The Wood Stove Excels at Reducing Fossil Fuels—But Can it Get Clean Enough?

By John Ackerly | March 21, 2011

Wood and pellet stoves are the only residential renewable energy system at scale in America today. According to the U.S. EPA, there are more than 10 million stoves in the U.S. compared to only about 300,000 residential solar photovoltaic (PV) systems. But one of the largest benefits of the wood and pellet stove is ignored: A $2,500 wood or pellet stove can reduce as much fossil fuel usage in the winter months as a $25,000 solar PV system does in a year. 

To leverage the enormous renewable energy production from wood stoves, we have to tackle emissions of older stoves and those produced today. In an average year, about 250,000 wood and pellet stoves are installed in America. Could we double that number and reduce emissions at the same time? Yes, but only if state and federal governments lower emission standards and incentivize the cleanest appliances. 

According to the U.S. Census, about 2 percent of Americans primarily heat their homes with wood or pellets. Another 3 to 5 percent use wood as a secondary source of heat. We estimate that wood and pellet stoves avoid 17.7 million tons of carbon from fossil fuel per year, equivalent to carbon emitted from more than four coal-fired power plants. 

While their ability to reduce the use of fossil fuels is extraordinary, only 3 million to 4 million of the 10 million stoves in operation are EPA certified. To resuscitate wood stoves as a technology that government can embrace, we need to achieve three things: a national incentive program to change out older stoves, stricter EPA emission standards for new stoves, and strategies to focus on pellet appliances instead of wood stoves in urban and air-quality non-attainment areas.

Using life-cycle emission analysis instead of point-of-combustion analysis, some wood and pellet stoves are getting close to fossil fuel emissions. While wood stoves emit almost all their particulates at point of combustion, fossil fuels emit vast quantities in their extraction, refining and transportation. Engineers are pushing the envelope and starting to produce both pellet and wood stoves that are under 0.5 grams an hour (g/hr). Most major companies produce multiple stoves in the 2.0–3.0 g/hr range. Currently, the EPA permits up to 7.5 g/hr, and exempts classes of stoves, allowing many stoves to be installed that are not clean enough. 

The EPA is developing New Source Performance Standards for wood and pellet stoves and early indications point to a recommendation of setting 4.5 g/hr for both wood and pellet stoves. While a 4.5 g/hr standard for wood stoves represents a modest advance, 4.5 g/hr for pellet stoves is too high. Today the average pellet stove produces about 2.0 g/hr. Some EPA officials believe the marketplace itself will drive down emission levels. There is little evidence to support this theory, however. The driving force for the development of stoves with lower emissions has been Washington state, which lowered its standard to 4.5 g/hr for wood stoves and 2.5 g/hr for pellets and catalytic stoves in 1995. The industry soon began building to that standard with little difficulty. The marketplace thus far has done little to nothing to drive down outdoor wood boiler emmisions, for example. 

The beauty of promoting the cleanest wood and pellet stoves is that they achieve many of the same goals of solar and geothermal programs and help Americans affordably meet energy needs. Wood and pellet stoves drive job creation because the cleanest wood and pellet stoves today are made in America. We can keep those jobs and that fossil fuel reduction potential by investing in this sector. The pellet stove and wood pellet were invented in America, but we are on the verge of losing any advantage to Europe and China. 

While European governments have invested in research and development and incentives for clean pellet stoves and boilers, the U.S. government has focused on promoting biofuels and to a lesser extent, on biomass for electricity. If we develop strict emission standards for residential pellet stoves and boilers and provide common sense incentives, this technology holds promise for our economy and domestic energy needs.

The U.S. relationship to wood stoves is different than Europe’s because we have a huge low-income population that relies on wood heat. If we want Americans to keep using renewable energy, we need to invest in next-generation wood heat technology with lower emission profiles.

Authors: John Ackerly
President, Alliance for Green Heat and Board Member, BTEC
(202) 596-3974


3 Responses

  1. Roger



    John, I agree with most of what you say but there are other variables that should be considered before jumping on the wood-burning stove bandwagon. First, the GPH label on all EPA certified stove is obtained after testing in an EPA certified lab under ideal conditions. Meaning, the burn cycle is controlled, wood is dried to an optimum level, and only one species of wood is used. Obviously manufacturers' can design their stoves to pass the test, but once the stove is installed in a home the variables used to obtain certification are not realistically reproducible. Hence, the GPH label means nothing and neighbors in proximity to the wood-burner pay the price. Also, even if engineers can design stoves to theoretically equal the emissions from fossil fuels' extraction, refining, and transportation that means nothing to the neighbor of a wood-burner who ends up breathing the Particulate Matter 24/7 from a neighbor who could care less about drying his wood to create less emissions. Unless manufacturers' design a stove that cannot be abused by the average home owner, wood burning will always be a contentious issue pitting neighbor against neighbor, especially now that the internet has given people access to the science of PM 2.5. To add validity to my arguments talk to neighbors in the vicinity of a Phase II EPA certified Outdoor Wood Boiler. The internet is full of stories where people had to sell their homes at incredible looses to escape the smoke from these so called efficient stoves. Until we solve the problems associated with wood-burning at the micro-level (home owner) all the macro level theory in the world will not bridge the gap between those who burn wood and those who do not. Respectfully, Roger

  2. John



    Technology exists to produce pellets that are 50% wood and 50% clean burning polymer that has carbon dioxide and water emissions. Particulate emissions will go way down but carbon dioxide emissions from a non-renewable source will go up for these pellets. Because the BTU/pound is 70% greater than that of 100% wood pellets the particulate emissions would drop to a very low level. Neighbors may not object so much and the land fills won't fill up so fast.

  3. Roger



    I wish it was that easy John. Unfortunately, cord-wood burners will dominate the market as long as people pereceive them to be cheaper than pellet stoves.


    Leave a Reply

    Biomass Magazine encourages encourages civil conversation and debate. However, we reserve the right to delete comments for reasons including but not limited to: any type of attack, injurious statements, profanity, business solicitations or other advertising.

    Comments are closed