Goals of the task
The major goal of Task 4.3 is to analyse the energy consumption of the case cities, to identify and quantify direct and indirect greenhouse gas (GHG) emissions and their mitigation.
Work done to achieve the goals
Firstly, in this task data was gathered via literature review, surveys and interviews regarding energy supply and demand of the case cities. Secondly, to have a general overview of the energy sector, its linkages within and interlinkages to other sectors were identified. A sector map was created, to visualise energy technologies and the entire chain of energy conversion of any relevant primary energy to the supply of services. It therefore serves as the basis of Task 4.3. Unlike several definitions of the energy sector, our approach also includes final consumption like cooking, electricity, heating, illumination and transportation.
Next step was to fill the aforementioned map with data, which is an ongoing process. The process chains in this sector contain several steps where GHG emissions and losses occur. Power plants, transfer and distribution networks were analysed in detail. This proves to be exceptionally difficult due to the lack of data in general and in the case cities in particular. Therefore, we developed a solving approach for uncertain, unreliable, unavailable or inadequate data that contained mainly a discussion and decision on assumptions and estimations.
Furthermore, the work included an initial analysis of climate relevant aspects as part of the life cycle assessment (LCA). Thus, the Life Cycle Inventory (LCI) database Ecoinvent 3.3 and the LCA software GABI were used. The groundwork was laid with an extensive literature review on functional unit, system boundaries and LCI data. GABI and other LCA software include their own database, therefore individual results are slightly different. The variances between the values are not taken into account due to low impact on the overall system. The cumulative impact assessment results (LCIA) are also different from one system model to the other. Thus, an agreement on the matter between all partners was initiated.
In this context, a combined approach of energy consumption and GHG emissions was developed. Due to the fact that approximately 90% of the energy demand for cooking in Rwanda is covered by biomass (charcoal and wood), this part of the energy sector was examined in detail. An MS Excel-based tool is currently under development, especially to visualise energy and emission related inputs and outputs by using different cooking methods. The purpose of the tool is to show GHG emission mitigation potential and cost involved. The expansion of the tool by VBA programming show significant progress due to the complexity of the model, but the data output has not yet been validated. A modelling approach for the emissions of dumpsites/ landfills is also under development.
Results so far
The analysis of the individual power plant portfolio provides valuable information for this task. Therefore, the efficiency rate of power plants and losses in the electricity transfer and distribution networks of the status quo show promising preliminary results concerning efficiency gains. Furthermore, the emission reduction potential per year (t CO2-e) depends largely on technology type. The expansion of renewable energies shows high potential for short-term and long-term GHG emission mitigation due to much lower life-cycle GHG emissions of hydro, wind and solar PV compared to fossil power plants. Initial findings on GHG emissions from energy generation and consumption, dumpsites/ landfills and cooking are now available. The efficiency of cooking stoves are particularly interesting in Kigali. Da Nang showed high potential in ventilation and air conditioning. Both have in common to improve lighting by using efficient LED lights.
For the purpose of illustration serves the example of cooking energy. Depending on the population and population growth rate, the tool for cooking energy in Kigali provides the user with the required amount of cooking energy in Kigali for the designated year. Then, the choice between different scenarios concerning improvements in cooking methods, their individual efficiency and other technical and economic parameters follow. By improvements of the traditional cooking stoves and a higher share of electricity and gas compared to the reference scenario, it is possible to cut down on over 100,000 tons of CO2-e. The estimated emissions of the “improvement” scenario are depicted in Fig. 40.
Fig. 40: Example of the “improvement” scenario: CO2 emissions of the cooking sector Kigali 2020
Detailed results are found in the Deliverable draft reports Model and datasets for energy demand and GHG emissions (D-4.8), Identification of promising energy efficiency gains (D-4.9) und City-specific reports and comparative assessment (D-4.10).