Assessing the change in national CO2 emissions from an investment in the local energy system - A case study of Gothenburg

Examensarbete för masterexamen
Master Thesis
Sustainable energy systems (MPSES), MSc
Zhang, Ruihua
Tengvall, Anders
More and more cities reduce CO2 emissions by making investments in the local energy system, such as solar power production and energy efficiency measures. One important step for decision makers considering such investments is to assess the impacts concerning CO2 emissions. The common methods used are average electricity production method and marginal electricity production method, which both have the drawback that they are not affected by the investment and do not consider power transfer limitations in the power system. Thus, the aim of the thesis is to estimate how investments in the local energy system will affect national CO2 emissions. In the thesis a dispatch model of the Swedish power system is presented, as an alternative to the two aforementioned methods used for assessing the CO2 emissions from an investment. The three methods are then employed in a case study where an investment is made in the heating sector of Gothenburg which results in a change in the production pattern from CHP district heating units. The result demonstrates that, for the case study, the changes in CO2 emissions using the three methods differ. More specifically, the dispatch model, average electricity production method and marginal electricity production method show approximately +16, -27 and +89 kton CO2 change respectively, for the Swedish power system as a whole. In the dispatch model, the investment has negligible effects on the electricity generation in Sweden. Instead, it leads to a change in import and export. The increased import mainly comes from Norway and Denmark, while the increased export mostly goes to Finland. Denmark is responsible for most of the increased CO2 imported to Sweden. In the average electricity production method, the investment is replaced by the Swedish average electricity generation, which has less CO2 emissions. In the marginal electricity production method, the investment causes a response by coal condensing power plants, which has much higher CO2 emissions. Hence, the dispatch model results in CO2 emissions between these two extremes. Furthermore, increasing the level of the investment, i.e. reducing the electricity contribution coming from CHP district heating units further, shows that both the average electricity production method and the marginal electricity production method have a linear trend in the changed CO2 emissions. However, the dispatch model indicates some fluctuations in the changed CO2. This is due to the fluctuations in the net import from Denmark and Finland. The change in electricity mainly comes from net imports from Norway, Denmark and Finland. Moreover, electricity generation from condensing power plants displays a continuous increase in electricity generation, and hence, the CO2 emissions from this technology increase.
Energi , Hållbar utveckling , Energiteknik , Energy , Sustainable Development , Energy Engineering
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Geografisk plats
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Teknik / material