Monday, January 11, 2016

Review of wood pellets for BTU, moisture and ash content

The Internet is full of opinions and reviews of wood pellet brands.  However, data of actual properties of various wood pellet brands is hard to locate.  It cost under $100 for a lab to test ash, moisture and BTU content of a pellet. We tested 4 popular brands, along with corn kernels, to see the variability between brands.  Our overall conclusion: much less variability than we expected (except for the corn).
Click on the brand name to see the full lab report from Twin Ports Testing for American Wood Fibers, Pennington, Curran Renewable Energy, Nation’s Choice , and Takoma Park Silo corn.

Conventional wisdom is that you should buy a couple bags of pellets to see how they work on your stove before buying a ton or more.  That's good advice, as some stoves handle a much wider range of pellets, while others do not.  It’s especially good advice in light of the lab testing we did, that shows little variation between moisture, ash and BTU content of four popular brands.  

The four brands we bought – made by American Wood Fiber, Curran, Pennington’s, and Nation’s Choice – are all major brands but only represent a small fraction of available brands.  Two of them are PFI certified, which means that they must meet certain quality guarantees and cannot have more than 1.0% ash, 8.0% moisture, and 0.5% fines, among various other requirements.  All four brands of pellets we tested fell within the parameters required by PFI premium grade, for the criteria that we tested – ash and moisture.  We did not test for fines or for durability or bulk density or chlorides – things that can be important for performance.  The cost for testing those qualities is about $250, more than we wanted to spend for each test.

Pellet manufacturers, whether they are PFI certified or not, usually do not disclose actual BTU, ash or fines, but just say that they do not exceed a certain level. 
Ash content: Ash is one of the biggest concerns of consumers since high ash pellets can clog up some stoves and require more cleaning.  Of the four brands we tested, the ash content was relatively similar, ranging from about 0.3% to 0.6%, far below the acceptable level under the PFI certified standard of 1.0%.

BTUs: 
Whether your stove is 60% efficient or 80% efficient, you will get more heat from a pellet with more BTUs.  Some pellet brands may have up to 8,800 BTUs per pound and some only 8,000. Still, only a 9% difference, would be $250 a ton and $272 a ton.  The higher BTU pellets we tested had 8,439 BTUs per pound, 5% more than the lowest BTU brand, which had 8,011.  

Moisture content:
Moisture content varied even less than ash and BTU content between the four brands we tested. The low was 5.1% and the high was 5.8%.  PFI allows up to 8%.

Price:
Price on all these 4 brands can vary depending on the time of year, the location, the seller, and whether or not a ton is purchased. Pennington’s, Nation’s Choice, and Curran have all been available at big box outlets in the $250/ton range over the past several months.  The American Wood Fiber Ultra Premium White Pine is more expensive, as 100% softwood pellets tend to be, especially on the east coast.

Options for future testing
Testing and publishing the BTU, moisture and ash content of dozens of common wood pellet brands would be a great resource for consumers.  Please let us know if you agree or have suggestions about how to develop and maintain a reliable, independent data base of pellet characteristics.


This report and the pellet testing was supported in part by a grant from the Maryland-based Rouse Charitable Foundation.