Advancement of Bioenergy Technology in South Africa

Abstract

South Africa has been experiencing an energy crisis since 2007 and continues to the present. This has resulted in load-shedding (action to interrupt electricity supply to avoid excessive load on the generating plant). One way to address this problem is to further explore the potential and contribution of bioenergy through research conducted and implementing energy reports. Therefore, the study aims to provide the state of bioenergy and its contribution to the country’s economic sector and to enhance the replacement of fossil fuels with bioenergy resources and technology. A total blackout of 15,913 h has been experienced since 2014, according to the weekly system status report released by ESKOM. The power utility (Eskom) responsible for power generation and utility has attributed this problem to insufficient generation and capacity. Based on this, the country is embarking on solving this problem. Although the country is dominated by coal (fossil fuel), constituting 73.8% of the total energy supply, this poses a serious environmental risk and health hazard. Renewable energy is considered an alternative energy source, and its introduction and implementation look promising in reducing and solving the current energy crisis. With abundant renewable energy potential, representing 8.7% of the total energy supply, around 85% is bioenergy. This review’s findings revealed that bioenergy contributed mainly towards heat, and fuels admit other energy sources, which is recommended. Therefore, its deployment on a large scale is promising and possible. This study will guide and further encourage the deployment of bioenergy projects in South Africa.

1. Introduction

Fossil fuel, due to the productive coalfield, has been the primary reliance of energy supply in South Africa. The country’s grid is managed solely by the parastatal company known as Eskom, which is also responsible for generating energy [1]. In 2007, the South African energy crisis started, and Eskom is currently struggling to keep the power on, thereby not being able to meet the increasing energy demand. This has led to a steady increase in load-shedding experience in the country. As a result, this has prompted significant growth in the renewable energy sector [2]. One of the most extensively researched renewable energy resources is biomass. For instance, Searcy et al. [3] conducted a study on the transportation of biomass, Basu [4] worked on biomass as a conversion technology, and Dehghani Madvar et al. [5] published an article on the maturity of bioenergy. Ratshomo and Nembahe [6] looked at the energy demand in various sectors and the production cost of biomass [7]. In South Africa, renewable energy generally makes up roughly 7% of the country’s overall energy supply. It accounts for 10% of the total energy consumed. Biomass produces around 88% of renewable energy and is only utilized to produce heat, mostly for industrial and domestic purposes [8]. With 92% of its electricity and 57% of its thermal energy demands met by coal, South Africa is a country with a preponderant coal-based energy source. Nonetheless, there is a chance to effectively implement the production of bioenergy, primarily by substituting solid biomass for coal in already-existing assets and modernizing conventional bioenergy with newer kinds of bioenergy [8]. All the same, South Africa suffers from a deficiency in service delivery that impedes the execution of energy policies, particularly those pertaining to the supply of decentralized energy services. This has a major positive impact on sustainable development. Previously, rural areas and historically underserved towns in South Africa have benefited from the installation of decentralized waste-to-energy systems, particularly micro-bio-digesters. The National Development Plan [2030] states that by fostering new commercial opportunities, enhancing social dynamics, and halting the depletion of natural resources, the implementation of these decentralized energy systems promotes sustainable development.

Having stated that there is an energy crisis in South Africa, it is necessary to briefly look at bioenergy as a potential and promising renewable energy for the country. To this effect, renewable energy has been seen as the future of South Africa’s energy supply. Bioenergy replaces fossil fuels and has a short life cycle [9]. Regarding the bioenergy process, carbon absorption from the atmosphere occurs as biomass grows, which is released into the environment through incineration. During this process, biomass becomes a carbon-neutral fuel, and its development will be of great importance if the dependence on fossil fuels is to decrease shortly. This will help reduce greenhouse gas emissions, global warming, and climate change [10]. South Africa is among the 30 countries that have announced their renewable energy production from biological materials and converted them into products such as food, animal feed, and bioenergy [11].

The review sought to answer the question regarding the recent advances made by bioenergy in South Africa and at what stage, thereby focusing on various areas. Some of these areas include the current electricity generation in South Africa, the quantities of biomass and distribution within the country, and the conversion technology that is efficient and economical to replace fossil fuel energy in South Africa. In an effort to respond to the question, the review explores the literature on what has already been studied and reviewed in these areas, thereby obtaining their findings and making a recommendation. There have been published articles on renewable energy, and they are related to South Africa on a general basis. Thus, during the literature review and various reports on energy read by the authors, as well as their vast knowledge of renewable energy, it was observed that there are few or limited studies specifically on bioenergy in South Africa focusing on its current state and extent, contribution, research conducted, and publications in scientific journals. Hence, this study contributes to the knowledge of renewable energy (bioenergy), which South Africa needs because of its abundant resources and biomass. On the other hand, although the government is releasing energy report updates regarding renewable energy as an alternative source of energy, there is a need for such reports to be reviewed in combination with academic research, whereby the findings are published and presented in a scientific journal. This is necessary for the audience, such as energy researchers, consultants, and academics. Therefore, the objective of this review is to explore the potential of bioenergy further and its progress, as well as its contribution in terms of research conducted and reports to improve the state of the country. In so doing, they are harnessed and tapping for the impact and benefit of socio-economic factors, mostly on the rural communities. Specific areas in the study are outlined as follows:

• The electricity generation in South Africa;
• The potential status of bioenergy;
• Recent research on bioenergy;
• The contribution made by bioenergy;
• Socio-economic impact of the technology as well as the South African process.

Background of the Study

Bioenergy is a renewable energy source, and biofuels have the potential to displace fossil fuels due to their short life cycle. Carbon from the atmosphere is absorbed by biomass throughout its growth and released back into the atmosphere upon incineration. Because of this, biomass is a carbon-neutral fuel, and its advancement is crucial to reducing future reliance on fossil fuels. Fossil fuel consumption must decline to lower greenhouse gas emissions, which, in turn, must lower global warming and climate change [9]. More than 30 nations have declared that they will boost their production of renewable resources from biological materials and transform them into goods as interest in the expansion of bioenergy production has grown. The production of biomass from a wide range of various raw materials for prospective end-use applications will be important in mitigating the effects of land usage and the associated potential competition between the production of food and fuel [12]. In Africa, biomass-based sources generate over 90% of the entire primary energy supply derived from renewable energy sources, with renewable energy making up around 50% of this supply. Africa, on the other hand, produces the least electricity and liquid fuels from biomass because it is mostly utilized for heating and cooking [13].

In Africa, biomass is an essential energy source that can help reduce reliance on fossil fuels. However, in South Africa, more biomass use would result in sharply falling crop yields, putting millions of people at risk of malnutrition, mostly in the country’s rural areas [14]. In South Africa, water shortage is a major issue that has somewhat impeded the growth of biomass production. Thus, growing the appropriate raw material and executing the appropriate technology is imperative. For the growth of bioenergy, maintaining the equilibrium between biomass and food production is essential. The technologies employed must be able to use a range of resources to lessen their reliance on resources used in food cultivation [15]. To minimize the effects of growing the use of biomass for bioenergy applications, the emphasis must be on using feedstocks that can be grown and cultivated on land that will not directly compete with current agricultural resources [16]. Stafford et al. [17] stated that when used effectively, bioenergy presents a chance to replace fossil fuels as a source of energy and produce renewable energy. A more advanced and integrated sustainable agriculture system, as well as better natural resource management, would result from the production and use of biomass.

2. Methodology

This section describes how the study was conducted. It describes the information and data collection and how they were used to achieve the results and findings. First, a literature study was conducted to identify the problem. The essence and research question for the study was then formulated. Notably, the study used a kind of literature evaluation called a conceptual review. Systematic reviews, narrative reviews, traditional reviews, critical reviews, and state-of-the-art reviews are some other forms of literature reviews [18]. The goal of the study, which is to synthesize conceptual information in order to improve comprehension of a given issue, forms the basis of the conceptual review. A conceptual review is most appropriate for the study since it offers a thorough and in-depth summary of the literature on bioenergy in South Africa. Additionally, the conceptual review style was determined to be the most appropriate due to the extensive and intricate study that contained a large amount of data. Consequently, reliable databases like Springer, ScienceDirect, SCOPUS, Web of Science, and Google Scholar were used to gather the study’s findings. Significant material and information from industry reports, conferences, and proceeding papers publications were employed.

Collection of Data

The issue of data and categorizing sources in the field of science draws assumptions about whether the information is useful or not. Primary sources are regarded as information and sources that the authors have produced. In contrast, secondary sources are seen as information that does not deal with the scope of the author’s research area [19]. The study’s primary information will consist of data collected from government-owned sites that focus on and deal with renewable energy development in South Africa. Secondary data sources consist of information and data collected from published journals, as mentioned earlier, on the subject matter and then analyzed. “Bioenergy technology in South Africa” is the keyword used in the study for both primary and secondary sources. This showed information and data on Google, and the necessary ones that fit the study were chosen, discussed, and analyzed. Several data used in the study were made available and obtained from the CSIR, IEA Bioenergy report, and ESKOM; these are government-owned institutions responsible for promoting, analyzing, and developing, as well as monitoring progress made in renewable energy and other energy sources in South Africa. In terms of analytical techniques, for the purpose of the study, all sources (primary and secondary) were analyzed scientifically and otherwise, as suggested by Blomkvist and Hallin [19]. Information and data are compared with previous studies, thereby making conclusions and recommendations where necessary. It is interesting to state that most related studies on the area of the study are government annual reports from various agencies. However, there is a need for academic and scientific publication of these reports in journals to be reviewed by experts and peer reviewers.

3. Landscape of South Africa

With a population of 58.6 million and a total land area of 1.21 million km², South Africa is one nation that makes up Southern Africa. At 48 persons per km², this is a comparatively low population density. As seen in Figure 1, South Africa’s geographic coordinates are latitude 22° to 35° S and longitude 17° to 33° E. South Africa’s interior consists of a vast, mostly flat plateau and sparsely populated scrubland. Regarding land use, 10% of the land is arable, 14% is forest land, 69% is permanent meadows and pastures, and 6% is for other land use (See Figure 1). Generally, the country has a temperate climate, from extreme desert to subtropical climates [20].

Economically, the country is one of the upper-middle-income economies on the African continent and accounts for 24% of the continent’s gross domestic product (GDP). As of 2020, the most recent, South Africa is the second biggest economy in Africa, with a GDP of USD 301.9 billion after Nigeria (USD 432.3 billion). The country’s mining sector, since 2013, has contributed about 8% to the GDP, recording a long-term downward trend of 21% in the 1970s [9]. Though there has been a decline when considering the growth rate of the South African economy, mining still caters to 19% of private sector investment. Currently, 30% of South Africa’s total merchandise export is said to come from minerals (Chamber of Mines, 2014). South Africa is rated the largest platinum, gold, and chromium producer globally. Industrially, the country is blessed with mining, automobile assembly, iron, steel, chemicals, fertilizer, and many others [20].

As regards the energy scenario in South Africa, the country is the fifth and seventh largest producer of coal in the world and Africa, respectively. Interestingly, 77% of the country’s power generation is from coal. On record, it was reported that 232 TWh of electricity was generated from coal in 2014. This information is said to make South Africa the sixth-largest producer of electricity from coal. With this good news, the mining and use of coal negatively impact the environment (land, water, and air). Jain and Jain [21] stated that South Africa’s greenhouse emissions are the highest, having reported 437.37 Mt of CO₂ emissions annually or 8.10 t CO₂ per capita per annum. Reportedly, the industry sector contributes 40% of final energy consumption, while transport and residential services contribute around 30%.

Electrical Generation in South Africa

Based on the recent report released by the Department of Mineral Resources and Energy, the total domestic capacity of electricity generation in South Africa is estimated at 58.095 megawatts (MW) from all sources.

Table 1. Generation capacity of energy sources in South Africa [8] World Energy Balances and Renewables Information.

Energy Source	Generation Capacity (MW)
Hydro	3.485
Thermal	48.380
Wind	2.323
Solar	2.323
Others	580

shows the breakdown of the electricity generation capacity in South Africa. This generation capacity takes care of 59.31% of the population of South Africa as of 2020.

Having known that coal is the primary energy source in South Africa, which is evident in Table 1 as the most significant generation capacity (48.380 MW), it contributes to 80% of the country’s energy mix. Looking forward, it was predicted that in the next 10–30 years, the Integrated Resources Plan (IRP) was programmed to decommission conventional thermal power sources, particularly coal. However, the total capacity of coal as the main energy source is said to decline over the years because of the initiative of renewable energy. One of the steps towards this goal was signing a 27-power purchase agreement signed in June 2018 by the South Africa Renewable Energy Independent Power Producer Programme (REIPPPP). This is specifically for utility-scale transactions. Before that, electricity generation in South Africa was about 75% of the highest in Sub-Saharan Africa [21]. Jain and Jain [21] mentioned that the population of rural communities with access to electricity is about 55% compared to 88% in urban areas. In late 2007, South Africa experienced a power crisis and could not meet its electricity demand. Various factors contribute to the low electricity generation in South Africa. These include an increase in the internal demand for electricity from an increased population, an increase in economic activities, a lack of investment by the Government for maintaining aging and replacing generation capacity, and the inability of the generation capacity to meet the energy demand [21]. The Electric Supply Commission (ESKOM) manages the electricity generation in South Africa. ESKOM began in March 1923 based on the Electricity Act of 1922. The primary role of ESKOM is to satisfy the country’s demand for electricity by supplying interrupted and affordable electricity to South Africans. In so doing, the electricity giant has been acquiring independent plants, commissioning new ones, and doing many more to meet the demand. Noteworthy, ESKOM is still one of the most reliable and efficient power providers in the African continent, outperforming Nigeria Akinbame et al. [22].

4. Overview of Bioenergy in South Africa

This section presents an overview of bioenergy sources in South Africa. It has been the country’s heartbeat to move the energy source from coal to renewable energy. Based on this, the South African National Development Plan (NDP) 2030 has initiated a long-term plan for the country. By 2030, the NDP predicts South Africa will have an energy sector that provides a reliable and efficient energy service. The energy provided should be cheap, environmentally friendly, and pollution-free. To achieve this desire and vision, the NDP brought out a point of reference in collaboration with the Integrated Resource Plan (IRP) 2010–2030. This action was promulgated in March 2011 [8]. However, the type of renewable energy source derived from organic material directly or indirectly in the form of solid, liquid, and gas is known as biomass energy [23]. Biomass energy is usually found in rural communities for non-commercial use. Its primary usage includes cooking and space heating through burning wood, burning tree branches and charcoal, and using animal manure [24]. In these rural areas, modern electricity generation has not been adopted or is experiencing disconnection from the electricity grid [25]. In South Africa, there will be a significant increase in the demand for bioenergy energy within the next two decades.

Table 2. Energy demand from bioenergy—Stated Policy Scenario [9].

Year	2018	2030	2040
Energy demand	293 PJ	418 PJ	544 PJ

presents the energy demand from bioenergy.

Discussing South Africa’s primary energy supply, in 2018, this was 5880 PJ; three years later (2021), it is sitting at 5200 PJ, according to the Statista report. However, bioenergy has contributed to the South African energy supply. Figure 2 and

Table 3. Total energy supply in South Africa from 2019–2024 [8,27].

Energy Supply	2019	2023–2024
Coal and coal products	72.4%	73.8%
Renewable energy	6.6%	8.7%
Nuclear energy	2.5%	3.6%
Natural gas	3%	2.4%
Crude oil products	16%	11.5%

present the total energy supply in South Africa as of 2018 and 2019, as well as from 2023 to 2024.

Coal has been the dominant fuel of the total energy supply, representing 69.90% in 2018, 72.4% in 2019, and currently, 73.8% in 2023–2024. This is followed by crude oil, NGL, and oil products (15.30%) in 2019 and renewable energy (6.6%) in 2019 and 2023–2024 (8.7%), respectively (See Figure 3 and Table 3). There has been an increase in coal as the main supplier of energy in the country from 69.90% to 72.4% and then 73.8%. Figure 3 shows the total energy supply in South Africa. Unfortunately, renewable energy decreased from 9.30% (2018) to 6.6% (2019) and then increased to 8.7% (2023/2024). The fluctuation or shift can be attributed to climate change, air quality, and energy security, as reported in Cummins’s [28] global shift of energy transition. This is also the case for nuclear energy, where there was also a shift in the value of the energy supply from 2018 to 2019 and later increased (Nuclear Power in South Africa). Notably, the permanent dormant of coal has been positioned since 1880, when coal from the Vereeniging area was supplied to the Kimberly diamond field. This is because of the later gold discoveries in the Witwatersrand and the growing rail infrastructure, which has increased coal demand. Based on this, as South Africa evolved into a giant mining country, coal generated steam, compressed air, and electricity [29]. Dikgwatlhe [30] has attributed the dominance of coal as a major energy source in South Africa to higher prices of oil and natural gas, including environmental concerns in relation to nuclear waste.

However, the country’s total energy supply increased in 2008 and stabilized at around 5700 PJ. Looking at the contributions of different energy sources, it is observed that they have been relatively stable; coal fluctuated between 4000 and 4300 PJ, which represents three-quarters of the total energy supply in South Africa. For oil products, its contribution fluctuated around 750 to 1000 PJ (16%), and gas fluctuated between 160 and 180 PJ (2%). Renewable energy in South Africa has been interesting. Its contribution towards total energy supply declined from 10% in the early 2000s to 6–7% since 2006. As a result, a growing level of solar and wind power contributes around 1% of the total energy supply, albeit quite modest. It was recalled that a five-year pilot program on the biofuel industrial strategy was released in 2007 by the country [31]. In 2013, the White Paper on Renewable Energy from the Department of Mineral and Energy (DME) revealed that bioenergy would contribute to 35% of the target set by the country on renewable energy production. Further, in the same year (2013), it was also projected that 2% biofuel penetration into the national liquid fuel by 2013 was envisaged. This was meant to translate into 400 million liters of biofuel per annum. Unfortunately, this was not achieved [32].

The total energy supply of fossil fuels is reported as 4250 PJ (coal), 938 PJ (oil products), and 167 PJ (natural gas) (See Figure 3). Other energy sources, such as nuclear energy, have a total energy supply of 145 PJ (2%). In contrast, renewable energy represents 7% (386 PJ) of the total energy supply, as earlier mentioned, around 88% of it being bioenergy. As regards the role in the energy system, this distribution overestimates the role of resources producing electricity due to the high share of unused waste heat such as nuclear plants.

Table 4. Sources of primary energy supply in South Africa (adapted by authors).

Type of Energy	Source/Extraction
Coal and coal products	Underground mining or surface mining
Crude oil, NGL, and oil products	Remains of dead organisms and formed in permeable rocks trapped below impermeable rock
Renewable energy	Wind and solar power, bioenergy, and hydroelectric
Nuclear energy	Uranium
Natural gas	Shale and sedimentary rock formation via drilling

presents the sources where these primary energy supplies are extracted.

With over 93.5% of South Africa’s total energy supply coming from bioenergy as a renewable energy source, solar, wind, solar PV, thermal, and hydropower energy make up the remaining 6.5% (See Figure 4). Pelkmans and Bali [26] stated that the country’s total energy supply from bioenergy is 509 PJ. Figure 4 shows the total energy supply from renewable energy in South Africa.

From Figure 4, it is observed that the majority of renewable energy sources in South Africa come from bioenergy. This is attributed to its substantial biomass energy potential, having 42 million ha of natural woodlands, 1.35 million ha of plantation, and significant tree resources outside the forest supplying an existing 1.2 million tons of wood fuel. It is reported that ESKOM currently uses none of these for electricity production [32]. The appreciable amount of bioenergy is used for non-commercial purposes, such as cooking and heating through the burning of wood and tree branches, as well as burning charcoal and animal waste [24]. With the total energy supply around 5880 PJ, bioenergy accounts for only 8.7%. This implies that a lot of biomass is already being used to supply energy [9]. From Figure 4, hydropower (0.5%) is regarded as the lowest supply of renewable energy sources because of the low annual rainfall rate of 500 mm experienced in the country, although the country has about seven hydropower power stations owned by ESKOM [33]. Ratshomo and Nembahe [6] stated that the industry sector is the most required and needed of the energy supply. Based on this, bioenergy has the potential and capacity to supplant some of the demand required in the industry sector for the country to lessen its dependence on coal (See

Table 5. Demand for energy by sector in South Africa [9].

Demand of Energy by Sector	Capacity (PJ)
Industry	1549
Transport	568
Commerce and public sector	428
Residential	244
Agriculture	167
Non-specified	32
Total	2988

). Other energy demands by sectors include transport, commerce, public service, residential, and agricultural, as shown in Table 5.

From Table 5, the highest capacity of 1549 PJ reported for the industry sector is because of the specific capacity of various energy demands present in the industry sector, such as coal (548 PJ), electricity (390 PJ), renewable energy (379 PJ), gas (150 PJ), and petroleum (80 PJ). Agriculture sector (167 PJ) is the only sector capable of producing biomass for bioenergy production and this benefits the farmers most. They are in a better position for the current logistics of fuel distribution, thereby providing incentives for the adoption of such technologies [9]. The 167 PJ for the agriculture sector is based on petroleum products, which have 144 PJ, electricity (21.2 PJ), and coal (0.8 PJ).

Looking at the total bioenergy supply in South Africa, overall, there has been a steady decline from 450 PJ in the year 2000 to 350 PJ (2018) in the past years. The IEC 2021 [8] reported that these are exclusively solid biofuel, divided between residential applications, industry use of biomass, and transformation processes mainly of charcoal, of which 30% is exported. However, the report did not mention any information on liquid biofuels or biogas. Figure 5 shows the development processes of total energy supply from bioenergy (primary solid biofuels).

Table 6. Total energy supply development from bioenergy [8].

Primary Soild Biofuels	2000–2018/PJ
Transformation process	450–350
Industries	300–280
Residential, service, and others	230–150

shows evidence of a decline in bioenergy in South Africa when considering the three phases of primary solid biofuels. The final energy consumption, mainly electricity, transportation, and heat, was 10% in 2019. However, bioenergy makes up 8.5% of the total energy share.

Aliyu et al. [34] mentioned that biomass energy would continue to increase, provided the renewable energy sources follow the trend of the nation’s policy and strategies. To this effect, the reduction of conventional fossil fuel, which led to the increase in the use of renewable energy, has prompted an interest in bioenergy in recent times. Many applications, such as packaging paper and sugar mills bagasse in South Africa, employ the use of power generated from biomass of roughly 210 GWh of electricity yearly. Records show that Kwazulu-Natal and Mpumalanga are regarded as the provinces with the highest bioenergy levels in the country [34]. The country has 4300 km²ha of sugar cane plantation and 13,000 km² of forestry farm area for biomass application.

5. Potential and Status of Bioenergy

To improve the overall costs and benefits of bioenergy in South Africa, the biomass feedstock, technology of the conversion, and bioenergy value chain had to be determined. Various conversion pathways produce bioenergy via biomass, which is used as feedstock.

Table 7. Examples and feedstock and conversion processes for bioenergy [8,25].

Feedstock	Specific Examples	Conversion Processes/Technologies
Sugary and starchy crops	Sugarcane, sugar beet, sweet sorghum, maize, wheat	Fermentation of sugary and starchy crop: ethanol and alcohols (butanol)
Ligncellulosic biomass/agriculture and forest residues	Grass, straw, corn stover, baggasse, husks, shell, saw dust, cutter shaving, etc.	Gasification process: hydrogen, syngas, and methane
Oil-rich crops and waste	Soya, sunflower oil, canola, and non-food oils	Mechanical pressing and transesterification: biodiesel
Organic waste	Manure, sewage, organic fraction of municipal soild waste, and other food wastes	Anaerobic digestion: biogas then upgraded to biomethane
Algal biomass	Aquatic micro-algae and macro-algae	Pre-treatment, anaerobic digestion, mechanical pressing, etc.: biogas, ethanol, and biodiesel

presents the bioenergy pathways in South Africa.

As seen in Table 7, various conversion processes and technologies can utilize different feedstock to produce bioenergy, which is recommended in South Africa. In terms of efficiency and economics, conversational bioenergy is already available commercially, whereas other advanced and developing conversion technologies are still in progress via research and development.

6. Recent Research on Bioenergy in South Africa

There have been previous successful studies in bioenergy in South Africa. However, this section briefly discusses the selected recent research on bioenergy in South Africa, focusing on design, performance monitoring, modeling, simulation, and optimization.

Obileke et al. [35] developed a mathematical model and validation for methane production using cow dung in an underground biogas digester. The study was conducted in one of the renewable energy research institutions in the Eastern Cape Province of South Africa. In their study, 286 datasets were used as the trained dataset for the model development, and 144 datasets served as the test data for the validation of the model. This makes it 430 measured datasets of all predictors. The findings from the study revealed that 0.962 and 0.920 were obtained as the determination coefficient (R²) and p-value for the measured and calculated methane yield. The high R² confirms a good correlation between the model and experimental value.

The potential of biogas production from agricultural (pig manure) and agro-processing waste (clear beer and wineries) in South Africa was conducted by Mugodo et al. [36]. The study aimed to generate electric energy for energy supply using biogas. It was reported that the agro-processing waste obtained the highest biogas potential of 35 × 106 m³/year and the least agricultural waste of 0.02 × 106 m³/year. Thus, the total biogas yield from the biogas digester was 86 × 106 m³/year. The authors reported that the obtained biogas yield equals 148 GWh of electrical energy. This finding is twice the target of 2030 for biogas, which is 75 GWh in South Africa.

To reduce greenhouse gases and global warming, Mamvura et al. [37] conducted a study on the torrefaction of waste biomass for application in energy production in South Africa. The study is motivated by the climate change and global warming brought about by power plants. In so doing, the employment of torrefaction usually improves the energy content of biomass. When co-fired with coal, this process reduces greenhouse gases and global warming. The following parameters were obtained from the study to achieve the best biomass properties compared to coal. These are temperature (275–300 °C), heating rate (10 °C/min), and residence time (20–40 min). For energy production, co-firing biomass with coal is possible, and this should be recommended.

In a similar study, the possibility of utilizing landfill food waste for biomass co-firing was studied by Pahla et al. [38]. The study’s methodology deals with generating food waste with biochar of an optimum higher heating value (HHV). The findings on the torrefied food waste’s thermochemical properties were like those of bituminous coal. The study proves that coal can be substituted with food waste for energy production.

Nwokolo et al. [39] employed gasification as a substitute method for the conversion of waste to energy. The authors investigated gasifying eucalyptus as wood chips for syngas production and analyzed the results using thermogravimetry in a nitrogen environment. Palladium/nickel (Pd/Ni) gas sensors and non-dispersive infrared sensors were used to measure the composition of the syngas. The results indicated that the eucalyptus syngas’ hydrogen, carbon monoxide, and methane had a higher heating value (HHV) of 6.08 MJ/Nm³. Furthermore, 22.3–22.5% hydrogen, 22.3–24.3% carbon monoxide, 1.9–2.1% methane, 9.8–10.7% carbon dioxide, and 41.5–42.9% nitrogen make up the volumetric content of the syngas produced. The study clearly shows that the syngas generated is a perfect and advised product for combustion in combined heat and power plants by the application of diesel or compression ignition engines.

When it comes to biomass systems, dimensions, and building materials are taken into consideration. A study by Obileke et al. [40] on designing and constructing a plastic biogas digester for biogas generation provided evidence of this. A design equation addressing the biomass system’s shape was created in their research. Additionally, bricks and cement were used to build the inlet and exit chambers, while high-density polyethylene (HDPE) plastic was used to construct the system chamber. With a methane production of 2.18 m³ (54.50%) and a carbon dioxide yield of 1.77 m³ (44.25%), the system produced 4.00 m³ of biogas. As a result, the study suggests a composite material suitable for producing biogas.

7. Contribution of Bioenergy in South Africa’s Energy Supply

The significant contribution of bioenergy in South Africa has been narrowed down to different sectors, such as electricity, heat, fuel, and transportation. Without a doubt, the different sectors of the South African economy have benefited from renewable energy, yet, as

Table 8. Contribution of renewable energy and bioenergy in a significant sector of the South Africa Economy [8] World Energy Balances and Renewables Information.

Sector of Economy	Bioenergy Contribution (%)	Renewable Energy Contribution (%)	Overall Consumption (PJ)
Electricity	0.2	4.6	241 TWh (867 PJ)
Transportation	0.0	0.1	804
Fuel and heat (Industries/residential)	Direct biomass: 19.7	20.1	1241
Total final energy consumption	8.5	10.0	2902

illustrates, the overall energy consumption of these sectors is only 10%. In total, 8.5% of the energy share is made up of bioenergy. It is interesting to note that these claimed numbers exceed the percentages of the entire energy supply. For example, unutilized waste heat from the manufacturing of nuclear or fossil fuels is included.

Table 8 shows that renewable energy contribution for electricity had a share of 4.6%. The power production in South Africa is primarily dominated by coal (See Figure 5). This produces more than 90% of electricity, generating up to 220–230 TWh. Nuclear power contributes 5–6% (11–15 TWh) in the past decade. According to the IEA [8] report 2014, wind and solar power have steadily grown, with 4% of electricity contribution in 2019 (See Figure 5). Therefore, the contribution of biomass-based electricity is marginal at 0.2%. Figure 5 presents the evolution of the electricity output in South Africa from the year 2000 to 2018.

The total electricity demand in the year 2022 was similar to that of 2021 but still 5.2 TWh, which is less than the pre-locked level by 2.2% in 2019. With coal accounting for 80% (176.6 TWh) of the entire system demand, as can be observed in Figure 5, coal presently dominates the South African energy mix. It is interesting to note that in 2022, the installed capacity of renewable energy climbed to 6.2 GW, accounting for 7.3% (16.2 TWh) of the entire energy mix. Diesel energy accounted for 1.6% (3.6 TWh) of the total energy, with nuclear energy accounting for 4.6% (10.1 TWh). According to the analysis, the output of concentrated solar power and solar photovoltaic systems started to decline in 2022 [41]. According to the author’s perspective on renewable energy and information from the literature and energy reports, the evolution of South Africa's electrical mix can be attributed to a few policies. These consist of the Department of Minerals and Energy (2003), which focuses on the white paper on renewable energy, the National Energy Regulator of South Africa, the REIPPPP, the National Environmental Management Act 107 of 1998, the National Energy Act 34 of 2008, the Gas Act 48 of 2001, and the Electricity Regulation Act, 2006 [8]. In the economic sector, where fuel and heat are applied and utilized, bioenergy has contributed to those areas. These areas include industries, residential, commercial, and public services. Bioenergy consumption in South Africa mainly comes from solid biofuel, primary solid biofuel, and charcoal used in residential applications. Often, these are used traditionally, such as cooking, heating, and open fire [8]. Fossil fuel (coal) has been primarily responsible for providing heat, with over 56%. Others include oil and gas, with 17% and 6%, respectively, whereas bioenergy represents around 20% of heat provision [8,22]. Figure 6 shows the contribution of different energy carriers in terms of fuel and heat.

In Figure 6, besides the fossil fuel (coal and coal products), bioenergy utilized the fuel and heat consumption rate from 2000 to 2018. It can be depicted that the contribution of bioenergy was at its best in 2009, which happens to be the peak at 1380 PJ. Hence, the heat and fuel consumption from bioenergy fluctuated from 850 PJ in the year 2000 to 1200 PJ in 2018 because of the reaction time, reaction temperature, concentration of catalyst, etc. However, the use of biomass and charcoal for residential applications declined steadily and was partly compensated by a slight increase in the use of solid biomass as fuel in industries. As shown in Figure 3, the application of biomass as a fuel is mostly for industry and residential use, considering the contribution of renewable energy to fuel and heat.

Table 9. Renewable energy contribution for fuel and heat consumption [8].

Years	Solar Thermal (PJ)	Direct Biomass (Industry) (PJ)	Direct Biomass- Residential (PJ)	Heat Renewable (PJ)
2000	330	330	250	230
2018	290	270	150	130

shows a decline in fuel and heat consumption via renewable energy from 2000–2018.

8. Current Socio-Economic State of Bioenergy in South Africa

It is well known that South Africa is the most developed nation in Southern Africa in terms of bioenergy production and industrialization. A few industrial-scale biogas plants use biogas from municipal organic waste, sewage, etc., to produce heat and electricity as well as transport fuel. Several hundred-scale biogas units provide heat for cooking; small and medium-sized businesses use waste from animal husbandry and abattoirs [42]. Also, the country has many small- and medium-scale biodiesel plants that use waste cooking oil and an industrial scale of more than 20 million liters per annum of bioethanol plants [43].

Bioenergy is crucial for addressing the energy needs of approximately 3.5 million South African households facing challenges in meeting their energy requirements. These households often struggle with high electricity costs, frequent power outages, and poor socio-economic conditions [44,45]. Due to their decentralized nature, bioenergy systems, such as small-scale biogas digesters and biomass stoves, play a vital role in providing energy access to rural communities in South Africa, where grid electricity is limited or unavailable [9]. Over 60% of these households are rural and not connected to the national grid, making it unlikely for them to receive electricity within the National Development Plan (NDP) 2030 timeframe [9,46]. However, a significant portion of this energy is derived from biomass and is used inefficiently as solid biofuels for cooking, heating, and open fires. This usage does not fully harness the true energy potential of biomass [9,47]. According to available data from 2018, South Africa’s total bioenergy consumption was 517 PJ (petajoules).

Out of this total, primary solid biofuels accounted for 274 PJ, while charcoal usage in residential applications amounted to 34 PJ. When considering various sectors together, biomass accounted for approximately 27% of heat generation. In the domestic sector specifically, biomass constituted 66% of fuel consumption. This reliance on solid biofuels for bioenergy consumption underscores South Africa’s current focus on utilizing biomass resources for energy production. The South African government has recognized the potential of bioenergy as a renewable energy source. It has implemented measures to foster the growth of the bioenergy sector and attract private investments for commercial-level biofuel production. One such initiative is the REIPPP program, which has existed since November 2011. Its primary objective is to diversify the country’s energy mix by incorporating a greater share of renewable energy sources. The program aims to procure 3725 megawatts (MW) of renewable energy capacity from various technologies, including wind, solar, biomass, and small hydro. The REIPPP has proven effective in attracting significant investments and has played a crucial role in expanding South Africa’s renewable energy sector [48].

The Ngodwana Energy Biomass Project is a significant milestone in South Africa’s pursuit of renewable energy generation, showcasing its commitment to diversifying its energy mix [49]. Although Sappi is not a completely new plant, it had previously generated electricity using this method to power its pulp and paper products mill and sold surplus energy to Eskom. Likewise, many other similar power stations have been constructed throughout the country since the 1930s. For example, on Thesen Island, a power plant that provided power to the towns of Knysna and Plettenberg Bay was later transformed into the Turbine Hotel and Spa, incorporating much of the original machinery into its design. In addition, many sugarcane mills in KwaZulu-Natal and Mpumalanga also have their own power stations to supply electricity for their processing operations. However, Sappi’s Ngodwana Mill in Mpumalanga is considered South Africa’s first biomass power plant constructed under the REIPPPP [49].

The Biofuels Industrial Strategy (BIS) was also initiated to foster a supportive policy environment and encourage investment in biofuels [48]. Certain incentives were introduced to achieve this, including waiving the fuel levy on biofuels and exemptions for potential biodiesel and bioethanol producers. These provisions granted biodiesel producers a 50% exemption, while bioethanol producers enjoyed a full 100% exemption from the fuel levy [50]. Although BIS experienced significant changes, it has been crucial in formulating South African bioenergy policies and programs. South Africa has a low demand for transport fuel due to low vehicle ownership per capita. According to reports, Africa produces less than 1% of the world’s total ethanol because of domestic market demand. Due to their lack of developed transportation infrastructure, many African nations—including South Africa—are landlocked, which reduces their ability to export viable commercial biofuel production. This, combined with a lack of legislative support, has made it difficult for Africa to build sustainable biofuel value chains [51]. It is interesting to note that, despite neighboring nations having more arable land and higher biomass yield, South Africa has the highest demand for biofuel [52,53]. This suggests that the growth of biofuels in the SADC may be made possible by the regional supply-demand model of cooperation. The development of biofuel will need to take into account a number of factors in addition to techno-economic viability in order to guarantee the production of biomass, biofuel, and bioenergy that is sustainable and renewable [15,18].

However, progress in the bioenergy sector has been slow compared to other renewable energy sources, such as solar and wind. Only four out of one hundred and five projects in the Independent Power Producer (IPP) database are biomass-powered [30]. As a result, bioenergy presently contributes only 3% to South Africa’s total energy production, while solar energy accounts for approximately 61% and wind energy contributes around 29% [8]. South Africa’s capacity for bioenergy production still lags that of other developing countries like Brazil, where biomass-generated electricity production exceeds 500 TWh (terawatt-hours) compared to South Africa’s just over 200 GWh (gigawatt-hours) [23]. Bioenergy production in South Africa is still an emerging sector with significant growth potential [8].

9. South Africa’s Progress

South Africa has recently made significant strides in developing bioenergy technology, focusing on creating sustainable and efficient biomass energy solutions. Researchers have explored the potential of biowaste biorefineries in South Africa, which can convert agricultural waste and industrial waste to valuable products like biofuels, biochemicals, and biomaterials.

According to a recent study, South Africa uses some biowaste valorization techniques, like turning biomass from invasive alien plants into bioenergy [54]. The Department of Science and Technology (DST) commissioned the creation of a Bioenergy Atlas for South Africa to better inform the bioenergy industry. Before the end of 2015, the atlas is anticipated to become publicly accessible. It offers extensive data and a detailed study of the nation’s bioenergy resources’ viability, potential, and availability. The atlas examines the viability, accessibility, and utilization of biomass derived from domestic waste and diverse processing technologies, considering suitable and ideal dimensions, positions, and varieties [22].

One essential advancement in bioenergy technology in South Africa is using invasive alien plants (IAPs) as feedstock for biofuel production. South Africa has more than 750 alien tree species, and 161 are considered invasive, mostly woody plant species. The biomass derived from IAPs in KZN can produce biofuel, such as jet fuel, creating new job opportunities and supporting socio-economic development in the province. The aviation industry is considering alternative, cleaner energy options to support air transport, and bio-jet fuel can reduce greenhouse gas emissions and dependency on petroleum for fuel [55]. The Bioenergy Atlas has identified several process technologies that convert woody biomass into jet fuel. These technologies include fermentation, gasification, and chipping. The spatial logistical modeling platform developed for the atlas was utilized to create scenarios for locations where jet fuel-producing facilities can be built [56]. The creation of the South African Solar Thermal Technology Roadmap (SA-STTRM) is another step in bioenergy technology in South Africa. The primary focus of this industry-specific strategy is solar heating and cooling, especially solar heating. In order to fully realize the potential contribution of solar thermal technology, the SA-STTRM will need to increase installed collector surface area by 25% annually compound growth rate over the next 15 years. In order to meet this goal, the nation’s industrial, commercial, and residential sectors would need to adopt a sizable number of solar heating and cooling systems [57].

10. Challenges of Bioenergy Technology in South Africa

South Africa is in a position where there are no defined policy guidelines or frameworks for biomass energy. As a result of this, there is a lack of well-thought-out and comprehensive biomass policies and regulations at a national level. In the Banti et al. [58] study, policies that do not adhere to the plans and regulations of the energy sector are usually required or promote the growth of a particular renewable energy source. On another development, delay in implementing policies from these initiatives—IRP, NDP, REIPPPP, etc.—seems challenging. It is reported that appropriate personnel are usually unavailable to monitor the industry based on set targets. Therefore, it is challenging to grow biomass energy because subsidies and governmental support are absent [23].

Considering the food insecurity in the country, most of the feedstock for energy generation via biomass are crops (sugar cane, corn, maize, cassava, etc.) and are referred to as primary crops. Therefore, using these food crops for energy production will compete with food production. For instance, it was reported that crops (biomass) used for biofuel production in 2013 were sufficient to feed 280 million people [59]. This tends to be a challenge at a time when the population of South Africa needs to grow more food, thereby reducing the cost of food.

Scarcity and unavailability of land pose a substantial challenge, especially in rural areas. Landowners are likely to object to the use of land for large-scale applications for biomass activities such as biofuel production, biogas digester construction, gasification, etc., because they depend on this land for farmland for their livelihood. Hence, given that this land is used for energy production, other foods need strong conviction, knowing that the bioenergy industry requires large land for energy crops and plants. Therefore, this could impact, on the other hand, the supply of raw materials for bioenergy production due to the obstacle to large-scale cultivation from communal land ownership [60].

Biomass has not been implemented to expectation because of the problem associated with feedstock production and transportation costs. South Africa can only generate bioenergy on a small scale. However, large-scale bioenergy generation requires capital investment and throws off the economic curve. Therefore, the author opined the need for subsidies to help farmers and manufacturers where transport and feedstock costs are downstream uneconomical [9].

11. Prospects and Recommendations

Seeing the challenges facing biomass energy in South Africa, South Africa has an excellent prospect for employing and utilizing biomass resources. Most significantly, the Eastern Cape Province is the major province with a high quantity of organic waste, mostly animal manure. Effective and efficient treatment of this organic waste is useful for biomass energy for biogas/energy production through co-firing with coal in coal power plants. To this effect, an efficient waste management scheme should be embarked on and provided. It is recommended that kitchen waste and agricultural waste should be managed and utilized effectively. Rodseth et al. [59] stated that over 30% of the waste generated in South Africa is kept on the roadside or dumpsite. This makes them inefficiently combusted, especially in rural communities. Biomass is a great resource in recovering the country’s energy demand. This is because of its low cost of production and is the least expensive fuel compared to renewable energy sources. Therefore, in improving biomass energy in South Africa, the government and other renewable private initiatives should pay more attention to overcoming technical and commercial blockades, thereby implementing and funding projects relating to biomass energy. More research regarding biomass energy is recommended in South African universities by students and academics [60]. Conducting an evaluation involving the value chain of bioenergy and feedstock for energy production via biomass is paramount. Towards this, determining the amount of bioenergy that can be tapped into any feedstock is one of the decisions concerning the prospect of biomass in South Africa. Therefore, the foliage, animal feedstock, and bioenergy feedstock are said to be assessed and compared. Importance is required in determining the competitive need for food and bioenergy production, thereby evaluating its relevant technology and prices [58].

Another prospect of biomass deals with the involvement and collaboration of the government and stakeholders with institutions/universities regarding research and development. South African Universities is regarded as the best institution in Africa and one of the best in the world in terms of research and development. With this in mind, studies and research need to be conducted on environmental and social risks (soil erosion, loss of biodiversity, water resources stress, impact of land use, and climate change) with the government and stakeholders’ cooperation. Findings and outcomes of scientific and industrial research relating to biomass energy in the country need to be published and made available to the public, including the government, for awareness and implementation.

On the part of the government, Benti et al. [58] recommend that the government should take time to develop bioenergy. To achieve this, proper time and consideration should be taken in assessing the risks involved in the bioenergy sector, such as focusing on and referencing climate change mitigation, energy security, and development enhancement. In so doing, sustainable bioenergy via biomass is possible. There is the possibility that biomass will eventually emerge as the critical policy strategy in substituting conventional fuel for fuel. This is because of the increasing trend of biofuel in the country’s transportation sector. Further, it is predicted that electricity generation via biomass will have a greater potential than the production from conventional mineral fuels. Based on this, developing a biofuel economy focusing on policies involving government intervention needs to be researched [61]. Bioenergy from biomass provides employment and promotes the source of income for farmers, thereby enhancing the local economy.

12. Limitations of the Study and Possible Suggestions for Future Research

Having discussed the challenges facing bioenergy in South Africa and its prospects and recommendations, the costs of various raw materials for bioenergy production remain an issue and unclear. Future research should be considered and conducted to address the impact of various costs of raw materials on the final bioenergy production price. Successful research in this regard would increase bioenergy production in the country and become the farmers’ major source of income. Furthermore, studies on the mitigation of CO₂ emissions in the biofuel industry in South Africa need to be considered. This will also help address the low electricity generation via bioenergy, which currently sits at 200 GWh annually compared to other developing countries like Brazil (500 TWh). Research that provides and deals with a case study of driving the integration of bioenergy technology into the present energy mix of the country needs to be carried out. The findings might form a white paper to be implemented to address the issue of land and other limitations.