Integrated greenhouse gas accounting model for the Philex-Padcal Mine Project in Benguet Province, Philippines

A spread-sheet-based model was developed to determine the carbon fluxes into and from mining project operations of Philex-Padcal Mine in Benguet Province, Philippines. Using 2014 as base year, the model was able to track the emissions of the entire project operations from mine, mill processes and auxiliary activities. Results showed that the project has a total emission of 267,801.26 t CO2 sub e, broken down as follows: Scope 1 (fuel and fugitive emissions): 14,026.46 t; Scope 2 (purchased electricity): 238,400.85 t; Scope 3 (air travels, LPG for domestic use, power sold or rented and waste disposal): 14,161.43 t; and Scope 4 (biomass loss): 1,212.49 t. The power consumption has the highest percentage share of emissions due to its source from coal power plant which has a higher emission factor and GWP. Energy sources from electricity and fuel garnered the bulk of emissions (94%) of the entire project operation. A separate accounting was done on the CO sub 2 sequestered by the project's mining forests, which were classified as high, medium and low density stand. It has an average biomass density of 176.83 t/ha with equivalent C and CO2 stored of 169.74 t/ha and 622.37 t/ha, respectively. Given the total area of 12,185 ha at a mean biomass annual increment of 6.55 t/ha/ yr with equivalent of 2.95 t/ha/yr C or 10.81 t/ha/yr CO sub 2, the Padcal mining forests have a total CO sub 2 storage of 153,451.87 t/yr. Financial analysis of the study showed that the reforestation will be profitable at a carbon price of less than or equal to US $ 40 (BCR of 1.06) in the carbon trading market with POI of PhP 0.06/yr and payback period of about 17 years. The proposed 600-ha reforestation sites to be established up to 2020 have a projected mean annual sequestration rate of 10,199.18 t CO sub 2/yr. Further, the project's energy saving measures (PLS and shift from fluorescent to LED lamp) resulted in total peso savings of PhP 5,283,799.44 and CO sub 2e removed of 708 t/yr. Likewise, the shift from fluorescent to LED lamps resulted to a profitable BCR of 3.6, ROI of PhP 2.56/yr and five months payback period. Based on the projected net CO sub 2 change with the mitigation scenario, the project will have a net CO sub 2 uptake 15,758.32 t/yr contributed by energy saving measures, new reforestation projects and reduction in half of its electricity emissions by shifting to renewable energy source.