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The major renewable resources in Uganda include hydro, biomass, solar, geothermal, solar etc (Twaha et al., 2016). Solar energy and its related technologies have made consistent advancements in Uganda. In essence, Uganda has adopted these technologies to meet the increasing energy needs of its population in a manner that is socially, economically, and environmentally viable, with the goal of achieving 80% access to the national grid by 2040. The current situation indicates significant advancements in the utilization of solar photovoltaic technology, driven by the abundant sunlight available, characterized by solar irradiation levels averaging around 5-6 kWh/m2/day. In Uganda, there exists a substantial market opportunity for solar energy, especially among the more than six million households lacking access to electricity, representing the overall market potential. Among various solar Photovoltaic systems, rooftop solar Photovoltaic systems have emerged as the most favorable choice, with ground-mounted solar Photovoltaic systems following closely. In rural regions, solar energy generated by home Photovoltaic systems is primarily employed for domestic purposes such as charging cellphones, illuminating spaces, and powering radios. Consequently, solar power has garnered significant interest as a research topic among scholars in recent years (Saur Energy International, 2019; Kavuma et al., 2021; KENPRO, 2023).

In Uganda, over 90% of total energy consumption is attributed to the utilization of low-grade energy sources, particularly traditional or solid biomass fuels (Okello et al., 2013). In the context of bioenergy, there are also nonsolid biomass improved technologies that the country is making transition on such as biogas, bioethanol, bioethanol, biodiesel, and hydrogen (Bongomin and Nziu, 2022). The shift from conventional biomass sources such as wood and charcoal for fuel to contemporary biomass and biofuel production and utilization is a primary focus of governmental efforts to adopt environmentally sustainable energy systems by the year 2050 (Fashina et al., 2019).

Hydropower sector is the most utilized technology in the renewable energy sector among all in electrical generation. The large hydropower potential in Uganda along River Nile is estimated at about 2000 MW. The untapped hydropower potential in the country exceeds 1300 MW. Private investors, including independent power projects and Chinese-funded initiatives, are primarily responsible for commissioning most hydropower projects in Uganda (Bongomin and Nziu, 2022).

Wind energy resource in Uganda is still unutilized; due to generally low average estimated wind speed of about 3.7m/s and less research data to fully understand its potential . This means that most parts of the country are not suitable.

Uganda is endowed with geothermal energy resources; however, this resource still remains untapped. There are over 40 sites that have been studied; 25 sites along the western arm of the rift valley have been confirmed to provide an estimated potential of 1,500 Megawatts (ERA, 2012).

Fig. 1. 
Latest global trends in renewable energy (www.irena.org).

Fig. 2. 
Renewable energy average prices for selected technologies in the market (World Energy Investment, 2023).

Waste-to-Energy incineration technology proves most effective when waste possesses a high calorific value. The adoption of incineration could yield electricity, meeting the energy demands of manufacturing industries and local communities, thereby bolstering energy security (Nagawa, 2022). Regarding the new clean technologies (coal gasification/liquefication, hydrogen and fuel cells), Uganda is generally at initial stages or no progress in the new technologies categorized under environmentally friendly clean (Ram et al., 2021).

South Korea has great potential for utilizing solar energy because of its advantageous location between 35.9° N latitude and 127.7° E longitude (Alsharif et al., 2018). In South Korea, solar Photovoltaic energy is mainly used for power, heating, and transportation (Masson et al., 2022). In 2015, South Korea's technology level for silicon-based solar cells was 89.0%, ranking fourth among major developers compared to the USA, the global leader. The order of technology levels, in comparison to the USA, was Japan at 99.6%, the EU at 98.5%, South Korea at 89.0%, and China at 82.7%. In non-silicon solar cells, South Korea ranked fourth at 87.0%, with the EU at 97.3%, Japan at 95.7%, and China at 75.2%. A Korean research group at the Korean Research Institute of Chemical Technology achieved the world's highest efficiency record (over 24%) for perovskite solar cells (Kim et al., 2023).

In the field of solar thermal technology, scientists have created environmentally sustainable solar homes that utilize various renewable energy technologies such as solar heating and hot water, geothermal heat pumps, and photovoltaic systems to enhance energy efficiency. South Korea lacks high-temperature geothermal resources linked to active volcanic or tectonic processes. Consequently, the country primarily relies on ground-source or geothermal heat pump systems for geothermal energy utilization.

South Korea’s three-fourths of its land area is surrounded by the sea, a favorable geographical condition for offshore wind power. Offshore wind turbines can be deployed on either stationary or floating platforms, contingent upon the depth of the water. Presently, established stationary offshore wind farms are viable in areas with water depths as minimal as 50 meters, whereas floating offshore wind farms can be situated in regions with water depths ranging from 50 meters to 300 meters (Choi et al., 2023). In South Korea, the development and implementation of Solid Refused Fuels (SRF) production and utilization commenced in the late 1990s, with operational commercial-scale facilities emerging in 2006. The ongoing developments include cost-effective SRF production plants with high efficiency, organic waste fuel systems with hydrolysis reactors, and the creation of dry fuel from high-moisture waste with minimal energy consumption.

In the early stages of renewable energy growth in South Korea between 1991 and 2006, the government mainly put funds into the small-scale hydropower industry, specifically concentrating on hydraulic turbines. Since then, approximately 4.5 billion Korean won has been designated for allocation, with a notable increase in the government's investment budget, particularly in research initiatives targeting small and medium-sized hydropower installations. Given that approximately two-thirds of its geographical area is comprised of oceanic regions, South Korea possesses considerable potential for the development of wave and tidal power generation. Hence, research on ocean thermal power generation is underway (Noh et al., 2015).

Experimental trials for the distribution of bioethanol have been carried out and are presently under assessment for potential integration. Current investigations are centered on the pilot-scale production of lignocellulosic-based bioethanol by SK Innovation, the Rural Development Administration, and Changhae Ethanol. GS Caltex has devised a method for manufacturing biobutanol from agricultural and forest residues and operates a commercial biobutanol plant in Yeosu. SK Chemicals have initiated the commercial manufacturing of bio heavy oil for power generation subsequent to biodiesel production. The Waste Energy Recovery Co-Generation Project in South Korea is the first Verified Carbon Standard initiative in the country. It focuses on setting up a 400-megawatt co-generation facility at Hyundai Steel that efficiently uses surplus waste gases to produce electricity and steam. The project is expected to generate around three million megawatt hours of electricity and over one million tons of steam, benefiting both the plant and the local electric grid (Zaferani et al., 2021).

South Korea has made impressive progress in fuel cell technology, including achieving milestones like being the first to produce hydrogen fuel cell vehicles on a large scale and setting up the world's biggest fuel cell power plants and communities powered by hydrogen. South Korea is particularly skilled in water electrolysis technology, enabling the diverse application of hydrogen energy beyond just transportation (Fan et al., 2021). The fuel-cell power generation capacity in South Korea stands at 262 MW, distributed across 36 locations. South Korea has made significant investments in extensive fuel cell research, leading to the acquisition of substantial technological expertise over time. The nation demonstrates industrial competitiveness in machinery, electricity, and electronics sectors, particularly those related to the advancement and implementation of fuel cell systems. This reflects South Korea's commitment to leveraging its expertise and staying at the forefront of fuel cell technology development and deployment.

In Uganda, there is a great potential for solar photovoltaic, solar heat, bioenergy, geothermal energy, hydropower, and limited opportunities for wind power. Solar resources are abundant in Uganda due to its location along the equator, receiving ample sunshine with a solar irradiation of about 5.1 kWh/m2/day (Kavuma et al., 2022). The typical daily duration of sunlight in Uganda is approximately 8 hours, providing optimal conditions for various solar technology implementations. This level of solar isolation facilitates year-round utilization of solar energy in the country. Uganda's bioenergy resources are evenly distributed throughout the country. Uganda has abundant biomass resources due to the nature of its climate. Most bioenergy resources are traditionally utilized with low-efficiency technologies. Biomass, especially wood, is commonly used either in its natural state or as charcoal. Uganda's bioenergy resources are deteriorating due to poor utilization, potentially causing climate impacts in society.

Hydropower stands as the most extensively employed renewable energy source in Uganda for the purpose of generating electricity. Though Uganda is a landlocked country, it has several rivers and tributaries that support both small and large hydropower projects. Uganda's major hydropower generation is mainly along the river Nile, one of the longest rivers in Africa, with its source in Uganda. Although hydroelectric power dominates the power sector in Uganda, there are a lot of challenges due to climate change, making Uganda's national grid unstable. Other resources, such as wind, geothermal, and new technologies, remain unutilized, even though they show potential. The wind resource is still not utilized on a commercial basis due to insufficient data and inadequate attention given by the government; however, a few research studies have been conducted. In regard to geothermal energy, its utilization is in the planning stage, and most of the projects are still in the paperwork phase. However, there is hope to utilize geothermal resources in the near future. On new technologies, a lot of research needs to be done to better utilize them in Uganda, as there is very little or no research at all on these technologies.

In South Korea, solar photovoltaic and solar thermal technologies have higher theoretical and technical potential. This resource is attributed to South Korea's strategic location, which receives abundant sunshine throughout the year, with an estimated average solar radiation of 4.01 kWh/m2/day (Kim et al., 2023). The radiation levels differ between 2.56 kWh/m2/day in December and 5.48 kWh/m2/day in May. Hence, they can utilize solar energy resources throughout.

Wind and ocean energy are important resources that South Korea has a high potential for. Approximately 75% of South Korea's territory is bordered by the sea, which provides a favorable geographical condition for offshore wind and ocean energy. Additionally, South Korea also has onshore wind energy opportunities, which account for about 7% of renewable energy facilities. In relation to water resources, South Korea's potential for hydropower cannot be ignored. South Korea has rivers that contribute to the development of both small-scale hydropower and large-scale hydropower.

Additionally, South Korea's extensive marine area contributes to its potential for offshore wind energy. Additionally, South Korea possesses a vast marine area that presents a range of prospects for the advancement of ocean energy technologies, including tidal and wave energy.