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.
| Technology | Small | Intermediate | Large |
|---|---|---|---|
| Eligible Woody Biomass Systems | N/A | < 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:
- Forest-Derived Thinnings
- Forest-Derived Residues
- Forest Salvage (Residues)
- Non-Forest-Derived Residues:
- Forest products industry residues
- Agricultural land use change residues
- Wood waste
- 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:
| Fuel Quality Specifications | Pellets | Chips |
|---|---|---|
| Calorific value | >8,000 Btu/lb | ≥5,500 Btu/lb |
| Moisture | ≤8% | ≤35% |
| Ash content by weight | ≤1% | ≤1.5% |
| Particulate size (percent retained by a half inch mesh screen) | Not applicable | 75% or adhere to manufacturer's protocol |
| Chlorides | ≤300 ppm | Not applicable |
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
| Performance Requirement | Pellets | Chips |
|---|---|---|
| Thermal efficiency at nominal output | ≥85% Higher heating value | ≥75% Higher heating value or ≥80% Lower heating value if EN303-5 is used to verify particulate emissions |
| Start up | Adhere to manufacturer's ignition protocol | |
| Modulation/shut off | The system must automatically modulate to lower output and/or turn itself off when the heating load decreases or is satisfied | |
| Pressurized portion of the system | Compliant with 522 CMR 4.00 | |
| Thermal storage | Required, unless an exception is issued by the Department | |
| Fuel storage | The system must have covered bulk storage | |
| Feedstock conveyance | The system must be automatically fed from the feedstock storage to the furnace boiler | |
Particulate Matter Emissions Standards
A boiler of furnace of less than 3,000,000 Btu per hour rated heat input must meet applicable emissions below:
| Emission | Pellets / Liquid Biofuels / Biogas | Chips |
|---|---|---|
| Particulate Matter Emissions (PM) | ≤0.08lb PM2.5 per MMBtuinput or ≤0.03lb PM2.5 per MMBtuinput at sensitive populations2 | ≤0.10lb PM2.5 per MMBtuinput or ≤0.05lbs total PM per MMBtuinput if EN303-5 is used to verify submissions or ≤0.03lb PM2.5 per MMBtuinput at sensitive populations3 |
| Carbon Monoxide (CO)4 | 270 ppm at 7% oxygen | 270 ppm at 7% oxygen |
A boiler of furnace of greater than 3,000,000 Btu per hour rated heat input:
| Emission | Pellets / Liquid Biofuels / Biogas | Chips |
|---|---|---|
| PM, CO, and other relevant criteria pollutants | Commonwealth of Massachusetts Department of Environmental Protection (MassDEP) plan approval required, pursuant to 310 CMR 7.02(5). | |
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.
| Lead Boiler System Size (Heat Output) | Thermal Storage Required |
|---|---|
| <80,000 Btu/hr | 80 gallons |
| 80,000 Btu/hr - 119,000 Btu/hr | 1 gallon per 1 MBtu/hr |
| 119,000 Btu/hr - 1 MMBtu/hr | 119 gallons |
| >1 MMBtu/hr | 2 gallons per 1 MBtu/hr |
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.
Intermediate and Large Generation Units
Metering
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.
Timeline for Eligible Biomass Woody Fuel
| Milestone | Q1 | Q2 | Q3 | Q4 |
|---|---|---|---|---|
| Start | January 01 | April 01 | July 01 | October 01 |
| End | March 31 | June 30 | September 30 | December 31 |
| Statement of Qualifications Applications Due | May 15 | August 15 | November 15 | February 15 |
| Fuel Reports from Generation units Due | May 15 | August 15 | November 15 | February 15 |
| Department Notifies Distributors of Obligation | May 22 | August 22 | November 22 | February 22 |
| Fuel Report from Distributors Due | June 5 | September 5 | December 5 | March 5 |
| Supplier Fuel Registry Due | June 15 | September 15 | December 15 | March 15 |
| Minting of AECs | July 15 | October 15 | January 15 | April 15 |
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 July 2025
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.