ارزیابی ارزش پس انداز زیست توده کارخانه خمیر کاغذ در یک اقتصاد آگاهانه تغییرات آب و هوایی

Pulp mills use significant amounts of biofuels, both internal and purchased. Biofuels could contribute to reach greenhouse gas emission targets at competitive costs. Implementing process integration measures at a pulp mill in order to achieve pulp production with less use of energy (biofuels) has not only on-site consequences but also off-site consequences, such as substitution of fossil fuels elsewhere by the saved pulp mill biofuels, and less on-site electric power generation. In this paper a method, a linking model, is suggested to analyse pulp mill biofuel saving measures when carbon dioxide (CO2) external costs are internalised. The linking model is based on equilibrium economics and links information from CO2 constrained energy market future scenarios with process integration measures. Pulp mill economics and marginal energy market CO2 response are identified. In an applied study, four process integration measures at a Swedish pulp mill were analysed using five energy market future scenarios emanating from a Nordic energy model. The investigated investment alternatives for biofuel savings all result in positive net annual savings, irrespectively of the scenario used. However, CO2 emissions may increase or decrease depending on the future development of the Nordic energy market.

Biomass is attractive for energy purposes in at least three respects: Contribution to sustainable development, reduction of fossil fuel related anthropogenic greenhouse gas (GHG) emissions, and security of supply. To develop sustainable energy systems with low CO2 emissions it is necessary to not only increase the use of biofuels, but also to use such fuels as efficiently as possible. Stabilisation of GHG concentrations in the atmosphere calls for targets on anthropogenic global GHG emissions. A wide range of international energy market studies suggests that the use of biofuels is cost-effective to reach global targets, e.g. (Johansson et al., 1996; Nakicenovic et al., 1998; Azar et al., 2003; UNDP, 2000). In a Nordic perspective, different studies show that biofuels may play a significant role for cost-effective GHG reductions (Azar et al., 1998; Nyström and Cornland, 2003; Unger, 2003)

Results from the applied study indicate that the considered pulp mill PI measures all contribute to lower the total cost to reach a given CO2 emission target for the Nordic countries. Totally integrated evaporation unit technology saves biofuel and is also proven to be the most profitable. These conclusions are valid for all five future energy market scenarios considered. Since the external costs associated with CO2 emissions are internalised, the pulp mill NASs may be interpreted as total system cost savings. Hence, implementing a novel designed evaporation plant contributes to increased welfare. Net CO2 emissions associated with the PI measures considered result from a combination of off-site effects. Decreased on-site power generation increases marginal grid power CO2 emissions, whilst saved biofuels may lead to substitution of fossil fuels and thus decrease CO2 emissions. The electricity conversion efficiency at the pulp mill is fairly low, which implicitly means that the negative environmental impact that occurs due to decreased on-site biofuel-based electricity generation is overruled by the positive environmental value that is achieved due to the replacement of fossil fuels in the energy market with the supplied biofuels.