Environmental Life Cycle Assessment of Ethiopian Electricity Generation Systems: A Case of Hydro and Wind Power
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Date
2020-11
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Addis Ababa University
Abstract
Electricity is one of the most vital elements in modern society. Despite its significance to
improve human life, there are concerns on its environmental impacts. Life Cycle
Assessment (LCA) is a well-established tool for assessing the environmental burdens of
products (goods and services) throughout their life cycles. Several LCA studies were
conducted for electricity generation and supply systems. However, the LCA data of
electricity systems are country specific in their nature. In addition, existing LCA and
inventory modeling efforts are limited to the circumstances of the developed world.
Therefore, the need to evaluate the environmental performance and to develop country
specific LCA data that describe actual electricity systems remains important.
This thesis provides a picture of current electricity system and presents for the first
time the LCA results of hydro and wind power systems in Ethiopia. The assessment aims to
model existing hydro and wind energy systems and develop LCI and LCA datasets of the
country per 1 kWh electricity generated. For both case studies, process-based attributional
LCA has been applied using SimaPro software version 8.0.1 and ReCiPe 2008 as impact
assessment method.
The main midpoint environmental impacts of Ethiopian hydropower system
consisting of eleven hydropower plants operational in 2013-2017 were: climate
change(CC): 32 g CO2 eq., fossil depletion (FD): 0.82 g oil eq., freshwater eutrophication
(FWEU): 0.000132 g P eq., human toxicity (HT): 0.58 g 1, 4-DCB eq., metal depletion
(MD):1.04 kg Fe eq., marine ecotoxicity (MET): 0.01 kg 1,4-DCB eq., natural land
transformation (NLT): 8.3E-04 m2 eq., particulate matter formation (POF): 0.15 g PM10 eq.,
photochemical oxidant formation (POF): 0.03 g NMVOC eq., terrestrial acidification (TA): 0.02 g SO2 eq. and freshwater ecotoxicity (FWET): 0.005 g 1,4-DCB eq. per 1kWh electricity
generated.
The major midpoint environmental impacts of Ethiopian wind farms composed of 3
wind farms operational in 2015-2017 were: climate change (CC):33.36 g CO2 eq., fossil
depletion (FD): 8 g oil eq., freshwater ecotoxicity (FWET): 0.023 g 1,4-DCB eq., freshwater
eutrophication (FWEU): 0.005 g N eq., human toxicity (HT): 9.9 g 1,4-DCB eq., metal
depletion (MD): 18.7 g Fe eq., marine ecotoxicity (MET):0.098 g 1,4-DCB eq., particulate
matter formation (PMF): 0.097 g PM10 eq., photochemical oxidant formation (POF): 0.144
g NMVOC eq., terrestrial acidification (TA): 0.21 g SO2 eq. and natural land transformation
(NLT): 1.4E-06 m2 eq. per 1 kWh electricity generated. The cumulative energy demand and
the energy return on investment (EROI) are 0.393 MJ/kWh and 9.2 respectively.
The contribution analysis shows that the pre-operation phase of hydropower plants
contributes the highest share (62-99%) in most impact indicators, with the exception that
the operation and maintenance phase accounts for about 50 and 90% share in POF and CC
respectively. Moreover, medium-scale hydropower plants have higher potential
environmental impacts when compared to large-scale hydropower plants. Similarly, the
pre-operation phase of wind power is the largest contributor to all the environmental
impacts, with the shares ranging between 82 and 96%. In addition, the sensitivity and
scenario analyses indicate that the changes in lifespans, exchange rates for parts, capacity
factors, transport routes and treatment activities would result in significant changes in the
LCA results
The results of the assessment show that the lifecycle of wind power generation has
more impacts in most impact categories than hydropower generation, except particulate matter formation (PMF), natural land transformation (NLT) and water depletion. In many
cases, a single impact category is caused by many processes associated with few lifecycle
stages. This demands the engagement of many stakeholders including academia,
researchers, developers, operators and policy and decision-makers.
In general, these studies would give insight for operators and developers to pay
proper attention on determination of sites, capacities and lifespans of power plants and
end-of-life waste management options. More importantly, this study can serve as an input
to a comprehensive life cycle assessment database of the national energy system in
Ethiopia, which is in turn vital to develop communication metrics such as Environmental
Product Declarations (EPDs) for economically significant export products in Ethiopia,
including electricity itself. However, the results of this study should be interpreted within
the context of the data limitations encountered during the course of the research, namely,
lack of local datasets for electricity, transport and waste treatment activities relevant to
local conditions. Future efforts in Ethiopia should, therefore, be dedicated to undertaking
the creation of life cycle inventory databases with a focus on such background systems that
will serve as a backbone for all kinds of LCAs in the country, and in and beyond the Horn of
Africa region at large.
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Keywords
Environmental Life Cycle Assessment, Ethiopian Electricity Generation Systems, Hydro and Wind Power