EPA's cordwood test protocol for wood stoves moves forward

 AGH wrote to the EPA in June and again in early July, requesting public information about the stove testing that it is undertaking.  We had seen numerous references about the stove testing but could not find more details about it.  Rather than submitting a Freedom of Information request, which would likely provide a jumble of emails and miscellaneous documents, we urged the EPA to provide an overview.  Details about the EPA’s stove testing program are well known by HPBA insiders, and by staff at NESCAUM and NSERDA, yet we have consistently found that the EPA, nor those organizations, share information very well. This blog may be updated soon with rejoinders from experts who take issue with the EPA's narrative.  

This letter from the EPA partially explains how and why the EPA approved an IDC (ALT-140) test method without a full certification test report using that method.  NYSERDA and NESCAUM still have not produced certification level test data for their IDC method "although we [the EPA] understand that Alaska will be providing us with additional data demonstrating use of the ALT-140 for compliance testing."  

In the past 10 years, the EPA has rarely had any budget for lab testing, so its current budget of one million is significant.  AGH believes that its imperative for the EPA to develop its own data and not just rely either on industry or groups like NESCAUM and NYSERDA.  We reproduce below the email verbatim from Stef Johnson, leader of the EPA's Measurement Technology Group.  The photos were added by us.

July 20, 2021

Dear Mr. Ackerly: 

 

Thank you for the questions you forwarded in your July 9, 2021 email.  I appreciate the thoughtfulness of you questions and the opportunity to engage with you on this important topic.  In particular, I’d like to clarify the steps in EPA’s processes for: 

·         New Test Method Development and

·         Alternate Test Methods (ATM) 

 

New Test Method Development 

 

In the method development process, EPA creates new measurement methods for regulatory purposes.  In the case of EPA developing new test methods for wood heaters, EPA has embarked on a public process that engages stakeholders as we develop a new measurement method for this sector.  EPA’s Measurement Technology Group, the group I lead, began the process by convening a Roundtable consisting of manufacturers, Hearth Patio & Barbeque Association (HPBA) staff, state and local regulators, test lab technical staff, and multijurisdictional organization (MJO) representatives.  The Roundtable participants gathered to discuss the use and vetting of the Integrated Duty Cycle (IDC) method for certification of wood fired stoves and consider making that testing approach an EPA test method.   

 

After the January 2020 meeting where we discussed the IDC approach and the ASTM E3053 test approach, the agency determined that we would pursue development of the IDC as an EPA method.  We have been working in that direction ever since.  The process to conduct method precision testing of an IDC for wood heaters, one for hydronic heaters, one for forced-air furnaces, and one for pellet heaters is resource intensive and complex.   

 

EPA remains committed to transparency and open dialogue as we explore and develop new methods for compliance testing of wood heating appliances.  We have provided the Roundtable group information about our Quality Assurance Project Plan (QAPP), the IDC method for wood heaters -- the current subject of our trials, and the Tapered Element Oscillating Microbalance (TEOM) Standard Operating Procedures.  We have also shared supporting spreadsheets for using these methodologies.  We have posted this and other information in a public docket (EPA-HQ-OAR-2016-0130) and we have begun using this posted IDC, along with TEOM measurements in our contracted laboratory.     

 

The EPA is paying for 26 tests at PFS-
TECO testing in Portland, OR.

We are conducting 52 tests (26 paired tests) at a West Coast lab (PFS-TECO) and will be comparing those data to a duplicate effort that will be funded by NYSERDA and conducted at ClearStak laboratories in Connecticut.  Within each lab, we are doing paired testing to look at intra-laboratory variability -- known as repeatability testing.  We will be comparing the inter-lab variability (method reproducibility) between these bi-coastal sets of 26 test pairs.  This helps us understand the test method performance with respect to overall variability and informs our decisions as to the appropriateness of the test method for use with a given emissions standard.  EPA has committed nearly $1,000,000 to the West Coast portion of wood heater test method work, and to a study of TEOM precision to be done at EPA’s facility in Research Triangle Park, NC.  This type of data has never been collected for any wood burning appliance test method to date.   

 

All data we develop from our trials will be publicly available and placed into the same docket as the QAPP and IDC /TEOM methodologies.  We will convene the Roundtable after the wood heater precision testing is complete and we have data to discuss.  Certainly, there will be lessons learned along the way and improvements made.  As you may know, NYSERDA is also conducting wood heater precision testing, and we expect that they will make their data public.  East Coast testing will likely begin in mid-September.  We anticipate that a full data set will be available for discussion by in early 2022.  Again, this is for the development of a wood heater IDC compliance test method.  Finally, we will propose, take public comment, and finalize a new compliance test method.  All of this will be a public process, and all of the data will be available for review.   

NYSERDA is paying for 26 tests of
the same stoves at ClearStak in
Connecticut.  ClearStak offers
transparency in testing by video taping 
the tests but it is not known if these 
tests will be videotaped or if the tapes
will be released to the public.

 

Alternative Test Methods 

 

The Alternate Test Method (ATM) approval process is different than compliance test method development.   In the ATM process, the requestor is responsible for providing sufficient information to the agency to demonstrate that the proposed Alternate Test Method is appropriate for compliance testing purposes.   Requesting an ATM is an option available to any affected party. The proposed ATM must be deemed by the Measurement Technology Group to be appropriate with the final air pollution standard.  The entity requesting the ATM must demonstrate compliance with a Federal subpart regulated by 40 CFR Part 60, such as subparts AAA or QQQQ regulating wood burning residential heating appliances. 

 

EPA’s Measurement Technology Group receives requests for alternate means of compliance testing from affected source categories, from electric utilities to wood heater manufacturers and everything in between.  We are responsible for reviewing each request and make a technical determination about the appropriateness.  We either work in a direct back/forth manner with the requestor or we agree to the request with some stipulations. (You will note we listed several in our 2021 ALT-140 approval letter).  

 

In sum, the ATM approval process is a technical exchange with a requestor followed by a technical evaluation by my staff.  The goal is to approve compliance testing that meets a specific need and is appropriate for the compliance purpose as outlined in the rule.  While such evaluations may involve exchange of data between the requestor and EPA, each request is evaluated and assessed on a case-by-case basis.  

 

In situations where there is not any test method available, for example, EPA will evaluate the request differently than in situations where we have already approved an ATM.  With regard to ALT-140, we have had the opportunity to learn about the IDC development process through multi-party meetings from 2017 to 2020.  The information shared during this time about the IDC illustrated that this method provides a more rigorous test assessment of heater performance and therefore, provides a more conservative compliance demonstration approach.  Such conservative approaches (more difficult to pass the test) are nearly ideal for Alternate Test Method processes because one of our goals with the ATM process is to not relax the standard in any manner.   

 

That said, when EPA received Alaska’s request to approve an alternative test method for demonstrating compliance with the New Source Performance Standard Subpart AAA, Standards for New Residential Wood Heaters in December 2020, we were not aware of data that demonstrated that a wood heater could meet the emissions limit of the rule using the IDC.  Therefore, we asked Alaska to provide us with that information.  While what they provided to EPA is not an entire test report, it is credible enough for us to allow the use of the test method for compliance demonstration, where a compliance test must fully document all of the test method QA/QC details to satisfy EPA’s Office of Enforcement and Compliance Assurance (OECA)’s requirements.   

 

Finally, using an ATM itself is optional and my staff ensures that all alternative methods are equivalent or more stringent than the test method in the EPA regulation.  No one need ask to use one unless they decide that it is in their interest to do so.   In the case of the Alaska request, EPA’s approval of ALT-140 provides a cord wood compliance pathway for manufacturers wishing to sell in the Fairbanks-North Star area.  They are also free to conduct crib fuel tests and sell crib fuel tested units in that area.   

 

Finally, EPA has received 5 spreadsheets from NYSERDA/NESCAUM in support the Alaska ALT-140 request and they are available upon request.  To date, EPA has not received any other NYSERDA/NESCAUM test data used for their IDC method development purposes, although we understand that Alaska will be providing us with additional data demonstrating use of the ALT-140 for compliance testing.  

 

I hope this has been helpful for your understanding.   

 

Very sincerely, 

 

Steffan Johnson

Leader - Measurement Technology Group

US Environmental Protection Agency (EPA)

Related stories

Nine states urge the EPA to revoke the ASTM cordwood method (May 2021)

EPA announces overhaul of wood stove certification process (April 2021)

AGH response to NESCAUM report on wood stoves (March 2021)

EPA and states vigorously defend audits of wood stoves (Sept. 2020)

EPA finds lapses in cordwood certification testing (July 2019)

Rookie Wood Stove Makers Get Highest Score in Design Workshop

Taylor Myers and Ryan
Fisher with the Mulciber,
the highest ranking stove.

A stove designed and built by graduate engineering students received the 

highest score in an international Stove Design Workshop focused on automated wood stove technology.  The goal of the event was to assess innovative technologies that can help stoves reduce real-world emissions that result from poor operation by the consumer and use of unseasoned wood, both of which are widespread problems. 

Ten judges scored the stoves based on emissions, efficiency, innovation, market appeal and safety.  The highest scoring stove, the Mulciber, adapted emission control techniques that are in automobiles, such as an oxygen sensor that controls the fuel-to-air ratio, a continuously engaged catalyst and an exhaust gas fan.  The Mulciber was also tested with unseasoned, 50% moisture content wood and performed quite well.   The team, who had never built a stove before the 2013 Wood Stove Decathlon, overhauled their first prototype and have now formed the company MF Fire to bring the stove to market.  

The Workshop was held at the DOE’s Brookhaven National Laboratory in New York and brought together a diverse range of stakeholders - students, professors, industry, regulators, air quality experts - who spent a week together analyzing the problems and solutions to residential cord wood emissions.

Five stoves competed in the event, which is part of the ongoing Wood Stove Design Challenge run by the non-profit group, Alliance for Green Heat. In 2013, the Design Challenge hosted the Wood Stove Decathlon on the National Mall in Washington DC, a high profile event modeled after the Solar Decathlon.  This year, the event was at a lab so that stoves could be tested more rigorously and test data could be shared with the participants.

The core problem is that most consumers do not operate wood stoves well and many use unseasoned wood.  In addition, EPA certification testing for wood stoves do not simulate how wood is burned in people’s homes.  For decades, manufacturers have been building stoves to pass that test, but not necessarily to burn cleanly in homes.  This workshop addressed that by testing with cordwood that was not fully seasoned, capturing some start-up emissions in the test and assessing how automation can reduce operator error.  At Brookhaven, stoves were tested at four parts of their burn cycle: warm start, steady state 1, hot reload and steady state 2. The current EPA stove certification test uses seasoned 2x4s and 4x4s and only tests for emissions after the start-up period, once the stove is hot.

Automated stoves, where computers, not consumers, adjust the air-to-fuel ratio, cannot be tested by EPA test methods so they are not able to enter the US marketplace.   A major goal of the Workshop was to start designing an alternative test method to the EPA’s method, so that automated stoves can be tested and become certified in the US, as they already are in Europe. Tom Butcher, a senior scientist at Brookhaven Lab, hosted one of the public webinars during the week on that topic.

Rankings: The judges gave double weight to emissions and efficiency, as they did in the 2013 Wood Stove Decathlon, because of the importance of those values.  This year, the judges decided not to judge affordability since most of the stoves were prototypes or technologies designed to be integrated into other stoves and ultimate costs and pricing was too speculative. Each of the 10 judges scored each stove on innovation and market appeal.  The other three criteria were based on lab tests.

“We want to congratulate the MF Fire team - and all the teams - for participating in a process of sharing innovation, ideas and test results,” said John Ackerly, coordinator of the event and President of the Alliance for Green Heat.  “These stoves have many of the solutions to excessive smoke from modern-day wood stoves and are challenging the EPA and the stove industry, to catch up with new technologies and new opportunities,” Ackerly said.

The Wittus team with the Twinfire.

While MF Fire stove, the Mulciber, had the highest combined score, several of the other stoves stood out in key areas.  The German Twinfire, designed by the Wittus team, had the second highest overall efficiency, at 74%, and one of the lowest emission rates on a test run.  Its automated air regulation enabled the stove to perform consistently well at different part of the burn cycle and it received the highest score for consumer appeal, for its downdraft flame into a lower chamber.  

The VcV, wired to monitor
temperature in key spots

The VcV, a New Zealand mechanical device that operates without any electricity, achieved the highest average efficiency, at 82% based in part on the lowest average stack temperature at 167 degrees (F), and the lowest emission rate on one of its tests.  It also received the second highest marks for innovation.  This was the only stove that did not require electricity and will be very affordable. Three out of four tests were very, very good, but on one the hot reloads, something happened and that reduced its overall numbers, and took it out of contention for first or second place.  This device has undergone extensive R&D and is one of the entries that is closest to being ready for the market.

The Catalus Ventus by ClearStak, received the highest score of all for CO reduction, and the second

The ClearStak team with the
Catalus Ventus

highest for emissions.   It was a highly innovative entry, employing dual cyclones, a pre-heated, continuously engaged catalyst and a fabric filter.  Its sensors and controller kept the oxygen rates incredibly steady, within half a percentage point. The technology could be integrated into a new stove, or added on to an existing stove. The designers did not try to optimize efficiency, which impacted their overall score.   

The Kleiss, ready for testing.

The Kleiss arrived at the competition with the hallmarks of an innovative, automated stove that could handle wet wood and nearly eliminate operator error.  The stoves sensors and algorithms were designed to maintain very hot combustion temperatures and to allow the operator to call for more of less heat, while prioritizing cleanliness.  However, the stove did not perform as expected, with secondary air contributing to primary burning with a large fuel load.   

Test results for all the stoves are available here.  (References to grams per hour are not comparable to EPA gram per hour tests since the Workshop used tougher test protocols.) A series of presentations by the stove designers about their stoves and other stove and combustion experts are also available.

The Wood Stove Design Challenge is a technology competition that also strives to bring key stakeholders together to assess and learn about new stove technology.  Primary funding came from the New York State Energy Research and Development Authority (NYSERDA), the Osprey Foundation and the US Forest Service.  Testing support was provided by Myren Labs, Masonry Heaters Association and Testo and Wohler, two German companies who are pushing the envelope of accurate real time lab and field testing of particulate matter.  The Chimney Safety Institute of America and Olympia Chimney donated the chimney installations, and Blaze King and Woodstock Soapstone also provided support.

The 12 member Organizing Committee oversaw developing protocols, testing and scoring and included representatives from Alliance for Green Heat, Aprovecho Research Lab, Brookhaven National Lab, Clarkson University, Hearth.com, Masonry Heater Association, Massachusetts Department of Energy Resources, Myren Labs, NYSERDA, US Forest Service and Washington Department of Ecology. The Committee is now considering options for a 2015 Stove Design Challenge.

Test Results, Presentations and Photos from the 2014 Collaborative Stove Design Workshop

Test Results

Updated on Nov. 24

Part of the Workshop rules was a requirement that teams had to publicly share their test results, which is a key part of the collaborative and educational process. During the Workshop, each team presented their test data to the 50 attendees who had the opportunity to discuss the results and give feedback to the  team.  Unlike EPA test, which starts when the stove is already hot, we used a warm start, capturing some start-up emissions, we used cordwood instead of crib wood and we used higher moisture content wood. Note: any gram per hour (g/h) references in the below test results are not comparable to g/h values from EPA test labs because we did not follow the Method 28 test protocol. 

1. MF Fire, the Mulciber. Powerpoint link.
2. The Kleiss stove. Powerpoint link.
3. Wittus Twinfire, Powerpoint link.
4. The VcV, PDF link.
5. Catalus Ventus, PDF link.

Team Presentations about their Stoves
Each team presented the concepts and technologies in the stoves. For a brief technical overview of all the stoves with contact info for the Teams, click here.

1. The Mulciber (powerpoint)
2. The Wittus Twinfire (pdf)
3. The VcV (pdf)
4. The Catalus Ventus (pdf)
5. Kliess (powerpoint)

Expert Presentations
During the Workshop, there were a series of expert presentations and webinars about automation, traditional stove technology, public health implications, air quality, regulatory issues and other relevant topics.

1. Dr. Tom Butcher, Brookhaven National Lab, Review of the Automated Stove Test Protocol (powerpoint)
2. Webinar with the five teams, hosted by BTEC.
3. Glenn Miller, Fairbanks Air District,  Technology Improvements vs. Behavior Modification (powerpoint)
4. Ellen Burkhard, NYSERDA, Renewable Heat New York (powerpoint)
5. Norbert Senf, MHA, Emission Testing of Masonry Heaters (powerpoint)
6. Gael Ulrich, Smoke Particle Formation Fundamental, (pdf)
7. Peter Cullen, Wohler SM 5000 (powerpoint)
8. Phil Swartzendruber, Puget Sound Wood Stove Retrofit Open Challenge (pdf)

Feedback Survey: Results of a 10 question feedback survey about the Workshop by teams, participants and organizers.

Photos: Day 1

Ivana Sirovica, Jessica Peterson and Jeff Hallowell, from ClearStak Brookhaven National Laboratory.

Rebecca raking coal bed to prepare for the next load of fuel. 

Thanks to John Pilger and Chimney Safety Institute of America and Olympia Chimney for donating pipe and installation!

Indigo Hotel in Riverhead NY - our base for the week

The Testo shows real time emissions, with top line showing particulate matter (PM)

Rebecca Trojanowski removes filters. The dark circle in foreground are the particulates on a filter from the test burn that will be weighed to determine grams per hour.

Even the kindling is carefully weighed so that each stove gets the same warm up rick.

Jessica Peterson from ClearStak working late into the night to prepare for testing tomorrow.

Photos: Day 2

Taylor Myers showing a thermal image of the Mulciber stove. 

Ben Myren, Tom Butcher and Eric Schaeffer firing up the New Zealand VcV stove. 

Lab in Bldg 815 with the VcV and Kleiss stoves.  (They brought 2 of exact same stove in case they needed it.)

Taylor Myers showing a real time digital display, using bluetooth, of temperatures in his stove.

Developed by ClearStak, this real time digital display shows 154 degree stack temperature, 529 in the firebox and 451 in the catalyst. Estimated efficiencies were in the mid-80s. 

Glenn Miller from the Fairbanks Air District on the left, Rob Rizzo from Mass. Dept. of Energy, and Gaetan Piedalue and Marc Suave from Polytest Labs, a EPA accredited test lab. Ellen Burkhard from NYSERDA is peering into the stove. 

Ben Myren, Tom Butcher and Eric Schaeffer firing up the New Zealand VcV stove.

The Wittus Twinfire's downdraft mechanism, where the fire gets sucked into lower chamber and then passes through catalyts before going back up the stack.

Day 3

Corey Van, one of the young ClearStak staff that helped build the Catalus Ventus. 

Rebecca Trojanowski loads the Catalus Ventus.

The new Testo moisture meter that reads moisture without "pinning" the wood.

Norbert inspects the Condar, placed right below the triple walled pipe.

The tube on the right of black pipe is a Condar, which operates very similarly to a dilution tunnel. Norbert Senf is using it concurrently with the Testo PM analyzer.

A warm up test load made by Ben Myren. This top down burn, with smallest kindling on top, and larger kindling on the bottom is a very efficient way to start fires.

Amanda Aldridge of the EPA talks with Norbert Senf (behind flue pipe) about the Condar analyzer. Rob Rizzo from Mass. Dept. of Energy in upper right.

Electronic controllers that can be put in wood heating systems that were part of Jeff Hallowell's presentation. Harold Garobedian in red jacket on right, and Rafael Sanchez from the EPA behind him.

A new Testo moisture meter that works without pins. It can measure moisture at the center of the wood, not on the edge.

George Wei hangs almost upside down to put a temperature sensor in the top of the flue pipe to measure stack temperature. This is a key data point for determining efficiency.

Day 4                                          

John Ackerly on opening day, welcoming everyone and talking about how automated stoves can solve many problematic issues issues that come with widespread wood burning.

From the left to right - Ellen Burkhard from NYSERDA, Lisa Rector from NESCAUM, Amanda Aldridge from EPA and Mark Knaebe from US Forest Service.

We spent hours in this room, having different presentations every hour, with lots of discussion and debate. Here, Ben Myren is presenting the testing results of the VcV stove.

Brian Gauld of New Zealand, John Pilger of CSIA and Jeff Hallowell of ClearStak.

Team Wittus Twinfire

Gregory Elliiot and Peter Cullen from Wohler, and John Pilger from Chimney Safety Institute of America.

Ingo Hartman, measuring glass temperature on his Twinfire stove.

We managed to find a BYOB restaurant which led to more red wine consumption. From left - Rod Tinnemore, Dave Misiuk, Amanda Aldridge, John Ackerly, Norbert Senf, Ellen Burkhard and LIsa Rector.

Final Day

The Catalus Ventus shows incredible hot catalyst temps compared to the both the stack and the firebox. This was during start up, when it was emitting maximum smoke, but between the catalyst, the fabric filter, virtually no smoke came out the stack.

Ivana Sirovica, a Research Fellow from Alliance for Green Heat, and Ben Myren, as Ben finished the final test of the week.

Tom Butcher using the Wohler particulate analyzer on the VcV stove. Because we used wood that was often above 25% moisture content, we had to deal with more moisture in our testing instruments.

Underneath the VcV stove is where the magic happens, and mechanical valves automatically close or open the primary or secondary air, depending on what the stove needs to maintain a clean and efficient burn. THis stove maintained a steady low burn rate with beautiful swirling flames in the upper part of the chamber.

Ben Myren shows how his thermocouples could read the temperature in 10 spots of the stove at all times. The top of the flue could be 250, when the air entering the catalyst was nearly 800, and 1300 in the firebox.

Brian Gauld, the owner of the VcV travelled from New Zealand, where there is also demand for automation that can improve stove performance far more than stoves are likely to perform when operated manually.

         Dr. Phil Hopke of Clarkson University and Mattian Woll of Testo.

Our cord wood was kiln dried and then shrink wrapped so it would maintain a constant moisture content. The wood was far wetter, on average, than wood used in EPA test certifications, which helped us assess how these automated stoves could perform with higher moisture content wood.

Preparation of kindling for the tests.

George Wei and Yussef were two of Brookhavens talented technicians. Both have worked on improving oil combustion systems, outdoor wood boilers and stoves.

The last stove is taken out, and demonstrates the challenge of testing the same day as removing stoves that are still hot!