Harnessing hydropower's potential

Figure 1. Water reservoir on a hydroelectric power plant in the Upper Marsyangdi valley, Nepal.

Simon Trace, Energy and Economic Growth (EEG), funded by the UK’s Foreign, Commonwealth & Development Office (FCDO), UK, weighs up the hydropower potential of Sub-Saharan Africa and South Asia, looking at the capacity for growth as well as the challenges the industry faces.

Aflexible, cost-efficient, clean, and low-carbon source of energy, hydropower could be one of the key solutions for improving energy access and meeting growing energy demands across Sub-Saharan Africa and South Asia – especially if the electricity generated is traded between countries in these regions. However, hydropower faces significant challenges, including being particularly vulnerable to the effects of climate change and being associated

with social and environmental concerns. In some cases, the technology could also potentially be affected by the falling price of solar energy.

While hydropower accounts for more than 70% of the world’s installed renewable power generation capacity, across SubSaharan Africa and South Asia there is huge, largely untapped hydropower potential.1

For example, while some countries in Africa are already highly dependent on hydropower for the majority of their energy supplies (it provides 20% of energy generation across the entire Southern Africa region and accounts for over 90% of electricity generation in the Democratic Republic of Congo, Ethiopia, Malawi, Mozambique, Namibia, and Zambia), only 7% of Africa’s hydropower potential has actually been developed. The resources yet to be exploited include 28 GW on the River Nile and 13 GW on the Zambezi River. Meanwhile, in South Asia, the hydropower potential of Nepal, Bhutan, and India combined is 150 GW – but only 17% is currently utilised.

Meeting energy demands

In Sub-Saharan Africa and South Asia, hundreds of millions of people still live and work without access to electricity, and energy demands are growing. In Africa, demand for electricity is set to increase from the present level of 115 GW to almost 700 GW in 2040. In South Asia, it is expected to grow at an average rate of 6% per year.

Harnessing untapped hydropower resources could be one of the key solutions for meeting energy demands, while also helping to address climate change. Hydropower is generally viewed as a sustainable, clean, low-carbon source of energy. However, concerns have been raised about the impacts of carbon emissions associated with the actual construction of large dams and methane emissions from rotting vegetation in the reservoirs behind newly constructed dams under certain conditions. Nevertheless, hydropower is still generally viewed as contributing positively to low-carbon energy futures. Not only that, but the technology can aid the integration of wind and solar resources into electricity grids. High rates of variable, weather-dependent, renewable generation places additional demands on grids in terms of delivering constant, reliable electricity supplies – but hydropower’s flexibility and reliability (it provides an almost instantly available source of power), coupled with its storage capabilities, can help to balance out intermittency issues.

The case for hydropower can become even stronger if countries co-operate in developing infrastructure and/ or share available resources through large scale, crossborder ‘green grids’. These grids are made possible through long-distance, high voltage, direct current, cross-border transmission lines and digitised power management systems to manage the variety of inputs and outputs. Linking resources together offers better utilisation of regional generation capacity and potential, and could create a reliable supply of affordable, clean, secure energy across large areas of Sub-Saharan Africa and South Asia, while delivering economic benefits through the trading of electricity between countries.

Regional power trade

For example, the significant hydropower potential in Bhutan and Nepal (more than 100 GW combined) presents an opportunity to use resources more efficiently, meet electricity demands in the Bangladesh, Bhutan, India, and Nepal (BBIN) region, and reduce carbon emissions – as explained in an EEG-funded Energy Insight on cross-border electricity trade (CBET).² Nepal’s hydropower capacity is 1.3 GW, and in 2018, virtually all of the country’s electricity was produced by these resources (almost 78% of the population has access to gridconnected electricity, and its consumption is modest). The electricity generation mix of Bhutan is also predominantly based on hydropower. But in Bangladesh, natural gas-fired power plants supply almost 76% of the electricity produced and hydropower supplies 21%. In India, coal accounts for approximately 70% of electricity generation, but the country has one of the world’s most ambitious renewable energy plans.3 The diversified generation mix of the BBIN countries, their complementary energy demand profiles, and the immense hydropower potential in Nepal and Bhutan suggest all four countries would benefit significantly from CBET. In fact, in April 2021, the Indian Energy Exchange (IEX), India’s largest power trading platform, announced commencement of CBET on its platform, with Nepal being the first country to start trade in India’s day-ahead electricity market.4 Early indications from an EEG-funded research project, being led by Integrated Research and Action for Development (IRADe), suggest trade can help Nepal and Bhutan to utilise their hydropower potential.5 For example, in a no-trade case, the installed capacity of Nepal will reach only 15 GW compared to a high-trade case, where it reaches 44 GW (by 2045). Similarly, for Bhutan, under a no-trade case and a high-trade case, the installed capacity reaches 5 GW and 16 GW, respectively. Studies have pointed to positive socioeconomic impacts and substantial economic benefits from CBET. Furthermore, a study conducted using an electricity planning model for CBET in South Asia estimated an 8% reduction in CO2 emissions for the 2015 - 2040 period, associated with the introduction of a regional power sector. The IRADe research project is also investigating the impact of declining renewable energy costs on regional power trade in South Asia. Despite hydropower having attractive levelised Figure 2. Kariba hydroelectric dam in the Kariba Gorge of the Zambezi River between Zimbabwe costs, the price of renewable energy, and Zambia in Southern Africa. particularly solar, is falling dramatically,

which could reduce the appetite for the technology. In India, where the solar photovoltaics (PV) potential is approximately 749 GW, the solar PV levelised tariff dropped from INR 12 per unit in 2010 to INR 2.44 per unit in 2018. Hydropower has a levelised tariff of INR 5 per unit (kWh).

Therefore, the question of whether hydropower will still have a market in the BBIN region is being analysed. On one hand, lower-cost domestic sources of renewable energy may reduce the need for cross-border power trade. On the other, flexible hydropower capacity may help South Asia’s abundant but variable solar and wind resources to be harnessed more easily in regional power grids.

In Africa, electricity is traded between countries across ‘power pools’ (electricity systems and markets shared across economic blocs) and potentially between pools, to help meet domestic demand or sell excess supply. The Southern Africa Power Pool (SAPP) was the first to be established in 1995, and is now the most advanced power pool on the continent.

It is thought the development of hydropower plants on Africa’s transboundary river systems can often improve regional co-ordination and enhance collaboration through the benefit-sharing and distribution of electricity and revenue. The Rusumo Falls project, with shared electricity supplies for Burundi, Rwanda, and Tanzania, provides a good example of how regional co-operation can lead to regional benefits.

Importantly, developing regional grids or power pools can also help mitigate the climate-related risks that hydropower is unfortunately exposed to.

Hydropower and climate change

Hydropower is particularly vulnerable to the effects of climate change. It is, for example, impacted by variations in rainfall, water availability, and protracted droughts. Reductions in overall rainfall, or changes to rainfall patterns that produce shorter more intense periods of rain followed by longer droughts, can reduce generation potential. Furthermore, extreme rainfall due to climate change can increase erosion and reduce reservoir storage capacity as a result of increased sedimentation.

It has been suggested that trading electricity from countries with available hydropower capacity to those where supply is curtailed due to climatic conditions could help

Figure 3. Dam Oudtshoorn, Karoo Western Cape, South Africa.

to mitigate risks to electricity supplies; when one basin is experiencing periods of low rainfall, another may not be.1

However, some proposed hydropower developments are geographically concentrated, potentially being exposed to the same climatic conditions, at the same time. For instance, 82% of capacity in Eastern Africa is to be concentrated within the Blue Nile, and 89% of capacity in Southern Africa in the Zambezi – these geographical clusters of proposed dams are exposed to the same climatic system, and thus the same wet and dry periods, which would affect multiple individual dams simultaneously.

The Zambezi’s exposure to the impacts of climate change has been highlighted by the Intergovernmental Panel on Climate Change (IPCC) for almost a decade – it stated that the basin exhibited the worst potential effects of climate change among 11 major African basins. What was not previously identified was the dual exposure of hydropower developments in Eastern and Southern Africa.

The effect that climate change can have on hydropower is already being seen. As an example, hydroelectric generation in Zambia has declined in recent years due to droughts and lower rainfall, with the deficit caused being managed through load shedding and the purchase of emergency power and expensive imports.6

And future climatic conditions are likely to be more variable than current or recent ones – but this, and the potential longer-term implications of climate change, are not being adequately considered in the design of many hydropower schemes. This is discussed in detail in an EEGfunded Energy Insight on hydropower in Africa.1

The paper explains that potential impacts are currently estimated through scenarios projected across the expected lifespan of a hydropower dam, which typically ranges from 50 to 100 years. In Africa, the storage capacity and operational flexibility of most hydropower systems have been designed to account for historical patterns of hydrological variability (with contingency measures enabling the mitigation of dry periods). Most early-stage technical assessments, including the World Bank’s Hydropower Sustainability Assessment Protocol, continue to rely on historical hydro-meteorological records.

There is a lack of capacity to systematically generate, analyse, and integrate climate projections into longer-term planning and investment decision-making. Technical design modifications to increase the resilience of hydropower dams have generally been made on a case-by-case basis, with no structured guidelines for widespread adoption.

Mixed messages from climate projections make it increasingly difficult for decision makers to plan and adapt appropriately. For example, hydropower generation could decline by more than 60% in the Zambezi Basin under the driest climate scenarios, but could increase by up to 25% under the wettest scenarios.

Increasing resilience

There is clearly an urgent requirement to effectively generate and integrate climatic projections into investment and decision-making processes for the planning, design, and operational management of hydropower schemes, and to place more importance and resources on defining the potential impacts of climate change – before schemes move beyond the preliminary planning stages.

Partnerships between governments, energy providers, and regional hydrological/meteorological agencies will be important, as will the sharing of technology and information, such as regional climate models, weather information systems, and climate monitoring networks.

Investing in renewable energy generation, such as wind and solar (where appropriate and feasible), can also help to reduce hydropower’s exposure to changing climatic conditions, as well as of course being important for meeting global carbon emission reduction targets.

Social and environmental concerns

Alongside climate change challenges, many major hydropower schemes are also associated with serious social and environmental concerns.1 Upstream of retention dams, the flooding of natural habitats results in loss of biodiversity, with involuntary displacement of people and loss of cultural property. Downstream, a reduction in the hydrological flow can undermine ecosystem services, cause loss of biodiversity, negatively affect water quality, and impact water availability for other sectors.

It has been suggested that nature-based solutions (as an alternative to hard infrastructure) can improve water resource management throughout basins and enhance the livelihoods of the people who are dependent upon the ecosystem services it provides – but they have yet to gain political buy-in.1

While hydropower generation has clear benefits for improving energy access and meeting energy demands, especially when the electricity is traded across borders, it is important to consider the challenges it faces. In particular, the potential long-term climate-related risks must be addressed. Hydropower infrastructure has a long lifespan, exposing operations to decades of climatic uncertainty, at a time when accurately forecasting future weather conditions is becoming more difficult. Focusing on the short-term runs the serious risk of designing infrastructure that is not suitable for the climate of the future. To avoid investments being undermined, there is an urgent need to understand how hydropower production can become more adaptable and resilient to climate change.

Note

All information on hydropower/energy in Africa has been taken from the EEG Energy Insight: ‘Will climate change undermine the potential for hydropower in Africa?’, unless otherwise referenced. All information on hydropower/energy in South Asia has been taken from the ‘Crossborder electricity trade in the Bangladesh-Bhutan-India-Nepal (BBIN) Region: A costbased market perspective’, unless otherwise referenced.

References

1. BROOKS, C., ‘EEG Energy Insight: Will climate change undermine the potential for hydropower in Africa?’, March 2019. 2. THAKUR, J., HESAMZADEH, M.R., WOLAK, F., ‘Cross-border electricity trade in the Bangladesh–Bhutan–India–Nepal (BBIN) Region: A cost-based market perspective’, May 2021. 3. SHARMA, V., ‘India’s wicked problem: how to loosen its grip on coal while not abandoning the millions who depend on it’, July 2021. 4. IEX, ‘IEX pioneers cross border electricity trade in an endeavour towards building an integrated South Asian regional power market’, April 2021. 5. EEG, ‘Interview with Dr Jyoti K Parikh, IRADe’, April 2021. 6. CARDENES, Dr I., COOKE, K., ‘EEG Energy Insight: Electricity in Zambia’, March 2020.