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Partial Thermal Storage Test Method

The following is the content of a letter and associated attachment received by DEC from the Brookhaven National Laboratory, dated February 15, 2013. The attached is listed in the right column as a PDF document.

Attached for your consideration is "A Test Method for Certification of Cord Wood-Fired Hydronic Heating Appliances with Partial Thermal Storage: Measurement of Particulate Matter (PM) and Carbon Monoxide (CO) Emissions and Heating Efficiency of Wood-Fired Hydronic Heating Appliances with Partial Thermal Storage".

This proposed test method is a major modification of EPA Method 28 WHH intended to provide a method to evaluate a specific type of advanced wood heating boilers. These boilers typically achieve low emissions through the use of two-stage gasification combustion, are relatively low in mass, and require external thermal storage. The use of the external storage enables these boilers to operate for a great part of the heating season in a low-emission, high-burn-rate mode and offer the potential for reduced emissions with wood heating statewide. These units burn a load of wood primarily to heat the storage and the stored heat, in turn, is then used to heat the home between burns.

While these units offer significant potential for reduced emissions, they cannot be tested under the current Method 28 WHH, which does not include storage. If operated without storage, these units go into a high emission slumber mode and typically overheat.

Due to these considerations, NYSERDA was approached by the US EPA to provide financial support to BNL to develop an appropriate test method for this new technology. This request was further supported by regulatory agencies, biomass heating trade groups, and manufactures of advanced 2-stage wood boilers. Those supporting this project include NYSDEC, the Biomass Thermal Energy Council, NY Biomass Energy Alliance, Econoburn, TARM USA, Lopper NA, Evoworld, SP Technical Research Institute of Sweden, and Bioenergy 2020+ of Austria. NYSERDA saw this as an important project that would allow for 3rd party evaluation of efficiency and emissions performance of advanced wood boiler designs. Developing the test method would allow consumers and air regulators to consider objective performance measures and promote a market-based move to high-efficiency wood heating.

The current Method 28 is intended to measure emissions of particulate matter (PM) over complete burn cycles. The proposed method attached extends this in several important ways. First it also includes carbon monoxide (CO) emission. Both PM and CO are criteria pollutants.

High concentrations of PM can cause serious health issues for children, elderly, and those with existing cardiovascular or pulmonary illness such as asthma or chronic obstructive pulmonary disease (COPD). CO is also a very important consideration for immediate health and safety. It is a colorless, odorless gas and emitted in much higher quantities from wood combustion devices than from oil or gas heating systems. Second, the method provides a way to isolate the startup, steady state, and end portions of a typical firing cycle. This provides better understanding of the emission profiles and allows assessment of the local, short term environmental impacts.

The attached test method was developed after a year of research on boiler systems of this type. It is a rigorous test method yet was developed with strong consideration of the cost of implementation. It includes a method for determining the emission rate of both PM and CO in grams/hour, grams per kg of fuel, as well as on an output basis (lb/MMBtu). The test method is realistic in that the system is operated in a manner similar to how it will be used by a consumer, and the fuel used in the test is cord wood, not dimensional lumber or a "crib". It allows determination of a representative annual efficiency and incorporates quality control procedures.

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