On the systematic underestimation of methane conversion factors in IPCC guidance. (May 2018)

• Record Type: Journal Article
• Authors: VanderZaag, Andrew C.
• Is Part Of: Waste management. Volume 75(2018)
• Page Start: 499
• Page End: 502
• Publication Date: 2018-05
• Subjects: Manure management -- Greenhouse gas emissions -- Jensen's inequality -- Non-linear averaging; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2018.01.037
• Languages: English
• ISSNs: 0956-053X

Abstract

Highlights: IPCC 2006 systematically underestimates Methane Conversion Factor for liquid manure. Annual temperature cannot be used in a non-linear Arrhenius function to predict CH4 . Largest underestimation in temperate regions with high intra-annual temperature range. Smallest underestimation in equatorial regions with small intra-annual temperature range. Retention time should be taken into account when determining liquid manure MCF. Abstract: This paper documents a systematic underestimation in how the Tier 2 methane conversion factors (MCF) are calculated in IPCC (2006) guidelines for liquid manure management . The first issue is the use of annual average temperature as an input to a non-linear function describing methane production. As expected based on Jensen's inequality, the MCF calculated based on annual average temperature is always an underestimate. In regions with large intra-annual temperature ranges, such as temperate climates, the underestimation can exceed 30%. A second issue is the lack of consideration for volatile solids retention time. Future updates to the IPCC methodology should therefore account for intra-annual temperature regime and retention time—not simply annual average temperature.