Implications of energy efficiency improvement for CO2 emissions in energy-intensive industry

Abstract

This thesis explores how energy efficiency improvement implemented in industrial plants contributes towards achieving CO2 emission reduction. The measurement of energy efficiency and CO2 emissions are related issues. The implications of the following challenges in measuring energy efficiency have been evaluated based on constructive case studies: variables affecting energy efficiency, the allocation problem, system boundary definitions and energy valuation. In addition, the realisation of emission reduction potential is analysed. The thesis shows that, among other things, the utilisation of recycled materials is an important variable that has to be taken into account when the energy efficiencies of different plants are compared. In the case of CHP production, some cost allocation methods, such as the energy method, may overestimate the feasibility of heat conservation investment from the industrial mill perspective. Due to heat conservation, CHP electricity production may be reduced at the mill site, which increases the demand for external electricity. The purchase of external electricity has implications for energy consumption and CO2 emissions at the national level. Therefore, the realised CO2 reduction of heat conservation investment may seem totally different from the mill site and national perspectives, which demonstrates the importance of the system boundary definition when evaluating the contribution of an individual energy efficiency investment towards fulfilling the commitment to reduce CO2 emissions. Also, increased operational flexibility and changing market conditions, such as energy and emission allowance prices, complicate the evaluation of the emission reduction potential and often reduce the exploitation of the full emission reduction potential. The thesis contributes to the research on monitoring energy efficiency and CO2 emissions in connection with the implementation of energy and climate policy.