Output Based Standards and Conservation Credits can Help Manufacturers Comply with Boiler MACT
Above Photo: 40MW CHP installation at ArcelorMittal Indiana Harbor in East Chicago, Indiana including a blast furnace gas recovery boiler and a condensing steam turbine.
Enhancing energy efficiency can be a cost-effective way to reduce emissions. This is increasingly recognized in EPA rules and policies, including rules issued under Section 112 of the Clean Air Act regulating hazardous air emissions from industrial, commercial, and institutional (ICI) boilers and process heaters. These Maximum Achievable Control Technology (MACT) standards (“boiler MACTs”) for major and smaller “area” sources include several provisions that support energy efficiency, including requirements for periodic boiler tune-ups and for one-time energy assessments for certain facilities.
One notable feature is that the rules offer boiler owners the option of using output-based standards (OBS). An OBS provides an incentive for efficiency by imposing limits per unit of useful output as compared to traditional input-based standards that impose limits based on the heat content of fuel burned. OBS can reward combined heat and power (CHP), waste heat recovery, and other high efficiency approaches.
Oak Ridge National Laboratory (ORNL) recently released guidance to help boiler operators calculate and apply credit towards compliance based on the emissions reduced from undertaking energy efficiency measures.
Applicability of the Rule
The rule for major sources applies to facilities that have the potential to emit “10 tons per year or more of a hazardous air pollutant or 25 tons per year or more of a combination of hazardous air pollutants” (source). Facilities that are below these thresholds are classified as area sources. EPA estimates that approximately 13,840 boilers are subject to the major source rule. Of these, the most stringent emission limits are placed on coal-, distillate-, and biomass-fired units. Natural gas-fired boilers face relatively modest requirements under the rule.
Save Energy and Reduce Emissions
Output-based rules are a promising avenue for advancing energy-efficiency as a compliance strategy. EPA’s boiler MACT rules and proposed modifications allow owners the option to base emissions limits on useful heat output (pounds of pollutants per MMBtu of steam output or MWh) rather than per MMBtu of fuel input. This means that adoption of CHP as well as other measures, such as increasing waste heat recovery, improving condensate recovery, optimizing boiler blowdown, enhancing steam system insulation, better management of steam traps and leaks, and reducing end-use steam requirements can count toward environmental compliance while also saving facilities valuable fuel.
As mentioned, other energy-efficiency provisions are included in the rule as well. Firms with boilers or process heaters at major source facilities are required to have a qualified energy assessor perform a one-time assessment evaluating and reviewing energy using systems and energy management practices. The assessor must provide a report detailing opportunities for energy-efficiency improvements, with their associated costs and payback periods. While none of the recommendations are mandatory, some plants may want to reevaluate the energy-efficiency projects discussed in the assessment.
Energy intensity improvements—whether achieved through better energy management or one-time projects—can generate emissions credits as a strategy toward compliance when combined with the output-based limits. This path requires emissions benchmarking, documented boiler energy use, normalization to production, and an Implementation Plan before credits are calculated. A formula based on the energy performance improvement is used to calculate the credits. The ORNL guidance outlines calculation methods addressing three areas of performance improvements: condensate recovery, distribution, and end use.
Technical Assistance is Available
The Department of Energy through the Clean Energy Application Centers plans to offer technical assistance—set to include specific technical guidance and costs—to the affected major source sites. A pilot program in Ohio is currently being run with the Public Utilities Commission of Ohio to assist in CHP deployment as a strategy toward Boiler MACT compliance. Building energy-efficiency as a cornerstone of compliance with Clean Air Act regulations offers industrial firms an avenue that maximizes efficient use of fuels and can enable wider CHP implementation across the country.
