an environmental group appeal of a decision by the Minnesota commission to approve the new air emissions controls for Boswell Unit 4 under the state’s Mercury Emissions Reduction Act (MERA). The plaintiffs, including the Sierra Club, tried to argue that shutting down the unit and replacing it with new natural gas-fired capacity, not air emissions controls, was the best way to comply with the act. The air controls, proposed by Minnesota Power in 2012, had been signed off on by the Minnesota Pollution Control Agency (MPCA) during the commission’s review process. “In short, the plain language of MERA indicates that the legislature intended to regulate, not replace, coal-fired power plants,” said the court ruling.
The project will bring the 585-MW Boswell Unit 4 into compliance with state and federal regulations. WPPI Energy owns 20% of Boswell 4 and will pay a share of the upgrade cost.