When Is a Coal Sample a Sample?

By ML Juszczak, Project Manager, ECSI GHG Programs

The USEPA has issued its Greenhouse Gas Rule in the form of 40 CFR Part 98.  Companies subject to the rule must begin reporting annual greenhouse gas emissions for the year beginning on January 1, 2010.   Although the rule fills hundreds of pages in the Federal Regiater,  it still leaves important questions unanswered.  For example, what is  the proper way to sample coal for laboratory analysis?

Coal must be analyzed for calorific value to determine the fuel’s high heat value, or HHV, in two of the four CO2 emission calculation methodologies defined in the rule (specifically, Tier 2 and Tier 3).  A facility choosing either of these methodologies must sample and analyze each lot of coal that it receives (a lot being a “shipment or delivery of a single fuel comprised of a shipload, barge load, group of trucks, or group of rail cars”.)   The rule also specifies in §98.34 that ASTM D 5865-

07a – Standard Test Method for Gross Calorific Value of Coal and Coke be used.  If you read no further, you may think this is a fairly simple and straightforward matter.  As is often the case, however, this matter is neither simple nor straightforward.

The difficulty that arises does not concern the analysis of the sample, but rather how to compose a sample, how often to compose it and, how to prepare it prior to analysis.  Two other ASTM standards enter the picture:

  • ASTM D 2013-07 – Standard Practice for Preparing Coal Samples for Analysis
  • ASTM D2234/D2234M-09a – Standard Practice for Collection of a Gross Sample of Coal

 These are incorporated into the rule by reference in §98.7(e), and they are interrelated as follows:

  • ASTM Method D5865-07 references  ASTM D 2013-07, and
  • ASTM D 2013-07 in turn references ASTM D2234/D2234M-09a.

ASTM D2234 requires that 15 “increments” of mechanically cleaned coal, or

35 “increments” of raw coal, be gathered at separate times from each lot to form a “gross sample.”  There are three increment quantities:

1 pound for coal with a top size of ?“

 3 pounds for coal with a top size of 2“

 7 pounds for coal with a top size of 6“

Therefore, a gross sample can be from 15 pounds all the way up to 245 pounds. 

ASTM D2234 also defines a lot as 1,000 tons of coal.  If a true lot is larger than

1,000 tons, sampling increments are either increased proportionately, or the total quantity is subdivided and each sub-lot is sampled individually.  This is a significant difference from the EPA’s definition of a lot found in §98.34.

ASTM D 2013-07 prescribes how the gross sample is to be ground, mixed, and divided using milling and rifling equipment (rifling is a type of sorting process) to yield a quantity that remains representative of the whole, while being suitable in size for analysis.  The test method in ASTM D 5865-07a calls for 0.8 grams to 1.2 grams of material with a particle size of ?250 micrometers. 

The simple matter of gathering a sample of coal and sending it to the laboratory now has become quite an arduous procedure requiring some sophisticated and specialized apparatus—apparatus that many facilities may not have access to.  And, it may need to be done much more frequently than once per shipment.   While

40 CFR Part 98 does not specifically prescribe the above sampling and preparation methods, it names no alternative protocol either.  A valid conclusion would then be that the ASTM standards are intended to be part of the rule, and not adhering to them could result in a violation of the law.  Alternative interpretations will no doubt be made as the regulated community grapples with this new rule.  What procedures a company ultimately uses will need to be supported by sound reason, and tempered by its tolerance for risk. 

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