Enviros claim Boswell 4 air project a ‘trojan horse’ for unit life extension

Several environmental groups told the Minnesota Public Utilities Commission that air emissions projects for the coal-fired Boswell Unit 4 (BEC4) of Minnesota Power aren’t needed for the reasons that the utility has stated.

The commission is reviewing an August 2012 application for approval of these projects. In May 14 testimony filed with the commission on May 15, the groups contended that although Minnesota Power asserts that the BEC4 Retrofit Project is needed for Mercury and Air Toxics Standards (MATS) and Minnesota Mercury Emissions Reduction Act (MERA) compliance, it appears that the opposite is true.

“Minnesota Power’s flawed assessment of BEC4’s present capabilities to meet MATS and MERA strongly suggests that those regulatory requirements are not the primary objectives of the BEC4 Retrofit Project,” the groups wrote. “Environmental Intervenors submit that Minnesota Power’s proposal more likely relates to extending BEC4’s operating life until 2035 and/or to resolving EPA-identified violations of the Clean Air Act alleged to have taken place at the Boswell facility between the years 1981 and 2001.”

The groups added: “The standards under MERA were not established to consider twenty-year life extension projects for coal, nor to weigh the prudence of imposing on ratepayers hundreds of millions of dollars to make up for a utility’s prior environmental infractions. The Commission should not allow Minnesota Power to use this MERA proceeding for either purpose.”

The comments were submitted on behalf of the Izaak Walton League–Midwest Office, Fresh Energy, the Sierra Club and the Minnesota Center for Environmental Advocacy,

They said that Minnesota Power’s proposal extends the operating life of BEC4 another 12 years from previous company expectations, to 2035. During that time BEC4 would emit around 4 million tons of CO2 each year, they added.

“The long-term environmental impacts of the BEC4 life extension move Minnesota in the opposite direction from the imperative to stabilize and reduce the effects of climate change,” they claimed. “Environmental Intervenors believe that clean energy alternatives are better for ratepayers and the environment than paying hundreds of millions of dollars to retrofit aging plants.”

The groups said their analysis shows that the MATS and MERA standards can potentially be met with much simpler and more cost-effective measures that would end the life of BEC4 sooner than the utility plans under its current “Trojan horse” retrofit/life extension plan.

Groups say MATS and MERA compliance not an overly expensive issue

Under MATS, BEC4 already meets the emissions rates for acid gases that MATS requires, the groups said. Actual test data for BEC4 shows that the unit emissions were substantially below the MATS Hydrochloric acid (HCl) standard, with an ample margin. “This is also true for the other BEC units for which test data is available,” the groups added. “In addition a review of the coal chlorine content data for Minnesota Power’s expected future coals indicates that HCl emissions are expected to be similarly low in the future as well. Quite clearly, MATS does not require further reductions in BEC4 emissions of acid gases.

The most recent testing at BEC4 shows that it can meet the MATS limit for filterable particulate matter (PM) as well, the groups said. “Minnesota Power’s Petition overstates BEC4’s actual PM emissions prior to applying the MATS rule that sets a 0.03 lbs/MMbtu standard for filterable PM emissions,” they contended. “This means that Minnesota Power overstated reductions in PM emissions that are necessary for BEC4 to reach MATS requirements. On the other hand, Minnesota Power understated or disregarded alternative and lower cost means by which BEC4 could meet the MATS particulate standard. Minnesota Power states in Table 7 of its Petition that its current baseline for BEC4 PM emissions is 0.06 lb/MMBtu. The most recent testing at BEC4, however, shows that BEC4 PM emissions rates are between 0.0352 and 0.0405 lb/MMBtu. In other words, the necessary BEC4 reductions in PM to meet the MATS limit of 0.03 lb/MMBtu are much smaller than Minnesota Power maintains in the BEC4 Petition.”

Another factor at work here is that the MATS rule allows site-wide averaging to establish compliance with the PM limit, the groups added. Using the approved calculation methods under MATS, and the test data Minnesota Power has completed for each of its four BEC units, it is clear that the utility can easily rely upon current plant-wide particulate controls to achieve the small PM reductions that MATS requires, the groups said. “According to our expert’s calculations, Minnesota Power could meet the PM standard with a 22% compliance margin without the BEC4 Retrofit Project,” they said.

Minnesota Power has not analyzed two additional approaches that might further reduce filterable PM emissions at BEC4 – which would also further lower the site-wide PM average and enhance the compliance margin for the MATS rule limit, they said. The first is exploring the option (or the ramifications) of using all four existing BEC4 scrubbers (as opposed to the usual current mode of operating three of the scrubbers and leaving the fourth one as a spare). Since excess scrubber capacity currently exists, the ability to use it should be fully “fleshed out” in the record, the groups said. The second is the option of lowering the bypass gas stream (which passes through a small electrostatic precipitator) to less than 5%, which is the typical bypass amount.

There are several alternative MERA options, the groups claim

As for MERA compliance, the environmental groups wrote: “MATS is not controlling for BEC4 mercury reductions because MERA’s 90 percent mercury reduction goal is more stringent. Yet Minnesota Power’s massive and expensive BEC4 Retrofit Project scope is unnecessary to meet the Minnesota mercury reduction law. Quite simply, Minnesota Power has already tested low-cost mercury controls that can achieve the statutory goals without the BEC4 Retrofit’s significant capital investment.”

Minnesota Power’s petition states that Mer-Cure and KNX Powdered Activated Carbon (PAC) injection system is a component of the overall BEC4 Retrofit Project. “It is apparent, however, that operating BEC4 with the Mer-Cure/KNX system is likely all that is required to meet MERA’s mercury reduction goals,” the groups said.

Also, MERA expressly allows Minnesota Power to rely on “supplemental units” to provide mercury reductions to supplement those technically feasible at a “targeted unit” such as BEC4. Minnesota Power did not examine using supplemental units’ “over-compliance” with mercury reductions to reduce control costs and technology feasibility at BEC4, due to its “preference” not to do so, the groups said.

And the commission should keep in mind that other mercury reductions are planned with Minnesota Power’s announcement that it plans to convert the Laskin Energy Center to a gas peaking unit and to retire Taconite Harbor 3. “Ceasing coal combustion at Laskin and Taconite Harbor 3 reduces Minnesota Power’s system-wide mercury emissions by another 50-60 lbs per year,” the groups noted. “Even though Laskin and Taconite Harbor 3 are not ‘supplemental units’ as MERA defines the term, the Commission should consider the environmental impact of those plant changes.”

Minnesota Power says BEC4 Project is needed

On March 7, within the case begun last August, Minnesota Power petitioned the commission for a rate recovery ride for the BEC4 Project. Notable is that WPPI Energy is a minority owner of BEC4 and will be paying a proportionate share of the costs of this project.

“Minnesota Power plans to execute an environmental retrofit project on BEC4 as a multi-pollutant solution for reducing mercury, particulate matter, sulfur dioxide, and other hazardous air pollutants being addressed by United States Environmental Protection Agency (‘EPA’) regulations while also reducing plant wastewater,” the March 7 filing said. “Minnesota Power plans to install a semi-dry flue gas desulfurization system (‘FGD’), fabric filter (‘FF’) and powder activated carbon injection system (‘PAC’) to help achieve compliance with the Minnesota Mercury Emissions Reduction Act (‘MERA’), the EPA Mercury and Air Toxics Rule (‘MATS’), and other enacted or pending federal and state environmental rulemakings regulating air and water emissions and solid byproducts from coal-fired power plants. Through multi-pollutant control technology, Minnesota Power will cost-effectively achieve the mercury emission reduction required by MERA while ensuring compliance with other regulatory programs over the long term.”

BEC4 was placed into service in 1980. Its boiler is a tangentially-fired steam generator that operates at over 635 MW gross capability and 585 MW net capability available as net output due to 50 MW of existing station service required to operate auxiliary equipment, the utility noted.

“Thorough engineering analysis of the environmental control technology selected has shown that the proposed BEC4 Project will be a practical and cost-effective solution for BEC4 given its size, baseload use and the other environmental requirements that must be addressed in the coming years,” Minnesota Power added.

Several semi-dry FGD system technologies were considered for this project and in October 2012, Minnesota Power awarded the contract to Alstom. Alstom’s CDS technology will also further reduce emissions of acid gases, including HCl and trace metals, the utility said.

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.