Study of pellet stoves shows environmental advantages - and corporate exaggerations

An independent assessment of popular pellet stoves conducted by the Alliance for Green Heat  found that pellet stoves, unlike most wood stoves, can achieve low levels of emissions in real world settings that are in line with laboratory results.   

The Alliance for Green Heat ran a battery of tests on popular pellet stoves designed to approximate how they would perform in the real world.  The group found that half of the stoves operated as clean at the end of the thirty-day test than they did at the beginning and the others were only slightly dirtier.

All six stoves, from the least to the most expensive, operated well, and produced enough heat for a small to medium- sized home in most of the United States.  One of the biggest differences was that the three more expensive stoves tested (above $4,000) needed very little weekly cleaning and maintenance.  The less expensive stoves ($1,200 to $3,300) needed daily or at least bi-weekly cleaning of their burn pots and glass.

The study also found a lack of accepted reporting standards, leading to exaggerated claims about efficiency, BTU output and pellet hopper size on manufacturer websites and promotional literature. 

The Alliance for Green Heat tested the stoves to give consumers better tools and make better purchasing decisions.  The study is part of a yearlong Pellet Stove Design Challenge that assesses the state of existing pellet stove technologies.  The Design Challenge will culminate in a competition for the cleanest and most efficient stoves, modeled after the Department of Energy’s Solar Decathlon.

Approximately one million American homes are heated with pellet stoves, more than twice the number that have solar panels.  In Italy alone, 2 million households heat with pellets. Pellet stoves often serve as primary heat sources, enabling homes to eliminate or drastically reduce fossil heating fuel.  Last year, about 40,000 pellet stoves were sold in the U.S. and they may outsell wood stoves in the near future.

The Alliance tested the England Stove Works 25-PDCVC, the Enviro M55 insert, the Harman Accentra 52i insert, the Piazzetta Sabrina, the Quadra-Fire Mt. Vernon AE, and the Ravelli RV80.  The group assessed each stove on its cleanliness, efficiency, maintenance, heat output and visibility of glass.  The overall winner was the Quadra-Fire Mt. Vernon AE, which received top marks in three of the five categories.  The Harman Accentra received top marks in two of the five categories.

The results of this study underscore that pellet stoves tend to burn substantially cleaner than wood stoves in real world settings, but it challenges the notion that pellet stoves generally have higher efficiencies than wood stoves.  The efficiencies of the six stoves were low to medium, which is partially the result of companies not having to test and report actual efficiency numbers. 

“Our testing confirmed that pellet stoves are an effective and affordable renewable energy technology,” said John Ackerly, President of the Alliance for Green Heat. “We hoped to see higher efficiencies, but efficiencies should improve in coming years,” Ackerly added.

Click here to read the full report on our website.
Click here to download a PDF of the report (the PDF does not have all the links and photos that the online version has).
Click here to download a PDF of the background materials to the report.

The Alliance for Green Heat promotes modern wood and pellet heat as a low-carbon, sustainable and affordable residential energy solution. The Alliance works to advance cleaner and more efficient wood heating appliances and focuses on low and middle-income families.  Founded in 2009, the Alliance is a 510(c)(3) non-profit organization based in Maryland. 

US government projects continued increase in wood and pellet heating

On October 6, the US government agency responsible for tracking energy supply and usage released its annual winter fuels outlook. The report predicted that next winter will be warmer than average but energy prices will be lower. Consequently, consumers are expected to pay 10 – 20% less on their household heating than last winter. 

The report notes that the use of cord wood and wood pellets as the primary residential space heating fuel has increased by 33% since 2005 and estimates that about 2.6 million households mainly used this fuel source in 2014. About 8% of households use wood as a secondary source of heat, making wood second only to electricity as a supplemental heating fuel.

The report, produced by the Energy Information Agency (EIA), projects primary wood and pellet heating to grow by 1.4% during the 2015-2016 winter. Electric heating is projected to rise even faster, by 2.5%. Natural gas is projected to remain basically flat, and oil and propane heating are projected to decline by 4.4% and 3.4%, respectively.

The overall national residential wood heat rise of 1.4% includes quicker projected growth in the Northeast and a slight decline in the West. Wood and pellet heating is projected to rise fastest in the Northeast at 2.8% and the South at 2.6%. It's only projected to rise 0.8% in the Midwest and decline by 0.3% in Western states.

In 2014, the Pellet Fuels Institute reported that shipments of pellet stoves grew by 41%. On average, 2 out of every 5 new stoves sold is a pellet stove and 3 are wood stoves. This ratio does not include the popular, though polluting, uncertified wood stoves that are still on the market until the end of this year.

"The trend towards more pellet heating is crucial as wood heat expands in America," said John Ackerly, President of the Alliance for Green Heat. "The growth in pellet heating, even as oil and gas prices fall, show a demand for a cleaner, local fuel that still can be greatly scaled up," Ackerly said.

Wood heating was increasing faster than electric heating for many years, but since 2008, wood has increased by nearly 10% and electricity increased by nearly 15%.

In terms of the amount of energy generated by residential renewables, wood continues to be the dominant player, generating 66% of all residential renewable energy in 2014. Solar produced less than half the energy as wood and pellet stoves, making up 29% of residential renewable energy in 2014. Geothermal produced nearly 5%.
 

However, solar will soon be catching up to wood according to EIA projections, thanks to extensive state and federal subsidies. In 2016, the EIA projects that wood and pellet stoves will only produce 54% of residential renewable energy and solar will produce 40%. Geothermal is projected to rise to nearly 6%.

The EIA did not include data or projections on wood and pellet hearing until their 2012 report. Senator Shaheen (D-NH), the Alliance for Green Heat, and other groups pressed the agency to be more inclusive of the technology that was used by more households than oil or propane. Since then, the EIA has gone much further and is about to start surveying wood pellet producers to provide accurate and timely data about pellet production and usage.

Click here for a full copy of the EIA report.