1747 4.1 Emissions estimated using DAE The results for the cradle-to-gate system boundary from DAE show that the majority of emissions originate from material handling operations, which ranged between 66% and 94% (see Error! Reference s ource not found.). Diffuse dust emissions are, for the most part, associated with internal transport operations. Additionally, it can be observed that the CO2 and NOx emissions during the production process are not reported in Error! Reference source not found.. This is because the processing circuit used for the production process is powered by electricity supplied from the grid, and the DAE method does not account for emissions associated with electricity generation (secondary emissions). 4.2 Environmental impact quantified using LCA From the LCIA phase of LCA, environmental impacts from producing 1 tonne of aggregates were quantified for a cradle-to-gate system boundary. presents the results for several impact indicators from the LCIA phase of LCA. From Error! Reference s ource not found., it can be observed that the majority of the cradle-to-gate impact originated from material handling operations across all of the indicators (except ODP and EP-freshwater indicators). The contribution from material handling ranged between 65% to 98% of the total impact. This contribution was mainly attributed to diesel consumption. For ODP and EP-freshwater indicators, at least 40% of the total impact originated from production processes. Note: Note: In Error! Reference source not found. and Error! Reference source not found., the Pe rcentage columns show the contributions of different operations to the total emissions and impacts, respectively. Table 38 – Direct emissions to air per 1 tonne of aggregates produced at the site. Table 39 – Environmental impacts of producing 1 tonne of aggregates produced at the site. Emissions Extraction Material handling Production process Total Value (kg) Percentage Value (kg) Percentage Value (kg) Percentage CO2 4.99E-02 5.67% 8.29E-01 94.33% - 0.00% 8.79E-01 NOx 1.33E-03 13.47% 8.56E-03 86.53% - 0.00% 9.90E-03 TSP 1.10E-03 0.83% 1.18E-01 88.94% 1.35E-02 10.23% 1.32E-01 PM10 5.78E-04 1.30% 3.85E-02 86.65% 5.36E-03 12.05% 4.44E-02 PM2.5 5.77E-04 7.84% 4.86E-03 66.09% 1.92E-03 26.07% 7.36E-03 Impact indicators Extraction Material handling Production process Total Value Percentage Value Percentage Value Percentage GWP-total 3.10E-01 21.42% 1.12E+00 77.10% 2.15E-02 1.48% 1.45E+00 GWP-fossil 3.10E-01 21.73% 1.10E+00 76.77% 2.15E-02 1.50% 1.43E+00 GWP-biogenic 7.10E-05 1.50% 4.65E-03 97.91% 2.81E-05 0.59% 4.74E-03 GWP-LUC 2.12E-03 12.91% 1.43E-02 87.03% 1.01E-05 0.06% 1.64E-02 ODP 7.98E-13 21.73% 8.80E-13 23.95% 2.00E-12 54.32% 3.67E-12 AP 2.69E-03 33.71% 5.24E-03 65.62% 5.37E-05 0.67% 7.99E-03 EP-freshwater 8.14E-07 15.99% 2.10E-06 41.32% 2.17E-06 42.69% 5.09E-06 EP-marine 1.02E-03 28.81% 2.51E-03 70.91% 9.75E-06 0.28% 3.54E-03 EP-terrestrial 1.35E-02 32.47% 2.79E-02 67.30% 9.90E-05 0.23% 4.15E-02 POCP 2.53E-03 27.09% 6.74E-03 72.20% 6.59E-05 0.71% 9.34E-03 ADP-minerals & metals 3.74E-08 24.19% 5.57E-08 35.98% 6.16E-08 39.83% 1.55E-07 ADP-fossil fuels 4.14E+00 21.93% 1.44E+01 76.06% 3.80E-01 2.01% 1.89E+01 WDP 1.95E-01 46.93% 1.59E-01 38.22% 6.18E-02 14.85% 4.16E-01 PM 4.45E-07 23.59% 1.43E-06 75.87% 1.02E-08 0.54% 1.89E-06
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