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City of Pleasanton GHG Analysis of Natural Gas Replacement with RNG the procured RNG to meet SB 1383 procurement requirements, a contractual agreement will be required to demonstrate that the RNG has been legitimately procured and meets the eligibility requirements to be counted towards the jurisdictions procurement target. In addition to a contract, there must also be documentation demonstrating: 1) that the procurement compliance attribute is being supplied exclusively to the jurisdiction and there are no duplicate sales or double counting of the same RNG; 2)the total quantity of RNG supplied to the gas utility pipeline system and the total quantity procured is not in excess of the actual pipeline supply; and 3) that the total quantity procured does not exceed the amount used for municipal operations.z Generally this type of documentation would satisfactorily demonstrates the transfer of environmental attributes to the jurisdiction purchasing RNG through a contract (i.e., book-and-claim accounting).To ensure compliance with SB 1383 procurement eligibility,the City should review the terms of the regulations (14 CCR Section 18993.2). GHG Emission Reductions The combustion of fossil natural gas results primarily in the release of carbon dioxide (CO2) as well as some methane (CH4) and nitrous oxide (N20), all of which are considered a release of anthropogenic GHG emissions to the atmosphere.Alternatively,the combustion of RNG releases biogenic CO2, as well as some CH4 and N20. Biogenic CO2 refers to the carbon in biodegradable materials such as organic waste or wastewater that was originally fixed from the atmosphere by plants.When that same CO2 is released back to the atmosphere through combustion,the result is a net neutral impact because the CO2 does not contribute additional carbon dioxide to the atmosphere. However, the CH4 and N20 released during RNG combustion still contribute to atmospheric GHG emission levels due to their increased global warming potentials (GWP) as compared to CO2.The GWP refers to the ability of each gas to trap heat in the atmosphere. For example, one pound of CH4 gas has 25 times more heat capturing potential than one pound of carbon dioxide gas.The GWP of N20 is 298.3 As such, GHG emission reductions associated with the procurement of RNG in replacement of fossil natural gas are calculated as the difference between combustion of fossil natural gas and RNG where the biogenic CO2 emissions are considered zero.Table 1 presents the emission factors and GWP applied to the combustion of fossil natural gas versus RNG.The emission factors were obtained from the City's inventories for consistency. Table 1 GHG Emissions Factors Source lbs CO2 lbs CH4 lbs N20 MT • • CO2e/therrn 1,4 Natural Gas 1.17E+01 1 2.27E-04 2S 4.S3E-06 298 5.31E-03 Renewable 1.17E+01 0 2.27E-04 2S 4.53E-06 298 3.18E-06 Natural Ga S3 Notes:MT CO2e=metric tons carbon dioxide equivalaents z Procurement Questions and Answers-CalRecvcle Home Page 3 IPCC.AR4 Synthesis Report: Climate Change 2007.Accessed at: https://www.ipcc.ch/report/ar4/syr/ Page 2