Exposures to Carbon Monoxide from Off-Gassing of Bulk Stored Wood Pellets

Soto-Garcia, Lydia; Huang, Xinrui; Thimmaiah, Devraj; Rossner, Alan; Hopke, Philip K.

doi:10.1021/ef5021186

Cited by 23 publications

(37 citation statements)

References 7 publications

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“…In general, the pellet samples were ~6 mm in diameter and 6–25 mm in length with a bulk density of ~18 kg/m 3 (40 lbs/ft 3 ). For more details, refer to Soto-García et al 3 …”

Section: Experimental Systemmentioning

confidence: 99%

“…Thus, it is important to understand their potential health impacts to building occupants. While immediate health concern with wood pellet storage is the off-gassing of carbon monoxide (CO), 3 another concern is the adverse impact of indoor air quality due to the off-gassing of volatile organic compounds (VOCs) from storage of wood pellets. 4–6 VOCs constitute a significant class of indoor air contaminants.…”

Section: Introductionmentioning

confidence: 99%

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VOCs Emissions from Multiple Wood Pellet Types and Concentrations in Indoor Air

et al. 2015

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Wood pellet storage safety is an important aspect for implementing woody biomass as a renewable energy source. When wood pellets are stored indoors in large quantities (tons) in poorly ventilated spaces in buildings, such as in basements, off-gassing of volatile organic compounds (VOCs) can significantly affect indoor air quality. To determine the emission rates and potential impact of VOC emissions, a series of laboratory and field measurements were conducted using softwood, hardwood, and blended wood pellets manufactured in New York. Evacuated canisters were used to collect air samples from the headspace of drums containing pellets and then in basements and pellet storage areas of homes and small businesses. Multiple peaks were identified during GC/MS and GC/FID analysis, and four primary VOCs were characterized and quantified: methanol, pentane, pentanal, and hexanal. Laboratory results show that total VOCs (TVOCs) concentrations for softwood (SW) were statistically (p < 0.02) higher than blended or hardwood (HW) (SW: 412 ± 25; blended: 203 ± 4; HW: 99 ± 8, ppb). The emission rate from HW was the fastest, followed by blended and SW, respectively. Emissions rates were found to range from 10−1 to 10−5 units, depending upon environmental factors. Field measurements resulted in airborne concentrations ranging from 67 ± 8 to 5000 ± 3000 ppb of TVOCs and 12 to 1500 ppb of aldehydes, with higher concentrations found in a basement with a large fabric bag storage unit after fresh pellet delivery and lower concentrations for aged pellets. These results suggest that large fabric bag storage units resulted in a substantial release of VOCs into the building air. Occupants of the buildings tested discussed concerns about odor and sensory irritation when new pellets were delivered. The sensory response was likely due to the aldehydes.

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“…In general, the pellet samples were ~6 mm in diameter and 6–25 mm in length with a bulk density of ~18 kg/m 3 (40 lbs/ft 3 ). For more details, refer to Soto-García et al 3 …”

Section: Experimental Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

VOCs Emissions from Multiple Wood Pellet Types and Concentrations in Indoor Air

et al. 2015

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“…5,6,18,19 Gauthier et al 20 documented several deaths arising from CO poisoning in large pellet storage areas and reviewed previously reported incidents in marine vessels and commercial and residential pellet and chip storage facilities in Europe. The illness and deaths associated with pellet storage clearly demonstrate risk to human health and the need to fully understand the emission rates and concentrations of CO. SotoGarcia et al 9 showed elevated CO concentrations in a variety of storage facilities but did not observe values in the range of the extremely high values reported by Gautier et al 20 To characterize the off-gassing rate for softwood pellets, Kuang et al 7 developed a kinetic model of CO, CO 2 , and CH 4 emissions from British Colombia pellets (widely used in Europe) made from Pinus sylvestris (Scots pine). This model assumes that the gas formation reaction is first-order because their results showed that the gas concentrations initially increased exponentially over time and then tended to a constant plateau after a few days.…”

Section: ■ Introductionmentioning

confidence: 99%

Measurement and Modeling of Carbon Monoxide Emission Rates from Multiple Wood Pellet Types

et al. 2015

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There is a potential hazard associated with bulk storage of wood pellets because they have been shown to off-gas carbon monoxide (CO). The risk to building occupants from the emission of and exposure to CO from stored pellets has not yet been fully studied. The present study was designed to measure the emission rates from wood pellets and develop a model to predict the CO emission rate. The 20 gallon steel drums were filled to approximately 50% of their volume with wood pellets and CO, and oxygen (O 2 ), carbon dioxide (CO 2 ), temperature (T), and relative humidity (RH) were measured as a function of time.A variety of conditions were tested including the type of wood, age of the pellets, volume of the headspace, humidity, surface/ volume ratio, and temperature. An improved kinetic model was developed to predict the CO emission rate. The model assumes that the reaction generating CO is surface-area-limited. The measurements were well-fit by the mathematical model (R 2 in the range of 0.93−0.99), suggesting that the model is a good predictor of the CO emission rates. ■ INTRODUCTIONWood pellets, a renewable biomass solid fuel, are becoming a more attractive source of energy for heating and power in the U.S., Canada, and Europe as oil prices rise and/or the need to reduce greenhouse gases increases the use of renewable energy. 1,2 Wood pellets are made from compacted sawdust from cut trees or wastes from sawmilling and other wood product manufacture. Pellets are formed by extruding the sawdust through a die, resulting in a typical size of 12−20 mm long and 6 mm diameter cylinder. They have a low moisture content (4.5−8.0%) and a low ash content (0.5−0.8) that allows them to be burned with a very high combustion efficiency, resulting in gross calorific values of the order of 8100−8470 Btu/lb. 3 In New York State, a series of demonstration projects has been initiated to introduce highefficiency, low-emission wood pellet boilers based on European designs into homes, schools, and commercial buildings. 2,4 After wood pellets are manufactured, they are stored in pellet bins, shipping vessels, boxcars, or at the owner's facility. While in storage, pellets emit a variety of gases, including carbon monoxide (CO), carbon dioxide (CO 2 ), methane (CH 4 ), and volatile organic compounds (VOCs), that can result in CO concentrations and depleted O 2 that can reach toxic concentrations. 5−8 A recent study has shown that concentrations of CO in domestic and commercial-scale pellet bins can exceed guidance and regulatory limits for CO exposure. 9 These emissions have also been observed from other hydrocarbon products. 10,11 The amount of emitted gases will depend upon the temperature (T), relative humidity (RH), headspace (HS) volume, surface of pellets available, mass, and type of wood. 12−17 The proposed mechanism of CO emission has been studied by Levitt et al.,10 observing that organic matter, stored at room temperature, particularly in the presence of air and light, emitted small amounts of CO and the emission rate increases ...

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“…The topic has been investigated in several recent publications, e.g. [6,7] but the exact nature of the chemical processes at play do still not appear to be well-understood.…”

Section: Wood Pellet Chemical Off-gassing Risksmentioning

confidence: 99%

Fatal Accidents During Marine Transport of Wood Pellets Due to Off-Gassing: Experiences from Denmark

Hedlund¹,

Hilduberg

2017

Biomass Volume Estimation and Valorization for Energy

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The atmosphere in unventilated wood pellet storage confinements, such as the cargo hold of marine vessels transporting pellets in solid bulk, can be severely oxygen deficient and contain deadly concentrations of harmful gasses, of which the most feared is the poisonous and odour-less carbon monoxide. The hazard has been known for over a decade and has been responsible for many accidents. We examine three fatal accidents on marine vessels in or near Danish waters and argue that they share strikingly similar aetiologies, if not repetitive patterns. It is generally recognized that accidents should be thoroughly investigated and lessons learned shared widely in order to minimize the number of times the same lessons have to be learned. The three Danish cases suggest that this learning process is deeply troubled for the solid biomass segment. The International Maritime Organization IMO/SOLAS has recently revised its guidance on entering enclosed spaces aboard ships in response to the ongoing problem of confined space incidents. We argue that the interpretation of the concept of an "enclosed space" is of utmost importance because accidents take place in rooms that are not considered enclosed by the crew.

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Exposures to Carbon Monoxide from Off-Gassing of Bulk Stored Wood Pellets

Cited by 23 publications

References 7 publications

VOCs Emissions from Multiple Wood Pellet Types and Concentrations in Indoor Air

VOCs Emissions from Multiple Wood Pellet Types and Concentrations in Indoor Air

Measurement and Modeling of Carbon Monoxide Emission Rates from Multiple Wood Pellet Types

Fatal Accidents During Marine Transport of Wood Pellets Due to Off-Gassing: Experiences from Denmark

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