Abstract
Purpose
The overall aim of this study is to contribute to the creation of LCA database on electricity generation systems in Ethiopia. This study specifically estimates the environmental impacts associated with wind power systems supplying high voltage electricity to the national grid. The study has regional significance as the Ethiopian electric system is already supplying electricity to Sudan and Djibouti and envisioned to supply to other countries in the region.
Materials and methods
Three different grid-connected wind power systems consisting of four different models of wind turbines with power rates between 1 and 1.67 MW were analyzed for the situation in Ethiopia. The assessment takes into account all the life cycle stages of the total system, cradle to grave, considering all the processes related to the wind farms: raw material acquisition, manufacturing of main components, transporting to the wind farm, construction, operation and maintenance, and the final dismantling and waste treatment. The study has been developed in line with the main principles of the ISO 14040 and ISO 14044 standard procedures. The analysis is done using SimaPro software 8.0.3.14 multi-user, Ecoinvent database version 3.01, and ReCiPe 2008 impact assessment method. The assumed operational lifetime as a baseline is 20 years.
Results and discussion
The average midpoint environmental impact of Ethiopian wind power system per kWh electricity generated is for climate change: 33.6 g CO2 eq., fossil depletion: 8 g oil eq., freshwater ecotoxicity: 0.023 g 1,4-DCB eq., freshwater eutrophication: 0.005 g N eq., human toxicity: 9.9 g 1,4-DCB eq., metal depletion: 18.7 g Fe eq., marine ecotoxicity: 0.098 g 1,4-DCB eq., particulate matter formation: 0.097 g PM10 eq., photochemical oxidant formation: 0.144 g NMVOC, and terrestrial acidification: 0.21 g SO2 eq. The pre-operation phase that includes the upstream life cycle stage is the largest contributor to all the environmental impacts, with shares ranging between 82 and 96%. The values of cumulative energy demand (CED) and energy return on investment (EROI) for the wind power system are 0.393 MJ and 9.2, respectively.
Conclusion
The pre-operation phase is the largest contributor to all the environmental impact categories. The sensitivity and scenario analyses indicate that changes in wind turbine lifespans, capacity factors, exchange rates for parts, transport routes, and treatment activities would result in significant changes in the LCA results.