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100% renewable energy with pumped-hydro-energy storage in Nepal

100% renewable energy with pumped-hydro-energy storage in Nepal Target for Nepal for 2065: 100% Renewable energy in Nepal • 100% renewable energy 2020 status • Catch up with developed countries • 15 MWh per capita per year solar electricity Electricity consumption: 0.2 MWh/person/year 2065 target Hydropower is dominant in electricity, biomass is dominant at home Nepal target: install 200 Watts of solar per person per year Energy resources in Nepal Australia: installing 250 Watts of solar & wind per person per year Solar PV: 50,000 TWh/year Hydro: 500 TWh/year Bio, wind etc:small 2020 2030 2040 2050 2060 2070 Year Keywords: solar photovoltaics; pumped-hydro-energy storage; traditional biomass; renewable energy; national energy mix; current scenario; greenhouse gas Received: 5 February 2021; Accepted: 7 April 2021 © The Author(s) 2021. Published by Oxford University Press on behalf of National Institute of Clean-and-Low-Carbon Energy This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (http:// creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, 243 provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com Per capita electricity, MWh Downloaded from https://academic.oup.com/ce/article/5/2/243/6275217 by DeepDyve user on 18 May 2021 244 | Clean Energy, 2021, Vol. 5, No. 2 financing that tap high quality resources, solar PV is now the Introduction cheapest source of electricity in history’ [ ]. 2 Energy is an essential commodity. Rapidly increasing popu- Fossil fuels produce three-quarters of global green- lations and economic growth are causing global energy house gases [3]. According to the Intergovernmental Panel demand to increase, especially in emerging-market econ- on Climate Change, to limit global warming to 1.5°C, rapid omies. Energy supply is interwoven with global warming, reductions in greenhouse-gas emissions are required [4]. local pollution, national and international security, eco- Importantly, developing countries such as Nepal can bypass nomic growth and the ability to meet basic human needs. a fossil-fuel era and transition directly to zero-emission re- A radical and rapid transformation to a sustainable newables at low cost. global energy system is underway. Solar photovoltaics (PV) Novel themes in this paper are that: and wind now comprise three-quarters of the global net new electricity-generation-capacity additions (Fig. 1). Coal, • Nepal can meet all of its energy needs from solar PV by oil, gas, nuclear, hydro and the other renewables comprise covering 1% of its area with panels, even after (i) Nepal the balance [1]. Solar and wind energy are vast, ubiquitous, catches up with the developed world in per-capita use non-polluting and indefinitely sustainable, and accord well of energy and (ii) all energy services are electrified, with the United Nations Sustainable Development Agenda eliminating fossil fuels entirely (an increase of 70-fold for affordable and clean energy. in electricity production). The deep renewable electrification of energy services al- • Identification of off-river pumped hydro as a vast, low- lows solar and wind to eliminate fossil fuels, not just from cost, mature storage opportunity; Nepal has 17 times the electricity system. Renewable electrification includes more off-river pumped-hydro-energy-storage sites conversion of land transport to electric vehicles; use of than it will ever need even under the zero-fossil-fuel electric heat pumps for low-temperature air and water scenario described above, thus eliminating the need for heating; powering of industrial heat with electric furnaces; on-river hydro storage. Pumped hydro is much cheaper and, for the chemical industry, replacement of hydrogen than batteries for overnight storage. from fossil fuels with hydrogen from water splitting. • Damming of Nepalese Himalayan rivers is unnecessary Many jurisdictions are committing to net-zero emis- because PV is competitive with and vastly more avail- sions by 2050–60 including Japan, the European Union, able than hydro and can be more readily implemented China, the USA and Korea. Most countries are expected to at both small and large scales. follow suit in the next few years. Solar photovoltaics and wind energy are now the cheapest Section 1 of this paper describes a scenario in which Nepal forms of electricity available in regions with good solar and catches up with developed countries in terms of per-capita wind resources, respectively, except perhaps for very fa- energy consumption. Section 2 describes the renewable- vourable hydroelectric sites. A  dramatic acknowledgement energy options for Nepal to meet this consumption and of the rapid pace of change in world energy markets comes identifies solar PV as by far the most prospective. Section from the 2020 World Energy Outlook from the International 3 describes methods of balancing high levels of solar PV. Energy Agency, which states that ‘[f]or projects with low cost Section 4 summarizes policy implications and the conclu- sion follows. Net new global capacity additions in 2020 Hydro + bioenergy + geothermal + ocean + solar thermal Solar PV Wind Other renewables Fossil + nuclear Fig. 1: Global net new electricity-generation-capacity additions in 2020 [1] Gigwatts Downloaded from https://academic.oup.com/ce/article/5/2/243/6275217 by DeepDyve user on 18 May 2021 Lohani et al. | 245 compatible with production of electricity at a cost of US$40 1 Renewable energy in Nepal per MWh once the Nepalese solar industry becomes ma- Traditionally, energy from biomass has dominated the ture, falling to <US$30/MWh in 2030 [7]. domestic energy supply for most people in Nepal and oil The speed of development of the global solar industry, was important for motorized transport. However, electri- arising from rapid price reductions, is so fast that previous city is becoming increasingly important. In the past, most reports on energy options require updating. developing countries followed a path of increasing de- Nepal is located at a latitude of 26–30° north latitude, pendence on fossil fuels as they industrialized and raised with the sun shining for >300  days per year. It has rela- living standards for their populations. In the future, most tively high insolation of an average of ~17 megajoules developing countries will transition directly to solar and 2 2 per m per day (1.7 TWh per km per year) and national wind energy, and bypass a fossil-fuel era. average sunshine hours of 6.8 per day. This makes Nepal Nepalese people can expect to achieve a high living a country with moderately high solar potential [ , 8 9]. All standard over the course of the twenty-first century. The parts of the country are reasonably favourable for solar per-capita electricity consumption in developed coun- energy, as shown in Fig. 2. tries such as the European Union, Japan, China, the USA, A solar-energy-system conversion efficiency of 20% Singapore and Australia is 5–15 megawatt-hours (MWh) (utilizing solar cells with efficiency of 25% [10]) will soon per person per year. In developed countries, complete re- become available, which corresponds to 0.2 gigawatts (GW) newable electrification of all energy services and complete per km . This assumes close-packing of solar modules to elimination of oil, gas and coal allow the avoidance of most form a dense array. Nepal has an area of 148 000 km . Thus, greenhouse emissions. To achieve this, electricity produc- if Nepal were covered entirely by solar cells, it could gen- tion must double or triple to 15–30 MWh per person per 2 2 erate 50 000 TWh per year (148 000 km × 1.7 TWh per km year, depending substantially on the degree of participa- per year × 20% conversion efficiency). The nominal power tion of the country in the chemical industry [5]. Net-zero capacity would be 30 000 GW. emissions in 2050 strictly require such a transformation. This approximate calculation shows that Nepal can Electricity demand in Nepal is rising because supply is generate 100 times more solar electricity than would be being extended to the whole population, per-capita con- needed for the 500-TWh goal of high per-capita consump- sumption is increasing and the population is growing. We tion (similar to developed countries) coupled with the adopt the following assumptions: complete electrification of energy services and the elim- (i) that Nepal with catch up with developed countries in ination of fossil fuels. Equivalently, 1% of Nepal (1500 km ) terms of per-capita energy consumption; would need to be covered by solar panels. (ii) that the energy systems of Nepal are fully electrified, Under our assumption of electricity consumption of including transport, heating and industry, with zero 15 MWh per person per year, the area of land required for fossil-fuel use; and solar collectors is 44 m per person with a nominal power (iii) that the per-capita electricity consumption in the capacity of ~9 kilowatts (kW). second half of the twenty-first century in Nepal will Large amounts of solar PV can be accommodated on increase to 15 MWh per person per year for a popula- residential, commercial and industrial rooftops, building tion of 33 million people. facades and in other urban areas. The global per-capita leader in rooftop solar, Australia, has 3 million rooftop Thus, Nepal’s electricity consumption may reach in the solar systems with a combined capacity of ~13 GW (550 range of 500 terawatt-hours (TWh) per year. This is referred Watts (W) per person) [11]. Most of this is located on resi- to in this paper as the ‘500-TWh goal’. Of course, the exact dential buildings, although other sectors are rising quickly. number cannot be reliably predicted, but these assump- The amount of rooftop solar in Australia may increase to tions are adopted to illustrate trends as Nepal catches up 3.7 kW per person according to the Step Change scenario with developed countries in energy consumption. This of the Australian Energy Market Operator [12]. This repre- 500-TWh goal compares with current consumption of sents 40% of the 9-kW-per-person target required to meet electricity in Nepal of ~7 TWh per year [6]. the 500-TWh goal for Nepal. Solar PV systems can be located in food-growing areas (Agrivoltaics, APV) whereby widely spaced solar panels 2 Renewable-energy options for Nepal shade 10–30% of the crop or pasture but cause only a 2.1 Solar energy modest loss of production because the reduction in sun- Solar energy is by far the largest and most sustainable en- shine is offset by a reduction in wind speeds and evapor- ergy resource in Nepal. The solar resource is two orders ation rates [13–22]. Maize, wheat, millet, jute, sugarcane, of magnitude larger than Nepal will require to meet the tea, tobacco, coffee soybeans, beans, lentils, fruit and 500-TWh goal. vegetables may all be suitable for APV in Nepal. However, Very rapid reductions in the price of solar PV over recent rice farming appears to be incompatible, since partial years has opened up enormous markets in developed and shading proportionally reduces rice output. Animal hus- developing countries alike. The solar resource in Nepal is bandry (cows, buffaloes, goats, sheep, pigs, horses) is also Downloaded from https://academic.oup.com/ce/article/5/2/243/6275217 by DeepDyve user on 18 May 2021 246 | Clean Energy, 2021, Vol. 5, No. 2 Fig. 2: Global horizontal irradiation and solar photovoltaic power potential in Nepal (redder is better) [8] compatible with APV. APV offers a second cash crop for electricity is now sourced from solar PV and wind, and this farmers. Detailed research will be required to establish figure is tracking towards 50% in 2025. The state of South the trade-off between agricultural and electricity yields for Australia sourced 60% of its electricity from solar PV and each crop, and hence to determine the amount of electri- wind in 2020 [24] and is heading towards 100% by 2025. city that could be provided through APV. The area of land Plainly, rapid transition to solar and wind energy is feasible. devoted to agriculture in Nepal is ~41000 km [23]. Thus, As the price of solar-energy systems continues to fall, an average shading of 3.6% of agricultural areas by APV is solar energy becomes ever more affordable. The price of sufficient to meet the 500-TWh goal for Nepal. utility-scale solar systems (tens to hundreds of mega- Substantial numbers of panels may be accommodated watts) in countries that have large-scale annual deploy- on non-forested lower slopes of hills and mountains with ment (and have thereby achieved critical mass of people a southerly aspect. Waste land can become productive and capability) is ~US$0.7 per Watt and is likely to decline through the installation of PV systems, including around to <US$0.4 per Watt in 2030 [10]. These prices are afford- the transport infrastructure. For example, the area occu- able in most countries, including Nepal. However, prices pied by roads in an advanced economy is a substantial for infrequent construction within a country can be much fraction of the required solar PV area per person (44 m ) higher due to immature supply chains. to meet the 500-TWh goal. Some solar systems can be Solar PV is unique among energy technologies in that floated on lakes and hydroelectric reservoirs, although the small-scale (kilowatts) and large-scale (gigawatts) instal- area available is small compared with the 1500-km target. lations are built using the same basic unit (a solar panel) Further work is required to quantify these opportunities. and have similar energy costs. A roof-mounted system has To reach 9 kW of solar panel per person by 2065, Nepal low land, engineering, approval and financing costs while would need to install 200  W per person per year (~6 GW a large-scale system has low panel and deployment costs. per year). To put this in perspective, Australia is currently Electrification can proceed both by grid extension and installing 250 W per person per year of new solar- and through house- and village-scale small solar systems with wind-energy systems (Fig. 3) [1]. This is 10 times faster battery storage. than the global average and 4 times faster than in the USA, Small-scale solar systems for individual house- China, Japan and Europe. About one-quarter of Australian holds or villages provide major benefits for lighting, Downloaded from https://academic.oup.com/ce/article/5/2/243/6275217 by DeepDyve user on 18 May 2021 Lohani et al. | 247 telecommunications, water pumping, grain grinding and 2.2 Hydropower refrigeration. When many people in a village deploy house- Hydropower is one of the two sources of energy in Nepal hold solar, then microgrids can form, comprising distrib- that can play an important role in Nepal’s future economy. uted solar panels and battery storage, which can gradually However, the hydro potential is a tiny fraction of the solar increase in scale and power by interconnection with other PV potential. Table 1 represents the annual energy esti- microgrids, eventually leading to widespread intercon- mate and power potential of four major river basins: nection [25, 26]. Larger-scale systems can power cooking, Narayani, Saptakoshi, Karnali and Mahakali of Nepal. heating, industry and transport, particularly in combin- Though Saptakoshi is the largest river basin of Nepal, the ation with extension of the electricity grid to most citizens. Narayani river basin has the largest annual energy pro- Nepal’s currently installed solar capacity is ~60 MW duction of ~113 TWh and power potential of ~18 GW [31]. (2 W per person) [27]. Much of this is in the form of 1.1 Presently, hydropower plants with a combined capacity million small home systems that are not grid-connected. of 1.2 GW have been installed in Nepal. Most are run-of- Institutional solar PV systems up to a capacity of 2 kW river with output varying according to rainfall and provide have been installed in thousands of institutions such as little storage [32]. schools, health posts and homestays. More than 10  000 Approximately 50% of the total hydropower assets are solar streetlights have been installed [28, 29]. owned by the Nepal Electricity Authority, a government The construction of Nepal’s largest solar-energy plant agency, and the rest is owned by independent power pro- with an installed capacity of 25 MW began in April 2018 in ducers. An important achievement in 2018 was the com- the Nuwakot district and is now in the early stage of pro- missioning of a new Dhalkebar Muzaffarpur cross-country ducing electricity [30]. transmission line between Nepal and India, giving an add- An important advantage of solar is that millions of in- itional boost to Nepal’s energy-trading system [33]. dividuals can acquire and own their own rooftop solar It is important to understand the environmental de- system. These systems can connect to a battery or the struction usually associated with large-scale hydropower grid, or both. This sidesteps institutional barriers at the projects, particularly if they include energy storage in large national level. reservoirs. These include displacement of people, flooding To put this in perspective, Australia has a population of of farmland, destruction of river ecosystems, forest clear - 25 million, only a little less than Nepal. Most people live in ance and methane release due to the decay of a large south-east coastal cities where the annual solar resource number of plants and organic residues. is similar to that of Nepal. According to the government’s Importantly, the cost of solar energy has fallen below all Clean Energy Regulator, Australia is installing 3 GW per but the most favourable hydroelectric systems. year of new rooftop solar systems and there is now a total of 3 million rooftop solar systems with a combined cap- 2.3 Wind energy acity of >13 GW [11]. Individuals install these systems be- cause they compete with retail prices, which are much Nepal has a low potential for the large-scale utilization of higher than wholesale prices. wind energy (Fig. 4) [34]. Typical expected capacity factors GermanySweden UK Europe Japan China India Vietnam Rest of USA Rest of Africa WorldAustralia Asia Americas Fig. 3: Deployment rate of renewables (principally solar PV and wind) in various regions in terms of Watts per person per year [1] Watts per persom per year Downloaded from https://academic.oup.com/ce/article/5/2/243/6275217 by DeepDyve user on 18 May 2021 248 | Clean Energy, 2021, Vol. 5, No. 2 are <20% except on the high ridges of the Himalayas, 2.4  Biomass which are largely inaccessible for wind turbines. This Biomass in various forms, including wood, agricul- means that wind energy will be much more expensive tural residue, animal dung and biogas, is an important than solar energy. small-scale energy source for millions of people in Nepal. There is potential for small turbines in some favourable However, biomass can never be a large-scale source of locations. Various government and private organizations energy. The primary reason is that the conversion of are taking initiatives to promote small-scale wind energy solar energy into biomass and then into useful energy in Nepal [35]. At present, there is no ongoing wind-turbine- occurs with very low efficiency—orders of magnitude installation project that uses wind energy alone [36]. The lower than via solar PV. This means that a great deal of Energy Sector Management Assistance Program of the land is required to supply energy services, and this com- World Bank has had a project since 2015 for the ground- petes directly with food and timber production and with based measurement of wind potential at 10 sites (Mustang environmental values. (2); Morang; Siraha; Panchthar; Dang (2); Jumla; Ramecchap; Electricity can readily replace biomass and fossil fuels Banke) [37, 38]. This has allowed reliable wind-power esti- for heating, cooking and lighting. Importantly, electricity mation that can be used by potential wind-power devel- eliminates indoor air pollution. Use of biomass may de- opers in Nepal. cline over the next several decades, as has occurred in most other countries as their economies have developed. Nepal produces a large amount of organic solid waste, Table 1: Annual energy and power potential of major river ba- manure and sewage sludge along with various types of sins of Nepal [31] organic industrial waste. This waste needs to be man- aged properly to protect the environment. Landfilling is Annual energy Power potential not an environmentally friendly option. Anaerobic diges- River basins estimate (TWh) (GW) tion of these wastes is an environmentally beneficial and Narayani 113 18 energy-efficient waste-management option to recover Saptakoshi 109 17 biogas (about 60% methane) and digestate sludge as a Karnali 102 16 by-product that is used as an organic fertilizer. This helps Mahakali 150 2 Nepal to replace chemical fertilizer and biogas can be used Solar PV potential 50 000 30 000 for cooking, heating and industrial applications. Fig. 4: Wind-capacity factors in Nepal (redder is better) [34] Downloaded from https://academic.oup.com/ce/article/5/2/243/6275217 by DeepDyve user on 18 May 2021 Lohani et al. | 249 and very much less than the land alienated by an equiva- 3 Balancing high levels of solar lent river-based system. electricity Nepal has enormous potential for off-river PHES. The Balancing high levels of variable solar energy over every Global Pumped Hydro Storage Atlas [42, 43] identifies hour of every year is straightforward. Storage via batteries ~2800 good sites in Nepal with combined storage capacity and pumped hydro allows the daily solar cycle to be ac- of 50 TWh (Fig. 6). To put this in perspective, the amount of commodated. Sharing power over large areas via high- storage typically required to balance 100% renewable en- power-transmission lines spanning Nepal from east to ergy in an advanced economy is ~1 day of energy use [44]. west allows the smoothing-out of local weather and de- For the 500-TWh goal, this amounts to ~1.5 TWh. mand variability. Seasonal variation in solar-energy supply in Nepal is Australia is installing variable solar and wind faster moderate, fluctuating from 75% of the mean in winter to per capita than any other country. Australia only de- 125% in spring [9]. This means that significant seasonal rives ~6% of its electricity from hydro, and hence lacks storage may be required. A  simple analysis of data in [9] the smoothing ability of hydroelectric generation backed suggests an upper bound in seasonal storage of 50 TWh, by large dams. In response, Australia is deploying mul- which could be accommodated with off-river pumped- tiple gigawatts of new off-river pumped hydro, gigawatt- hydro storage [40]. In practice, far lower storage would scale batteries and new gigawatt-scale transmission [39]. be needed. Large-scale demand management is also being deployed The amount of storage needed is a trade-off between through pricing structures to encourage the transference the cost of the storage and the cost of providing additional of consumption to times of excess renewable-energy solar generation to cover winter. The latter implies sub- availability. stantial excess solar electricity in summer. Because the cost of solar-energy systems continues to fall, the eco- nomic optimum is likely to favour the overbuilding of solar 3.1 Pumped-hydro-energy storage (PHES) rather than the deployment of large amounts of seasonal PHES entails pumping water from a lower to an upper res- storage. ervoir when excess solar energy is available and allowing Interconnection with neighbouring countries to the the water to run down through a turbine at a later time to north and south, where large wind-energy resources are recover the energy [40]. Typical round-trip efficiency is 80%. located, could substantially reduce the need for seasonal PHES comprises ~95% of global electricity-storage storage. Excess summer solar generation can be used for power (~170 GW) and a higher fraction of storage energy underground seasonal thermal storage and can be ex- [41]. Most existing pumped-hydro systems are associated ported to neighbouring countries. with river-based hydroelectric projects with large reser - voirs. This generally entails flooding large areas of land. PHES systems can be located away from rivers. Since 3.2 Batteries most of the land surface of Earth is not adjacent to a Batteries have a typical round-trip efficiency of ~90% for river, a vastly larger number of potential sites are avail- battery chemistries based on lithium [45]. Batteries are able for off-river (closed-loop) PHES compared with river- being deployed at the gigawatt scale around the world to based PHES. Off-river PHES comprises a pair of reservoirs support rising levels of wind and solar. For storage-time (20–500 hectares (Ha)), separated by a few kilometres, but periods of seconds to hours, batteries have an economic at different altitudes (200–1200 m altitude difference or advantage. For several hours, overnight and seasonal ‘head’) and connected by a pipe or tunnel (Fig. 5). Water storage, pumped hydro is much cheaper. Batteries and is pumped uphill on sunny/windy days and energy is re- pumped hydro are complementary storage technologies. covered by allowing the stored water to flow back through the turbine. The water oscillates indefinitely between the two reservoirs. 3.3 Hydrogen For example, a pair of 100-Ha reservoirs with a head of 600 m, an average depth of 20 m, a usable fraction of water Hydrogen production in Nepal is unlikely to be significant. of 90% and a round-trip efficiency of 80% (accounting for Hydrogen or hydrogen-rich chemicals such as ammonia losses) can store 18 gigalitres of water with an energy po- could be used to store and transport energy in Nepal. tential of 24 GWh, which means that it could operate at However, this is unlikely to occur because the efficiency is a power of 1 GW for 24 hours. These reservoirs are very very low compared with those of batteries, pumped hydro small compared with river-based hydros. Water require- and thermal storage, which unavoidably translates into ments (initial fill and evaporation minus rainfall) are very high costs. small compared with a comparable coal-fired power sta- Hydrogen can be sustainably produced using renew- tion (cooling tower). It amounts to a few square metres of able electricity to electrolyse water. Hydrogen is difficult land per person for the 500-TWh goal, which is much less to store. Options include liquefaction at very low temper - than the land needed for the associated solar PV systems atures and conversion to a more tractable chemical such Downloaded from https://academic.oup.com/ce/article/5/2/243/6275217 by DeepDyve user on 18 May 2021 250 | Clean Energy, 2021, Vol. 5, No. 2 Fig. 5: Google Earth synthetic image of a gigawatt-rated off-river PHES system [40] at Presenzano in Italy, showing the two reservoirs (upper right and lower left) with a head of 500 ms (vertical scale is exaggerated) Fig. 6: Hundreds of 50-GWh off-river pumped-hydro sites in Nepal [42, 43] as ammonia. Conversion of hydrogen energy to a useful milliseconds to grid disturbances and have a 90% round- form such as electricity or motive power is a low-efficiency trip efficiency. It is difficult to see how hydrogen could process. Typically, the round-trip efficiency of electricity– compete with pumped-hydro storage for overnight and hydrogen–electricity is 20–30% [46] compared with 80–90% longer storage because pumped-hydro storage has an 80% for batteries or pumped hydro. Basic physical constraints round-trip efficiency and is mature and already low-cost. mean that hydrogen storage can never have a high round- Electric vehicles are being produced at the multi-million trip efficiency. This is a large economic barrier to the use of scale per year. In contrast, hydrogen-powered vehicles hydrogen as an energy-storage medium. have a miniscule market share. The enormous advantage It is difficult to see how hydrogen could compete with of incumbency means that electric vehicles are likely to batteries for short-term storage because batteries react in dominate land transport in the future, which eliminates Downloaded from https://academic.oup.com/ce/article/5/2/243/6275217 by DeepDyve user on 18 May 2021 Lohani et al. | 251 the automotive market for hydrogen. This includes heavy and development of sustainable energy, Nepal joined the vehicles and long-distance transport. For example, the UN Secretary General’s Sustainable Energy for All (SE4ALL) Tesla electric semi with a 35-tonne load has an expected initiative in 2012, targeting the provision of clean energy range of ≤800 km (similar to the width of Nepal) [47]. to all by 2030. Hydrogen is needed in the chemical industry for the syn- Concerning legislation, Part 4 of Article 51 of the thesis of materials such as fertilizers, explosives, plastics, Consitution of Nepal (2015) states that the government synthetic jet fuels and the reduction of iron oxide. Nepal will adopt policies regarding the protection, promotion is unlikely to play a significant part in the international and use of natural resources to guarantee appropriate, hydrogen chemical industry because other countries have affordable and sustainable energy to citizens. Nepal has far better wind and solar resources and land availability, established various relevant strategies and guidelines for and will be able to produce hydrogen much more cheaply. the promotion and development of renewable energy. Some of these relevant to large-scale renewable-energy promotion include the White Paper on Energy, Water and 4 Government policy Irrigation- Present Situation and Future Prospect 2018 and the Guidelines for Development of Alternative Electricity Government energy roadmaps in many countries are being Connected to Grid 2018. These have elements that seek to overtaken and rendered obsolete by a sustained rapid de- support the large-scale promotion of renewable-energy cline in the cost of solar energy and sustained rapid growth technologies in Nepal. More specifically: in solar-energy deployment. New solar-energy-generation capacity is being deployed about twice as fast as the net • The White Paper on Energy, Water, and Irrigation: new coal-, gas-, oil-, nuclear- and hydro-generation cap- Present Situation and Future Prospect, released by the acity combined. In leading countries such as Australia, Ministry of Energy and Water Resources and Irrigation solar and wind comprise 99% of the new generation cap- in 2018, sets targets of increasing household electricity acity [1]. usage to 700 kWh within 5 years and 1500 kWh within The demonstrated pathway to high levels of solar de- 10  years, and to have electric cookstoves in all house- ployment in countries with leading per-capita deployment holds by 2030. It also aims to promote a renewable- rates such as Australia and Germany is two-fold: deploy- energy mix mainly from solar, wind and biomass to ment of millions of small residential rooftop solar systems reduce dependence on a single energy source and to of a few kilowatts each and the parallel development of improve energy security. multiple 10- to 500-MW solar farms. The experience gained • As per the Guidelines for Development of Alternative is synergistic, since there is much in common between the Electricity Connected to Grid 2018, published on 8 markets. February, people can feed electricity generated from Early deployment is relatively expensive because of solar, wind and biogas plants into the national grid and the initial lack of skill and supply chains coupled with the get paid a fixed amount of money per kilowatt hour of perceived risk due to inexperience with solar technology. energy. The generation licence will have a validity of However, it is important to look beyond the initial high 25  years and the Nepal Electricity Authority will pay prices to understand the low and falling cost of solar en- producers US$62/MWh (1 USD = NRs 116 (exchange rate ergy in a mature market that has gained critical mass. in February 2021)) [48]. Government and international support for a few hun- This is an attractive price once the solar PV industry is dred megawatts of rooftop solar and solar farms in Nepal mature enough to enable low costs. These policies and re- will help to overcome the initial hurdle, leading to rapidly sponses will require extensive modification once the low increasing solar infrastructure and deployment skill, and a prices available from a mature solar industry in Nepal be- rapidly declining solar-electricity price. come available. Government can leave the development of solar farms and solar rooftop systems to the private sector. However, there is an important government role in facilitating ad- 5 Conclusion equate transmission and storage. In particular, govern- ment has an important role in selecting and facilitating Nepal has good solar resources by world standards and the construction of several off-river PHES systems as and moderate hydro resources, but negligible wind- and fossil- when they become necessary. energy resources. The solar-energy resource is two orders The federal, provincial and local governments of Nepal of magnitude larger than the hydro resource. Solar en- have been working for some time in coordination with ergy is likely to be competitive with new hydro in Nepal. energy-sector stakeholders of Nepal to promote clean and Government energy roadmaps made earlier than 2020 are sustainable energy. The Ministry of Energy, Water Resources largely outdated by the rapid progression of solar. and Irrigation is the line ministry having the primary juris- Solar collectors equivalent to ~1% of Nepal’s land area diction and authority to plan, develop and implement na- are required to allow Nepalese citizens to have the same tional energy policy and strategy. To ensure the promotion per-capita energy consumption as those in developed Downloaded from https://academic.oup.com/ce/article/5/2/243/6275217 by DeepDyve user on 18 May 2021 252 | Clean Energy, 2021, Vol. 5, No. 2 [3] U.S. Environment Protection Agency. Global Greenhouse Gas countries and with zero fossil-fuel utilization. This includes Emission Data. https://www.epa.gov/ghgemissions/global- the electrification of transport, heating and industry. These greenhouse-gas-emissions-data (17 September 2020, date last panels can be accommodated on rooftops, in conjunction accessed). with agriculture and on lakes and unproductive land. [4] Rogelj J, Shindell D, Jiang K, et al. Mitigation pathways com- Since most existing Nepalese hydro is run-of-river, sub- patible with 1.5°C in the context of sustainable development. stantial new storage is required to support a solar-based In: Masson-Delmotte V, Zhai P, Pörtner HO, et al. (eds.). Global energy system. Nepal has enormous potential for the de- Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global ployment of off-river PHES systems, which have a much greenhouse gas emission pathways, in the context of strengthening lower environmental and social impact than river-based the global response to the threat of climate change, sustainable de- hydro storage. velopment, and efforts to eradicate poverty. Geneva, Switzerland: The economic advantage of solar PV over fossil and World Meteorological Organization, 2018. hydro energy in a mature and competitive market is com- [5] Lu B, Blakers A, Stocks M, et al. A zero-carbon, reliable and af- pelling. However, several factors can impede the rapid de- fordable energy future in Australia. Energy, 2021, 220:119678. ployment of solar PV. Perhaps the most important is the [6] International Energy Agency. Key Energy Statistics, 2018. https://www.iea.org/countries/nepal (10 October 2020, date relatively high cost of solar until the critical mass of skilled last accessed). people and supply chains is obtained—then costs will fall [7] Verlinden  PJ. Future challenges for photovoltaic manufacturing rapidly towards international norms. Another important at the terawatt level. 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100% renewable energy with pumped-hydro-energy storage in Nepal

Clean Energy , Volume 5 (2) – Jun 1, 2021

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Copyright © 2021 National Institute of Clean-and-Low-Carbon Energy
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Abstract

Target for Nepal for 2065: 100% Renewable energy in Nepal • 100% renewable energy 2020 status • Catch up with developed countries • 15 MWh per capita per year solar electricity Electricity consumption: 0.2 MWh/person/year 2065 target Hydropower is dominant in electricity, biomass is dominant at home Nepal target: install 200 Watts of solar per person per year Energy resources in Nepal Australia: installing 250 Watts of solar & wind per person per year Solar PV: 50,000 TWh/year Hydro: 500 TWh/year Bio, wind etc:small 2020 2030 2040 2050 2060 2070 Year Keywords: solar photovoltaics; pumped-hydro-energy storage; traditional biomass; renewable energy; national energy mix; current scenario; greenhouse gas Received: 5 February 2021; Accepted: 7 April 2021 © The Author(s) 2021. Published by Oxford University Press on behalf of National Institute of Clean-and-Low-Carbon Energy This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (http:// creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, 243 provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com Per capita electricity, MWh Downloaded from https://academic.oup.com/ce/article/5/2/243/6275217 by DeepDyve user on 18 May 2021 244 | Clean Energy, 2021, Vol. 5, No. 2 financing that tap high quality resources, solar PV is now the Introduction cheapest source of electricity in history’ [ ]. 2 Energy is an essential commodity. Rapidly increasing popu- Fossil fuels produce three-quarters of global green- lations and economic growth are causing global energy house gases [3]. According to the Intergovernmental Panel demand to increase, especially in emerging-market econ- on Climate Change, to limit global warming to 1.5°C, rapid omies. Energy supply is interwoven with global warming, reductions in greenhouse-gas emissions are required [4]. local pollution, national and international security, eco- Importantly, developing countries such as Nepal can bypass nomic growth and the ability to meet basic human needs. a fossil-fuel era and transition directly to zero-emission re- A radical and rapid transformation to a sustainable newables at low cost. global energy system is underway. Solar photovoltaics (PV) Novel themes in this paper are that: and wind now comprise three-quarters of the global net new electricity-generation-capacity additions (Fig. 1). Coal, • Nepal can meet all of its energy needs from solar PV by oil, gas, nuclear, hydro and the other renewables comprise covering 1% of its area with panels, even after (i) Nepal the balance [1]. Solar and wind energy are vast, ubiquitous, catches up with the developed world in per-capita use non-polluting and indefinitely sustainable, and accord well of energy and (ii) all energy services are electrified, with the United Nations Sustainable Development Agenda eliminating fossil fuels entirely (an increase of 70-fold for affordable and clean energy. in electricity production). The deep renewable electrification of energy services al- • Identification of off-river pumped hydro as a vast, low- lows solar and wind to eliminate fossil fuels, not just from cost, mature storage opportunity; Nepal has 17 times the electricity system. Renewable electrification includes more off-river pumped-hydro-energy-storage sites conversion of land transport to electric vehicles; use of than it will ever need even under the zero-fossil-fuel electric heat pumps for low-temperature air and water scenario described above, thus eliminating the need for heating; powering of industrial heat with electric furnaces; on-river hydro storage. Pumped hydro is much cheaper and, for the chemical industry, replacement of hydrogen than batteries for overnight storage. from fossil fuels with hydrogen from water splitting. • Damming of Nepalese Himalayan rivers is unnecessary Many jurisdictions are committing to net-zero emis- because PV is competitive with and vastly more avail- sions by 2050–60 including Japan, the European Union, able than hydro and can be more readily implemented China, the USA and Korea. Most countries are expected to at both small and large scales. follow suit in the next few years. Solar photovoltaics and wind energy are now the cheapest Section 1 of this paper describes a scenario in which Nepal forms of electricity available in regions with good solar and catches up with developed countries in terms of per-capita wind resources, respectively, except perhaps for very fa- energy consumption. Section 2 describes the renewable- vourable hydroelectric sites. A  dramatic acknowledgement energy options for Nepal to meet this consumption and of the rapid pace of change in world energy markets comes identifies solar PV as by far the most prospective. Section from the 2020 World Energy Outlook from the International 3 describes methods of balancing high levels of solar PV. Energy Agency, which states that ‘[f]or projects with low cost Section 4 summarizes policy implications and the conclu- sion follows. Net new global capacity additions in 2020 Hydro + bioenergy + geothermal + ocean + solar thermal Solar PV Wind Other renewables Fossil + nuclear Fig. 1: Global net new electricity-generation-capacity additions in 2020 [1] Gigwatts Downloaded from https://academic.oup.com/ce/article/5/2/243/6275217 by DeepDyve user on 18 May 2021 Lohani et al. | 245 compatible with production of electricity at a cost of US$40 1 Renewable energy in Nepal per MWh once the Nepalese solar industry becomes ma- Traditionally, energy from biomass has dominated the ture, falling to <US$30/MWh in 2030 [7]. domestic energy supply for most people in Nepal and oil The speed of development of the global solar industry, was important for motorized transport. However, electri- arising from rapid price reductions, is so fast that previous city is becoming increasingly important. In the past, most reports on energy options require updating. developing countries followed a path of increasing de- Nepal is located at a latitude of 26–30° north latitude, pendence on fossil fuels as they industrialized and raised with the sun shining for >300  days per year. It has rela- living standards for their populations. In the future, most tively high insolation of an average of ~17 megajoules developing countries will transition directly to solar and 2 2 per m per day (1.7 TWh per km per year) and national wind energy, and bypass a fossil-fuel era. average sunshine hours of 6.8 per day. This makes Nepal Nepalese people can expect to achieve a high living a country with moderately high solar potential [ , 8 9]. All standard over the course of the twenty-first century. The parts of the country are reasonably favourable for solar per-capita electricity consumption in developed coun- energy, as shown in Fig. 2. tries such as the European Union, Japan, China, the USA, A solar-energy-system conversion efficiency of 20% Singapore and Australia is 5–15 megawatt-hours (MWh) (utilizing solar cells with efficiency of 25% [10]) will soon per person per year. In developed countries, complete re- become available, which corresponds to 0.2 gigawatts (GW) newable electrification of all energy services and complete per km . This assumes close-packing of solar modules to elimination of oil, gas and coal allow the avoidance of most form a dense array. Nepal has an area of 148 000 km . Thus, greenhouse emissions. To achieve this, electricity produc- if Nepal were covered entirely by solar cells, it could gen- tion must double or triple to 15–30 MWh per person per 2 2 erate 50 000 TWh per year (148 000 km × 1.7 TWh per km year, depending substantially on the degree of participa- per year × 20% conversion efficiency). The nominal power tion of the country in the chemical industry [5]. Net-zero capacity would be 30 000 GW. emissions in 2050 strictly require such a transformation. This approximate calculation shows that Nepal can Electricity demand in Nepal is rising because supply is generate 100 times more solar electricity than would be being extended to the whole population, per-capita con- needed for the 500-TWh goal of high per-capita consump- sumption is increasing and the population is growing. We tion (similar to developed countries) coupled with the adopt the following assumptions: complete electrification of energy services and the elim- (i) that Nepal with catch up with developed countries in ination of fossil fuels. Equivalently, 1% of Nepal (1500 km ) terms of per-capita energy consumption; would need to be covered by solar panels. (ii) that the energy systems of Nepal are fully electrified, Under our assumption of electricity consumption of including transport, heating and industry, with zero 15 MWh per person per year, the area of land required for fossil-fuel use; and solar collectors is 44 m per person with a nominal power (iii) that the per-capita electricity consumption in the capacity of ~9 kilowatts (kW). second half of the twenty-first century in Nepal will Large amounts of solar PV can be accommodated on increase to 15 MWh per person per year for a popula- residential, commercial and industrial rooftops, building tion of 33 million people. facades and in other urban areas. The global per-capita leader in rooftop solar, Australia, has 3 million rooftop Thus, Nepal’s electricity consumption may reach in the solar systems with a combined capacity of ~13 GW (550 range of 500 terawatt-hours (TWh) per year. This is referred Watts (W) per person) [11]. Most of this is located on resi- to in this paper as the ‘500-TWh goal’. Of course, the exact dential buildings, although other sectors are rising quickly. number cannot be reliably predicted, but these assump- The amount of rooftop solar in Australia may increase to tions are adopted to illustrate trends as Nepal catches up 3.7 kW per person according to the Step Change scenario with developed countries in energy consumption. This of the Australian Energy Market Operator [12]. This repre- 500-TWh goal compares with current consumption of sents 40% of the 9-kW-per-person target required to meet electricity in Nepal of ~7 TWh per year [6]. the 500-TWh goal for Nepal. Solar PV systems can be located in food-growing areas (Agrivoltaics, APV) whereby widely spaced solar panels 2 Renewable-energy options for Nepal shade 10–30% of the crop or pasture but cause only a 2.1 Solar energy modest loss of production because the reduction in sun- Solar energy is by far the largest and most sustainable en- shine is offset by a reduction in wind speeds and evapor- ergy resource in Nepal. The solar resource is two orders ation rates [13–22]. Maize, wheat, millet, jute, sugarcane, of magnitude larger than Nepal will require to meet the tea, tobacco, coffee soybeans, beans, lentils, fruit and 500-TWh goal. vegetables may all be suitable for APV in Nepal. However, Very rapid reductions in the price of solar PV over recent rice farming appears to be incompatible, since partial years has opened up enormous markets in developed and shading proportionally reduces rice output. Animal hus- developing countries alike. The solar resource in Nepal is bandry (cows, buffaloes, goats, sheep, pigs, horses) is also Downloaded from https://academic.oup.com/ce/article/5/2/243/6275217 by DeepDyve user on 18 May 2021 246 | Clean Energy, 2021, Vol. 5, No. 2 Fig. 2: Global horizontal irradiation and solar photovoltaic power potential in Nepal (redder is better) [8] compatible with APV. APV offers a second cash crop for electricity is now sourced from solar PV and wind, and this farmers. Detailed research will be required to establish figure is tracking towards 50% in 2025. The state of South the trade-off between agricultural and electricity yields for Australia sourced 60% of its electricity from solar PV and each crop, and hence to determine the amount of electri- wind in 2020 [24] and is heading towards 100% by 2025. city that could be provided through APV. The area of land Plainly, rapid transition to solar and wind energy is feasible. devoted to agriculture in Nepal is ~41000 km [23]. Thus, As the price of solar-energy systems continues to fall, an average shading of 3.6% of agricultural areas by APV is solar energy becomes ever more affordable. The price of sufficient to meet the 500-TWh goal for Nepal. utility-scale solar systems (tens to hundreds of mega- Substantial numbers of panels may be accommodated watts) in countries that have large-scale annual deploy- on non-forested lower slopes of hills and mountains with ment (and have thereby achieved critical mass of people a southerly aspect. Waste land can become productive and capability) is ~US$0.7 per Watt and is likely to decline through the installation of PV systems, including around to <US$0.4 per Watt in 2030 [10]. These prices are afford- the transport infrastructure. For example, the area occu- able in most countries, including Nepal. However, prices pied by roads in an advanced economy is a substantial for infrequent construction within a country can be much fraction of the required solar PV area per person (44 m ) higher due to immature supply chains. to meet the 500-TWh goal. Some solar systems can be Solar PV is unique among energy technologies in that floated on lakes and hydroelectric reservoirs, although the small-scale (kilowatts) and large-scale (gigawatts) instal- area available is small compared with the 1500-km target. lations are built using the same basic unit (a solar panel) Further work is required to quantify these opportunities. and have similar energy costs. A roof-mounted system has To reach 9 kW of solar panel per person by 2065, Nepal low land, engineering, approval and financing costs while would need to install 200  W per person per year (~6 GW a large-scale system has low panel and deployment costs. per year). To put this in perspective, Australia is currently Electrification can proceed both by grid extension and installing 250 W per person per year of new solar- and through house- and village-scale small solar systems with wind-energy systems (Fig. 3) [1]. This is 10 times faster battery storage. than the global average and 4 times faster than in the USA, Small-scale solar systems for individual house- China, Japan and Europe. About one-quarter of Australian holds or villages provide major benefits for lighting, Downloaded from https://academic.oup.com/ce/article/5/2/243/6275217 by DeepDyve user on 18 May 2021 Lohani et al. | 247 telecommunications, water pumping, grain grinding and 2.2 Hydropower refrigeration. When many people in a village deploy house- Hydropower is one of the two sources of energy in Nepal hold solar, then microgrids can form, comprising distrib- that can play an important role in Nepal’s future economy. uted solar panels and battery storage, which can gradually However, the hydro potential is a tiny fraction of the solar increase in scale and power by interconnection with other PV potential. Table 1 represents the annual energy esti- microgrids, eventually leading to widespread intercon- mate and power potential of four major river basins: nection [25, 26]. Larger-scale systems can power cooking, Narayani, Saptakoshi, Karnali and Mahakali of Nepal. heating, industry and transport, particularly in combin- Though Saptakoshi is the largest river basin of Nepal, the ation with extension of the electricity grid to most citizens. Narayani river basin has the largest annual energy pro- Nepal’s currently installed solar capacity is ~60 MW duction of ~113 TWh and power potential of ~18 GW [31]. (2 W per person) [27]. Much of this is in the form of 1.1 Presently, hydropower plants with a combined capacity million small home systems that are not grid-connected. of 1.2 GW have been installed in Nepal. Most are run-of- Institutional solar PV systems up to a capacity of 2 kW river with output varying according to rainfall and provide have been installed in thousands of institutions such as little storage [32]. schools, health posts and homestays. More than 10  000 Approximately 50% of the total hydropower assets are solar streetlights have been installed [28, 29]. owned by the Nepal Electricity Authority, a government The construction of Nepal’s largest solar-energy plant agency, and the rest is owned by independent power pro- with an installed capacity of 25 MW began in April 2018 in ducers. An important achievement in 2018 was the com- the Nuwakot district and is now in the early stage of pro- missioning of a new Dhalkebar Muzaffarpur cross-country ducing electricity [30]. transmission line between Nepal and India, giving an add- An important advantage of solar is that millions of in- itional boost to Nepal’s energy-trading system [33]. dividuals can acquire and own their own rooftop solar It is important to understand the environmental de- system. These systems can connect to a battery or the struction usually associated with large-scale hydropower grid, or both. This sidesteps institutional barriers at the projects, particularly if they include energy storage in large national level. reservoirs. These include displacement of people, flooding To put this in perspective, Australia has a population of of farmland, destruction of river ecosystems, forest clear - 25 million, only a little less than Nepal. Most people live in ance and methane release due to the decay of a large south-east coastal cities where the annual solar resource number of plants and organic residues. is similar to that of Nepal. According to the government’s Importantly, the cost of solar energy has fallen below all Clean Energy Regulator, Australia is installing 3 GW per but the most favourable hydroelectric systems. year of new rooftop solar systems and there is now a total of 3 million rooftop solar systems with a combined cap- 2.3 Wind energy acity of >13 GW [11]. Individuals install these systems be- cause they compete with retail prices, which are much Nepal has a low potential for the large-scale utilization of higher than wholesale prices. wind energy (Fig. 4) [34]. Typical expected capacity factors GermanySweden UK Europe Japan China India Vietnam Rest of USA Rest of Africa WorldAustralia Asia Americas Fig. 3: Deployment rate of renewables (principally solar PV and wind) in various regions in terms of Watts per person per year [1] Watts per persom per year Downloaded from https://academic.oup.com/ce/article/5/2/243/6275217 by DeepDyve user on 18 May 2021 248 | Clean Energy, 2021, Vol. 5, No. 2 are <20% except on the high ridges of the Himalayas, 2.4  Biomass which are largely inaccessible for wind turbines. This Biomass in various forms, including wood, agricul- means that wind energy will be much more expensive tural residue, animal dung and biogas, is an important than solar energy. small-scale energy source for millions of people in Nepal. There is potential for small turbines in some favourable However, biomass can never be a large-scale source of locations. Various government and private organizations energy. The primary reason is that the conversion of are taking initiatives to promote small-scale wind energy solar energy into biomass and then into useful energy in Nepal [35]. At present, there is no ongoing wind-turbine- occurs with very low efficiency—orders of magnitude installation project that uses wind energy alone [36]. The lower than via solar PV. This means that a great deal of Energy Sector Management Assistance Program of the land is required to supply energy services, and this com- World Bank has had a project since 2015 for the ground- petes directly with food and timber production and with based measurement of wind potential at 10 sites (Mustang environmental values. (2); Morang; Siraha; Panchthar; Dang (2); Jumla; Ramecchap; Electricity can readily replace biomass and fossil fuels Banke) [37, 38]. This has allowed reliable wind-power esti- for heating, cooking and lighting. Importantly, electricity mation that can be used by potential wind-power devel- eliminates indoor air pollution. Use of biomass may de- opers in Nepal. cline over the next several decades, as has occurred in most other countries as their economies have developed. Nepal produces a large amount of organic solid waste, Table 1: Annual energy and power potential of major river ba- manure and sewage sludge along with various types of sins of Nepal [31] organic industrial waste. This waste needs to be man- aged properly to protect the environment. Landfilling is Annual energy Power potential not an environmentally friendly option. Anaerobic diges- River basins estimate (TWh) (GW) tion of these wastes is an environmentally beneficial and Narayani 113 18 energy-efficient waste-management option to recover Saptakoshi 109 17 biogas (about 60% methane) and digestate sludge as a Karnali 102 16 by-product that is used as an organic fertilizer. This helps Mahakali 150 2 Nepal to replace chemical fertilizer and biogas can be used Solar PV potential 50 000 30 000 for cooking, heating and industrial applications. Fig. 4: Wind-capacity factors in Nepal (redder is better) [34] Downloaded from https://academic.oup.com/ce/article/5/2/243/6275217 by DeepDyve user on 18 May 2021 Lohani et al. | 249 and very much less than the land alienated by an equiva- 3 Balancing high levels of solar lent river-based system. electricity Nepal has enormous potential for off-river PHES. The Balancing high levels of variable solar energy over every Global Pumped Hydro Storage Atlas [42, 43] identifies hour of every year is straightforward. Storage via batteries ~2800 good sites in Nepal with combined storage capacity and pumped hydro allows the daily solar cycle to be ac- of 50 TWh (Fig. 6). To put this in perspective, the amount of commodated. Sharing power over large areas via high- storage typically required to balance 100% renewable en- power-transmission lines spanning Nepal from east to ergy in an advanced economy is ~1 day of energy use [44]. west allows the smoothing-out of local weather and de- For the 500-TWh goal, this amounts to ~1.5 TWh. mand variability. Seasonal variation in solar-energy supply in Nepal is Australia is installing variable solar and wind faster moderate, fluctuating from 75% of the mean in winter to per capita than any other country. Australia only de- 125% in spring [9]. This means that significant seasonal rives ~6% of its electricity from hydro, and hence lacks storage may be required. A  simple analysis of data in [9] the smoothing ability of hydroelectric generation backed suggests an upper bound in seasonal storage of 50 TWh, by large dams. In response, Australia is deploying mul- which could be accommodated with off-river pumped- tiple gigawatts of new off-river pumped hydro, gigawatt- hydro storage [40]. In practice, far lower storage would scale batteries and new gigawatt-scale transmission [39]. be needed. Large-scale demand management is also being deployed The amount of storage needed is a trade-off between through pricing structures to encourage the transference the cost of the storage and the cost of providing additional of consumption to times of excess renewable-energy solar generation to cover winter. The latter implies sub- availability. stantial excess solar electricity in summer. Because the cost of solar-energy systems continues to fall, the eco- nomic optimum is likely to favour the overbuilding of solar 3.1 Pumped-hydro-energy storage (PHES) rather than the deployment of large amounts of seasonal PHES entails pumping water from a lower to an upper res- storage. ervoir when excess solar energy is available and allowing Interconnection with neighbouring countries to the the water to run down through a turbine at a later time to north and south, where large wind-energy resources are recover the energy [40]. Typical round-trip efficiency is 80%. located, could substantially reduce the need for seasonal PHES comprises ~95% of global electricity-storage storage. Excess summer solar generation can be used for power (~170 GW) and a higher fraction of storage energy underground seasonal thermal storage and can be ex- [41]. Most existing pumped-hydro systems are associated ported to neighbouring countries. with river-based hydroelectric projects with large reser - voirs. This generally entails flooding large areas of land. PHES systems can be located away from rivers. Since 3.2 Batteries most of the land surface of Earth is not adjacent to a Batteries have a typical round-trip efficiency of ~90% for river, a vastly larger number of potential sites are avail- battery chemistries based on lithium [45]. Batteries are able for off-river (closed-loop) PHES compared with river- being deployed at the gigawatt scale around the world to based PHES. Off-river PHES comprises a pair of reservoirs support rising levels of wind and solar. For storage-time (20–500 hectares (Ha)), separated by a few kilometres, but periods of seconds to hours, batteries have an economic at different altitudes (200–1200 m altitude difference or advantage. For several hours, overnight and seasonal ‘head’) and connected by a pipe or tunnel (Fig. 5). Water storage, pumped hydro is much cheaper. Batteries and is pumped uphill on sunny/windy days and energy is re- pumped hydro are complementary storage technologies. covered by allowing the stored water to flow back through the turbine. The water oscillates indefinitely between the two reservoirs. 3.3 Hydrogen For example, a pair of 100-Ha reservoirs with a head of 600 m, an average depth of 20 m, a usable fraction of water Hydrogen production in Nepal is unlikely to be significant. of 90% and a round-trip efficiency of 80% (accounting for Hydrogen or hydrogen-rich chemicals such as ammonia losses) can store 18 gigalitres of water with an energy po- could be used to store and transport energy in Nepal. tential of 24 GWh, which means that it could operate at However, this is unlikely to occur because the efficiency is a power of 1 GW for 24 hours. These reservoirs are very very low compared with those of batteries, pumped hydro small compared with river-based hydros. Water require- and thermal storage, which unavoidably translates into ments (initial fill and evaporation minus rainfall) are very high costs. small compared with a comparable coal-fired power sta- Hydrogen can be sustainably produced using renew- tion (cooling tower). It amounts to a few square metres of able electricity to electrolyse water. Hydrogen is difficult land per person for the 500-TWh goal, which is much less to store. Options include liquefaction at very low temper - than the land needed for the associated solar PV systems atures and conversion to a more tractable chemical such Downloaded from https://academic.oup.com/ce/article/5/2/243/6275217 by DeepDyve user on 18 May 2021 250 | Clean Energy, 2021, Vol. 5, No. 2 Fig. 5: Google Earth synthetic image of a gigawatt-rated off-river PHES system [40] at Presenzano in Italy, showing the two reservoirs (upper right and lower left) with a head of 500 ms (vertical scale is exaggerated) Fig. 6: Hundreds of 50-GWh off-river pumped-hydro sites in Nepal [42, 43] as ammonia. Conversion of hydrogen energy to a useful milliseconds to grid disturbances and have a 90% round- form such as electricity or motive power is a low-efficiency trip efficiency. It is difficult to see how hydrogen could process. Typically, the round-trip efficiency of electricity– compete with pumped-hydro storage for overnight and hydrogen–electricity is 20–30% [46] compared with 80–90% longer storage because pumped-hydro storage has an 80% for batteries or pumped hydro. Basic physical constraints round-trip efficiency and is mature and already low-cost. mean that hydrogen storage can never have a high round- Electric vehicles are being produced at the multi-million trip efficiency. This is a large economic barrier to the use of scale per year. In contrast, hydrogen-powered vehicles hydrogen as an energy-storage medium. have a miniscule market share. The enormous advantage It is difficult to see how hydrogen could compete with of incumbency means that electric vehicles are likely to batteries for short-term storage because batteries react in dominate land transport in the future, which eliminates Downloaded from https://academic.oup.com/ce/article/5/2/243/6275217 by DeepDyve user on 18 May 2021 Lohani et al. | 251 the automotive market for hydrogen. This includes heavy and development of sustainable energy, Nepal joined the vehicles and long-distance transport. For example, the UN Secretary General’s Sustainable Energy for All (SE4ALL) Tesla electric semi with a 35-tonne load has an expected initiative in 2012, targeting the provision of clean energy range of ≤800 km (similar to the width of Nepal) [47]. to all by 2030. Hydrogen is needed in the chemical industry for the syn- Concerning legislation, Part 4 of Article 51 of the thesis of materials such as fertilizers, explosives, plastics, Consitution of Nepal (2015) states that the government synthetic jet fuels and the reduction of iron oxide. Nepal will adopt policies regarding the protection, promotion is unlikely to play a significant part in the international and use of natural resources to guarantee appropriate, hydrogen chemical industry because other countries have affordable and sustainable energy to citizens. Nepal has far better wind and solar resources and land availability, established various relevant strategies and guidelines for and will be able to produce hydrogen much more cheaply. the promotion and development of renewable energy. Some of these relevant to large-scale renewable-energy promotion include the White Paper on Energy, Water and 4 Government policy Irrigation- Present Situation and Future Prospect 2018 and the Guidelines for Development of Alternative Electricity Government energy roadmaps in many countries are being Connected to Grid 2018. These have elements that seek to overtaken and rendered obsolete by a sustained rapid de- support the large-scale promotion of renewable-energy cline in the cost of solar energy and sustained rapid growth technologies in Nepal. More specifically: in solar-energy deployment. New solar-energy-generation capacity is being deployed about twice as fast as the net • The White Paper on Energy, Water, and Irrigation: new coal-, gas-, oil-, nuclear- and hydro-generation cap- Present Situation and Future Prospect, released by the acity combined. In leading countries such as Australia, Ministry of Energy and Water Resources and Irrigation solar and wind comprise 99% of the new generation cap- in 2018, sets targets of increasing household electricity acity [1]. usage to 700 kWh within 5 years and 1500 kWh within The demonstrated pathway to high levels of solar de- 10  years, and to have electric cookstoves in all house- ployment in countries with leading per-capita deployment holds by 2030. It also aims to promote a renewable- rates such as Australia and Germany is two-fold: deploy- energy mix mainly from solar, wind and biomass to ment of millions of small residential rooftop solar systems reduce dependence on a single energy source and to of a few kilowatts each and the parallel development of improve energy security. multiple 10- to 500-MW solar farms. The experience gained • As per the Guidelines for Development of Alternative is synergistic, since there is much in common between the Electricity Connected to Grid 2018, published on 8 markets. February, people can feed electricity generated from Early deployment is relatively expensive because of solar, wind and biogas plants into the national grid and the initial lack of skill and supply chains coupled with the get paid a fixed amount of money per kilowatt hour of perceived risk due to inexperience with solar technology. energy. The generation licence will have a validity of However, it is important to look beyond the initial high 25  years and the Nepal Electricity Authority will pay prices to understand the low and falling cost of solar en- producers US$62/MWh (1 USD = NRs 116 (exchange rate ergy in a mature market that has gained critical mass. in February 2021)) [48]. Government and international support for a few hun- This is an attractive price once the solar PV industry is dred megawatts of rooftop solar and solar farms in Nepal mature enough to enable low costs. These policies and re- will help to overcome the initial hurdle, leading to rapidly sponses will require extensive modification once the low increasing solar infrastructure and deployment skill, and a prices available from a mature solar industry in Nepal be- rapidly declining solar-electricity price. come available. Government can leave the development of solar farms and solar rooftop systems to the private sector. However, there is an important government role in facilitating ad- 5 Conclusion equate transmission and storage. In particular, govern- ment has an important role in selecting and facilitating Nepal has good solar resources by world standards and the construction of several off-river PHES systems as and moderate hydro resources, but negligible wind- and fossil- when they become necessary. energy resources. The solar-energy resource is two orders The federal, provincial and local governments of Nepal of magnitude larger than the hydro resource. Solar en- have been working for some time in coordination with ergy is likely to be competitive with new hydro in Nepal. energy-sector stakeholders of Nepal to promote clean and Government energy roadmaps made earlier than 2020 are sustainable energy. The Ministry of Energy, Water Resources largely outdated by the rapid progression of solar. and Irrigation is the line ministry having the primary juris- Solar collectors equivalent to ~1% of Nepal’s land area diction and authority to plan, develop and implement na- are required to allow Nepalese citizens to have the same tional energy policy and strategy. To ensure the promotion per-capita energy consumption as those in developed Downloaded from https://academic.oup.com/ce/article/5/2/243/6275217 by DeepDyve user on 18 May 2021 252 | Clean Energy, 2021, Vol. 5, No. 2 [3] U.S. Environment Protection Agency. Global Greenhouse Gas countries and with zero fossil-fuel utilization. This includes Emission Data. https://www.epa.gov/ghgemissions/global- the electrification of transport, heating and industry. These greenhouse-gas-emissions-data (17 September 2020, date last panels can be accommodated on rooftops, in conjunction accessed). with agriculture and on lakes and unproductive land. 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Journal

Clean EnergyOxford University Press

Published: Jun 1, 2021

References