Meet the judges
Brookhaven National Laboratory (BNL) on Long Island.
The large circle at the top is the Relativistic Heavy Ion Collider
The RHIC viewed from space
Judges’ meeting for the Wood Stove Design Challenge.
Clockwise from bottom: Norbert Senf (taking photo, not shown), Ray Albrecht, Rod Tinnemore, Mark Knaebe, John Ackerly, Melissa Bollman, David Agrell, Ellen Burkhard, Nathan Russel, Tom Butcher (our BNL host).
There were 34 entries, including 8 masonry heaters. 14 finalists were selected after some very detailed discussions.
Tom Butcher describes the Wohler SM500 real time particulate analyzer.
Visible clockwise from the left are Mark Knaebe (USDA Forest Service), Nathan Russell (NYSERDA), Melissa Bollman, David Agrell, John Ackerly, Peter Cullen (COO for Wohler USA), and Ellen Burkhard (NYSERDA).
From left: Rod Tinnemore, Bill Clarke (Osprey Foundation), Peter Cullen, Amanda Aldridge (EPA), Ray Albrecht (Technical Consultant to the Biomass Thermal Energy Council (BTEC)).
The small cyliner in front is a package of 10 filters.
Rear (exit side) of filter.
The sample probe has a heated line to prevent semi-volatiles from condensing before they reach the filter. The Wohler is able to weigh the filter to 0.0001 gram in real time and display real time particulates. This is an industry first. The instrument has been on the market in Germany for 3 months, and this is the first one to reach the United States. 
Particulates, CO and O2 are displayed in real time.
Melissa Bollman is Program Manager for the Wood Stove Design Challenge.
David Agrell is an associate editor for Popular Mechanics.
Tom Butcher demonstrates the Wohler. The measurement head is rotated 90 degrees to change out the filter, which is visible in the photo.
The filter is weighed continuously via a tapered element oscillating microbalance (TEOM).
Woodstock Soapstone donated a stove for testing.
Brookhaven may be contracted to calibrate the Wohler method against EPA Method 5-G.
There is a good chance that the Condar/Barnett portable sampler may be calibrated against both methods at the same time.
We lit the stove from a cold start with newspaper, twigs, and black walnut cordwood. Fairly high particulates are visible about 5 minutes after starting. The stove is equipped with a catalyst, which was not up to temperature yet.
The weather was fairly cold, around 10F. The heavy plume exiting the stack is mostly condensing water vapor. As the water plume vaporizes around 6 ft from the stack, the remaining plume is blue smoke, which is primarily tar (OC or organic carbon, as opposed to EC or elemental carbon (soot)).
Real time display of stack oxygen. Software is available to log to a laptop and change instrument settings, such as sample pump flow rate. Translation to English has not been completed yet. Here is the software manual in German.
Instrument manual in German.
Real time particulate display, a technological first for an instrument under $10,000.
Dirty filter on right
Rear of filter, which is considerably lighter than the front (above)
Data printouts from our demonstration test.
Tom Butcher’s division at BNL also does research into biodiesel, and more efficient combustion of fossil oil. BNL research has saved the Northeast more than 24 billion dollars due to better performance of fuels. NYSERDA is one of the major funders for this research.
The next day, we started with a webinar with Wohler headquarters in Germany via Skype. Also patched in was EPA headquarters in Research Triangle Park, NC.
Germany takes climate change seriously and has legislated carbon emission reduction targets as federal government policy.
As a result, Germany is committed to biomass use as a major renewable energy source. However, they are also serious about minimizing biomass emissions health impacts. A new regulation requires annual on-site verification of PM performance for all appliances over 13,500 BTU/hr (4 kW). This is about 160,000 appliances requiring annual testing. The regulation was conditional on suitable testing technology becoming commercialized. Several companies were competing to develop technology and bring it to market, and Wohler won the race. Orders for the SM500 are backlogged by several months.
A Wohler technician prepares a pellet stove for demonstration testing in real time at the German lab.
Inserting sample probe into the stack.
Instrument has completed the calibration cycle and is ready.
PM plot.
At 4 seconds into the test, the filter catch is 0.0mg
The door to the pellet stove is opened momentarily
At 2:02 minutes.
A particulate spike is immediately visible on the screen. The last bar has not finished plotting, so appears lower in the photo. However the particulate reading is cumulative, since the filter weight only goes in one direction.
Carbon monoxide screen at 2:50. Note the large spike when the door was opened.
Stack oxygen. Ambient air is 20.9%, so the 3.8% depression indicates about 550% excess air. Stochiometric air is regarded as 100%, by convention. The pellet stove is running very cleanly, but probably not very efficiently. John Gulland has identifed efficiency as a major issue for pellet stoves.
Test results.
The German test cycle lasts 15 minutes. Average O2 was 17.7%, or 653% excess air. Filter catch was 3.5 mg, which translates to an PM emissions factor of 169 mg/m3. Average CO was 97ppm, unadjusted for excess air. Normalized to 13% oxygen, CO concentration was 294 mg/m3.
“U” denotes uncertainty of the measurement, which for PM was determined to be 61 mg/m3 from prior testing. For CO, the uncertainty is defined in the regulation as 265 mg/m3. The Germans subtract the uncertainty from the instrument results to arrive at the official number. Therefore, 169 mg/m3 measured PM translates to 108 mg/m3 “official” PM.
Even more interestingly, 294 mg/m3 of measured CO translates to 29 mg/m3 of “official” CO, or 9.8% of the measured value in this example. This disparity would be less for higher measured values.
One explanation may be that the results have serious potential consequences. If your stove flunks the test, you have to pull it out of your house.
Some interesting discussion followed. All of the judges were able to contribute facets of an overall picture, and everyone learned a great deal from the discussions. The challenge is to define a fueling and testing protocol that will treat a wide range of stoves fairly, and be doable onsite outdoors on the Mall in D.C.
Sitting next to David Agrell is Jim Meigs, Editor in Chief of Popular Mechanics.
After our official business was done, we got to tour another lab that was conducting boiler testing.
Dilution tunnel hood. Under the EPA test method, the stack exits inside the lab at 15′ – 16′.
Rod Tinnemore (burgundy shirt) and Ellen Burkhard.
Rod is the Washington State Department of Ecology Wood Stove Co-ordinator.
Ellen is a Senior Project Manager at NYSERDA (New York State Energy Research and Development Authority). Check out NYSERDA’s recent outdoor boiler study.
The dilution tunnel is powered by the fan shown here.
Brookhaven was originally an army base. It is the site of the first peace time nuclear research reactor, known as “The Pile”. There is still evidence of its early days.
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