Energy and Natural Resources

New Discovery Makes Wood Pellet Storage Safer

16 November 2017
Wood pellets release harmful CO during storage; Image Source: Clarkson University

A research project conducted by Clarkson University for the New York State Energy Research and Development Authority (NYSERDA) has led to the discovery of a new process to eliminate dangerous carbon monoxide gas emissions during wood pellet storage.

Wood pellets are a biofuel made of compressed sawdust and are used for heating and cooking. Manufactured from waste from the milling of lumber, furniture making and building construction, they are the most common type of pellet fuel in use today.

Pellet biomass usage in Europe varies from country to country. The Netherlands, Belgium and UK use pellets mainly for large-scale power plants. Pellet biomass use in Denmark and Sweden is primarily for large-scale and medium-scale power plants as well as residential and industrial heating. Residential heating is the most common use in other European countries. In the United States, wood pellets are primarily used for industrial and residential heating.

Wood biomass consumption. Data Source: US Energy Information AdministrationWood biomass consumption. Data Source: US Energy Information Administration

According to estimates from the US Energy Information Administration (EIA), wood biomass will be the source fuel used to generate 112,000 megawatt hours per day of electricity in 2017. Total wood pellet consumption of the electric power, industrial, commercial and residential sectors is anticipated to be nearly two quadrillion Btu (quad) per year for 2017 and 2018. U.S. wood biomass consumption for the residential sector is expected to grow .118 quad next year.

The EIA estimates 2.229 million households will use wood as the primary fuel to heat their homes during the 2017-2018 heating season. This includes 388,000 households in the Northeast, 553,000 in the Midwest, 569,000 in the South, and 718,000 in the West. While the Northeast and Midwest will see decreased numbers compared to the 2016-2017 season, the South is expected to see a 4.4 percent growth and the West a 0.7 percent increase.

There is some debate on the effect to the environment, but wood pellets are typically viewed as carbon neutral. In addition, pellet burning equipment has relatively low volatile organic compound emissions compared to other combustion heating. (See "Wood Can Help Shrink Global Carbon Footprint, UN Agency Says")

The main hazard associated with wood pellets is off-gassing of carbon monoxide and methane during pellet storage, even leading to fatal accidents involving workers in large pellet storage shipping vessels and storage facilities. Additional studies have revealed that oxygen levels are depleted as well, prompting the development of ventilation safety requirements for pellet storage.

Led by Professor Phillip Hopke, the Clarkson University team confirmed that CO was being released in stored pellets. They identified the chemical pathway by which it was being produced and then found a way to prevent the release by exposing the wood fibers to ozone prior to pellet creation.

After successful tests in the lab, Clarkson worked with two New York manufacturers, Curran Renewable Energy of Massena, which produces pellets, and Queenaire Technologies, Inc. of Ogdensburg, which supplied an ozone generator to test the system in an industrial environment. Both companies were able to successfully show that the process worked at the industrial level. Curran Renewable Energy is now producing the world's first wood pellets to be safe from CO emissions.

“The safety of workers in our State can never be taken lightly,” said State Labor Commissioner Roberta Reardon. “This breakthrough will ensure that no workers in the facilities where these pellets are stored are harmed. I applaud the NYSERDA and Clarkson University teams that developed this process and I’m gratified that they were able to leverage the Department of Labor’s expertise in workplace safety to achieve a safer work environment for New Yorkers in this industry.”

The solution is simple and a relatively inexpensive process to implement. As more pellet manufacturers adopt the process, this new discovery will ensure that workers in pellet storage facilities will be unharmed by harmful exposure to CO.

Clarkson University’s research articles are available on NYSERDA's website:
https://www.nyserda.ny.gov/About/Publications/Research-and-Development-Technical-Reports/Biomass-Reports

To contact the author of this article, email ken.thayer@ieeeglobalspec.com


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