Industryweek 5967 Boiler Mact 1

Boiler MACT Offers Chance to Boost Efficiency, Lower Costs

Jan. 13, 2014
Manufacturers should not consider the required boiler energy assessments an unnecessary but obligatory expense. Boiler energy assessments provide real opportunities for large facilities to assess energy-saving options such as fuel switching, thermal energy recovery, insulation upgrades, and steam end-use.

In January 2013, the U.S. EPA issued Boiler MACT, the common name for a new set of rules imposing stricter emission limits on industrial boilers. A key stipulation is that industrial facilities must conduct energy assessments on boilers. This article explains why these assessments offer manufacturers opportunities for significant efficiency increases and savings, and provides an example.

The large energy demand of boilers in manufacturing and industrial facilities creates opportunity to increase efficiency, reduces fuel use (lowers operating costs), and allows facilities to reduce emissions.

One-time boiler energy assessments are now required by the EPA’s “MACT” and “GACT” Rules. Sources of hazardous air pollutant (HAP) emissions must complete boiler energy assessments by March 21, 2014, or January 31, 2016, depending on the level of HAP emissions from the facility and boiler capacity.

(MACT = Maximum Achievable Control Technology required by 40 CFR Subpart 63 Subparts DDDDD for major HAP sources; GACT = Generally Available Control Technology required by 40 CFR Subpart 63 Subpart JJJJJJ for area HAP sources.)

Manufacturers should not consider the required boiler energy assessments an unnecessary but obligatory expense. Boiler energy assessments provide real opportunities for large facilities to assess energy-saving options such as fuel switching, thermal energy recovery, insulation upgrades, and steam end-use. During the assessment, the boilers may also be evaluated for combustion and thermal efficiency.

The requirement to evaluate major systems (e.g., process heating and cooling, facility heating, machine drive) that consume a minimum of 20% of the energy output by the affected boiler(s) as part of the assessment also provides an opportunity for facilities to assess energy conservation measures.

Facility decision-makers have a choice of whether the energy assessment is performed internally or by an external resource. A facility could benefit from an external third party auditor performing the energy assessment because the third party provides objective understanding of energy conservation measures and brings the knowledge of efficiency improvements that have been applied at similar facilities successfully.

Alternatively, you may have the ability to conserve funds dedicated to regulatory compliance by using a team approach to facilitate the energy assessments. Portions of the energy assessment such as data gathering (e.g., fuel records, maintenance procedures and logs, energy use system records), documentation of boiler operating constraints, and leak checks may be performed internally or by the boiler manufacturer/ service company. And aspects of the energy assessment such as boiler inspections, efficiency / energy saving conservation measures, facility modifications, and payback periods / cost of improvements may be provided by a hired external consultant or energy auditor.

Improving efficiency of boilers may also save financial resources by:

  • Reducing fuel demand through improved boiler efficiency and thermal-energy recovery.
  • Reducing fuel costs by switching to more economical fuel types if fuel switching proves favorable based on payback analysis.
  • Lowering actual air emissions, thereby reducing annual emission fees paid to state regulatory agencies.

Case In Point

As an example, a facility that has a 10-million-Btu-per-hour boiler that operates for approximately 4,000 annual full-load hours is likely to be required to perform an energy assessment per the Boiler GACT rule.

As summarized in the table below, prior to the assessment being performed, the thermal efficiency of the boiler may be 83%. Basic recommendations resulting from the energy assessment could include more frequent cleanings, adding a condensing economizer, a combustion air pre-heater, blowdown waste heat recovery, and/or oxygen trim controls. By implementing these procedures and technologies, the boiler’s thermal efficiency could be increased to 91%, thereby decreasing annual fuel use and cost (savings of approximately $72,000 per year) and decreasing greenhouse gas emissions by more than 250 megagrams of carbon dioxide equivalent per year.

An additional higher-level recommendation that could be considered includes an upgrade to a highly efficient natural gas burner. The fuel switch for a boiler of this size would result in an annual fuel cost savings of more than $400,000. The fuel switch also has the potential to decrease greenhouse gas emissions by more than 700 megagrams of carbon dioxide equivalent per year.


Pre-Energy Assessment

Post-Energy Assessment: Basic

Post-Energy Assessment: High-Level

Thermal Efficiency




Fuel Type

No. 2 Fuel Oil1

No. 2 Fuel Oil1

Pipeline Natural Gas

Annual Fuel Use

285,700 gallons

260,600 gallons

364,800 therms

Annual Fuel Cost




Direct CO2 Emissions4

2,917 Mg

2,661 Mg

1,934 Mg

CO2eq Emissions5

2,922 Mg

2,666 Mg

1,945 Mg

1The heat content of No. 2 fuel oil is assumed to be 0.14 MMBtu/gallon.
2Assumes $2.88 per gallon of No. 2 fuel oil.
3Assumes $0.90 per therm.
4Assumes combustion of No. 2 fuel oil results in 10.21 kg CO2/gallon and combustion of natural gas results in 53.02 kg CO2/MMBtu based on Table 12.1, U.S. Default Factors for Calculating CO2 Emissions from Fossil Fuel and Biomass Combustion, of The Climate Registry's 2013 Default Emission Factors.
5Based on direct CO2, CH4, and N2O emissions and the assumptions that the global warming potential (GWP) of CH4 is 21 and the GWP potential of N2O is 310.

For those facilities required to perform boiler energy assessments, this example demonstrates the reduction in emissions and potential value of improved efficiency that can result from high-level recommendations of the energy assessor. Regulatory boiler energy assessments are far from just an obligatory expense.

Heather Little is senior project manager with Sanborn Head & Associates Inc. Contact her at 802-431-0164 or [email protected].

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