Multiple power stations in Cameroon generate electricity from various resources. Both fossil fuels (HFO, LFO, NG), as well as biofuel, and hydraulic sources are used in production [6] [27] [28] .

Electricity in Cameroon is transmitted through three separate linked systems. The electricity generated at the hydroelectric power stations of Song Loulou and Edéa and the thermal power plants of Oyomabang, Bassa, Logbaba, Limbé, and Bafoussam is transported to the consumption areas through the South integrated network (SIN). The SIN has 17 substations (4 interconnection stations and 13 source stations providing the distribution networks), 480 kilometers of 225 kilovolt (kV) lines, and 870 kilometers of 90 kilovolt (kV) lines. Central, Southern, Littoral, Western, Northwestern, and Southwestern are all part of the SIN’s coverage area. The interior (Central and South Regions), the coast (Littoral Regions), and the western (West, Southwest, and Northwest Regions) parts make up its three primary divisions. The spatial arrangement of the SIN is shown in Figure 1 [28] [29] .

The power plants at Lagdo and Djamboutou use the North Interconnected Network (NIN) to provide their output to the many centers of demand in the region (Garoua, Maroua, Ngaoundéré, and Meiganga). Four source stations and a total of 600 kilometers of transmission lines (400 kilometers of 110 kV and 200 kilometers of 90 kV) make up the NIN. Figure 2 presents the NIN’s geographic reach into three northern areas [28] [29] .

The Eastern Interconnected Network (EIN): There is no strictly speaking of an interconnected transport network. Only two 30 kV lines can evacuate energy to the consumption centers around the Bertoua power station [28] [29] .

In 2020, Cameroon’s electricity generation infrastructure comprised three hydroelectric facilities, each equipped with three reservoir dams for the regulation of Sanaga River storage. The total storage capacity of these facilities was 7.6 billion cubic meters, with Mbakaou, Mapè, and Bamendjin accounting for 2.6 billion

cubic meters, 3.2 billion cubic meters, and 1.8 billion cubic meters, respectively. Additionally, the country had thermal power plants that utilized either light fuel oil (LFO) or heavy fuel oil (HFO), including natural gas. According to sources [5] and [27] . Table 1 presents an overview of the primary power plants in Cameroon and their respective allocation across the interconnected networks.

It is noteworthy that in 2019, Cameroon possessed a generating capacity of 1529 MW, which was primarily derived from hydroelectric dams and thermal power plants. These sources were distributed in the following manner: The energy mix comprises 62.0% hydraulic sources, 17.4% gas thermal sources, 8.2% light fuel thermal sources, 11.2% heavy fuel thermal sources, and 1.2% renewable sources, primarily solar photovoltaic. The distribution of Cameroon’s electricity generation in 2019 is depicted in Figure 3, as reported by sources [5] [6] [27] , and [30] .

The aforementioned capability encompasses that of ENEO, a prominent electricity distribution enterprise, along with autonomous producers such as the Dibamba Power Development Company (DPDC) and its Yassa-Dibamba power station (86 MW fueled by heavy fuel), and the Kribi Power Development Company (KPDC) and its Kribi facility (216 MW fueled by gas) [5] [6] [27] , and [30] .

The study analyzed three distinct electric power generation technologies, namely heavy fuel oil, light fuel oil, and natural gas. It has been posited that a mean level of production technology, encompassing energetic and exergetic efficiency, is prevalent in Cameroon. Furthermore, the current state of affairs is believed to be indicative of the socio-economic climate in Cameroon, with the proportion of imports being determined based on the extant quantity and quality of petroleum product production, spanning the time frame from 2006 to 2019.

The issue of methane emissions during the process of oil and natural gas extraction was examined. The calculated average energy and exergy yields have been taken into account for thermal power stations, as reported in references [5] [6] , and [27] .

Table 2 presents a summary of the operating parameters and estimated electrical energy output over the lifespan of various production systems.

The assumed source of crude oil for production is offshore fields located in the Gulf of Guinea, specifically Rio Del Rey. The Logbaba plant obtains its natural gas supply from either “Gaz du Cameroun” or the National Hydrocarbons Company’s (NHC) field of operation in Kribi, which is situated in the broad Atlantic Ocean [5] [6] , and [27] .

In order to evaluate the energetic and exergetic performances of thermal power generation systems in Cameroon, we used data from the International Energy Agency (IEA) [27] . The reliability of these data was verified and validated on the basis of the reports of the national structures and more precisely the report of the Ministry of Water and Energy of Cameroon of 2014 (MINEE) [8] , the operating data of the Kribi Power Development Company (KPDC) [28] and the Dibamba Power Development Company (DPDC) [29] , the 2011 Cameroon Energy Information System (SIE-Cameroon) report, and the 2013 National Institute of Statistics Cameroon) [30] . The International Energy Agency provides data on primary energy consumption by source as well as electricity production data from each of these sources. It should be noted that the primary sources used in Cameroon are light fuel or diesel, fuel oil, natural gas for fossil sources and biofuels (agro-industrial residues, wood waste...) for renewable sources.

Table 3 shows the evolution of primary energy consumption by source. The assessment of all quantities (Embodied energy, GHG emission…) is based on these available data and the results obtained will be used to evaluate the evolution of the global emission factors for Cameroon.

The concept of embodied energy pertains to the total amount of energy that is utilized in various activities required to facilitate a particular process. In the context of power generation systems, it is necessary to consider the energy expenditure associated with the complete production cycle. This encompasses the processes of raw material extraction and transportation, plant construction, energy generation, and eventual recycling or disposal following utilization. The diagram depicted in Figure 4 illustrates the embodied energies pertaining to every stage of the life cycle of a power generation system, with a focus on the useful electrical output that serves as the intended end product [12] .

The concept of embodied energy encompasses both direct and indirect forms

of energy. According to scholarly sources, direct energy pertains to the energy utilized in primary processes, whereas indirect energy is necessary for the production of goods and services utilized in the primary processes [12] .

In the context of power generation, the energy required for the production of electricity can be categorized into direct and indirect forms. Direct energy pertains to the actual generation of electricity, while indirect energy is associated with the extraction and transportation of raw materials, plant construction, decommissioning, and recycling of the power plant. This classification has been previously documented in literature sources [14] [31] .

Equations (1) and (2) are utilized to assess energy indicators, namely life cycle energy payback (LCEPB) and life cycle energy cost (LCEC), in order to compare the efficacy of various power generation technologies [12] [24] [32] [33] .

LCEPB = E el CV ( GJ ) E Inc CV ( GJ ) (1)

LCEC = E Inc CV ( MJ ) E el CV ( kWh ) (2)

E el CV is the electrical energy produced by the system during its lifetime and E Inc CV the embodied energy necessary for these productions.

It is suggested that the embodied energies required for the worldwide production chain, with the exception of the energy directly consumed in power plants for electricity production, are derived from the combustion of coal or fuel oil, depending on the type of facility, namely LFO, HFO, or natural gas.

Table 4 presents the emission factors (EF) for various greenhouse gases, expressed in grams per gigajoule (g/GJ), as per the 1996 IPCC Guidelines [18] . These factors have been determined for each fuel type analyzed in the study. The computation of the comparable emission factor pertaining to a specific fuel involves the consideration of the global warming potential of each greenhouse gas over a period of 100 years. This entails assigning a value of 1 to CO₂, 21 to CH₄, and 310 to N₂O, as in Equation 3 (3).

EF i c o m b = ∑ i GWP i ⋅ EF i c o m b (3)

where GWP i (in kg de CO₂eq/kg) is the global warming potential of the greenhouse gas i, EF i c o m b the emission factor GHG i with respect to the fuel.

Equation (4) has been utilized to determine the quantity of greenhouse gas emissions released during a specific stage of the electricity generation process.

E m j k = EF eq c o m b ⋅ E n r j k (4)

where E m j k is the total quantity of CO₂-eq issued (in g/kWh) corresponding to the consumption of a quantity of energy E n r j k (GJ/kWh) during phase j of the type of fuel k.

The calculation of the GHG emission factor denoted as LCE eq k for the thermal generation system in Cameroon involves the summation of emissions from various phases, as per Equation (5). The resulting value is expressed in grams per kilowatt-hour.

LCE eq k = ∑ j E m j k (5)

Equation (6) is used to determine the quantity M CO 2 -eq k of CO₂-eq emitted during the production of an electric quantity E e l k by the technology k.

M CO 2 -eq k = LCE k ⋅ E e l k (6)

By conducting a material balance analysis, we were able to determine the embodied energies required for the production of each kilowatt-hour of net electricity in each respective system throughout the electricity production chain. The findings have been succinctly presented in Table 5.

The allocation of shares for direct and indirect energies can be derived from the data presented in this table. The data indicates that the LFO, HFO, and Gas plants have direct fuel usage rates of 97.6%, 89.4%, and 88.9%, respectively, throughout their life cycles. Additionally, the indirect fuel usage rates for these plants are 2.4%, 10.6%, and 11.1%. A notable amount of energy is consumed by gas plants, primarily for the processing of fuel.

Table 6 displays the energy performance of the three technologies in terms of Life Cycle Energy Pay Back and Life Cycle Energy Cost. Based on the findings, it can be concluded that gas technologies exhibit superior performance compared to alternative options. The primary energy conversion efficiency of gas technologies is higher, which is reflected in the E (effect) indicator, similar to performance. The second metric pertains to the amount of energy required to generate a single kilowatt-hour of electricity.

Our calculations are based on the hypothesis that the energy required for certain indirect phases of the production cycle can be sourced from either coal or heavy-fuel oil combustion. Table 7 shows the results of the above calculations.

The data presented in the table indicates that gas power plants exhibit a relatively high percentage of indirect emissions (14.5%) and a correspondingly low percentage of direct emissions (85.5%). The share of indirect emissions from natural gas-fired power plants is relatively higher for the following three reasons. Firstly, the liquefaction of natural gas requires a considerable amount of energy, as natural gas is generally transported in the form of liquefied natural gas (LNG). Secondly, the CO₂ produced when raw natural gas (NG) is extracted is released into the air during refining. For example, raw natural gas extracted from some gas wells can contain a considerable amount of CO₂, up to almost 11% molar. Thirdly, the CO₂ emissions linked to the maritime transport of NG are greater than those linked to the transport of coal and oil. This is because ships carrying NG travel faster than those carrying coal or oil, which requires significant energy consumption.

Based on our analysis of the life cycle of thermal energy generation technologies in Cameroon, we have determined the emission factors for each type. The LFO plants have an emission factor of 872.74 g/kWh, the HFO plants have an emission factor of 943.94 g/kWh, and the gas plants have an emission factor of 576.65 g/kWh.

The values presented in Table 8 indicate that they are relatively high when compared to those reported in the literature. It is worth noting that the thermal power generation technologies in Cameroon produce emissions that exceed the average mix of Cameroonian electricity, which is estimated to be 207 g of CO₂-eq by the International Energy Agency (IEA). High emission rates can be attributed to various factors such as the obsolescence of production equipment, inadequate maintenance practices, and low yields.

This comparison is further illustrated by the graph in Figure 5.

It is clear that the emission factors of thermal power plants in Cameroon are higher than those of industrialized countries such as France and Japan, and almost on a par with those of a developing country like Singapore. This high level of emissions is further exacerbated by the aging nature of the production facilities, combined with the fact that maintenance programs are not adhered to, resulting in poor combustion and therefore very high emissions.

Based on our analysis of energy cycles, we have computed the CO₂-eq emissions

of various electricity generation technologies using data spanning from 2006 to 2019. Calculation of the aforementioned can be facilitated by employing Equation (6).

The graphical representation in Figure 6 depicts the progression of greenhouse gas (GHG) emissions for individual technologies over a span of 14 years, commencing in 2006 and concluding in 2019. Based on our analysis, it has been determined that the annual CO₂-eq emissions from the power plants utilizing fossil fuels (LFO, HFO, and Natural Gas) have an average of 1.17 million tons. The LFO plants contribute an average of 61.12%, while the HFO plants contribute 18.36%, and the gas plants contribute 23.09%.