By: The Working Forest Staff
The Wood Pellet Association of Canada is proud that one of its members – Ontario Power Generation (OPG) – operates the Thunder Bay Generating Station, which is the only plant worldwide that has been converted from coal firing to employ advanced wood pellets as the sole primary fuel.
OPG is seeking to expand its experience and knowledge about advanced wood pellets. To this end, the company is collaborating with Natural Resources Canada on a project aimed at evaluating advanced biomass fuels for use in power generation and other industrial sectors. Note: the generic term “advanced biomass” is intended to include all methods of thermal upgrading (torrefaction, steam treatment, carbonisation, etc) that are intended to improve the characteristics of the beneficiated fuel (calorific value, grindability, water resistance, etc).
The project has two primary objectives:
1. To improve the understanding of both suppliers and end users on the current state of advanced biomass fuel development and to improve the characteristics of the fuels as needed.
2. To assist in the development of standardised, objective tests to define and measure the criteria required by industrial end users.
OPG has already received interest from a number of Canadian and international utility companies who intend to participate in the project. These companies will provide feedback on the types of tests to be conducted and the actual methods employed. The unique properties of advanced biomass fuels offer several significant advantages to a utility generator but the means to evaluate fuels are not well developed.
Participation by fuel developers will be essential to the project’s success. Fuel developers will receive industry feedback on the characteristics that are important to end users and have the opportunity to adjust their feedstocks and processes to suit these needs, including the submission of additional fuels into the program for analysis.
Laboratory Scale Fuel Samples
OPG invites fuel developers to supply samples to support initial laboratory testing. Samples can use any feedstock and upgrading technique but must be densified in pellet or briquette form. Developers are encouraged to send multiple samples that might employ the same feedstock with different processing conditions, or vice versa. One of the key objectives of this project is to assist the industry with exploring new low cost feedstocks and different processing conditions to meet the needs of end users. Samples that are provided to OPG for initial laboratory testing should meet the following requirements:
- Ten kilogram sample size.
- Base feedstock (SPF softwood, wheat straw, etc) and a 1 kg sample of that base feedstock should also be provided for analysis.
- Some information on the processing conditions should also be provided to identify the sample and distinguish the results from other similar fuels. This level of detail could be as simple as “Torrefaction, 280C, 20 minutes”, or similar.
- The laboratory scale testing of the advanced biomass samples should include a complete chemical analysis as well as a number of tests under development to evaluate the performance of the fuel in the areas of safety, storage and grindability.
The program will objectively rank all fuels tested regarding their relative performance to replace coal in the broad areas of handling and combustion performance. The results will be recorded in a public database. Suppliers may choose not to be identified in the database. The fuel ranking will help to highlight the relative ease to employ a given advanced biomass fuel within a coal displacement initiative.
Finally, as the definition of an acceptable fuel specification improves, results from this effort will be used to inform existing and future projects that focus on the development and adoption of national and international standards for test methods and fuel standardization.
Scale of Testing
Laboratory scale testing will be critical to the success of this project as the ultimate goal is to develop and adopt objective and cost effective methods that can be conducted by both fuel suppliers and end users. However, the applicability of some of these methods may need to be confirmed by more complex, larger scale efforts to ensure that the results are representative.
OPG expects to identify several fuels that are close to commercial readiness and consider a number of pilot scale tests on these leading candidates. The criteria to be tested and the methods used will be discussed among the end users participating in the program. This pilot scale testing will require fuel volumes in the 1 to 20 Mg range and could include:
- Long term weathering of samples stored outdoors for extended periods.
- Dust generation during handling via a drop test rig employing vertical drops similar to those in existing fuel handling systems.
- Grindability testing in a pilot scale milling facility.
Especially promising fuels will also be considered for full scale trials at the OPG Thunder Bay station or another site operated by one of the other utility participants.