Technical noteAn overview of small hydropower development in Lesotho: Challenges and prospects
Highlights
► Overview of setbacks inhibiting smooth running of small hydro plants are presented. ► Lesotho is endowed with hydro resources for development of small hydropower plants. ► Studies have identified 22 sites, with a combined potential of more than 20 MW. ► High capital investment and heavy siltation of small reservoirs are main challenges.
Introduction
From a global as well as a Southern Africa regional perspective, the electricity sector in Lesotho appears to have been trapped in a low-growth condition for a long time, mainly due to policy inertia. The impact of this is reflected in the lowest access to electricity figure in the Southern African Development Community (SADC) member states [1]. With ever increasing demand–supply gap, crumbling electricity transmission and distribution infrastructure, it is not possible to connect every household to the national grid. Hydropower is one possible method of generating electric power close to potential consumers, thereby cutting out expensive reticulation costs in widely spread rural areas. Lesotho is well endowed with enormous economically exploitable and viable hydro potential estimated at 450 MW for conventional hydropower systems and more than 3000 MW of pumped storage schemes [2]. However, as shown in Fig. 1, only 75.25 MW of the hydroelectric potential has been harnessed so far. The unexploited potential is 374.75 MW for conventional hydroelectricity. Lesotho lacks both financial and technical capacity to develop its own conventional hydroelectricity potential. This generally requires relatively large plants (capacity gt; 10 MW), constructed at huge capital investments in the order of tens of millions of British pounds (£). For example ’Muela hydropower station, the only conventional hydropower plant in country, commissioned in 1998 with a generation capacity of 72 MW, was constructed at a cost of £75.6 million [3]. Such huge capital investments are hardly affordable for a poor country such as Lesotho. The success of the project is largely attributable to involvement of a number of external partners and financiers. The plant is a joint venture between Government of Lesotho and Government of Republic of South Africa (RSA); and was financed by a mix of grants, soft loans, and commercial credits from a number financial institutions, including European Development Bank and African Development Bank [3]. Also, the country has very limited sufficiently trained and experienced personnel in the relevant engineering areas - largely due to its inability to compete with RSA labour markets in terms of remunerations for qualified personnel. The skills-deficit is exacerbated by lack of institution of higher learning offering the relevant engineering training programmes (electrical, mechanical, civil, etc) to degree level. This weakness is amply demonstrated by the fact that the plant relies heavily on RSA engineers for maintenance and servicing.
Notably, the present power generation level falls far short of national demand, and Lesotho remains a net importer of electricity mainly from the RSA to meet peak-load and part of base-load. The current situation presents an ideal environment for development of hydropower resources, particularly small hydropower sources whose financial and technical demands can be met by small investors from within or without the country with relative ease.
Electricity from the main grid is predominantly available to urban areas, serving a very small portion of the population, currently estimated at 15%. The major source of electricity that can be developed is hydropower. The Lesotho Government has prepared policy guiding documents; namely Poverty Reduction Strategy and Vision 2020, outlining the framework within which various sectors have to operate [4], [5]. Lesotho’ Vision 2020 emphasizes the need for economic growth, private investment and economic transformation supported by a reliable and affordable energy supply as a key factor for the development process. To achieve this transformation, the country will need to increase energy production and diversify into alternative energy sources.
Lesotho is a mountainous country with steep slopes and fragile soil formations. Altitude varies from 1500 m to 3482 m. The country is divided into four geographic zones namely:
- •
The mountain region which covers 18,037 km2 (59% of the total area of the country) and is characterized by the bare rock outcrops of the Maluti range and deep river valleys, with elevations of the order of 2000 m and above;
- •
The foothills region which covers 4529 km2 (15%) characterised by elevations of 1800 m to 2000 m and lies between the lowlands and the Maluti mountains;
- •
The lowland region which covers 5094 km2 (17%) is situated along the western border and consists of a narrow belt of land with elevation of 1800 m or less and width of 10–65 km;
- •
The Senqu Valley which covers 2690 km2 (9%) forms a narrow strip of land that flanks the banks of the Senqu (Orange) River and penetrates deep into the Maluti Mountains; elevations vary from mountains to lowlands.
This geographic situation has impacted on access to electricity services or energy services in general. The mountain and foothills regions are characterised by a scattered settlement pattern, suitable for isolated stand-alone generation systems.
Lesotho is located entirely within the Orange River basin. The major sub-basin river systems in Lesotho are:
- •
The Senqu (Orange), which drains two thirds of Lesotho (24,485 km2), originates in the extreme north of the country and leaves Lesotho near Quthing. In its catchment area, four large dams will be constructed under the Lesotho Highlands Water Project (LHWP).
- •
The Makhaleng, with a catchment area of 2911 km2, originates in the vicinity of Mount Machache and leaves the country near Mohale’s Hoek.
- •
The Mohokare (Caledon) marks the border with South Africa and has a catchment area of 6890 km2. It springs from Mount Aux Sources, and leaves Lesotho near Wepener. All its major tributaries are located in Lesotho.
Fig. 2 shows areas with hydropower potential in Lesotho and South Africa [6]. The eastern part of the country is endowed with the best potential for the development of small hydropower plants due to its terrain and rainfall patterns. The rivers are in the upper reaches of the mountain zone where the flow is swift and there are no floodplains, making this opportunity more feasible from economic point of view. Despite the great need for energy in both urban and rural communities, the hydropower potential of these basins remains largely untapped.
The increase in prices of fossil energy sources and their impact on the environment has made hydropower a more important and attractive energy source. Of all the renewable sources of energy, water seems the best choice, and small hydropower development seems the most cost-effective and reliable energy technology to be considered for providing clean electricity generation. In particular, the key advantages that small hydro has over wind, biomass and solar power are:
- •
A high efficiency (70–90%), by far the best of all energy technologies.
- •
A high capacity factor (typically gt; 50%), compared with 10% for solar and 30% for wind.
- •
A high level of predictability, varying with annual rainfall patterns.
- •
Slow rate of change; the output power varies only gradually from day to day (not from minute to minute).
- •
It is a long-lasting and robust technology; systems can readily be engineered to last for 50 years or more.
- •
It can be integrated with fishing, drinking and irrigation water projects, in order to share the costs between different beneficiaries.
Small hydropower development could offer a leading renewable alternative for meeting electricity demand in remote and mountainous parts of Lesotho, where the national grid extension is uneconomic. The advantages and attractiveness of these small hydropower plants are that they can either be stand-alone or in a hybrid combination with other renewable energy sources. Further, advantage can be derived from association with other uses of water (e.g. water supply, irrigation, flood control, etc), which are critical to the future economic and socio-economic development of Lesotho. Small hydro plants are not generally affected by the constraints associated with large hydro projects. They are more environmentally and ecologically acceptable. Large scale hydropower development is becoming a challenge due to environmental and socio-economic concerns, and more recently its vulnerability to changing climates [7]. Investment in large hydroelectricity generation requires substantial upfront investment capital.
The definition of small hydro varies but typically pertains to hydro projects generating up to 10 MW, a mini plant is generally less than 1 MW, and a micro plant is generally less than 100 kW. Small units of 5 or 10 MW at a cost of US$10–US$15 million have most of the attributes required economically and environmentally, even where they do not feed into the main grid. A 10 MW plant could be sufficient to power 10,000 huts (or 50,000 people) and a community centre, based on 1 kW per hut and a typical diversity factor. Small hydropower electricity is an ideal energy option for the rural areas because of its low operational, maintenance and repair costs. Even though the cost per unit electricity from stand-alone hydropower plants may be higher than that from the national grid, they present a category of energy which could substantially contribute to poverty reduction in rural households.
As indicated previously, the provision of universal access to electricity in Lesotho through the main grid is not possible in the foreseeable future. This leaves the options of electricity supply in these areas through stand-alone or isolated mini-grids system using any or hybrid of technologies such as Solar, Wind, Diesel generators and Small hydro as critical options.
The existing solar data clearly shows that the solar resource in Lesotho is high throughout the year [8]. With daily average solar radiation varying from 5.5 to 7.2 kWh/m2 and about 3200–4000 sunshine hours per year, Lesotho’s theoretical solar power reception is about 4500 Terawatt-hours per year (TW h/yr). However, the state of technology with regard to solar PV is limited by the wattage it can provide within reasonable costs. This in turn limits the size of load that one can match using PV system. For most industrial activities, the power demand is slightly higher than what a PV system can provide.
In terms of wind energy, there are several sites that have been identified where small to medium wind generators can be established. Although wind energy systems can provide more power than PV, they have disadvantage of wind availability varying significantly within a day and seasons of the year. A South African consultancy firm Net-group is developing a 25 MW wind power near the Letšeng-La-Terai diamond mine in the northern highlands of Lesotho. The total project cost is estimated to be $79.09 million. The construction of the project is expected to start by the end of 2011 and to start commercial operations by 2013. The wind farm will sell energy to the national utility, Lesotho Electricity Company. However, Lesotho does not have any feed-in tariffs for renewable energy at present, but is currently working on implementing a policy which should be in place by end of 2011.
Diesel generators are mostly used as a backup for small hydropower plants. These backup systems become very costly for small hydropower plants with limited economic activities in the surrounding areas. The Government is currently implementing a pilot project whereby a mini-grid will be powered by diesel generator. There are many challenges involved in using a diesel generator. The main challenge is the price of diesel and an appropriate type of tariff associated with it. It has been established that the cost/kWh of electricity generated by diesel is around M2.50 (US$0.36) [9].
Small hydropower plants have been developed to a limited extend in the country. Notable setbacks associated with these systems have been established; of particular importance have been seasonal fluctuation of precipitation and heavy siltation of small reservoirs due to extensive soil erosion. Arguably, if siltation can be controlled, small hydropower would be much more superior to other options of stand-alone systems. Notably siltation reduces available water at intake points significantly.
Section snippets
Experiences with small hydropower development
The potential for small-scale hydropower plants in the lowlands and highlands of Lesotho has been investigated in a number of studies. By 1990 a total capacity of 20 MW had been identified at 22 sites for the implementation of mini-hydro plants, as well as micro hydro plants. These include the 4 that have been developed already. Preliminary estimates on available capacity have been established for these sites. Furthermore, distances from the plant site to the nearest community are available [10]
Prospects for development of small hydro
The national energy policy recognises [11] the important role played by energy in improving the livelihoods of people and the protection of environment. Small hydropower systems are very amenable to these two issues. The development of small hydropower plants is one of the means of achieving reliable and sustainable energy supply in the rural areas of the country.
Several reforms have taken place within the electricity sector of the country since 2000. The first reforms were on legislation. In
Conclusion
The environment is presently conducive for development of small hydropower systems in the country. First the country has adequate hydro resources. The settlement pattern of the country in the rural areas favours decentralised systems of which small hydropower is one of the viable means of improving access to electricity.
The present legislation allows for independent power producers/distributors to operate in the county therefore there is no threat to International Partners willing to operate
References (11)
- et al.
The potential of renewable energy technologies for rural development in Lesotho
Renewable Energy
(2007) - Southern African Power Pool (SAPP) statistics report 2008. Available at: http://www.sapp.co.zw. [accessed...
Issues and options for rural electrification in SAPP member countries and rural electrification planning in Lesotho
(2003)- et al.
Lesotho highlands water project – design of the ’Muela hydropower station
(1997) Poverty reduction strategy 2004/2005–2006/2007
(2004)
Cited by (36)
Critically evaluating the purported global “boom” in small hydropower development through spatial and temporal analysis
2022, Renewable and Sustainable Energy ReviewsCitation Excerpt :Even European research framed as a regional study, engages in analysis through the lens of individual states [13,36]. Similar patterns are evident in studies emanating from Africa, for example; Lesotho [37], Malawi [38], Ethiopia [39] and Nigeria [40]. While studies from Asia have been situated in Thailand [41], Indonesia [42], Malaysia [43], Pakistan [44], Nepal [7,45], India [46], and China [20,21,47].
Disruptive innovation for inclusive renewable policy in sub-Saharan Africa: A social shaping of technology analysis of appliance uptake in Rwanda
2021, Renewable EnergyCitation Excerpt :Despite the successes recorded in many countries of the Global South, the sub-Saharan African mini-grid electrification narrative portrays failure and limited success [20]. The significant constraints against off-grid renewable energy-based electrification programs include lack of technical and managerial knowledge needed to run and maintain the systems, low-energy demand density, uncertainty of energy demand from households, disperse homestead, insufficient community engagement, inappropriate financial models, policy inconsistency and lack of political will [20–26]. These challenges limit the socio-economical developmental impacts of the rural off-grid renewable energy transition programs.
Estimation of solar and wind energy resources over Lesotho and their complementarity by means of WRF yearly simulation at high resolution
2020, Renewable EnergyCitation Excerpt :Thanks to its widespread network of rivers Lesotho has a good potential for hydropower generation. In the last decades, small [7,8] and large hydro generation were developed. Concerning large hydropower generation, since 1986 the Lesotho Highlands Water Project (LHWP), managed by the Lesotho Highlands Development Authority [9], started as a multi-phased project to generate hydro-electricity for Lesotho [10].
A state-of-the-art review of hydropower in Malaysia as renewable energy: Current status and future prospects
2018, Energy Strategy ReviewsCitation Excerpt :Limited local capacity to design and manufacture SHP components and lack of sufficient local specialists to perform feasibility studies and handle the designing, implementing, and costing of the schemes also have significant effects on small hydro development. Therefore, unwanted delays and high costs are frequently associated with the development of small hydropower projects [33]. Less income of rural people– Most small hydropower potential sites are located in remote rural areas.