Webinar Review: Preparing to Harmonize Methane Emission Measurements for Biogas Applications
by Michael Eggleston* (Advanced Biofuels USA) On January 18th, 2018, the Canadian Institute of Forestry hosted a webinar for the International Energy Agency (IEA) Bioenergy Task 37 which publically addressed that there is a need to harmonize methane emission measurements for biogas applications.
Part of IEA Bioenergy’s vision, to achieve a sustainable bioenergy contribution to future global energy demands, is the international working group, Task 37. Task 37 aspires to develop a sustainable criterion to assist biogas’ role in balancing the electricity grid as well in the production of high quality biofertilizer. This webinar addressed methods used for evaluation, presented selected results of measurements, proposed mitigation measures and put methane emissions in a context of a standard GHG balance in order to evaluate the impact of these emissions on the context of a sustainable biogas system.
- Time variant factors including open storage of digestate, the combined heat and power (CHP) engine, leaks and the pressure release valve (PRV) are most important sources of structural methane emissions that must be routinely monitored.
- Emissions from digestate storage should be minimized via gas tight tank storage with gas utilization or digestion of the substrate should minimize the possibility of emissions.
- Frequent control and documentation of CHP motor settings and frequent maintenance and control of methane concentrations can help minimize emissions. Although there are no catalysts for methane emission reduction available on the market, Selective Catalytic Reduction (SCR) is an option for optimizing the emissions from CHP since it allows the unit to operate at a lower air fuel ratio.
- Surveys should be conducted every 1 to 3 years with leakage detection systems such as methane cameras and handheld lasers to identify leakages. Monitoring for elevated levels from air inflated double membrane roofs should also be included in routine measures.
- Plant management should avoid PRV releases in order to minimize emissions and losses in general.
- Models based on remaining gas potential, filling level and temperature are the most precise option to estimate emissions from digestate storage.
- Changing digestate substrate to manure and waste materials improves greenhouse gas emissions (GHG) balance.
- Substrate type, heat utilization and parasitic energy demand must be taken into account when putting methane emissions into a context of a GHG balance of the bioenergy system.
Precision, reproducibility and representativeness of methods used for methane emission quantification must be improved in the future. A method harmonizing a protocol will be necessary to compare results from different measurements. Only comparable results in combination with a sufficient number of plants analyzed will lead to a better understanding of the emissions from the whole sector and a reliable data base for emission inventory. When comparing results, particular attention should be paid to the limitations of the methods used, the duration of measurement, the completeness of plant components measured, potential sources included but not belonging to the biogas facility and the operational mode of the plant.
Only if the industry is sensitive to this subject, can emissions be further reduced.
On February 1st, 2018 a workshop on quantifying methane emissions will be held in Lund, Sweden benefiting biogas plant owners, operators, plant personnel, policy makers and researchers. For more information about the event and to register click here.
The full report of IEA Task 37’s research on investigating methods for measuring methane emissions from biogas plants is available here.
To watch the webinar yourself via Adobe Connect and download the presenter’s slides click here.
* Michael Eggleston is a chemical engineering student specializing in the interdisciplinary & intercultural communication of sustainable development practices with the University of Rhode Island’s International Engineering Program and spending a semester abroad at the Technische Universität Darmstadt in Darmstadt, Germany. He will be reporting on and representing Advanced Biofuels USA at international conferences.