Off-river pumped hydro energy storage will help solve the issue of power wastage in the wet season from hydropower plants as daily and seasonal storage could be planned. Rather than planning on exporting electricity, why not focus on storing it for daily and seasonal balance while efforts are made to increase demand from inside the country?
Despite the abundant resources, Nepal had faced a severe energy crisis with daily power cuts lasting several hours and an acute shortage of liquid petroleum gas (LPG) for cooking other petroleum products in the not too distant past. However, since 2018, with proper power management, including increased imports from India, added power generation in the country, construction of the Dhalkebar-Muzaffarpur transmission lines, and reduction in technical power losses, people got relief from the load shedding schedules. However, industries are having to face power cuts due to the current energy crisis across the globe and inability to import the desired quantity of electricity from India.
The current electricity generation mix in Nepal is dominated by a single source, hydropower (96% electricity comes from it),while a lower fraction is shared by thermal (3.7 %), which is mostly not in operation, and a minuscule share by solar photovoltaics (PV) (0.1 %), according to the 2020/21 annual report of Nepal Electricity Authority (NEA).
One of the desired components of energy security is to have diverse sources of energy generation in the energy mix for an uninterrupted and reliable supply of electricity. However, Nepal's energy policy plans for only 5-10 per cent of installed generation capacity from sources other than hydropower. This will be a sheer policy failure, which will undoubtedly be witnessed by the country in the days ahead. Changes in the weather and/or rain pattern and melting glaciers due to the effects of climate change have already started to damage Nepali hydropower projects. Despite these warning calls by nature, Nepali policymakers are still reluctant to diversify the energy sources for electricity generation.
Nepal lies in a sunbelt region and holds tremendous solar power potential, which can support a 100 per cent-solar-based energy system to provide universal energy access in the country. However, our bureaucrats and policymakers undermine its enormous generation potential and are reluctant to mainstream it as one of the major sources of electricity, citing its intermittent availability and difficulty in balancing it in the power system. That is why a 5-10 per cent cap has been enforced.
This is an important piece of evidence to show how lack of knowledge and understanding, poor leadership and lack of innovativeness have barred the country's progress, which after half a decade of being free of load-shedding has once again forced it to resort to power cuts in industry.
Nearly 95 per cent of our hydropower plants are run-of-river (RoR), which is a great threat to the energy security of the country. The world has been moving towards solar and wind energy, with 80 per cent of new additions coming solely from solar and wind in 2021.To balance the intermittent source of energy (solar and wind), a few measures have been applied, including distributed generation, long-range transmission, pumped hydro energy storage (PHES) together with battery storage for short-term usage, which have shown successful results.
Many countries and regions have been moving towards 100 per cent renewable energy. For example, around 60 per cent of southern Australia's electricity is currently generated from the sun and wind and is tracking towards 100 per cent by 2025.
The major unbalance of the electricity system with RoR projects is surplus electricity during the wet season (July-August), which goes as spillage and is hard to manage, while in the dry season, there is an acute drop in power generation. Even to balance the ROR-generated electricity in Nepal needs storage projects.
However, building river-based hydro storage projects are a daunting task for countries like Nepal for many reasons, including finance. It is hard to bring foreign investment for river-based storage projects as they are not considered environmentally-friendly and socially-acceptable. In such circumstances, Nepal seems to be lost, except for some fragmented discussions and talks.
RoR hydropower and solar energy generation both need a storage system for an uninterrupted electricity supply. Thus, Nepal could focus on installing a solar photovoltaic system that requires a short time to complete even mega projects together with storage projects. Among the various technologies for energy storage adopted worldwide, due to the topography and technical readiness level, an environmentally-friendly and economically viable option in the country would be to go for off-river pumped hydro energy storage.
The global pumped hydro atlas has identified about 2800 sites in Nepal with a combined storage capacity of 50 TWh (terawatt hours). The off-river PHES potential of Nepal is 17 times more than what it will ever need under the zero-fossil-fuel scenario.
Currently, PHES constitutes 95 per cent of global energy storage. In 2020, NEA stated that such storage projects would be constructed with floating solar PV in Kulekhani. In April this year, Minister for Energy, Water Resources and Irrigation Pampha Bhusal had urged the private sector to invest in reservoir-based projects rather than RoR projects. However, the policies seem to be non-adaptive for the construction of solar PV and PHES yet.
The installation of off-river PHES will ease the financial issues as foreign investment could be attracted for such projects while balancing the energy system for both RoR hydropower projects as well as solar photovoltaic projects. It will further solve the issue of power wastage in the wet season from hydropower plants as daily and seasonal storage could be planned. This raises the question: rather than planning on exporting electricity, why not focus on storing it for daily and seasonal balance while efforts are made to increase demand from inside the country?
Lohani and Dhakal are with the Renewable and Sustainable Energy Laboratory (RSEL) at the Department of Mechanical Engineering, Kathmandu University.
A version of this article appears in the print on June 02, 2022, of The Himalayan Times.
