Feasibility study of renewable energy-based microgrid system in Somaliland’s urban centers

1. Introduction

 Renewable energy (RE) has recently attracted considerable global awareness. However, techno-economic feasibility studies of the RE potentiality in Somaliland are indeed very rare. To the best of the authors’ knowledge, the work of Pallabazzer and Gabow [1] is probably the only one of its kind carried out in Somaliland. In fact, there is a need to investigate the application of RE sources and the ease of introducing them into the energy and electricity markets of Somaliland. In a country that has enormous solar and wind potential, but still faces extreme shortages of power, it is believed that this research is timely to address some of Somaliland’s needs to drive forward its energy sector development for the purpose of improving energy scarcity levels as well as the national economy.

 Due to the poor economic condition of the country, Somaliland is in need of alternative energy sources in small amounts (10–100 kWh/day) supplied throughout the territory. Thus, small and medium-sized hybrid systems are sufficient to contribute to the already existing energy production mechanisms so that the present and the near future energy demands are appropriately met. Having known that the amount of energy consumption has been globally accepted as development indicator [2], increasing energy production and reducing its costs might as a result lead to an increased energy consumption among the general public and hence accelerate the desired development targets.

 Many researchers from different parts of the world have been studying hybrid micro-power systems (HMPS). The viability of the hybrid system depends on the quality of RE resources as well as the climatic, economic and regulatory conditions at that given location/country. Consequently, researchers universally gave much attention to the specific conditions of many different countries while proposing the best RE resource that could readily be of benefit to the given communities.

 The research carried out on HMPS designs could be grouped into two major categories based on their research objectives. First, many research works look at the design aspects of the systems under study and focus on the knowledge contribution without giving much attention to in the area under study. Such studies include the works of Hafez and Bhattacharya [3] and Bagen and Roy Billinton’s work [4], tonameonlya few. The second group of researchers focus on the techno-economic viability and/or the practical aspect of the hybrid systems in a given situation, most notably in areas where grids are not available such as rural areas [5–7] or island electrification [8–10]. Inaddition to that, researcher salso focus on specific site applications such as a university campus [11], hotels [12] and resorts [13,14] or any other building that might require some considerable amount of electricity.

 This work focuses on the second category. The uniqueness, however, of this study is the fact that it considers a post-conflict situation where the electricity shortage is due to the poor economic conditions and the scarcity of skilled human capital as opposed to low population density or remoteness of the locations considered. On that basis, a hybrid PV/Wind/Diesel microgrid system for an urban residential load is proposed in comparison with a diesel-only microgrid system using the performance metrics of net present cost (NPC), cost of energy (COE) and renewable fraction (RF).

 Taking a close look, this study tries to achieve the following objectives:

1. To propose an RE-based power system for Hargeisa by conducting a techno-economic feasibility assessment.
2. To analytically justify that the high capital investment related to RE installation projects is superior to diesel-only based plants by reducing the energy costs of private utility operators as a result of the fuel cost reduction of the diesel generators.
3. To examine which uncertain parameter related to either RE resources or future fuel price fluctuations would affect most notably the economic prospect of a hybrid microgrid system.
4. To comparecost of technology options for electricity generation for the same specific community need.

 1.1. Energy background of Somaliland

 Somaliland is a de-facto state in the horn of Africa region. Due to the political instability in the country from 1980s to early 1990s and lack of recognition for its sovereignty status, the country has largely remained under-developed. The energy and in particular the electricity infrastructure of the country, as in the case of many African nations, is still grossly under-developed [15]. The people, whether urban or rural, mostly rely on the biomass resources to meet their energy needs. It is estimated as much as 87% of the energy sources are biomass resources [16]. Electricity is only available in urban centers and “is almost exclusively produced from imported diesel” [17]. Diesel-powered generators are generally available throughout Somaliland’s urban centers. This causes extreme price fluctuations to its customers as oil prices depend on the world’s fluctuating oil market prices.

 Following right after the civil wars, private independent power producers (IPPs) slowly established electric utilities in the urban centers. The IPPs’ mini-grids typically operate islanded (the many IPPs are not interconnected and every one manages their own small electrical distribution network). The diesel generators often operate at low-efficiency, part-load conditions due to the changing electrical demand coupled with low local technical know-how. The fully burdened cost of fuel for the IPPs is above $1.15/L [18,19].

 Furthermore, according to a World Bank report [17], the electricity “network is characterized by poor servicing, inefficient production, aging generation and idle capacity. Power losses are estimated at between 25% and 40%, far from the 10% to 12% international target.”

 These network problems are basically due to the lack of established electricity institutions that would have administered the power industry. Without this, the electricity sector is generally left unregulated. Furthermore, customers face extreme and unpredictable price fluctuations in their electricity bills owing to, in addition to many others, the lack of fixed tariff system. The newly launched Somaliland investment guide [20,21] predicts that the electricity tariffs in Somaliland are “probably the highest in Africa” reaching as high as $1.4/kW h. On account of the scarcity of capable human capital in the IPPs’ institutions and the poor economic income of the local population, Somaliland never had any type of conventional large-scale power plants and national grid either.

 The conventional electricity supply produced by the centralized energy production systems is not only economically unattainable, but also lacks the appropriate electric infrastructure to equitably distribute power throughout Somaliland. Lack of water, electricity, and communication facilities in rural areas have caused uneven migration of people from rural to urban areas, resulting in an irregular population distribution. The dependence on wood and charcoal for fuel has inevitably led to deforestation and desertification due to the lack of re-plantation and soil rehabilitation schemes [22].

 It is worth mentioning that the government of Somaliland (GoSL) has been trying to solve some of the adversities related to electricity and energy sector in general for the last five years. The GoSL has put in place the first Electrical Energy Act (currently discussed in the parliament), the first wind energy pilot plant and the first wind energy monitoring stations in four major urban centers in Somaliland [21]. In line with these government efforts, it is hoped that this study will potentially trigger future technical studies that will drive RE deployment in Somaliland. The study can also act as a typical case study for RE deployment for many other post-conflict territories dispersed throughout the world.

 The rest of the paper is organized as follows: Section 2 describes the different data (mainly the load data and energy source information) used in the study. The design specifications of the two models are detailed in Section 3 while Section 4 presents the main results of the study. Section 5 draws general conclusion.

2. Data collection

 2.1. Electrical load

 One of the most important steps in this type of studies is proposing a realistic model of the electrical load. In this study, a typical contemporary Somali urban house load requirements are presented in Table 1. The most important uses of electricity in this house are mostly lighting, entertainment and refrigeration. In addition to these major usages, there are also other possible usages for electricity in an urban environment such as the use of electric washing machines, irons, and other electronic stuff. In a contemporary urban setting, these later equipment are considered essential amenities. However, the case in Hargeisa’s urban population is different as the majority of the population are largely in poor economic condition when compared with the urban population of the developed countries. Unlike a typical modern household, most of Hargeisa’s urban homes use charcoal as their main source of energy for cooking purposes and because of that, cooking appliances were not listed as an load appliance in

 Table 1. Electricity tariffs are still high throughout Somaliland’s main urban centers. As a result, many household consumers’ electronics are considered luxurious rather than a necessity for most of the households. Besides, a sample of 50 houses is used in this study in order to look at a reasonable urban scale of sampling.

 Fig. 1 illustrates the load profile of the hypothetical community in Hargeisa. The average electricity consumption of the sample population is 1283 kW h/day with 211 kW of peak demand. The daily power load is generally represented by a base load with double peaks; one in the morning and another in the evening, and double troughs; the night-time and afternoon nap time. Unlike a conventional modern urban lifestyle, Hargeisa experiences an afternoon break where most of the city activities slow down between 1.00 pm until 4.00 pm. It is quite common that people will take a considerable rest time at their own houses with minimum household activities at this time of the day.

 To make this synthetic load data look more practical-oriented, a random variability of 20% day-to-day and 15% time-step-to-timestep were introduced. These two inputs would allow the residential load to have some degree of variability at different times of the year.

 2.2. Energy sources

 The study conducted by Pallabazzer and Gabow [1] has revealed the scholarly awareness of the high prospect of RE availability in Hargeisa. The available RE sources that can provide electricity are wind and solar sources. The following sub-sections give the details of the two RE sources and diesel.

 2.2.1. Solar energy resource

 The daily radiation and clearness index of Hargeisa was taken from HOMER, which uses NASAsatellite data at approximately this location. The data is imported online through HOMER software by entering the latitude (91540N) and longitude (441030E) of Hargeisa in Homer’s solar input window. Fig. 2 depicts Hargeisa’s monthly average of two solar parameters, which confirms the steady availability of solar radiation throughout the year. The annual average solar radiation for this city is 6.4 kW h/m2/day. Thus, solar radiation qualifies to be a considerable alternative source for hybrid microgrid system in Hargeisa city.

 2.2.2. Wind energy resource

 Pallabazzer and Gabow [1] highlight that the winds in Somaliland are more intense inland than near the sea, owing to the abrupt massif that covers all the territory. The wind regularity was also found to be almost the same throughout the country”. Their work calculates the linear and cubic mean wind speeds of Hargeisa to be 11.6 m/s and 15.9 m/s based on anemometer data collected at government meteorological stations in the 1980s. Contrary to that data, the data records obtained from the NASA Surface Meteorology and Solar Energy website assessed a 10 year averaged annual wind speed for the Hargeisa city to be only 5.468 m/s at the same 10 m height [23]. Since even Pallabazzer and Gabow admit the data collected at the site in Hargeisa has “too poor resolution” and since their work does not also give the monthly averages of wind speed that are required for HOMER simulation, their data will not be used for the analysis of this study. Instead, data obtained from NASA will be used.

 Fig. 3 illustrates the monthly averaged wind speed at Hargeisa. The wind speed is measured at 10 m height. It is observable that the maximum measured wind speed is within the period from June to September, reaching a monthly average wind speed of more than 8m/s in July, while it is lowest in April. This information about wind speed in Hargeisa proves that wind energy can be exploited in generating supporting energy for the existing diesel stations in most of the months per year.

 2.2.3. Diesel

 Diesel is the source of energy of the dispatchable and back-up-oriented generators used in this study. In view of that, diesel price occupies a big concern in modeling or proposing any system. Currently, the diesel price in Hargiesa is 1.15 $/L [19] but this price is not constant; it fluctuates depending on the global market changes. The total NPC as well as the COE will change as the diesel price fluctuates. This increases the risk in the business and makes the utility vulnerable in the long term.

3.1. Case study development

 The hypothetical residential load modelled for this study is a small area, described in Section 2.1 in detail, potentially located in Hargeisa’s suburbs. It is expected that the residential location would be in the suburbs to ensure that the land availability for wind and solar resources would not pose a serious drawback to any potential deployment of this system on the ground. In terms of economic benefits and resource availability, it is more feasible to build these kinds of systems in a place where physical destruction is at its lowest level particularly for the wind resource. The load is assumed to operate in off-grid condition due to the lack of proper interconnection between Hargeisa’s power producers. The schematic diagram of the stand-alone hybrid power system under investigation is shown in Fig. 4 whereby an AC load is supplied by a central AC feeder.

 Hargeisa currently relies primarily (almost 100%) on diesel generators for electric power. To evaluate the impact of increasing wind penetration in Hargeisa, two scenarios are modelled with different rates of wind and PV penetration and diesel generators progressively replaced by wind farms and PV farms. The scenarios are briefly described here.

1. Base (without-RE) scenario: In the base case, energy is produced by three generators: small (with a capacity of 30 kW), medium (200 kW) and large (500 kW). The medium and large generators are base-load generators. In addition, to satisfy demand in any given hour, it may be necessary to have a small peak-load.