Grantee Research Project Results
2023 Progress Report: Cleaner Cordwood Heating Technology for Tribal Communities: Needs Assessment and Preliminary Design
EPA Grant Number: SU840405Title: Cleaner Cordwood Heating Technology for Tribal Communities: Needs Assessment and Preliminary Design
Investigators: MacCarty, Nordica , Zhang, Shaozeng , Still, Dean K , Evitt, David , Kilkenny, Kiernan , Laun, Michael , Coto, Paula , McDonough, Zachary , Stadtler, William , Mathis, Christopher
Institution: Oregon State University , Confederated Tribes of the Umatilla Indian Reservation , Confederated Tribes of Coos, Lower Umpqua and Siuslaw Indians
EPA Project Officer: Spatz, Kyle
Phase: I
Project Period: July 1, 2022 through June 30, 2023 (Extended to June 30, 2024)
Project Period Covered by this Report: July 1, 2022 through June 30,2023
Project Amount: $25,000
RFA: 18th Annual P3 Awards: A National Student Design Competition Focusing on People, Prosperity and the Planet (2021) RFA Text | Recipients Lists
Research Category: Air , P3 Awards
Objective:
Today residential wood heating contributes to nearly 25% of all area source air toxic cancer risks and over 50% daily wintertime fine particle emissions. Exposure to these toxics is inversely correlated with income, disproportionately affecting low-income households and especially tribal communities in the north and southwest US. In 2014, EPA developed the Indoor Air Quality Tribal Partners Program, highlighting the health risk created by old pot-bellied wood stoves, and recommending that old stoved be gradually changed out. However, progress on this front has been limited, with few appropriate and affordable replacement options available. This project is one of the first to combine a detailed needs assessment and use-centered design approach in multiple underserved and/or rural communities by a team with decades of collective experience designing and disseminating appropriate biomass combustion technologies for households. Recent breakthroughs in forced draft combustion by the team sponsored by recent DOE and EPA SBIR I and II grants were applied to these household heating systems to develop affordable, effective, and cleaner-burning solutions for this acute unmet need.
Leveraging an interdisciplinary team of engineers, social scientists, and entrepreneurs from academia, non-profit organizations, and the wood heat sector, this research seeks to design (Phase I) and refine (Phase 2) cleaner and more efficient wood heating technologies. These diverse mentors will engage undergraduate and graduate students at Oregon State through curricular and co-curricular pathways that allow them to contribute to these research activities. Surveys, interviews, and site visits assessed community needs to inform the technical design in the laboratories at Oregon State and Aprovecho Research Center. Engineering students completed the preliminary design of a novel, high-performance stove incorporating fan-driven staged combustion air and enhanced heat transfer. Low-cost improvements to existing stoves in the form of chimney heat exchangers were also explored.
Progress Summary:
Outputs and outcomes of this research investigated the efficacy of technological modifications to the household heating system possible at an affordable price and in a way that builds local capacity for education and installation. This included chimneys retrofits to transfer more heat into the home rather than losing it through the chimney. Five different configurations were explored and it was determined that placing fins on the chimney would be the most efficient and cost-effective solution, while a counterflow heat exchanger around the chimney could also enhance heat transfer at a relatively low cost. A heat spreader also had potential. but would require re-design for maintaining draft and cleaning purposes. In addition, an advanced staged forced-air combustion in a new preliminary stove design was developed that meets EPA 2020 regulations, achieving 2.3g/hr of PM in lab tests.
The primary goal of this project is to provide cleaner-burning, effectively vented, and more efficient technologies for wood heat in homes that reduce the stationary point source emissions of fine particulate matter, VOCs, carbon monoxide, and products of incomplete combustion to the local ambient air and the indoor environment, specifically in underserved communities.
Future Activities:
The outline of Phase 2 activities include:
Objective #1: Optimize and user test the cordwood prototype. Households that heat exclusively with woods are a demanding use case that commonly require over 8 hours of burn time unattended. In phase one a new stove concept was developed to meet the specific needs of this market segment of extended burn time with low emissions by applying fan-driven jets of staged air instead of a catalyst for emissions reductions. This configuration could potentially offer improved robust emissions performance at a lower cost by removing the catalyst, the single most expensive component.
Additional research is needed to optimize the air delivery and controls, and refine the design based on customer feedback. Gruadtae student David Evitt will lead this objective with the work on optimizing air delivery and ocntrols forming part of his PhD dissertation supported by the NSF Graduate Research Fellowship Program. Project partner Aprovecho Research Center is a subcontractor for the iterative prototype modifications, emissions testing the prototype, and user testing. The tasks associated with this objective include:
- User testing in a laboratory setting at the Aprovecho Research Center. It is extremely difficult to mitigate the liability associated with field testing a prototype wood stove in customer homes. As a practical alternative we will invite example target users to operate the stove prototype at the Aprovecho Research Center to assess the functional, aesthetic, and usability attributed of the prototype concept. Aprovecho is located in a rural area of oregon facilitating access to our target market.
- Refining the detailed dsign of the stove concept. Feedback from potential customers from our target marked of rural or low-resource households will be used to refine the prototype design and operation with multiple rounds of iteration between lab development and customer feedback.
- Optimizing the air delivery, and control system. Cost optimization will examine opportunities to achieve the same functionality at a reduced price. For example, closed loop control of secondary air based on exhaust oxygen in the prototype stove will rely on an automotive sensor and supporting circuitry. It may be possible to replace the oxygen sensor with creative use of temperature sensors for secondary air control reducing the equipment cost of the production stove with only a small increase in emissions. High-momentum turbulent jets of air enhance mixing in the combustion zone to reduce products of incomplete combustion but increase the size, cost and noise from the driving fans. Various levels of system operating pressure and fan requirements will be evaluated for performance, cost and aesthetic tradeoffs.
Objective #2: Evaluate, optimize, and promote low-cost chimney heat exchanger retrofits. Phase one research showed that the best performing chimney retrofits increased the heat transfer from the chimney by five times. This ultimately would result I more heat into the room and therefore less wood expense for the user and reduced emissions into the airshed and atmosphered. The cost and materials associated with producing these are relatively low, and the potential for scaling them into many households is significant as a part of a chimney retrofit program in addition to or in place of full changeouts. This would reduce fuel consumption and association emissions, potentially act as a passive “scrubber” to further remove emissions of smoke and soot and dispose of it as solid waste, and help to increase safety in low-resource homes and potentially improve indoor air quality as well.
More research is needed to determine the optimal retrofit design that blends high performance with ease of installation and maintenance at a low cost. The tasks associated with this objective include:
- Develop detailed models to guide design of most promising options. A Master’s student specializing in thermal fluid science will develop detailed analytic or CFD models to optimize the configuration of the most promising designs. These include fins, spreaders, counterflow heat exchangers, convective heat reclaimers, as well as technologies like coils inside the chimney to induce swirl.
- Conduct rigorous experiments with both proxy burners and real wood stoves to evaluate and benchmark performance of new and off-the-shelf designs. Using a variety of existing heating stoves at Aprovecho Research Center, the prototypes will be evaluated for performance and to determine the percentage increases in efficiency achieved on real wood stoves. Fouling and other usability issues will also be investigated, as well as the effect of the retrofit on stove draft and combustion performance.
- Optimize two of the “best” designs for performance, cost, usability, and manufacturability. Once the most promising configurations are identified, we will work with manufacturers such as our partner USStove Manufacturer and designers to further optimize the detailed design to maximize performance, minimize cost of materials and manufacturing, and enhance usability of installation and maintenance.
- Test with users. Throughout the project, we will work with example low-resource and rural users to seek their feedback about the practicality, aesthetics, an function of the various designs. This will ensure that the designs that we deem as optimal in the technical analysis are also acceptable from the user perspective.
Completing this design and disseminating results via publications, webinars and outreach with our extensive network of regulatory, industry, and community experts in the wood heat sector, and readily-available consumer products will help promote the environmental benefits associated with efficiency gain resulting in reduced wood consumption and associated emissions. In addition, safety and indoor air quality will be improved due to better chimney-installation and function, and there is a potential for the device to act as a “passive smoker scrubber”, encouraging condensation and collection of smoke and soot on the heat exchanger surfaces with can then be cleaned out as solid waste rather than released as air toxics.
Objective #3: Develop business plan and partnerships to scale – We will recruit partners for manufacturing and installing the intervention solutions developed in this program seeking to develop local capacity in tribal communities. Research partner Aprovecho Research Center is working closely with US Stove Manufacturing Company, a large stove manufacturer with distribution relationships with box stores frequented y rural, low-income users, to produce and sell a cleaner-burning pellet stove that Aprovecho has designed. Therefore we will utilize this direct relationship with an established manufacturer that is interested in elevating the performance of their existing product line of pellet stoves, cordwood stoves, and chimney heat reclaimers and taking these technologies to the big box store market.
Objective #4: Communities findings to stakeholders. The insights from this work will be shared in peer-reviewed journals, webinars to stakeholders, and popular press. Several papers on the needs assessment for this project are in preparation, including “Results of Surveys Regarding Wood Stove Use” and “Understanding Wood Stove Use to Inform Research and Development”. Papers regarding the technical development are planned as well, including “Measuring In-Situ Performance of Cordwood Stoves” and “Application of Turbulent Air Jets for Emissions Control in Cordwood Heaters”. We will also disseminate our findings via webinars to stakeholders and our advisory groups in industry, regulatory, and community sectors.
Supplemental Keywords:
Indoor air quality, Air Quality Index, wood burning appliancesRelevant Websites:
Aprovecho Research Center Exit
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.