Monday, March 17, 2014

Can the EPA Set Future Emission Limits Using a Cordwood Test?

In the proposed new regulations for residential wood heating devices, known as the New Source Performance Standards or “NSPS”, the EPA is not only trying to reduce the amount of smoke allowed from new stoves, but it is also proposing to switch the fuel used for testing devices in future years.

Traditionally, stoves have been tested using “crib” fuel, meaning Douglas Fir 2 x 4s and 4 x 4s that are stapled together to maximize the consistency of the fuel load.  EPA is proposing to allow manufacturers to use either crib wood or cordwood (which is more similar to the split wood logs that stove users typically burn) to test new stoves during the first phase of the proposed rule.  However, EPA would require that only cordwood be used to test stoves during the later phases of the rule.  Using cordwood for testing makes sense because a test using cordwood would likely come closer to what the real-world emissions from new stoves might be.

EPA is proposing that new stoves would be required to emit no more than 1.3 grams of particulate matter (smoke) an hour during the later phases of the rule (within 5-8 years) as demonstrated using cordwood.  Some observers have pointed out that although 1.3 grams an hour is already achievable today with some stoves tested with crib fuel, it is not clear how many (or if any at all) could pass the test using cordwood.  There is not any way to convert between tests using crib wood and tests using cordwood, and very few stoves have so far been tested using cordwood. 

Industry has voiced concerns, saying EPA cannot legally set a standard where there is insufficient data to back it up.  However, there are a number of ways EPA could still set a standard based on cordwood, even if it doesn’t have a mountain of data right now.  For example, there is legal precedent supporting EPA’s setting a rule based on what it reasonably predicts a technology could achieve in the future even if it doesn’t have hard data when it proposes a new rule.  In addition, there are many options for EPA to obtain more data before it finalizes the NSPS of which the wood stove community should be aware.

First, if EPA learns of new data using cordwood testing before it issues the final rule, it can issue a Notice of Data Availability, or “NODA” that makes the data available and requests additional comment.  Even absent a NODA, the EPA can consider comments and data submitted after May 5, but it is not required to do so.  This approach could allow EPA to collect more data about cordwood testing during the rest of 2014.

Second, EPA could issue an “Information Collection Request” under the Clean Air Act that would require manufacturers to test and turn in data on their stoves’ emission using a cordwood test.  

Third, EPA could re-open and re-consider the NSPS after it issues the final rule.  For instance, the agency could open a discrete part of the rule in 2 or 3 years for the sole purpose of setting or adjusting the emission limits for wood stoves using a cordwood test method.  EPA would have to go through the notice and comment process, but a technical update to the rule that adjusts the test method or emission limit based on new data could be completed relatively quickly, with a shorter comment period and fewer comments for EPA to consider.  

If the EPA ultimately sets very strict limits using cordwood for later phases of the NSPS, there is only a small chance that any lawsuit could stop the regulation from initially going into effect.  To prevent a regulation from going into effect, there is a very high burden of showing irreparable harm.  Also, courts are supposed to give EPA a lot of leeway in interpreting contested scientific or technical information (such as the achievability of the 1.3 gram per hour limit using cordwood).  Since the initial emission limits will be based on cribwood tests and will have little impact on the wood stove industry for the first several years, the wood stove industry will be hard pressed to show immediate, irreparable harm.  Warm air furnaces, outdoor boilers and other exempt appliances may have a better chance at showing irreparable harm as they have not been regulated before and there are manufacturers of those appliances who are more likely to be harmed or go out of business.  But those are the appliances that industry, states and others most want to be regulated, and where the greatest air quality benefits will come from.  However, EPA could also agree to stay the rule if industry is able to persuade it to do so.

As long as EPA itself doesn’t agree to stay the rule, the regulations would likely go into effect immediately upon final rulemaking, and all the initial emission limits would become law and would be effective even if industry sued.  If the industry were successful in suing EPA, a court could strike down certain provisions or remand the rule to the EPA.  Thus, a lawsuit by industry is very unlikely to stop the regulations from taking effect, may not succeed in the end, and would only prolong the uncertainty that industry has had to face to date.


  1. This is not a thorough review of the situation manufacturers face. In addition to changes in the test method, the EPA's current test method includes weighted averages for wood stoves. These weighted averages take into account four different burn rate performances. The proposed 1.3 gr/hr is proposed to be a standard set on "worst case scenario" testing. Few if any wood stoves on the market today would qualify at 1.3 gr/hr on their worst run.

    1. For a single burn rate test, cribs would actually make a lot of sense. Limited data so far indicates excellent repeatability when moisture is kept within very tight specs.

      I don't think anybody knows yet if cordwood will work - you could be looking at throwing cash at the lab hoping your lucky number comes up. The cart is before the horse at this stage.

      Has EPA specified what burn rate will be used for the single burn rate test?

  2. This article misses a critical ingredient. The current test method requires four different burn tests, determined upon fuel load consumption. These four burn categories are then placed into a weighted formula so as to reflect how a given stove performs over a wide spectrum. The EPA 1.3 standard is proposed to be based upon only one run, the worst run and tosses out the entire notion of weighted averages. Therefore, few if any stoves on the market today make a 1.3 gr/hr on their worst run.

    1. True, we did not get into that change in the test method, which is yet another variable the EPA is introducing. But I think the EPA only needs to show a few stoves can meet its proposed standards and the idea is that redesign and innovation will lead lots of them to meet the standards over a few years. But we think many more stoves are already meeting the proposed standards than industry claims. Remember, the EPA has proposed eliminating the conversion from 5G to 5H, so many stoves will test much cleaner. Some in industry understand this, but don't appear to be sharing that with others.

  3. We've just conducted a study of crib testing for masonry heaters. Based on our data, cribs are very repeatable, and the emissions fall right in between "real world" burning of cordwood (about 1.3 g/kg of PM in our testing) and "manufacturers instructions" burning of cordwood (about 0.5 g/kg in our testing).

    This is for single crib batch burn testing in a masonry heater, which admittedly is much different than a metal stove EPA test, where the crib is loaded onto a hot charcoal bed, and has to be tested at 4 different burn rates.

    It does, however, provide a good counter example to the current group think in favor of cordwood.

    Nobody knows yet what the repeatability of cordwood testing is, compared to cribs. The testing simply has not been done, and no public agency is stepping up to provide funding.

    It could turn out, for example, that you need to run 10 tests with cordwood to average out the variability, whereas you might only need 3 tests with cribs. Nobody knows.

    Opinion rules, because there is no data.

  4. Manufacturers had their chance with the voluntary program but didn't. The result were wood boilers that caused a lot of pain and suffering for us that want clean air. I think the FBI should look at lobbyist that caused this non clean air! Its criminal even the EPA maybe be found guilty!

  5. To be clear..the EPA required that outdoor wood boilers be tested with crib wood. Boilers were therefore designed to meet emissions standards with crib wood and that same equipment performed poorly in the field with cord wood. The EPA's insistence on a crib wood test continues to be responsible for dirty equipment that has "blessed" by the EPA. If they want to stop this travesty the new rule should require that all equipment be tested and certified with the actual fuel that will be used....cord wood.