Wood Stove Challenge

The Puget Sound is home to more than 100,000 wood stoves, many of which are older and emit a lot more pollution than newer, certified stoves. These devices are the largest source wintertime air pollution in the Puget Sound. Replacing older stoves can be expensive. There is limited financial assistance available in some areas with the highest pollution levels, but there just isn’t enough for the rest of the region.

The Wood Stove Retrofit Open Challenge



Fine particulate matter (PM) pollution is a widespread wintertime problem in the Pacific Northwest. Over the years, many members of the public and agency staff have wondered if some type of pollution reduction device could be added to older wood stoves. In 2013, the Puget Sound Clean Air Agency, working with Washington State Dept of Ecology, obtained a grant to search for and test devices that can reduce PM and PAH (polycyclic aromatic hydrocarbons) emissions.

In late 2014, we ran an open competition on the crowdsourcing site, Innocentives, to find new and emerging retrofit technologies. We received 32 proposed solutions which we narrowed down to four semi-finalists. The four semi-finalists were then tested in an EPA accredited lab in Portland, OR. The lab tests looked at the emissions from two old, uncertified stoves first without the retrofits. Then, each of the retrofits was installed and run through a series of tests. All four of our semi-finalists showed significant reductions in PM, with three devices beating our Challenge goal of a 75% reduction! Congratulations to all of our semi-finalists and especially our three Finalists! Our three semi-finalists also showed similar reductions in PAHs!

Each of the three Finalists has a somewhat different technical design and so has different strengths and weakness. Two of the devices have small heaters that help insure steady pollution reduction performance, while the third uses the latest catalytic technology and doesn’t need a heater. The two active devices reduced fine particle emissions by about 90%, and the passive device reduced fine particles by about 80%. In the end, our panel of judges was split on how to the rank the devices and settled on a three-way tie. Initial cost estimates are in the range of $500-$1000, but this could change depending on the production quantity and other factors. Below is a figure of the average particle pollution reduction for each retrofit for both stoves.

So what does the future hold for these retrofits? A real-world pilot study in a small town or community would be a great next step. But, there are still a number of issues and challenges to be addressed, including finding a funding source. All of our finalists are eager to move forward and would be able to begin production in early 2016. We are working on pulling together all of the pieces for a pilot study, but there are still a lot of unknowns. If a pilot study goes well, the air quality community would then work to find the best way to take advantage of a new air quality protection tool.

A Final report on the Challenge is being prepared and should be released in a few weeks. Once the report is available, a link will be added here and in our document library.

In this section, you can find further information and links provided by our semi-finalists:
  • ClearStak
  • Grace Fire
  • Grahn
  • MF Fire
THIS PROJECT HAS BEEN FUNDED WHOLLY OR IN PART BY THE UNITED STATES ENVIRONMENTAL PROTECTION AGENCY UNDER PUGET SOUND ECOSYSTEM RESTORATION AND PROTECTION COOPERATIVE AGREEMENT GRANT PC-00J20101 WITH WASHINGTON DEPARTMENT OF ECOLOGY. THE CONTENTS OF THIS DOCUMENT DO NOT NECESSARILY REFLECT THE VIEWS AND POLICIES OF THE ENVIRONMENTAL PROTECTION AGENCY, NOR DOES MENTION OF TRADE NAMES OR COMMERCIAL PRODUCTS CONSTITUTE ENDORSEMENT OR RECOMMENDATION FOR USE.
Wood Stove Retrofit Challenge Pollution Reduction Chart