In the United States, there has been a resurgence of heating homes with wood heaters. This trend is due to economic pressures and the movement to reduce our dependence on foreign oil. Internationally, nearly half of the world’s population uses biomass-fueled stoves to cook. It is estimated that these cookstoves contribute to approximately 4 million pre-mature deaths annually and many more illnesses.
Last Wednesday, Feb. 3rd, the EPA finalized a rule for New Source Performance Standards (NSPS) for Residential Wood Heaters. The finalized rule applies to the manufacture and sale of new residential wood heaters and does not apply to existing appliances already installed in peoples’ homes.The new air standards for residential wood heaters and stoves have not been updated in 27 years. According to the Clean Air Act, EPA is required to review NSPS for each category every eight years, but three separate eight-year-periods have past since the implementation of the Residential Wood Heater standards in 1988. These new standards are a result of a consent decree signed in New York v. McCarthy. As a result, the EPA was under Feb. 3, 2015 deadline to finalize revised emission standards with respect to the Wood Heater NSPS Standards, with such modifications as EPA deems appropriate under the Clean Air Act § 111(b)(1)(B).
Wood heaters carbon monoxide, volatile organic compounds (VOCs), black carbon, and air toxics such as benzene. Black carbon, otherwise known as soot, is second only to CO2 in heating the planet. The new rules should decrease the amount of emitted black carbon and other pollutants, ultimately impacting global climate change. Black carbon creates regional warming through the absorption of incoming and reflected solar radiation, absorbing more than one million times more energy than the same unit mass of carbon dioxide. Black carbon also decreases the reflection of solar radiation from snow and ice surfaces, which in turn, increases melting. The encouraging aspect of black carbon is that mitigation has been shown to reduce near-term climate change and protect public health. The reduction in near-term rate of climate change is a result of black carbon’s short lifetime in the atmosphere (days to weeks).
Climate change is not confined to political or even continental borders. The issue of wood heater emissions, whether the source is international or domestic, has an effect on climate change here in the Unites States and abroad.
These new domestic wood heater regulations in addition to efforts to make international cookstove efficiency research will hopefully lead to a decrease in black carbon emissions and therefore near-term climate change.
This reduction may have the greatest domestic and international effects on low-income communities because they are disproportionately impacted by climate change.
In addition to climate change impacts, these regulations will have a positive human health impact domestically. Wood smoke from cookstoves causes many counties (mainly in the Northeast) to exceed national ambient air quality standards (NAAQS) for PM2.5. This type of particulate matter, a component of soot, is believed to pose serious health risks because of its small size (approximately 1/30th the average width of a human hair) and therefore, its ability to lodge deeply into the lungs. Nationally, residential wood combustion accounts for 44 percent of total stationary and mobile polycyclic organic matteremissions, nearly 25 percent of all area source air toxic cancer risks and 15 percent of non-cancer respiratory effects. One in three people in the United States are at an elevated risk of negative health effects from PM2.5 due to age or rate of respiration, such as children, the elderly, and people who exercise outdoors due to deeper lung penetration during physical activity.
These rules would not directly affect the efficiency of cookstoves used in developing nations, but they are still intertwined. EPA’s own research on international cookstove efficiency was used as evidence to show that they must revise the NSPS. By revising the NSPS for residential wood heaters, the United States is also acting as an example for other countries, developing or not. EPA has recently rewarded $9 million to support further research on efficient cookstove technologies.
The final rule would require that new wood stoves meet a fine particle pollution limit of 2 g/hr in 2020, up from the agency’s initial target of 1.3 g/hr in their proposed rule before public comments were incorporated. Some are skeptical of the new standards, but the EPA asserts they changed to limit from 1.3 to 2 g/hr because many wood heater manufacturers are small businesses and the change in rules gives them more flexibility. From an environmental perspective, John Ackerly, president of the Alliance for Green Heat, said that “Overall, we think the EPA did a good job and released a fair rule that includes many compromises between industry and air quality agencies, . . . We think these rules are good for consumers and will not drive prices up hardly at all, but will result in more efficient appliances that will save consumers time and money.” According to EPA, for each dollar spent on this regulation, we will see $75 to $176 in health and other benefits.
Looking ahead, the EPA believes development of wood heaters that perform well in cordwood testing is important because many people use cordwood in their wood heaters for residential heating.
Up and coming wood stove technologies focus on efficiency and emissions. For example, some new models employ computer technology, gas-flow analyses, or catalytic converters to reduce emissions and increase efficiency. Many of these newer technologies were put on display at the 2013 Woodstove Decathlon hosted by the Alliance for Green Heat. Developers at the University of Maryland used a thermoelectric generator, which derives energy from the heat of the stove, to power a fan that pulled warm exhaust air back into the stove, improving efficiency while also conserving heat. The competition’s winner, the Ideal Steel Hybrid from Woodstock Soapstone, was able to achieve 82 percent efficiency while delivering as little as 0.54 g/hr of particulate emissions.
The promulgation of the final NSPS for Residential Wood Heaters is a step in the right direction to control emissions domestically and to mitigate climate change globally. While the new rules do not apply to appliances already in use, they will ensure that manufacturers will continue to produce and sell wood heaters with a focus on efficiency and emissions.