Forests 2022 , 13 , 1856
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In Equation (1), C h is theCO 2 emission from logging and timbering operation activities (10 6 t), e d is theCO 2 emission factor of diesel fuel (tCO 2 /t), E h is the energy consumption of logging and timbering (10 6 t), W h is the volume of paper logging (m 3 ), and W ah is the average fuel consumption of chainsaw in logging operation (t/m 3 ).
Mechanical ropeway skidding operations:
2
C m = e d × E m = e d × W m × W am × L m (2) In Equation (2), C m is theCO 2 emission of ropeway skidding operation activity (10 6 t), E m is the energy consumption of ropeway skidding (10 6 t), W m is the volume of skidding (m 3 ), W am is the average fuel consumption of mechanical ropeway skidding (t/m 3 .km), and L m is the length of ropeway (km).
Material transport operations:
3
C l = e d × E l = e d × W l × W at × L l (3) In Equation (3), C l is the CO 2 emission from the vehicle timber transport activity (10 6 t), E l is the energy consumption of timber transport (10 6 t), W l is the volume of timber transported (m 3 ), W at is the average fuel consumption of timber transport (t/m 3 .km), and L l is the distance of timber transport (km). Assuming no damage to wood during skidding and transportation, i.e., W h = W m = W l . The final CO 2 emissions during the wood pulp raw material acquisition stage are C w = C h + C m + C l . The Process of Obtaining Raw Materials for Rice and Wheat Straw Pulp Rice-wheat straw pulp is one of the important ways to utilize straw as raw material. CO 2 emissions from this process include: 1 CO 2 from the use of agricultural chemicals (fertilizers, pesticides); 2 CO 2 from the consumption of diesel fuel for irrigation [30], tilling and harvesting with agricultural machinery, etc. Refer to the grain/straw ratio method. The formula is as follows. C n = n − 1 × ∑ i i = 1 AR i × c i × A (4) In Equation (4), A is the area of rice planted for papermaking, C n is theCO 2 emission in the non-wood pulp raw material acquisition stage (10 6 t), n is the ratio of rice-wheat straw pulp production to total non-wood pulp production, AR i is the i -th agricultural input per hectare of rice planted area (t/hm 2 , kW-h/hm 2 ). According to the statistics of the China Rural Statistical Yearbook, agricultural inputs include nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer, compound fertilizer, herbicide, insecticide, fungicide, diesel, agricultural film, rice seed and electricity. c i is theCO 2 emission factor of the i -th agricultural input (tCO 2 /t, tCO 2 /kW-h). CO 2 emissions in the raw material acquisition stage of the final paper product C A = C w + C n . 2.2.2. Accounting for CO 2 Emissions in the Pulp and Paper Stage The pulp and paper stage mainly generates CO 2 emissions from energy consumption. In this paper, the carbon emission nuclear algorithm is used to calculate CO 2 emissions based on the energy consumption of the pulp and paper stage and the CO 2 emission factor of energy, the formula is as follows.
j ∑ j = 1
C B = ∑ c j =
(5)
e j × f j
In Equation (5), C B is theCO 2 emission of the pulp and paper stage (10 6 t), c j is the CO 2 emission of various energy sources consumed in this stage (10 6 t), and e j is the physical quantity of various energy sources consumed (10 6 t,m 3 , kW-h). According to the statistical
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