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Effectiveness). This deterioration may be due to various reasons (e.g., waste increases [10], changes in the operating parameters [11], and deficient maintenance [12]), resulting in far lower and less efficient performance than initially desired. These GHGs may be grouped according to the Kyoto Protocol into carbon dioxide (CO 2 ), methane (CH 4 ), nitrogen oxide (N 2 O), hydrofluorocarbons (HFC), perfluorocarbons (PFC), and sulfur hexafluoride (SF 6 ) (IPCC 2014). The GHG emissions can be determined by aggregation into CO 2 equivalent (CO 2 -eq) units (henceforth CO 2 in this article). In the European Union (EU), the paper industry uses a fuel mixture consisting of 32% renewable energy from biomass, 3% fuel oil, and 65% natural gas [13,14]. Biomass is considered to be carbon neutral by the Intergovernmental Panel on Climate Change (IPCC) [15]. Almost all pulp and paper mills are a part of the EU Emissions Trading System (ETS), which has been in place since 2005. The direct emissions falling under the EU ETS mainly come from natural gas combustion and must be covered by credits, some of which are received for free and the remainder of which are bought at government auctions. This is a burden that competition in the pulp and paper industry in non-European regions does not have to bear. Among the GHG emissions by the European paper industry, the most important indicator in terms of amount and effect on global warming is CO 2 emissions. The great concern regarding the effects of CO 2 emissions in the intermediate and long term has led to awareness that such emissions must be curtailed to achieve a sustainable society [13,14]. Austin [16] showed that it is possible to reduce power consumption by controlling the variables associated with processes. Virtanen et al. [17] demonstrated the relationship between energy efficiency and productivity. In the pulp and paper industry, the current concepts of energy efficiency apply only to fossil fuels and are based on optimizing the use of energy to reduce consumption. Siitonen et al. [18] and Moya and Pardo [19] discussed the relationship between energy efficiency and CO 2 emissions in terms of the paper industry. Moya and Pardo [19] also observed how the adoption of the Best Available Technologies (BAT) enhanced by energy efficiency policies can help to reduce CO 2 emissions and be economically viable through the savings produced. However, the papermaking sector is very reluctant to prove new techniques due to the large investment required and the long life of the production facilities [20]. There are process variables that affect both energy efficiency and emissions as indi- cators for the paper industry [18], but they are not typically used to establish emissions reduction strategies as a result of planned maintenance measures or to address CO 2 emis- sions. Calvo and Domingo [21] demonstrated the relationship between the effectiveness of machinery processes and the influence of process conditions, equipment maintenance and operational parameters, and the generation of CO 2 emissions. Supervision and knowledge of the actual state of machinery operation and maintenance can lead to significant energy savings. This may result in a reduction in CO 2 emissions associated with the process. Investments in plant maintenance and improvement in energy efficiency can result in reducedCO 2 emissions [22] and can be profitable by themselves. Due to the pulp and papermaking process, which is an energy-intensive process, a study on installations and the reductions in CO 2 emissions are required. Papermaking has established indicators that relate CO 2 emissions to the energy efficiency of the drying process, called product benchmarks, which record emissions levels of 10% for the more efficient production processes for each grade of paper within the European Union [23–25]. This benchmark provides a valid measure of the effectiveness of the process indicators and allows us to compare the studied process to those of other factories in the same sector that produce the same products. The proper control of emissions can provide a competitive advantage for a particular industrial plant over others or could compromise its continuity due to inadequate management.
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