EPA bolsters legal case for NSPS with new data

Alliance for Green Heat, July 15, 2014 - On July 1st, the EPA released a NODA – a Notice of Data Availability – consisting of data from 3 stoves tested with cordwood and 106 stoves tested with crib wood. 

Vermont Castings combustion engineer
Doug Fongeallaz uses cord wood to test
a stove instead of  Doug fir cribwood,
according to the Valley News.

The NODA is a vehicle for letting people know the EPA is relying on this evidence to make their final rule, so parties won’t be able to say that the agency surprised them, in violation of procedure for issuing new rules, if the EPA cites it.  The NODA also provides stakeholders a chance to dispute the additional evidence since it was not available at the time the rule was proposed.  The fact that EPA has published this data and the NODA in the federal register now allows EPA to rely on this data for the final rule.  It is likely that HPBA will publicly respond and a number of manufacturers and agencies are also planning on responding.

This NODA lays a better legal basis to withstand a potential lawsuit from the hearth industry and also gives more insight into what final emission standard the EPA is able to set.  Many in industry claim that the EPA does not have sufficient data to set an emission standard based on cordwood.  And some manufacturers have data but are not sharing it with the EPA in an attempt to prevent the EPA from establishing a cordwood emission standard.

Overview

This new cordwood data shows that some catalytic stoves can already meet a 1.3 grams per hour standard with cordwood.  However, the non-catalytic stove performed far worse with cordwood than it did with crib wood, with grams per hour of 4.2 on the Category IV burn, 11.7 on Category III and a whopping 39.9 on Category II.  The stove was not able to burn at Category I, the lowest air setting, either with cordwood or in the crib wood certification test.  Among the 63 non-cat stove tests released by the EPA in the NODA, only 8 of them could be tested at Category 1, the low burn rate.  It is is unclear how many of these 63 stoves can be operated by the consumer at a lower burn rate than they were tested at in the lab. The HPBA campaign to raise the minimum burn rate from 1 kg/h to 1.15 kg/h could have significantly added to the problem of stoves not being tested the way consumers often use them.

The data partially confirms what industry has been arguing – that it's still too early to set a cordwood standard for non-cats.  Firstly, there is too little publicly available data, and, even if the standard remained at 4.5 grams per hour (but with cordwood), manufacturers may not be able to make non-cat stoves that qualify. The incredibly high emissions from this non-cat stove could be a factor in leading the EPA to postpone a cordwood certification standard.  Presumably the EPA would require cordwood testing over the next 8 years and possibly make cordwood certification optional, while continuing to rely on crib certification.

The data also partially confirms what many air agencies have been saying: that some stoves can readily meet a 1.3 grams per hour standard, which is all that is legally required by the EPA to meet the best available technology test.

At the core of this issue may be the decision by EPA, not contested by HPBA, to set a single standard for cat, non-cat and pellet stoves.  There is data to show that pellet and cat stoves can meet a 1.3 standard now, but without separating them, the non-cat stoves may delay reaping the low-emission benefits of those technologies. Some manufacturers, such as Jotul, initially argued that cat and non-cat standards should be delinked, but others were against delinking, including the Catalytic Hearth Coalition.  The Alliance for Green Heat and a few others argued for a separate category for pellet stoves.  The internal politics and public rift within HPBA over this issue contributed to the industry association remaining silent on the issue of single or separate standards for cat and non-cat stoves.  Only time will tell if this is a successful legal strategy.

An attorney who specializes in NSPS law and is familiar with this case says that "the EPA could, in theory, set a legally defensible emission limit for both cat and non-cat stoves that relies on emission rates that are achievable by catalytic stoves but that may not be achievable by non-cats. EPA can’t require a specific technology under section 111, but it has the discretion to set the emission standard at a level that has only been achieved by one type of technology.  I suspect EPA would probably win on this point if challenged, however at this early stage, such predictions are still very speculative.  Ideally, there will be more data points than just 2 stoves, but I don’t think that’s going to be fatal to EPA, especially if industry isn’t willing or able to produce cordwood test data contradicting EPA’s data."

(The Alliance for Green Heat does not support a cordwood standard such as 1.3 grams per hour that some cat stoves appear to be able to meet, but regularly consults legal experts to see what EPA can do.  The danger may be that regardless of the recommendations from the EPA's stove experts based in North Carolina, far more senior EPA officials in Washington may take a much harder line.)

Summary of Woodstock Soapstone stove

Tom Morrissey, back row, 2d from
right and the team that built the
Ideal Steel Hybrid that emits less
than 1.3 grams an hour with
cordwood and cribs.

Woodstock Soapstone voluntarily provided full cord and crib wood test results to the EPA, something that perhaps no other stove manufacturer did during the NSPS process.  Woodstock Soapstone is one of the few stove manufacturers that is not a member of HPBA and thus does not follow their advice and guidance on sharing information with the EPA and what positions to take on contentious NSPS issues.

Woodstock Soapstone's stove showed a very notable consistency in emissions of grams per hour between cord and crib wood.  Certification tests using crib wood produced between 0.3 and 1.3 grams per hour for the four burn rates.  R&D testing in the manufacturer's lab with crib wood produced 0.4 and 0.5 grams per hour and between 0.5 and 0.8 grams using cordwood. 

Similarly, the stove showed high levels of consistency in efficiency between cord and crib wood and the certification lab and the manufacturer’s lab. Crib tests were between 74 and 84.5% efficiency HHV, and between 74.2 and 82.3% for cordwood for all the burn rates.

Summary of catalytic stove #2

A second, unidentified manufacturer voluntarily provided test results for 2 catalytic stoves.  A summary note from Gil Wood said, “the test data show that these two EPA-certified catalytic wood stoves when tested using cordwood - and making no design changes to adjust for crib wood versus cordwood in the tests - have similar emissions as when they were tested for the official EPA certification tests using crib wood. That is, the test data show particulate emission rates (g/hr) using cord wood that are equal to or less than the corresponding test data using crib wood for Category 1 (minimum burn rate) and Category 4 (maximum burn rate).”

The stove produced between 0.3 and 0.8 grams per hour for cord wood for Category I and IV.  A second Category IV test came in at 0.8 as well.

Summary of non-cat stove

A popular non-cat stove was purchased for testing at Brookhaven National Lab that was under contract with EPA to test cordwood in non-cats.  According to the Brookhaven test report, “the test cord wood was guided by draft cord wood specifications and procedures under active development by ASTM.  Testing was successfully completed in Method 28 Categories IV, III, and II.  It was not found possible to achieve the Cat. I burn rate with this fuel when the air control damper was fully closed. In this case Method 28 provides a method for determining average emissions based on weighting the results of the other three categories in which the stove was tested. It should be noted that in the earlier certification testing with crib wood, Category I operation was also not achieved.”

One notable result is that this popular non-cat had three very reproducible emission rates over a 3-day period.  On Cat IV, the stove produced 4.2 grams per hour on May 19th, 4.1 on May 20th and 4.3 on May 21th for an average of 4.2.  Reproducibility fell apart on Category III, with burns over 5 days producing a range from 6.4 to 17.4 grams an hour, for an average of 11.7.  Category II had slightly better reproducibility when the stove was smoldering at very high rates of particulate matter.  It produced 36-48 grams per hour over 4 days for an average of 39 grams per hour.  The high emission rates may partially be the result of fuel where the core moisture content was sometimes above 30%, although an average of core and shell was always below 25%.

The stove was also tested with very high moisture content fuel of 48.4% moisture content on a wet basis. Brookhaven found that particulate emissions were extremely high: 50.6 g/hr over the run, and 11.8 times higher than the average emission rate with the drier test fuel in Category IV.

The Brookhaven report concluded: “For optimal performance of this stove on cord wood, some rebalancing of the primary air / secondary air ratio may be required. It is possible as well that the details of the air damper setting and the procedure for loading and the timing of the startup operations contributed to differences between cord wood and reported crib data.”

Summary of 106 stoves certified by EPA since 2009

The data on the 106 stoves released in this NODA consisted of EPA approved lab certification test reports conducted since 2009.  None of them contained any data about cord wood, but this data set may be extremely important if the EPA decides to continue using cribwood to certify wood stoves in the 2015 NSPS.  Analysis of this data set could form the basis of Step 2 emission standard that is considerably below 4.5 grams per hour.  Some experts expect that the EPA may ultimately designate a standard between 2.0-2.5 grams per hour that would likely take effect in 2020. 

This data set also contained efficiency numbers that had not been reported anywhere before.  A great majority of these stoves are presumably still on the market.  The average HHV efficiency for non-cats and pellet stoves were exactly the same: 71%. Cat stoves had an average efficiency of 79%, but the sample size of 3 stoves was very small.  This data set confirmed previous data sets, that the efficiency range of pellet stoves is far wider than wood stoves.  These certified pellet stoves ranged from 62 to 80% efficient with a standard deviation of 8.5, double the standard deviation of non-cats and four times the deviation of cat stoves.  Some pellet stoves on the market have efficiencies as low as 40% and are likely to be uncertified models. The Alliance for Green Heat will be releasing a separate analysis of these 106 stoves that also shows the correlation between efficiency and emissions.

The EPA is soliciting comments on this NODA before July 31. To comment, click here.

Click here for a related story summarizing comments to the EPA about the proposed regulations.