Qualifying Woody Biomass in the APS

The eligibility criteria and requirements for qualifying a Woody Biomass system in the Alternative Portfolio Standard.

Eligibility Criteria

All Renewable Thermal Generation Units must:

  • Generate useful thermal energy using sunlight, biomass, biogas, biofuel or naturally occurring temperature differences in ground, air or water
  • Deliver a useful thermal load to a facility located in Massachusetts
  • Have an operation date January 1st 2015 or later

Additionally, all woody biomass Generation Units must:

  • Generate useful thermal energy using sustainably-sourced woody biomass
  • Be automatically fed from a covered bulk fuel vessel
  • Meet efficiency and emissions standards 
  • Represent best-in-class commercially feasible technology
  • Utilize a thermal storage device

For a full list of eligibility requirements, please see the APS regulations, beginning on page 15. 

For more information on renewable thermal in the APS, please visit our APS Statement of Qualification webpage.

Size Classifications and Multipliers

Woody Biomass Generation Units are, regardless of application, determined to be either intermediate or large. Classifications are delineation at 1,000,000 Btu/hr. (1MMBtu/hr.). Sizing is important as it influences metering, reporting, and permitting requirements.





Eligible Woody Biomass Systems 


< 1 MMBtu/hr

> 1 MMBtu/hr

In accordance with the APS statute, certificate multipliers may only be applied to non-emitting technologies. Accordingly, woody biomass Generation Units are not able eligible for a certificate multiplier.

Fuel Specifications

All woody biomass fuels qualified under the APS must meet the criteria for Clean Wood (as defined in 310 CMR 19.006, definitions) and be from verifiably sustainable origins. Both forest-derived and non-forest derived fuels are potentially eligible for inclusion within the APS. To that end and with full consideration of sustainability, DOER has chosen to adopt the definition of Sustainable Forest Management as recorded by the Society of American Foresters. For eligibility within the APS characteristics of these fuels must be reported to DOER (either directly or via the Massachusetts Biomass Registry) to establish a traceable chain of custody.

Sources of Woody Biomass fuel include:

  1. Forest-Derived Thinnings
  2. Forest-Derived Residues
  3. Forest Salvage (Residues)
  4. Non-Forest-Derived Residues:
    1. Forest products industry residues
    2. Agricultural land use change residues
    3. Wood waste
    4. Agricultural wood waste

More information on the sources of fuel above can be found here

Green House Gas Reductions 

Generation Units are obliged to achieved 50% reduction in carbon emissions over a 30 year period vs the locally-available traditional fuel which has been replaced, calculated via a greenhouse gas lifecycle analysis established by DOER. This calculation tool, see below, is built on findings from the 2010 Manomet study. Implicit within these calculations is a measured apportionment of the involved fuels between thinnings and residues as defined within 225 CMR 16.00. Generation units not wishing to complete a GHG analyses may purchase their fuel from an entity on DOER’s Biomass Suppliers List, which pre-qualifies eligible fuel. 

Guideline on the Reduction of Greenhouse Gases for Eligible RTGUs Using Eligible Biomass Woody Fuel

Forest-derived Obligation

A further compulsion for woody biomass generation units is that a minimum of 30% of their fuel be forest derived.  This requirement can be met with the inclusion of fuels directly sourced from the forest (forest-derived thinnings and forest-derived residues) and post-primary forest product industry materials (slabwood, sawdust etc.).

Fuel Characteristics

In accordance with best in class commercially feasible technologies DOER has established the following fuel characteristic benchmarks:

For systems less than 3 MMBtu/hr capacity without an emissions control device:

For systems less than 3 MMBtu/hr capacity that utilize an emissions control device there are no require fuel specifications, which allows the inclusion of green chips (moisture content >35%). 

For systems greater than 3 MMBtu/hr the Department of Environmental Protection (DEP) will specify fuel quality specifications. 

System Performance Standards

To promote the utilization of best in class commercially feasible technologies DOER has established the following generation unit performance and emissions standards:

System Performance Standards

Particulate Matter Emissions Standards

Thermal Storage

All woody biomass thermal generation units involved in the APS must incorporate a thermal storage device (unless granted an exemption) as well as achieving the expectations (where applicable) of the United States Environmental Protection Agency’s New Source Performance Standards.  The purpose of this equipment is to reduce boiler cycling, a process that has been found to have a deleterious effect on emissions. All thermal storage tanks must have a minimum of R12 insulation and controls, integrating the central heater, and decrease the number of central heater starts and stops.

The unit’s thermal storage capacity should be sized based on the thresholds as seen below.

Eligible Boiler and Furnace List

The list below is a summary of the biomass boilers and furnaces that are eligible for consideration under the Alternative Energy Portfolio Standard (APS).  Each of the boilers and furnaces have undergone testing to an approved standard by an independent lab testing, which have been reviewed by DOER to determine if they meet the system performance requirements of the APS.  The list should not be considered an exhaustive list of approved boilers and furnaces and is to be used for informational purposes only.  Other boilers and furnaces may be eligible with or without emission control devices.

APS Eligible Biomass Boiler/Furnace List

Intermediate and Large Generation Units


With respect to metering, intermediate-sized woody biomass systems are divided into two subcategories.  Generation Units with a nominal capacity of less than 134,000 Btu/hr. will receive AECs based on a standard equation that utilizes verified fuel usage. Similarly, Generation Units 134,000 to 1MMBtu/hr. will also be assessed certificates based on direct fuel metering.  However, attribution for this second category will be based upon a custom equation utilizing the specifics of the system as described in the individual unit’s Statement of Qualifications.

Large woody biomass thermal Generation Units will receive AECs, based on their metered thermal production. Metering shall include thermal, flow, and fuel information all of which are computed into BTU’s and logged into a data acquisition system.  Generation Unit owners should review the Guideline on Metering and Calculating the Useful Thermal Output for Renewable Thermal Generation Units – Parts 1 & 2 (Metering for Intermediate and Large Generation Units) for information on metering requirements.

Application Requirements 

All woody biomass systems will be recorded via the Massachusetts Clean Energy Center (MassCEC) registration portal. Systems with nominal capacity of less than 1MMBtu/hr. may select their system from a list of pre-qualified equipment. However, woody biomass systems larger than 134,000 Btu/hr. are required to submit the following in a Statement of Qualification Application:

  • Site and facility information
    • Site plan (attachment)
  • Contact information
  • Equipment specifications
  • Equipment arrangement drawing (attachment)
  • Annotated product literature for all major equipment (attachment)
  • Design Specifications
    • Description of System Controls and Sequence of Operations (attachment)
    • A process flow diagram (attachment)
    • A one line electrical diagram (attachment)
  • NEPOOL GIS information
  • A fuel plan (attachment)
  • Mass DEP air permit (if applicable, required for systems 3MMBtu/hr.)
  • APS Renewable Thermal Performance Workbook (attachment)
  • Independent Verifier request form (attachment)
  • A metering plan including a list of meters (attachment)
    • Annotated product literature for each APS meter (attachment)
    • Annotated product literature for the Data Acquisition System (DAS) (attachment)
  • Certified Performance Data Construct (intermediate Generation Units only) (attachment)

Biomass Reporting Procedures

All Generation Units utilizing woody biomass fuels or any supplier or distributor of woody biomass fuels to APS eligible Generation Units are required to report information regarding the Eligible Biomass Woody Biofuel to DOER. For more information on the reporting procedure, please reference DOER's Guideline on Biomass Reporting Procedures. Additionally, the timeline for Eligible Biomass Woody Fuel can be seen below:

Biomass Reporting Schedule


Biomass Suppliers List

The Department shall develop and maintain a list of suppliers and distributors of Eligible Biomass Woody Fuel on its website, see below. 

APS Biomass Suppliers List Updated December 22, 2022

To be added to the list, a biomass supplier or distributor will be required to submit an application to thermal.DOER@mass.gov. The application to become a biomass supplier or distributor can be found in the Guideline on Biomass Reporting Procedures, see below. 

Guideline on Biomass Reporting Procedures

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