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Contract No. DE-AC36-08GO28308

Technical Report

NREL/TP-6A20-72066

April 2019

Cross-Border Energy Trade between 

Nepal and India: Assessment of 

Trading Opportunities

Brendan McBennett, Amy Rose, David Hurlbut, 

David Palchak, and Jaquelin Cochran

National Renewable Energy Laboratory
NREL is a national laboratory of the U.S. Department of Energy

Office of Energy Efficiency & Renewable Energy

Operated by the Alliance for Sustainable Energy, LLC

This report is available at no cost from the National Renewable Energy

Laboratory (NREL) at www.nrel.gov/publications.

Contract No. DE-AC36-08GO28308

National Renewable Energy Laboratory

15013 Denver West Parkway

Golden, CO 80401

303-275-3000 • www.nrel.gov

Technical Report

NREL/TP-6A20-72066

April 2019

Cross-Border Energy Trade between 

Nepal and India: Assessment of 

Trading Opportunities

Brendan McBennett, Amy Rose, David Hurlbut, 

David Palchak, and Jaquelin Cochran

National Renewable Energy Laboratory

Suggested Citation

McBennett, Brendan, Amy Rose, David Hurlbut, David Palchak, and Jaquelin Cochran. 

2019. Cross-Border Energy Trade Between Nepal and India: Assessment of Trading 

Opportunities. Golden, CO: National Renewable Energy Laboratory. 

NREL/TP-6A20-72066. https://www.nrel.gov/docs/fy19osti/72066.pdf.
NOTICE

This work was authored by the National Renewable Energy Laboratory, operated by Alliance for Sustainable 

Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. Funding 

provided by U.S. Department of State’s Bureau of South and Central Asian Affairs Regional Connectivity Program. 

The views expressed herein do not necessarily represent the views of the DOE or the U.S. Government.

This report is available at no cost from the National Renewable 

Energy Laboratory (NREL) at www.nrel.gov/publications.

U.S. Department of Energy (DOE) reports produced after 1991 

and a growing number of pre-1991 documents are available 

free via www.OSTI.gov.

Cover Photos by Dennis Schroeder: (clockwise, left to right) NREL 51934, NREL 45897, NREL 42160, NREL 45891, NREL 48097, 

NREL 46526.

NREL prints on paper that contains recycled content.
iii

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Abstract

Recent developments in India and Nepal highlight new opportunities for increased cross-border 

energy trade (CBET). This study builds on several prior analyses of CBET in South Asia to 

explore potential trading opportunities among India, Nepal, Bangladesh, and Bhutan. Uniquely, 

this study uses a detailed 1-year, 1-hour resolution unit commitment and economic dispatch 

model of the South Asia power system in the year 2022 to examine the technical and economic 

impacts of CBET under different assumptions about hydropower development in Nepal and 

regional trade agreements. The study finds that although Nepal might have the physical capacity 

to increase annual exports to India if development of domestic hydropower is accelerated (to 

4,500 megawatts ), much of this increase would be uneconomic to export if current market 

inefficiencies between the two countries remain. But the economics of trade can improve 

dramatically with institutional changes. If market and system operating rules are revised to treat 

transactions with Nepal the same as transactions between Indian states, our findings suggest that 

annual net exports to India could increase threefold (to 9.0 terawatt hours), hydro curtailment in 

Nepal would decrease, and production costs for electricity in both countries would fall $359 

million. These factors—the level of hydropower development in Nepal and the ease of crossborder trade—are the biggest drivers of potential CBET in South Asia. The study also examines 

the impact of CBET on renewable energy development in India, a supply contract between Nepal 

and Bangladesh, and fully coordinated market operations across Bangladesh, Bhutan, India’s 

eastern region, and Nepal. Although this study does not provide a complete characterization of 

system operations within each South Asia country, it does capture many previously unconsidered 

intertemporal operational constraints. Additional work can include more detailed representations 

of the Bhutan and Bangladesh power systems and alternative trading arrangements with these 

countries, which could be especially fruitful in light of the benefits measured in this study. 
iv

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Acknowledgments

The authors are greatly indebted to the following individuals for sharing their thoughtful 

feedback throughout the project: Jeff Ficken and Olivier Garaud (U.S. Department of State); 

Monali Hazra, Priya Sreedharan, Michael Boyd, and Shanker Khagi (U.S. Agency for 

International Development); Manish Keshari and Narendra Sathvik (POWERGRID); and Mohit 

Joshi.

We also thank Brady Stoll from the National Renewable Energy Laboratory for her reviews and 

Britton Marchese for the technical edit to this paper. Any errors or omissions are solely the 

responsibility of the authors. 

This analysis was funded by the U.S. Department of State’s Bureau of South and Central Asian 

Affairs Regional Connectivity Program.
v

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List of Acronyms

ACE area control error

BAU business as usual

BBIN Bangladesh, Bhutan, India, Nepal

CBET cross-border energy trade

CO coordinated operations

DA day-ahead

EIM energy imbalance market

GW gigawatt

INR Indian rupee

ISO independent system operator

kV kilovolt

LDC load dispatch center

LMP locational marginal price

MW megawatt

NEA Nepal Electricity Authority

NREL National Renewable Energy Laboratory

POSOCO Power System Operation Corporation, Ltd.

RE renewable energy

ROR run-of-river

RT real time

UC&ED unit commitment and economic dispatch
vi

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Executive Summary

Recent developments on both sides of the border between India and Nepal highlight new 

opportunities for increased cross-border energy trade (CBET). First, CBET can promote 

coordinated use of energy resources and potentially reduce the need for investments in new 

infrastructure to meet anticipated strong growth in electricity demand in both countries. Second, 

projected growth in Nepal’s hydroelectric generating capacity presents an opportunity for 

hydropower developers to increase return on investments through export sales while also giving 

neighboring states in India access to low-cost hydropower. Third, coordinated regional trade can 

facilitate renewable energy (RE) integration by increasing access to resources available for 

balancing. 

This study explores potential CBET from an operations perspective among India, Nepal, 

Bangladesh, and Bhutan by examining the technical and economic impacts of trade on both 

systems in the year 2022. Our primary tool is a production cost model, which simulates optimal 

unit commitment and economic dispatch of the system subject to physical, operational, and 

market constraints. This study finds significant opportunities for increased trade between Nepal 

and India. These opportunities depend highly both on the level of hydropower expansion in 

Nepal and the level of coordination for power exchanges between the two countries. 

Increased hydropower development in Nepal decreases production costs by $106 

million annually.

1

Under an accelerated hydroelectric investment scenario, annual exports from Nepal to India 

increase by 60% and production costs in the combined India and Nepal system could fall by 

0.3% compared to a low investment scenario. However, existing coordination barriers between 

the two countries limit further exports, and 45% of available hydropower energy from Nepal is 

not used in the accelerated development scenario. 

Combining increased coordination with accelerated hydropower development provides 

the largest savings to both countries.

Coordinating operations between Nepal and India, such that trade with Nepal is institutionally no 

different than trade between Indian states, can maximize the use of Nepal’s hydropower 

resources. Increased coordination enables Nepal to become a net exporter of hydropower in the 

wet and dry seasons and also expands economic opportunities for Nepal to compete with India’s 

western region as a supplier of energy to the northern region. As a result, combining increased 

coordination with accelerated hydropower development could decrease annual production costs 

by $462 million annually, or 1.3%, compared to a base case with uncoordinated operations and 

low hydropower development. 

Access to Nepal’s hydropower and increased coordination has little effect on wind and 

solar integration in India.

Increased hydropower exports from Nepal to India have little effect on wind and solar integration 

in India, largely because most of Nepal’s new hydropower is run-of-river, which lacks storage. 

On the other hand, increased wind and solar deployment in India can reduce the potential market 

 1 Currency values are converted to U.S. dollars except where otherwise noted. The assumed exchange rate is 65

Indian rupees to 1 U.S. dollar.
vii

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for Nepal’s hydropower exports unless institutional barriers to trade are reduced through 

coordinated operations. 

There is adequate demand for Nepal’s exports without an additional supply contract 

with Bangladesh.

Increased levels of coordination, including a supply contract with Bangladesh, does not 

materially change Nepal’s generation or exports because the Indian market absorbs all available 

hydropower exports from Nepal. The added supply contract essentially redirects power flows 

internally within India, particularly from coal generation. 

Increased coordination across Bangladesh, Bhutan, Nepal, and India’s eastern region 

(BBIN) can further reduce production costs.

Costs per unit generated in the combined region can decrease by 5.4% if system operations were 

more coordinated compared to current levels of coordination. With increased internal 

coordination, the BBIN region also exports more power to the rest of India. If operations are 

fully consolidated within an independent system operator, an additional 1.1% savings are 

possible. 

Although the study identifies many previously unconsidered impacts on CBET between India, 

Nepal, Bhutan, and Bangladesh, including local impacts in different Indian states and regions 

and intertemporal operational constraints, it does not provide a complete characterization of 

system operations within the entire region. Future work could include detailed modeling of the 

Bhutan and Bangladesh power systems to examine the impact of CBET on these systems in 

greater detail. Complementary analysis could identify policy and regulatory pathways to remove 

nontechnical barriers to CBET and capture the benefits identified in this study. 
viii

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Table of Contents

1 Introduction........................................................................................................................................... 1

1.1 Background ................................................................................................................................... 1

1.2 Study Approach............................................................................................................................. 2

1.3 Structure of the Report .................................................................................................................. 3

2 Study Scenarios, Modeling Methodology, and Assumptions.......................................................... 4

2.1 Study Scenarios............................................................................................................................. 4

2.1.1 Hydro Buildout................................................................................................................. 4

2.1.2 Hurdle Rates..................................................................................................................... 5

2.1.3 India Wind and Solar Capacity ........................................................................................ 8

2.1.4 Bangladesh ....................................................................................................................... 8

2.2 Model Setup and Execution .......................................................................................................... 8

2.3 Data Sources and Assumptions..................................................................................................... 9

2.3.1 Transmission .................................................................................................................... 9

2.3.2 Hydro Capacity ................................................................................................................ 9

2.3.3 Hydro Constraints .......................................................................................................... 10

2.3.4 Load................................................................................................................................ 12

2.4 Integrating the South Asia Models.............................................................................................. 13

2.4.1 Nepal–India Interface..................................................................................................... 13

2.4.2 Model Parameters and Other Constraints....................................................................... 15

2.4.3 Bhutan and Bangladesh.................................................................................................. 15

3 Production Cost Modeling Results................................................................................................... 16

3.1 Increased Nepal Hydropower with No Other Changes............................................................... 16

3.1.1 Electricity Production Cost ............................................................................................ 17

3.1.2 Electricity Generation by Resource................................................................................ 18

3.1.3 Energy Flow between Nepal and India .......................................................................... 20

3.1.4 Transmission Congestion ............................................................................................... 21

3.2 Increased Nepal Hydropower with Coordinated Operations....................................................... 22

3.2.1 Electricity Production Cost ............................................................................................ 22

3.2.2 Electricity Generation by Resource................................................................................ 23

3.2.3 Energy Flow between Nepal and India .......................................................................... 25

3.2.4 Transmission Congestion ............................................................................................... 27

3.3 Nepal Hydropower with Renewable Energy Integration in India ............................................... 27

3.3.1 Electricity Production Vost ............................................................................................ 27

3.3.2 Electricity Generation by Resource and RE Curtailment............................................... 28

3.3.3 Energy Flow between Nepal and India .......................................................................... 29

3.4 Increased Trade with Bangladesh................................................................................................ 30

3.4.1 Electricity Production Cost ............................................................................................ 31

3.4.2 Electricity Generation by Resource................................................................................ 31

3.4.3 Energy Flow between Nepal, India, and Bangladesh..................................................... 33

3.4.4 Transmission Congestion ............................................................................................... 34

3.5 Full Regional Integration ............................................................................................................ 34

3.5.1 Electricity Production Cost ............................................................................................ 35

3.5.2 Electricity Generation by Resource................................................................................ 36

3.5.3 Energy Flow between Nepal and India .......................................................................... 37

3.5.4 Transmission Congestion ............................................................................................... 37

4 Summary ............................................................................................................................................. 39

References................................................................................................................................................. 41
ix

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List of Figures

Figure 1. Methodology for determining Nepal’s 2022 hydro generation capacity..................................... 10

Figure 2. Average monthly capacity factor by major Nepalese river basin, capacity weighted ................. 11

Figure 3. Nepal-India interface illustration................................................................................................. 14

Figure 4. Price in Bihar and Uttar Pradesh relative to hurdle rate on Nepal’s exports by season, Base –

BAU and High Build – BAU scenarios. ................................................................................ 18

Figure 5. Nepal hydro generation and curtailment by resource type, Base–BAU, and High Build–BAU 

scenarios................................................................................................................................. 19

Figure 6. Difference in generation in the High Build–BAU scenario compared to the Base–BAU scenario, 

by region. ............................................................................................................................... 19

Figure 7. Average hourly net interchange between Nepal and India by Indian state, Base–BAU, and High 

Build–BAU. ........................................................................................................................... 20

Figure 8. Seasonal flows from Nepal to Indian states................................................................................. 21

Figure 9. Production cost savings for Nepal and India due to Coordinated Operations, High Build ......... 23

Figure 10. Nepal hydro generation and curtailment by resource type, all scenarios .................................. 24

Figure 11. Difference in generation, by fuel type, due to Coordinated Operations for both hydro capacity 

scenarios................................................................................................................................. 24

Figure 12. Average hourly net interchange between Nepal and India by Indian state, all scenarios.......... 26

Figure 13. Generator dispatch and load in Nepal on March 15, Base scenario with and without 

Coordinated Operations ......................................................................................................... 26

Figure 14. Annual generation in Nepal and India by resource type, all scenarios...................................... 28

Figure 15. Average hourly net interchange between Nepal and Indian state, High Build–CO–Low RE vs. 

High Build–CO. ..................................................................................................................... 30

Figure 16. Major changes in generation by region and state with an added Bangladesh supply contract 

(TWh)..................................................................................................................................... 32

Figure 17. Major changes to India’s internal annual interstate flows and generation after adding 

Bangladesh supply contract (TWh)........................................................................................ 33

Figure 18. Change in annual generation for the BBIN region and the rest of India under different wheeling 

charge scenarios..................................................................................................................... 37
x

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List of Tables

Table 1. Study Scenarios............................................................................................................................... 5

Table 2. Hurdle Rates Associated with Different Scenarios......................................................................... 6

Table 3. Basic Information on the Modeled 2022 Nepal Transmission Network......................................... 9

Table 4. Nepal 2022 Database Hydro Capacity by Generator Type, Base/High Build Scenario (MW) .... 11

Table 5. Nepal 2022 Database Hydro Constraints by Generator Type....................................................... 12

Table 6. Nepal-India Interface Definition................................................................................................... 14

Table 7. Optimization Parameters and Units in Combined India and Nepal “South Asia” Model............. 15

Table 8. Key Assumptions in the Base–BAU and High Build–BAU Scenarios ........................................ 16

Table 9. Electricity Production Costs in the Base–BAU and High Build–BAU Scenarios (USD millions)

................................................................................................................................................ 17

Table 10. Hours of Congestion on Transmission between Nepal and India Base and High Build Scenario

................................................................................................................................................ 22

Table 11. Scenarios Examined, Coordinated Operations............................................................................ 22

Table 12. Electricity Production Costs in the Coordinated Operations Scenarios, and Difference from 

BAU Scenarios (USD millions)............................................................................................. 23

Table 13. Transmission Congestion between Nepal and Neighboring Indian States, All Scenarios.......... 27

Table 14. Scenarios Examined, RE Integration .......................................................................................... 27

Table 15. Net Flows between Nepal and Indian States with Different Renewable Energy Levels in India 

(GWh) .................................................................................................................................... 29

Table 16. Scenarios Examined, Bangladesh, BAU, and Coordinated Operations...................................... 31

Table 17. Effect of Increased Generation to Serve Bangladesh on Total Production Costs (USD millions)

................................................................................................................................................ 31

Table 18. Transmission Congestion between Nepal and Neighboring Indian States, High Build–CO 

Scenarios with and without Bangladesh (hours).................................................................... 34

Table 19. Scenarios in the Analysis............................................................................................................ 35

Table 20. Generation and Production Cost Differences between ISO Scenarios ....................................... 35

Table 21. Transmission Congestion between Nepal and Neighboring Indian States, All Scenarios (hours)

................................................................................................................................................ 38
1

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1 Introduction

Recent developments on both sides of the border between India and Nepal highlight new 

opportunities for increased cross-border energy trade (CBET). First, both countries anticipate 

continued strong growth in electricy demand. As demand grows, CBET can promote coordinated 

use of energy resources and potentially reduce the need for investments in new infrastructure. 

Second, Nepal’s power system planners anticipate significant growth in the country’s 

hydroelectric generating capacity. Power trade with India provides hydropower developers an

opportunity to increase return on investments through export sales while also giving neighboring 

states in India access to low-cost hydropower. Third, falling technology costs and national 

energy policies have led to significant growth in renewable energy (RE) investments in India, 

with much more expected in the coming years. Coordinated regional trade can facilitate RE 

integration by increasing access to resources available for balancing. This study explores 

potential CBET from an operations perspective among India, Nepal, Bangladesh, and Bhutan by 

examining the technical and economic impacts of trade on both systems in the year 2022.

1.1 Background

India has an installed generation capacity of 331 gigawatts (GW), with coal and renewable 

energy sources accounting for 193 GW (58%) and 63 GW (19%), respectively, and a peak 

demand of 164 GW (CEA 2017a). The Government of India has set a target of 175 GW of RE by 

2022, including 100 GW of solar and 60 GW of wind. India anticipates its electricity demand to 

grow 5.9% annually over the next decade, with peak demand reaching 230 GW by 2022 (CEA 

2017b). Furthermore, in 2016 the Government of India Ministry of Power released updated 

guidelines on CBET that allows for trading of power through the Indian Power Exchanges under 

certain conditions.2

Nepal’s power system differs significantly from that of India in both size and composition. The 

installed capacity is 968 megawatts (MW) and almost exclusively hydropower, with two thermal 

plants accounting for 6% of installed capacity (NEA 2017). A major earthquake in 2015 

damaged several existing hydropower plants and delayed construction on others, resulting in 

persistent load shedding for consumers and increased reliance on imports from India. Imports 

from India accounted for 35% of annual consumption in the 2016–2017 operating year. 

Investments in new plants and repairs to damaged infrastructure have gradually improved 

electricity supply in Nepal and, in the last year, major urban centers experienced their first 24-

hour periods without load shedding since the earthquake. Continued development of 3.8 GW of 

planned hydropower projects could eliminate the remaining load shedding in the coming years 

and shift the trade balance between Nepal and its neighbors, allowing Nepal to become a net 

exporter. Electricity demand in Nepal is projected to grow by 7.2% annually, increasing from 4 

gigawatt hours (GWh) in 2016 to 10 GWh in 2022 (WECS 2017).

The Nepalese and Indian power systems are already connected by multiple cross-border 

transmission lines and there are plans to further integrate the two systems with new 400-kilovolt 

(kV) transmission connections. Previous studies have investigated potential impacts of specific 

cross-border projects (ADB 2015) and coordinated long-term planning (WB 2015; SARI/EI 

 2 https://powermin.nic.in/sites/default/files/webform/notices/Guidelines%20for%20Cross%20Boarder%20Trade.pdf
2

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2017) between India and Nepal. The Asian Development Bank assessed the potential benefits of 

a single 400-kV transmission line using power flow models under different scenarios of 

hydropower development in Nepal and found the benefits of the line could far exceed its costs in 

all scenarios due to reduced costs of operations and unserved energy. Looking beyond a single 

project, capacity expansion modeling by the World Bank found that coordinated planning and 

unrestricted trade among seven South Asian countries could save U.S. $226 billion, or U.S. $7 

billion annually. The SARI/EI study connected power system planning with a larger energy 

sector model to assess the broader economic impacts of increased CBET between India and 

Nepal. The study finds increased CBET results in increased hydropower development and 

household electricity consumption in Nepal but impacts in India are negligible given its larger 

economy and power system.

1.2 Study Approach

This study aims to advance the discussion surrounding CBET between India and Nepal through 

the unique contribution of a detailed simulation of system operations of the South Asia region. 

The study is supported by the U.S. Department of State’s Bureau of South and Central Asian 

Affairs Regional Connectivity Program.

Our primary tool is a production cost model, which simulates optimal unit commitment and 

dispatch of the system subject to physical, operational, and market constraints. There are two 

main benefits to modeling a full chronological time series of system operations. First, in systems 

with high levels of variable RE, production cost models can capture hour-to-hour variability in 

load and RE generation. This modeling capability is increasingly important as wind and solar 

generation grow in India. Second, production cost models can capture potential opportunities for 

trade and greater utilization of the most efficient generating units that arise when peak demand 

occurs at different times in different areas. The detailed production cost model captures the

flexibility requirements necessary to balance generation and demand every hour of the year and 

the cost associated with those operational decisions. This study is the first attempt to examine 

CBET over a full year of system operations and with detailed representations of the generation 

and transmission systems of each country. 

This study builds on a detailed production cost model of the Indian power system developed 

under the Greening the Grid program, an initiative co-led by India’s Ministry of Power and U.S. 

Agency for International Development to support the iniatives taken by India’s Ministry of 

Power for large-scale integration of RE. The model was developed by a collaborative modeling 

group from India’s Power System Operation Corporation, Limited (POSOCO), National 

Renewable Energy Laboratory (NREL), and Lawrence Berkeley National Laboratory, with 

additional input from a wide range of experts from across the Indian power sector. Its initial use 

was for an analysis of the operational impacts of 175 GW of variable RE on the Indian power

system in 2022 (Palchak et al. 2017).

Analysis of CBET required building a Nepal model to be added to the India model. The Nepal 

model was developed by NREL based on data and guidance from engineers at Nepal Electricity 

Authority (NEA). 
3

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1.3 Structure of the Report

Section 2 presents the study scenarios and methods used to create the production cost model and 

input databases. The model results are presented in Section 3. Finally, Section 4 summarizes the 

findings and presents final conclusions.
4

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2 Study Scenarios, Modeling Methodology, and 

Assumptions

The objective of this study is to provide an empirical foundation for identifying the opportunities 

and associated characteristics and value of CBET across Nepal, India, Bangladesh, and Bhutan, 

with a primary focus on trade between Nepal and India. To meet this objective, we use a detailed 

model of the Nepal and India power systems combined with a simplified representation of 

Bhutan and Bangladesh to simulate a year of system operations at one-hour resolution.3 The test 

year is 2022.

Because project development and institutional changes could affect CBET opportunities, the 

study evaluates results under several scenarios. The following sections describe the study 

scenarios, the model setup and execution, and data sources. This section also presents 

assumptions for the South Asian power system and explains the countries’ integration into a 

single combined model.

2.1 Study Scenarios

The study analyzes nine scenarios constructed by varying four parameters: 

• The amount of hydro capacity that will exist in Nepal in 2022

• Hurdle rates on certain transmission corridors4

• The amount of wind and solar capacity that will exist in India in 2022

• Bangladesh power supply contract with Nepal.

Table 1 outlines the parameter configurations used in each scenario. The remainder of this 

section describes each parameter’s variation.

2.1.1 Hydro Buildout

Hydro capacity is set to either Base (2,840 MW) or High (4,552 MW) in each scenario. These 

two numbers represent a plausible range of the hydroelectric capacity likely to be operational in 

Nepal by 2022. Section 2.3 describes the process of determining the set of generators modeled in 

each case. Juxtaposing results from these two scenarios will help determine the extent to which 

CBET is sensitive to the amount of hydro built in Nepal.

 3 Representation of Bhutan was simplified for lack of quality data and represents only a fraction of the potential 

hydro generation that is likely to be available to the region in the future. This could impact the results, however the 

total generation is small compared to the capacity and energy needs of the region and would likely have marginal 

impact to the scenarios analyzed.

4 Hurdle rates are not a cost and do not add directly to the production cost. However, they do create price 

differentials between adjacent parts of the grid that affect the scheduling and dispatch of generators, and therefore 

indirectly affect the total cost. The rates are measured in Indian rupee (INR) per unit of energy transferred. 
5

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Table 1. Study Scenarios

Scenario Name

Hydro 

Buildout Hurdle Rates

India Wind 

and Solar 

Capacity Bangladesh

Base–BAU Base Business as usual (BAU) 160 GW Not included

High Build–BAU High BAU 160 GW Not included

Base–CO Base Coordinated Operations (CO) 160 GW Not included

High Build – CO High CO 160 GW Not included

High Build – BAU – Low RE High BAU 70 GW Not included

High Build – CO – Low RE High CO 70 GW Not included

Bangladesh–CO High CO 160 GW Included

Bangladesh–BAU High BAU 160 GW Included

BBIN Independent System 

Operator (ISO) High None within ISO 160 GW Included

2.1.2 Hurdle Rates

Hurdle rates are a modeling technique to encompass all non-physical barriers to transmission 

utilization such as differences in scheduling practices that could impede trade. The hurdle rate 

represents a price differential that needs to be exceeded in order for trade to occur between two 

nodes. Previous modeling of the Indian power system suggests that the price differential for 

interstate trade is around INR 1,000/megawatt hour (MWh) (Palchak et al. 2017). We maintain 

this Indian interstate hurdle rate in this study. 

In addition to the Indian interstate hurdle rate, we add location- and season-specific hurdle rates 

between Nepal and India to form the business as usual (BAU) scenario (Table 2). The hurdle 

rates between Nepal and bordering Indian states reflect existing economic barriers to CBET 

between the two countries. To proxy economic restrictions on the flow of power from India to 

Nepal, we use the current contract prices paid by NEA for imported power. These prices tend to 

be higher than energy prices on the day-ahead spot markets operated by the Indian Energy 

Exchange. The effect of using these hurdle rates is that the model does not move power across 

the border to Nepal unless the marginal cost of energy in Nepal exceeds the marginal cost of 

energy in Bihar or Uttar Pradesh or Uttarakhand by the amount of the hurdle rate. Only then does 

power flow from India to Nepal.
6

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Table 2. Hurdle Rates Associated with Different Scenarios

Direction Dry Season

(December–May)

Wet Season

(June–November)

BAU Scenario

Nepal  India INR 6,500 / MWh INR 3,000 / MWh

Bihar  Nepal INR 3,500 / MWh

Uttar Pradesh  Nepal INR 6,500 / MWh

Uttarakhand  Nepal INR 6,500 / MWh

Coordinated Operations Scenario

India  Nepal (net export charge) * INR 1,000 / MWh

BBIN ISO Scenario

Within Bhutan, Bangladesh, India’s Eastern 

region, and Nepal

INR 0 / MWh

*This is the same hurdle rate applied to transactions between Indian states. At INR 65 to 1 U.S. dollar 

(USD) exchange, INR 6,500 = USD 100; INR 3,000 = USD 46; INR 3,500 = USD 54; INR 1,000 = USD 15 

To represent BAU constraints on flows in the other direction, from Nepal to India, we use the 

prices at which NEA buys peaking run-of-river hydro generation from independent power 

producers (IPPs). This comports anecdotally with statements made by IPPs in interviews with 

NREL about the value of exporting their output to India. NEA pays about INR 6,500/MWh for 

peaking run-of-river (RoR) in the dry season and INR 3,000/MWh for all categories of hydro 

generation in the wet season. In addition, Nepal's Ministry of Energy directed NEA to include 

“take or pay” provisions in new purchase contracts with IPPs, meaning that for a specified 

quantity of production, NEA will pay even if it does not take delivery of the energy. Thus the 

fixed domestic purchase prices are essentially a “price to beat” for exporting Nepal hydro to 

India, in that the value to Bihar, Uttar Pradesh, or Uttarakhand has to be higher than what the IPP 

would forego by not selling its power to NEA. As detailed in the companion report to this study 

(Hurlbut, 2018), IPPs could provide nearly half of Nepal's power supply by 2020. Moreover, 

NEA would likely reserve the use of its own hydro resources to follow domestic load and 

otherwise maintain reliability on its own grid. All of this suggests that domestic IPP tariff prices 

are a reasonable starting point for representing BAU on exporting hydro from Nepal to India. 

While this approach results in relatively high hurdle rates, it still does not specifically include 

other factors such as domestic transmission limitations that could indirectly restrict hydro exports 

to India. The purpose of using hurdle rates is not to precisely value institutional limitations, 

however. Rather, it is to provide a reasonable basis for comparing one scenario with another by 

postulating a material change in institutional arrangements.

The Coordinated Operations (CO) scenario removes the charges derived from hydro tariffs and 

applies only the INR 1,000/MWh hurdle rate between Nepal and India. In other words, this 

scenario assumes that CBET between India and Nepal has the same market friction that exists 

between Indian states. A third scenario, BBIN ISO, has no hurdle rates on flows inside the 

combined territory of Nepal, Bhutan, Bangladesh and India’s Eastern region (BBIN), while the 

rest of India maintains the standard interstate hurdle rate. This framework represents full 
7

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coordination for commitment and dispatch among India’s Eastern region and its neighboring 

countries. This scenario is particularly relevant to the transfer of hydropower from Nepal to 

Bangladesh, in that it provides a benchmark based on the maximum achievable degree of 

operational coordination. (See the sidebar for examples of increasing coordination between 

neighboring regions.) 

“Coordinated operations” in practice

Operational coordination can encompass many practices, of which neighboring balancing authorities 

(i.e., system operators for each grid) might adopt several, few, or none. Therefore, coordination is not 

a simple binary condition. The INR 1,000/MWh hurdle rate used in the CO scenarios assumes some 

combination of practices that reduce some, but not all, of the transaction costs involved in moving 

power from one jurisdiction to another. Here we list a few examples of coordination ranging from low 

effort to high effort.

• Tariff reciprocity. Energy exchanges are charged the same regardless of which direction they 

flow.

• Sharing area control error (ACE). ACE is the instantaneous difference between a balancing 

area's net actual and scheduled interchange, i.e., a metric of a system operator’s ability to 

maintain balance according to schedule. Combining ACE across neighboring grids will usually 

produce a single ACE that is smaller and more easily corrected. Consolidating reserves and 

access to least-cost resources can result in additional savings.

• Shared area imbalances. An energy imbalance is similar to instantaneous ACE, but refers to 

how the operator schedules generators, imports, and exports against day-ahead forecasts or 

shortly before real-time delivery of electricity. As with sharing ACE, sharing imbalances tends 

to produce a smaller imbalance that is easier and cheaper to address from the combined 

least-cost resources of both grids.

• Common scheduling and unit commitment practices. Using the same standards for 

communications between each control area and the generators it schedules makes joint 

response to ACE and imbalances operationally seamless. This coordination also includes 

using common timelines for day-ahead schedule submissions and unit commitment and 

adjustments to real-time schedules.

• Energy imbalance market (EIM). An EIM is a formal market for balancing energy 

simultaneously across all participating control areas through a sequence of regular auctions. 

Often an EIM includes an hourly day-ahead component and a real-time or same-day 

component for each five- or fifteen-minute interval.

• Independent system operator (ISO). An ISO is an independent market and system operator 

that would merge two or more balancing authorities into a single operational entity responsible 

for maintaining balance. The ISO allocates transmission rights based on a system of bids and 

offers and optimizes unit commitment and dispatch decisions to minimize system costs. 

Depending on design, each participating control area may schedule its load and resources 

internally, but it then must transmit its schedule to the ISO. All energy balancing and ancillary 

services are under the ISO's control.

For more details, see “Balancing Area Coordination: Efficiently Integrating Renewable Energy into 

the Grid” https://www.nrel.gov/docs/fy15osti/63037.pdf. 
8

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2.1.3 India Wind and Solar Capacity

India wind and solar capacity in Table 1 refers to India’s 2022 installed wind and solar capacity. 

It is set to either 70 GW or 160 GW, corresponding to the intermediate and target RE scenarios 

modeled in Palchak et al. 2017.

5 The purpose of comparing the two RE capacity configurations 

is to test whether Nepal’s hydro can affect the operations of India’s grid with 160 GW of wind 

and solar capacity.

2.1.4 Bangladesh

Bangladesh’s power grid is not synchronized with the rest of South Asia. Instead, it connects to 

the Indian states of West Bengal and Tripura via a direct current (DC) tie and radial line, which 

supply Bangladesh with 1,000 MW and 100 MW, respectively (JTT 2016; PT 2018). As a 

scenario, we model a contract where Nepal continuously supplies Bangladesh with 1,000 MW 

through the DC interconnection with West Bengal (we do not represent the radial connection 

with Tripura). The purpose is to analyze, at varying levels of coordination, what might happen to 

the flow of hydropower from Nepal if there were an additional 1,000 MW obligation to serve 

Bangladesh: whether there might be additional flows from Nepal, or whether the same volume 

from Nepal would be reallocated contractually from India to Bangladesh.

2.2 Model Setup and Execution

To simulate power system operations, we use a unit commitment and economic dispatch 

(UC&ED) model. The model balances supply and demand in every hour of the 2022 simulation 

year, subject to physical and operator-imposed constraints. By simulating UC&ED in every onehour period of 2022, the study provides a full chronological picture of the year’s operations. The 

results capture intertemporal constraints that affect operator decisions, such as RE availability,

generator minimum up and down times, ramp rates, and maximum energy limits for hydropower 

plants. 

The UC&ED simulation relies on the commercially available mixed integer linear programming 

software PLEXOS Integrated Energy Model, developed by Energy Exemplar and configured 

here to use the XPRESS-MP solver. The software commits and dispatches generators to meet 

load at least-cost, while adhering to thousands of physical constraints, including transmission 

limits, generator parameters, and limits on water availability for hydropower generation. 

Transmission flows are calculated with a linearized DC optimal power flow approximation. The 

India-Nepal PLEXOS model has been configured to structure the mixed-integer optimization as 

three phases: (1) a single year-long step to plan scheduled outages, (2) a second year-long step to 

optimally translate multi-day hydro constraints into target end-of-day reservoir volumes, and (3) 

365 one-day optimization steps with one-hour resolution to schedule and dispatch the remaining 

generation to meet load.6

Although the UC&ED simulation captures the constrained cost-minimization problem at the 

heart of power system operations, it relies on a few key simplifying assumptions. The model 

does not include load and renewable energy forecast errors and does not account for units that 

may be committed for reliability or contractual obligations. This analysis aims to assess the 

 5 As of April 30, 2018, the installed wind and solar capacity in India was 55.7 GW (CEA 2018)

6 To emulate the decisions made in an operations room, which would weigh known changes to load or other factors 

beyond a single day, each one-day step solves for 48 hours and then discards the last 24 hours. 
9

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impacts of cross-border trade that are economically efficient and technically feasible on an 

already built system. As such, the UC&ED dispatch model does not optimize investment 

decisions or account for fixed costs. It also assumes UC&ED decisions between India and Nepal 

are coordinated apart from the transmission hurdle rates described above. 

2.3 Data Sources and Assumptions 

This study uses the India power system database developed for Greening the Grid, which 

simulates the operation of the Indian power system in 2022 with 175 GW of RE (Palchak et al. 

2017). This database was developed and validated in collaboration with experts from across the 

Indian power sector. Details of data sources and assumptions for load, generation, and 

transmission are provided in Section 2 of that report.

The Nepal power system database is based on data and guidance provided by NEA. Starting with 

transmission network data, we overlaid 2022 hydro generator locations, applied water 

availability constraints for hydropower plants, and derived a 2022 load profile, as described in 

the following sections.

2.3.1 Transmission

Transmission network data in the 2022 Nepal UC&ED model is derived from two 2022 PSS/E7

files supplied by NEA. Table 3 summarizes the number of transmission lines and nodes 

(substations) included in the 2022 model. Section 2.4 details the cross-border lines connecting 

Nepal and India.

Table 3. Basic Information on the Modeled 2022 Nepal Transmission Network

Voltage Number of Lines Number of Nodes

400 kilovolts 26 15

220 kilovolts 29 21

132 kilovolts 141 93

66 kilovolts 27 20

33 kilovolts - 20

2.3.2 Hydro Capacity

The uncertain status of many proposed and ongoing hydroelectric construction projects makes 

forecasting Nepal’s 2022 installed hydro capacity difficult. NEA’s 2022 PSS/E file gives 

network locations for 7,442 MW of hydro capacity—an upper bound on what could exist in that 

year. From this list of plants, we identified 2,891 MW of capacity to exclude from the model 

because it was either located inside India, terminated, not anticipated to be operational by 2022, 

identified by NEA for exclusion, or not locatable. The capacity remaining after these 

exclusions—4,551 MW—defines the High Build scenario. For the Base buildout scenario, we 

further excluded proposed projects that had not reached financial closure according to NEA 2017 

and projects that we were not able to identify as likely candidates within our study year 

 7 PSS/E is a transmission system planning software package developed by Siemens PTI. 
10

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timeframe. These exclusions totaled 1,712 MW, leaving 2,839 MW of installed capacity in the 

Base buildout scenario. 

Figure 1. Methodology for determining Nepal’s 2022 hydro generation capacity

NEA operates two thermal generators (Hetauda Diesel and Duhabi Multifuel) which together 

account for 1.6% and 1.0% of its installed capacity in the Base and High Build scenarios. 

Estimated variable cost information and other operational parameters for the two plants come 

from Palchak et al. 2017. No growth in wind or solar generation is assumed for Nepal.

2.3.3 Hydro Constraints

Representing hydro generation in a UC&ED model is inherently difficult for a number of 

reasons, including:

• Hydro plant operations must consider multiple time scales of minutes and hours and also how 

much water should be stored for future use over several weeks and months

• Available capacity is subject to seasonal and inter-annual changes that are exogenous to 

power system operations, such as rainfall and inflows, as well as losses due to evaporation, 

silting, and seepage

• Water use for electricity generation competes with water demand for other uses such as 

irrigation and recreation

• Operational planning for plants on the same river must consider interdependencies between 

upstream and downstream plants.

The 2022 Nepal database consists of 173 hydropower plants (in the High Build scenario), most 

of which are small RoR plants located on one of the tributaries that feed Nepal’s two main river 

basins. The generation from each plant is characterized based on its location within Nepal and 

head storage capacity. The key instrument in formulating Nepal’s 2022 hydro constraints is a log 
11

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of 19 months of historic plant-wise hydro generation from April 2016 to November 2017 (1 

Baisakh 2073 to 31 Kartik 2074) provided by NEA.8 Using the historical generation data, it is 

possible to derive average monthly capacity factors by major river basin as presented in Figure 

2.

9

Figure 2. Average monthly capacity factor by major Nepalese river basin, capacity weighted

Having categorized the generation fleet by river basin, a further categorization by storage 

capacity results in six generator types: two river basins (Koshi, Gandaki) crossed with three 

generator types (run-of-river, peaking run-of-river, and storage). In total, there are 165 run-ofriver plants, six peaking run-of-river plants, and two storage plants in the High Build scenario. 

Table 4 lists capacity by generator type in the Base and High Build scenarios and Table 5

indicates the constraints applied to each generator type.

Table 4. Nepal 2022 Database Hydro Capacity by Generator Type, Base/High Build Scenario (MW)

Run-of-River Peaking Run-of-River Storage

Koshi 900 / 1494 456 / 456 60 / 60

Gandaki 965 / 2082 339 / 339 120 / 120

 8 Nepal uses the Vikram Samvat calendar, which begins mid-April, rather than the Gregorian calendar. 9 Nepal’s three major river basins are the Koshi, Gandaki, and Karnali, which roughly cover the eastern, central, and 

western thirds of the country, respectively. Because of a low sample size, generators in the Karnali river basin are 

considered part of Gandaki. The minority of generators located outside of the three major river basins are then 

allocated to either Koshi or Gandaki.
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Table 5. Nepal 2022 Database Hydro Constraints by Generator Type

Run-of-River Peaking Run-of-River Storage

Inflow Source Historic basin-specific average monthly capacity factors

Inflow Units MW Cumec Cumec

Inflow Scalar Unit installed capacity Unit installed capacity Unit annual 

designed generation

Storage Capacity 0 hours 4.6–6.4 hours 336 hours

Run-of-river generators must maintain the basin-specific average monthly capacity factors in 

Figure 2 for every hour of the given month. They have no head storage and therefore must spill 

any water that cannot be used in the interval in which it arrives. 

Peaking run-of-river generators benefit from approximately six hours of head storage (i.e., 60 

MWh for a 10 MW generator) which allows them to optimize generation according to intraday 

demand, but not long-term variations in demand. Whenever possible, we use publicly available 

data (NEA 2018a) on storage volumes and cumec (cubic meters per second)-to-MW conversion 

efficiencies to determine peaking run-of-river parameters (accounting for the range of storage 

capacity shown in Table 5). For generators without data we assume exactly six hours of storage.

Nepal currently has one operational hydro storage generator (Kulekhani I) and one under 

construction (Tanahu Hydropower Project). Data inputs for each plant come from publicly 

available documents by the plant developers (NEA 2018b; THL 2018). We use data for reservoir 

storage volume and assume cumec-to-MW conversion efficiencies for both plants such that the 

reservoirs can supply two weeks of energy when operating at max capacity (i.e., 3.36 GWh for a 

10 MW plant). To account for silting, evaporation, irrigation needs, and other constraints that 

could cause storage generator capacity factors to deviate from the basin-wide average, we scale 

each storage natural inflow profile by its annual designed generation: 211 GWh for Kulekhani I 

and 585.7 GWh for Tanahu. An additional constraint requires Kulekhani II, a run-of-river 

generator directly downstream from Kulekhani I, to generate in proportion to Kulekhani I’s 

water release.

2.3.4 Load

Nepal’s 2022 load profile is derived from the same historic plant-wise hydro generation data as 

the hydro constraints. The data provided by NEA includes imports and load shedding in addition 

to domestic generation. By summing imports, load shedding, and domestic generation, we 

obtained a time series of potential domestic load for April 2016 to November 2017. 

NEA’s load shedding data quantifies the maximum power deliverable to a disconnected 

customer. It does not necessarily indicate the power that the customer would have consumed if 

connected. Unmodified, the discrepancy would cause load shedding—and thereby load—to be 

overestimated, particularly during peak periods. To approximate disconnected customer demand 

rather than maximum potential demand, we smoothed all load shedding values in excess of the 

monthly mean according to the following formula,
13

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LLmm,tt ∗ = LL�mm + (LLmm,tt − LL�mm)9/10

where,

LLmm,tt ∗ is the revised load shedding value in month mm at time tt

LL�mm is the average load shedding in month mm.

LLmm,tt is the original load shedding value in month mm at time tt

This formula was arrived at through a heuristic technique to create daily load profiles that 

tempered the extreme daily load factor (i.e., the difference between the daily valley and peak 

demand) found in the NEA load shedding data to realistic levels.

The NEA load data starts in April 2016 and ends in November 2017. To arrive at a complete 

Gregorian calendar year of load data, we scaled the data from November 17, 2016 to December 

31, 2016 by 1.087, Nepal’s average annual peak load growth since 2000, to represent the end of 

2017.

The Nepal Water and Energy Commission Secretariat’s 2014–2040 load forecast (WECS 2017) 

estimates total annual demand in 2022 will reach 10.3 terawatt hours (TWh). To create the 2022 

load profile while preserving the hourly load shape from 2017, we scaled all values such that 

total annual demand matches the national forecast. Based on this scaling, the 2022 peak demand 

is expected to reach 1,839 MW. 

2.4 Integrating the South Asia Models

The independently developed India and Nepal power system databases require careful 

integration to function as a single model. The following sections address the challenges of 

linking the models with cross-border alternating current (AC) ties and reconciling their model 

parameters.

2.4.1 Nepal–India Interface

Table 6 and Figure 3 show parameters and locations for the six transmission corridors at or 

above voltages of 132 kV expected to connect Nepal and India in 2022. The model ignores 

transmission between India and Nepal below 132 kV. Parameters for the six corridors come from 

a variety of sources including NEA’s PSS/E file, POWERGRID, CEA, and generic transmission 

line parameters (NEA 2017; Palchak et al 2017; MEA 2014; Shrestha 2016; ANI 2018). We 

assume the Nepalese and Indian grids will be fully synchronous by 2022.
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Table 6. Nepal-India Interface Definition

Nepal 

Substation

India 

Substation Voltage (kV) Circuit Conductor Type

Max Flow / 

Circuit (MW)

Dhalkebar Muzaffarpur 400 Double Twin moose 552

New Butwal Gorakhpur 400 Double Quad moose 1,105

Kushaha Kattaiya 132 Double Panther 84

Parwanipur Raxaul 132 Single Panther 84

Gandak Ramnagar 132 Single Panther 84

Mahendranagar Tanakpur 132 Single Panther 84

Figure 3. Nepal-India interface illustration.

Adapted from NEA 2017.

While transmission representation inside Nepal is at the substation level (nodal representation), 

transmission inside India is aggregated by state. The assumption is that India’s intrastate 

congestion is resolved endogenously and does not affect interstate flows, which greatly 

simplifies the UC&ED formulation. Preserving Nepal’s substation-level representation allows 

for an analysis of how each scenario impacts power flows inside Nepal and between Nepal and 

Indian states.
15

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2.4.2 Model Parameters and Other Constraints

Various optimization parameters and physical units must be standardized between the India and 

Nepal power system databases as a final step towards their integration into a combined South 

Asia model. Table 7 gives the optimization parameters used in the combined UC&ED 

simulation. The USD operating costs of Nepal’s two thermal generators are converted to INR at 

INR 65 = 1 USD, while Nepal’s zero marginal cost hydro generation requires no currency 

conversion. 

Table 7. Optimization Parameters and Units in Combined India and Nepal “South Asia” Model

Parameter / Unit Value

Currency INR

Value of lost load INR 1 crore

Value of reserve shortage INR 0.4 crore

The India model holds operating reserves at the regional level as in Palchak et al. 2017, which 

are equal to the capacity of the largest unit in the region plus 50% of the summed capacity of the 

largest unit in each state in the region. The Nepal region holds no operating reserves in the 

model.10

2.4.3 Bhutan and Bangladesh

The India database in Palchak et al. 2017 includes select data of the Bhutan power system 

necessary to capture power exports from Bhutan to India. Bhutan is a net exporter and, as such, 

the database does not include information on Bhutan’s load or the entire generation and 

transmission system. Transmission in Bhutan is represented by a single node with 19 crossborder lines between Bhutan and the Indian states of Assam and West Bengal. The database 

includes 60 MW of run-of-river that are involed in CBET. Monthly hydro availability in Bhutan 

is based on 2014 supervisory control and data acquisition (SCADA) data provided by POSOCO. 

For the Bangladesh scenario, we model only the increased demand that could come with a direct 

purchase of power from Nepal. We represent this as an additional 1,000 MW of constant demand 

at the Baharampur DC tie in West Bengal. 

Future work could include detailed modeling of the Bhutan and Bangladesh power systems to 

examine the impact of CBET on these systems in greater detail. 

 10 Nepal does hold operating reserves in reality, however optimal dispatch for energy in the model results in many 

periods where there is unrequisitioned capacity that could be used for reserves, and therefore the assumption of zero 

reserve provision is likely negligible on the results. 
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3 Production Cost Modeling Results 

The scenarios and results described in this section aim to inform the following questions.

• If Nepal’s hydropower capacity grew and nothing else changed (i.e., no changes in 

coordination, no additional transmission expansion), what would the effect be on production 

costs in Nepal, production costs in India, and cross-border electricity trading?

• If reforms are put in place such that exchanges between Nepal and India are treated the same 

as exchanges between Indian states, how would an increase in Nepal’s hydro capacity affect 

production costs in Nepal, production costs in India, and cross-border electricity trading?

• Would increased coordination between India and Nepal affect India’s integration of wind 

and solar generation?

• How would coordination affect the wheeling of Nepal hydropower through India to 

Bangladesh?

• How would complete operational integration among India’s Eastern Load Dispatch Center 

(LDC) area, Nepal, Bangladesh, and Bhutan affect generation costs and transmission 

congestion?

The results focus on the following outcomes:

• Changes in production costs for each area (including average cost per MWh generated)

• Changes in the types of generation dispatched

• Changes in transmission congestion between Nepal and India

• Changes in curtailment of energy from hydro, wind, and solar.

The results for India focus primarily on the areas adjacent to Nepal, represented by the Eastern 

and Northern LDC regions. Because CBET exchanges have less impact on the other regions of 

India, analyzing results on an all-India basis risks obscuring potentially significant sub-regional 

effects. One possible exception is how hydropower from Nepal might affect the integration of 

higher penetrations of wind and solar power across the subcontinent, which this analysis 

addresses on an all-India basis.

3.1 Increased Nepal Hydropower with No Other Changes

The Base–BAU and High Build–BAU scenarios provide a plausible range of the growth in 

Nepal’s hydroelectric capacity that could occur by 2022. Contrasting results from these two 

scenarios provides a view of the effects on CBET if growth in Nepal’s hydroelectric capacity is 

the only change—that is, if hydro capacity increases without any change in the level of 

coordination (represented by assumed hurdle rates) between India and Nepal. Table 8

summarizes the parameters used in each scenario. 

Table 8. Key Assumptions in the Base–BAU and High Build–BAU Scenarios

Scenario Hydro Buildout Hurdle Rates

India Wind and 

Solar Capacity Bangladesh

Base – BAU 2,839 MW

BAU 160 GW Not included

High Build – BAU 4,551 MW
17

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3.1.1 Electricity Production Cost

Generation from the additional 1,712 MW of hydro capacity in the High Build–BAU scenario 

translates into annual production cost savings of 0.3% or $106 million across both countries. The

production cost savings are the result of a $92 million decrease in variable costs (fuel and 

operations and maintenance) and a reduction of $14 million to the total costs of starting 

generators (Table 9). More than 80% of production cost savings accrue in India’s Northern and 

Eastern regions, where hydro imports from Nepal displace coal.

Table 9. Electricity Production Costs in the Base–BAU and High Build–BAU Scenarios (USD 

millions)

Base–BAU High Build–BAU Difference from Base (%)

Eastern Region $5,082 $5,016 -$66 (-1.3%)

Northern 

Region $8,170 $8,143 -$27 (-0.3%)

Rest of India $20,993 $20,979 -$14 (negligible*)

India + Nepal $34,245 $34,139 −$106 (-0.3%)

*Change is less than 0.1%.

Combined production cost savings accrue almost exclusively in India. Nepal’s system is much 

smaller than India’s, and its capacity consists of mostly zero-marginal-cost hydro generation 

(aside from two small thermal plants). Consequently, its production cost is well under 0.1% of 

India’s in both scenarios.

Across India, the additional amount of hydropower from Nepal reduces the average cost of 

generation from $20.99 per MWh to $20.94 per MWh. Hydropower imports from Nepal tend to 

displace the most expensive generation sources. As a result, roughly 75% of the production cost 

reduction accrues because India generates less of its own electricity while roughly 25% accrues 

because the energy that India does generate is less expensive.

Locational marginal prices (LMPs), which are indicative of localized wholesale power prices 

under efficient market conditions, are primarily a function of three factors: the marginal cost of 

generation, transmission system losses, and transmission congestion. If there are no constraints 

on transmission flows (i.e., no congestion), LMPs everywhere will converge on one value that 

represents the marginal cost of generation systemwide. When congestion or hurdle rates 

constrain transmission flows, LMPs at the points with excess generation relative to demand will 

drop while LMPs at the nodes with excess electricity demand will increase. LMPs do not fully 

account for dispatch decisions because of the impact of hurdle rates. When the difference in 

LMPs between India and Nepal are less than the hurdle rate associated with moving power 

across the border, load is met by more costly resources on one side of the border, while lowercost resources on the other side remain unused. We assume no transmission losses. 

In Figure 4 the LMP supply curves for Bihar and Uttar Pradesh are disaggregated into their 

seasonal components along with the hurdle rate for moving hydropower from Nepal to India. 

Nepal’s marginal cost of hydropower generation is near zero, thus the hurdle rate of CBET 

makes up most of the cost of importing Nepal hydropower in India. Furthermore, prices in India 
18

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tend to be inelastic with respect to the amount of hydropower imported from Nepal because total 

demand in India is large comparatively. The LMP in India, therefore, approximates the financial 

incentive for Nepal to export hydro generation; the hurdle rate represents the economic hurdle 

CBET must surmount. The intersection between the price duration curves and hurdle rate line 

approximates the proportion of periods in which hurdle rates, or lack of coordination, constrain 

flows from Nepal to India. CBET is hardly ever economic during the dry season, as evidenced by 

Nepal’s lack of exports (discussed below and illustrated in Figure 8). During the wet season, 

imports from Nepal are economic roughly 65% of the time to Bihar and 55% of the time to Uttar 

Pradesh.

Figure 4. Price in Bihar and Uttar Pradesh relative to hurdle rate on Nepal’s exports by season, 

Base – BAU and High Build – BAU scenarios.

Note: Duration curve excludes the highest 5% and the lowest 5% of values.

3.1.2 Electricity Generation by Resource

In the High Build–BAU scenario, a 59.3% increase in installed hydro capacity in Nepal results in 

a 10.7% increase in annual hydro generation. The additional hydro capacity is underutilized 

(despite its low cost) due in part to the lack of demand for the added energy within Nepal, 

physical transmission constraints, and periods when hurdle rates make CBET uneconomic. This 

results in curtailment, or spilling, of the extra hydro energy. Figure 5 shows annual generation 

and hydro curtailment in Nepal for both the Base–BAU and High Build–BAU scenarios.

— Base – BAU 

price curve

— High Build –

BAU price 

curve

- - Hurdle rate 

(Nepal to India)

Price India (USD/MWh)

Hurdle rate is high enough to 

suppress imports from Nepal.

Fractions of Periods
19

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Figure 5. Nepal hydro generation and curtailment by resource type, Base–BAU, and High Build–

BAU scenarios

Figure 6. Difference in generation in the High Build–BAU scenario compared to the Base–BAU 

scenario, by region.

Note: Indian regions: NR – Northern region; ER – Eastern region; NER – Northeastern region: SR – Southern region; 

WR – Western region. Negative generation means there is less in the High Build–BAU scenario than in Base–BAU; 

positive means more.

All of the increased capacity in the High Build–BAU scenario is RoR hydro, which is less 

flexible operationally than hydro with storage. Whatever generation potential is available must 

be used immediately or forfeited. Therefore, the increased RoR energy combined with relatively 

low demand and export potential leads to a substantial amount of unused RoR capability. The 

impact on peaking RoR and hydro with storage is smaller. Across all hydro technologies, 

curtailment of hydro energy is more than 45% in the High Build–BAU scenario compared to less 

than 20% in the Base–BAU scenario.
20

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Despite the higher curtailment levels, more hydro capacity increases Nepal’s net exports to India 

from 1.7 TWh in the Base–BAU scenario to 3.0 TWh in the High Build–BAU scenario. The 

additional 1.3 TWh of net exports primarily displace coal generation in India’s Eastern and 

Northern regions. Figure 6 shows the change in generation in Nepal and in the five Indian power 

grid regions between the Base–BAU and High Build–BAU scenarios. Reduced coal generation 

in Bihar accounts for more than 62% of the decrease in coal generation for all of India. The 

average variable cost of coal generation in Bihar is 54.7% higher than in the rest of India.

3.1.3 Energy Flow between Nepal and India

Under the High Build–BAU scenario, Nepal increases its annual exports to India and reduces its 

imports. Compared with the Base–BAU scenario, exports increase from 2,000 GWh to 3,200 

GWh and imports fall from 400 GWh to 300 GWh. 

Energy flows between Nepal and India vary seasonally and hourly in both scenarios. India’s 

greatest demand for power imports from Nepal tends to occur in the early evening and be 

negligible during the day. More hydro capability in Nepal allows an even higher level of export 

to India during the evening and early morning hours, as shown in Figure 7.

Figure 7. Average hourly net interchange between Nepal and India by Indian state, Base–BAU, and 

High Build–BAU.

Note: Positive flows indicate energy transfer from Nepal to India. Each state has its own vertical axis scale to illustrate 

scenario differences.
21

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Figure 8. Seasonal flows from Nepal to Indian states 

Nepal’s monthly net interchange with India is generally limited to the wet season months (June 

through November), when Nepal has the most available hydro. The High Build–BAU scenario 

results in significantly higher wet-season flows from Nepal to India despite the hurdle rates, as 

shown in Figure 8. The increase was proportionately larger for Uttar Pradesh, where CBET 

increased nearly fourfold. 

3.1.4 Transmission Congestion

Transmission between Nepal and Uttar Pradesh is never congested. On the other hand, 

congestion between Nepal and Bihar increases more than six-fold in the High Build–BAU 

scenario. All congestion between Nepal and Bihar occurs on the 132-kV lines connecting 

Parwanipur to Raxaul and Gandak to Ramnagar, not on the major 400-kV corridor between 

Muzaffarpur and Dhalkebar. Table 10 provides the annual hours of transmission congestion from 

Nepal to each neighboring Indian state. 

The lack of congestion on the border between Uttar Pradesh and western Nepal could result from 

transmission limits within Nepal that prevent electricity generated in the eastern part of Nepal 

from reaching the western part for export. However, the 400-kV connection from Butwal to 

Gorakhpur (included in all scenarios) never saw congestion so it is assumed that the current 

plans are sufficient to accommodate exports from Nepal.

Only one transmission line inside Nepal is congested more than 1% of the time in the High 

Build–BAU scenario.11 The line links not-yet-completed hydroelectric projects in the Koshi river 

basin to the rest of the grid. Upgrades to this existing transmission pathway could help reduce 

total production costs as new hydro projects become operational.

 11 The thermal loading limits of transformers is not considered in the DC-optimal power flow.

-1

0

1

2

3

wet

season

dry

season

wet

season

dry

season

Bihar Uttar Pradesh

Flow from Nepal to India (TWh)

Base-BAU High Build-BAU
22

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Table 10. Hours of Congestion on Transmission between Nepal and India Base and High Build 

Scenario 

Interface Base–BAU High Build–BAU

Nepal  Bihar 240 1,498

Nepal  Uttar Pradesh 0 0

Nepal  Uttarakhand 0 229

3.2 Increased Nepal Hydropower with Coordinated Operations

As seen in Section 3.1, hurdle rates on flows between Nepal and India restricts CBET. This 

section reexamines the Base and High Build scenarios using rates that treat Nepal the same as 

any Indian state—i.e., allowing price signals to work in a nondiscriminatory manner across the 

two countries. Table 11 summarizes the scenarios involved.

Table 11. Scenarios Examined, Coordinated Operations

Scenario

Hydro 

Buildout Hurdle Rates

India Wind and 

Solar Capacity Bangladesh

Base–BAU 2,839 MW

BAU

160 GW Not included

High Build–BAU 4,551 MW

Base–CO 2,839 MW

CO

High Build–CO 4,551 MW

3.2.1 Electricity Production Cost

Coordinated Operations greatly increase the production cost savings possible in the High Build 

scenario. Moving from the Base scenario to either High Build or Coordinated Operations 

scenarios alone results in some production cost savings—$106 million or $120 million, 

respectively. However, Coordinated Operations alongside High Build more than doubles 

production cost savings to $462 million, or 1.3% relative to the Base–BAU scenario. The 

positive interaction between the two, illustrated in Figure 9, is due to the coincidence of surplus 

hydro availability in Nepal (High Build) and improved trading opportunities with India 

(Coordinated Operations), which together facilitate higher exports from Nepal to India and 

reduce overall production costs.
23

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Figure 9. Production cost savings for Nepal and India due to Coordinated Operations, High Build

Regionally, the Northern and Eastern regions see the largest production cost savings when 

moving from the Base to High Build scenario with Coordinated Operations: $134 million (1.6%) 

and $194 million (3.8%), respectively. However, production costs in the more distant Western 

region also fall by $111 million (0.9%). The reduction in Western region’s production cost 

indicates that large-scale hydro imports from Nepal can affect energy flows within India.

Table 12. Electricity Production Costs in the Coordinated Operations Scenarios, and Difference 

from BAU Scenarios (USD millions)

Base–CO High Build–CO

Production 

Cost

Difference,

Base–BAU (%)

Production 

Cost

Difference, High 

Build–BAU (%)

Difference,

Base–BAU (%)

Eastern region $5,025 -$57 (-1.1%) $4,888 -$128 (-2.6%) -$194 (-3.8%)

Northern region $8,139 -$31 (-0.4%) $8,036 -$107 (-1.3%) -$134 (-1.6%)

Rest of India $20,961 -$32 (-0.2%) $20,858 -$121 (-0.6%) -$135 (-0.6%)

India + Nepal $34,125 -$120 (-0.4%) $33,783 -$356 (-1.0%) -$462 (-1.3%)

3.2.2 Electricity Generation by Resource

Lower hurdle rates reduce hydro curtailment in Nepal and increase exports from Nepal to India. 

The contrast is particularly prominent in the High Build scenario, as shown in Figure 10, which 

compares annual hydro generation and curtailment in Nepal across each scenario. In the Base 

scenario, Coordinated Operations leads to a reduction in curtailed energy of 10.7%, however, in 

the High Build scenario, Coordinated Operations lead to a reduction in curtailed hydro of six 

times. 

Base–BAU

High Build–BAU

(0.3% savings)

Base–CO

(0.4% savings)

High Build–CO

(1.3% savings)
24

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Figure 10. Nepal hydro generation and curtailment by resource type, all scenarios

Indian dispatch center regions: NR – Northern; ER – Eastern; NER – Northeastern; SR – Southern; WR – Western

Figure 11. Difference in generation, by fuel type, due to Coordinated Operations for both hydro 

capacity scenarios.

Note: Negative generation means there is less generation with Coordinated Operations; positive means more. High Build BAU vs. CO Base BAU vs. CO
25

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Nepal increases net exports to India by 9.0 TWh when moving from the Base-CO to High Build -

CO scenario. This is nearly three times what imports would be if Nepal simply increased its 

hydro capacity in the absence of Coordinated Operations. Figure 11 illustrates the effects that 

Coordinated Operations could have under a range of hydro buildouts in Nepal. Coal generation 

in the Northern and Eastern regions adjacent to Nepal decline as expected under either buildout 

level. However, a High Build of Nepal hydro also accelerates a reduction in coal generation in 

the Western Region in large part because the Northern Region replaces 3.5% of what it imports 

from the Western region with more hydro imports from Nepal compared to the High Build-BAU 

scenario. Nepal can more effectively compete with the Western region as a supplier of energy to 

the Northern region. 

3.2.3 Energy Flow between Nepal and India

With the combination of Coordinated Operations and High Build, Nepal continues to maximize 

exports during peak load times, but also consistently exports more than 1 GW to India between 

the morning and evening peaks. Figure 12 shows the Coordinated Operations scenarios alongside 

the BAU scenarios described in the previous section. Overall, CBET from Nepal to India is more 

than 50% higher than it would be if hydro capacity were to increase without reductions in hurdle 

rates.

The increase in exports to Uttar Pradesh and Uttarakhand is especially pronounced. CBET from 

Nepal to Uttar Pradesh increases 567% (4.4 TWh) when a high buildout of hydro in Nepal is 

augmented by Coordinated Operations. The increased volume to both Indian states is also closer 

to a baseload profile than exports under the other scenarios, which could contribute to the 

Western Region’s reduction in coal generation and exports to the Northern Region.

Coordinated Operations allows Nepal to become a net energy exporter during the dry season 

(December–May) but it also has an effect on Nepal’s imports from India under conditions of 

lower hydro buildout. Coordinated Operations increases the value of storage-augmented hydro 

during peak load hours. As these resources are held so they can be dispatched during peak 

demand periods, imports from India increase to meet Nepal’s domestic generation gap midday. 
26

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Figure 12. Average hourly net interchange between Nepal and India by Indian state, all scenarios.

Note: Positive flows indicate energy transfer from Nepal to India. Each state has its own vertical axis scale to illustrate 

scenario differences.

Put another way, the shift in utilization represents time-related price arbitrage between the 

middle of the day and the evening peak hours. Figure 13 uses dispatch on March 15 to illustrate 

the phenomenon. From 10 a.m. to 3 p.m. under the Base–BAU scenario, LMPs average about 

$41/MWh in Bihar and $36/MWh in Uttar Pradesh. From 6 p.m. to 9 p.m. that same day, the 

average is $86/MWh and $62/MWh, respectively. Increasing coordination allows Nepal’s 

peaking RoR and storage hydro plants to shift their generation to peak hours when it is most 

valuable. This shift tends to result in lower LMPs on the Indian side of the border.

Figure 13. Generator dispatch and load in Nepal on March 15, Base scenario with and without 

Coordinated Operations

CO

Mean Hourly Flow (MW)
27

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3.2.4 Transmission Congestion

Transmission congestion between Nepal and the Indian states with which it exchanges power is 

highest when high buildout of Nepal hydropower is combined with Coordinated Operations. 

Table 13 provides annual hours of transmission congestion between Nepal and each Indian state. 

As in the previous section, transmission congestion between Nepal and India occurs only on the 

132-kV lines between Parwanipur – Raxaul, Gandak – Ramnagar and Mahendranagar –

Tanakpur rather than on the higher-capacity 400-kV lines.

Table 13. Transmission Congestion between Nepal and Neighboring Indian States, All Scenarios

Interface Base – BAU

(hrs.)

Base – CO

(hrs.)

High Build – BAU 

(hrs.)

High Build–CO 

(hrs.)

Nepal  Bihar 241 1243 1498 5541

Nepal  Uttar Pradesh 0 0 0 0

Nepal  Uttarakhand 0 0 229 1900

3.3 Nepal Hydropower with Renewable Energy Integration in India

The previous sections suggest the importance of increased coordination in maximizing CBET 

benefits for both Nepal and India, with the benefits to India accruing mostly in states close to 

Nepal. In this section we examine whether greater hydropower development in Nepal could 

affect India’s ability to integrate high penetrations of wind and solar power nationwide at lower 

cost, and whether coordinated operations could have a comparable effect on those benefits. 

This section examines how different levels of CBET, as represented by extent of coordination 

with the High Build scenario, impact the challenges associated with operating a high RE power 

system in India, as represented by two levels of installed RE capacity. Table 14 describes the

scenarios compared in this section.

Table 14. Scenarios Examined, RE Integration

Scenario

Hydro 

Buildout Hurdle Rates

India Solar 

Capacity

India Wind 

Capacity Bangladesh

High Build–-BAU – Low RE

High

(4,551 MW)

BAU

20 GW 50 GW

Not included

High Build–BAU 100 GW 60 GW

High Build–CO – Low RE Coordinated 

Operations

20 GW 50 GW

High Build–CO 100 GW 60 GW

3.3.1 Electricity Production Cost

Under BAU hurdle rates for CBET and high buildout of hydropower in Nepal, increasing India’s 

wind and solar capacity from 70 GW to 160 GW reduces total production cost. Generation from 

wind and solar has zero fuel cost, and therefore contributes less to total production cost 

compared to the thermal generation that it displaces. The BAU cost reduction (moving from the 

lower to the higher level of RE capacity) is 14.9% for the modeled region. The cost reductions 
28

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are almost the same (within 0.1%) if the above RE capacity changes occur in the context of 

Coordinated Operations between Nepal and India. 

3.3.2 Electricity Generation by Resource and RE Curtailment

Figure 14 shows annual generation by resource type in both Nepal and India across the four 

scenarios. As discussed in Section 3.2, Nepal’s hydro generation rises when BAU hurdle rates 

are replaced by Coordinated Operations, which accounts for most of the differences between the 

two pairs of scenarios. 

Figure 14. Annual generation in Nepal and India by resource type, all scenarios

When CBET hurdle rates are held constant at BAU levels, more wind and solar generation in 

India correlates with a 1.5% drop in Nepal’s hydro generation. This suggests that India’s 

increased wind and solar generation displaces some of Nepal’s potential hydropower exports to 

India because Nepal’s hydro cannot compete as effectively in the Indian market due to the high 

hurdle rates. 

Under Coordinated Operations, Nepal’s hydro generation remains unchanged when India’s 

renewable energy penetration level increases. Therefore, Nepal’s vulnerability to hydro 

curtailment depends less on the amount of renewable generation in India and more on transaction 

costs for CBET between the two countries.

India’s wind and solar penetration and its renewable energy curtailment levels are unaffected by 

Nepal hydropower even with Coordinated Operations. The increased flow of hydropower from 

Nepal enabled by Coordinated Operations primarily displaces generation from India’s thermal 

Category
29

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plants and does not affect RE curtailment, which is 1.3% at wind and solar capacity of 160 GW. 

The new hydro generation in the High Build scenario is primarily run-of-river, which cannot be 

stored and delivered when its value for RE integration is greatest, which in this case is midday to 

reduce RE curtailments in India. For an analysis of how RE curtailment can occur in India under 

high RE penetrations, see Palchak et al. 2017. 

3.3.3 Energy Flow between Nepal and India 

Larger penetration levels of RE in India slightly reduce imports from Nepal under coordinated 

operations and at a modestly larger reduction under BAU hurdle rates. Under BAU hurdle rates, 

a system with 160 GW wind and solar capacity in India reduces flows from Nepal by about 197 

GWh compared to India at 70 GW wind and solar. The reduction occurs because higher hurdle 

rates handicap the ability of Nepal’s hydropower exports to compete in India when higher wind 

and solar penetrations reduce marginal costs. 

Most of this trade reduction is recovered with Coordinated Operations, however. The 12.3% drop 

in exports to Uttar Pradesh and the 3.5% drop in exports to Bihar both disappear under 

Coordinated Operations. Table 15 summarizes changes in net flows between Nepal and each 

Indian state.

Table 15. Net Flows between Nepal and Indian States with Different Renewable Energy Levels in 

India (GWh)

India Wind and Solar

Area Scenario 70 GW 160 GW Change

Bihar

BAU 2,176 2,099 -3.50%

CO 6,206 6,213 0.10%

Change 185% 196%

Uttar 

Pradesh

BAU 893 783 -12.30%

CO 5,224 5,222 0.00%

Change 485% 567%

Uttarakhand

BAU 79 69 -12.70%

CO 547 545 -0.4%

Change 596% 687%

Nepal-India 

Total

BAU 3,148 2,951 -6.26%

CO 11,977 11,980 0%

Change 280% 306%

Note: A positive change indicates that Nepal’s net exports to India increase, and vice versa.

The main difference in energy flows between Nepal and India when moving from 70 GW to 160 

GW wind and solar capacity is a slight dip in Nepal’s daytime net exports and corresponding rise 

in its nighttime net exports. India’s increased daytime solar energy in the 160 GW scenario 

explains the changed behavior. Figure 15 illustrates the effect under Coordinated Operations.
30

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Figure 15. Average hourly net interchange between Nepal and Indian state, High Build–CO–Low 

RE vs. High Build–CO.

Note: Positive flows indicate energy transfer from Nepal to India. Each state has its own vertical axis scale to illustrate 

scenario differences.

3.4 Increased Trade with Bangladesh

This section analyzes the impact of increased trade between Nepal and Bangladesh. While we do 

not explicitly model a contract between Nepal and Bangladesh, we add 1,000 MW of constant 

load in West Bengal at the DC tie with Bangladesh and examine how varying levels of 

coordination within the BBIN region affect the ability of Nepal to serve the increased demand. 

Existing CBET hurdle rates limit the flow of hydropower from Nepal to Bangladesh. In the 

scenario based on high buildout of Nepal hydropower and BAU hurdle rates, Nepal exports 3.0 

TWh to India. This is significantly less than the 8.7 TWh that would move through the DC 

flowgate from West Bengal to Bangladesh if Nepal were to supply the constant 1,000 MW of 

contracted capacity with its domestic generators. This suggests that no independent hydroelectric 

power producer in Nepal would be capable of fully meeting the contracted supply unless it 

operated under special CBET provisions, had a dedicated transmission line through India to 

Bangladesh, or CBET hurdle rates were lowered more generally. Instead, the actual power would 

come from India, primarily by increasing generation at coal plants in the Eastern region.

On the other hand, 12 TWh of power moves from Nepal into India under High Build–CO 

scenario, sufficient for supplying all contracted power to Bangladesh. We therefore use the High 

Build scenarios to examine the potential flow of hydropower from Nepal to Bangladesh. To 

evaluate the impact on total production costs of increased levels of coordination along with a 

Bangladesh supply contract, we use the High Build–BAU scenario for comparison. Table 16

summarizes the scenarios examined. Mean Hourly Flow (MW)
31

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Table 16. Scenarios Examined, Bangladesh, BAU, and Coordinated Operations

Scenario Hydro Buildout Hurdle Rates India Wind and 

Solar Capacity

Bangladesh

High Build–BAU High

(4,551 MW) BAU 160 GW

Not included

Bangladesh–BAU Included

High Build–CO High

(4,551 MW)

Coordinated 

Operations 160 GW

Not included

Bangladesh–CO Included

3.4.1 Electricity Production Cost

Adding a constant 1,000 MW of load anywhere on the system would naturally increase 

generation and, therefore, total production costs. Holding BAU hurdle rates and everything else 

unchanged, the added load in Bangladesh would increase total production costs in the Eastern 

region by 6.4%. Costs would increase 0.2% for the rest of India. As explained previously, most 

of the additional load would be met by increasing generation in India rather than using Nepal’s 

hydropower.

However, increasing coordination between Nepal and India along with adding 1,000 MW of load 

in Bangladesh would allow more low-cost hydropower from Nepal to be exported, offsetting 

much of the cost of generating additional power in India. Table 17 contrasts production costs 

under the key scenarios. Including both the supply contract with Bangladesh and Coordinated 

Operations increases total production costs in the Eastern region by only 3.4% instead of 6.4%

under BAU. 

Table 17. Effect of Increased Generation to Serve Bangladesh on Total Production Costs (USD 

millions)

Bangladesh–

BAU

Difference from High 

Build–BAU (%)

Bangladesh–

CO

Difference from High 

Build–BAU (%)

Eastern region $5,335 $319 (6.4%) $5,186 $170 (3.4%)

Northern region $8,214 $71 (0.9%) $8,098 -$54 (-0.7%)

Rest of India $21,025 $46 (0.2%) $20,928 -$51 (-0.2%)

India + Nepal $34,575 $436 (1.3%) $34,212 $73 (0.2%)

Average LMPs in Indian states bordering or near Nepal with Coordinated Operations are largely 

the same with or without the additional flows from West Bengal to Bangladesh.

3.4.2 Electricity Generation by Resource

As previously discussed, more CBET coordination results in more hydropower generation in 

Nepal, making it economic to export more power from run-of-river plants that were previously 

generating below their full capability. Adding demand to Bangladesh, however, has little 

additional effect on Nepal’s hydropower generation under the Coordinated Operations scenario. 

In this scenario, 141 out of 165 run-of-river plants are operating at their maximum output with 

no curtailment. Network congestion within Nepal or between Nepal and India constrains output 

from many of the remaining plants. Given these constraints, adding a contract with Bangladesh 
32

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does not affect hydro plant utilization in Nepal because, even without the Bangladesh contract, 

Nepal has adequate outlets for its exports in India. 

Instead of adding more hydropower from Nepal, the additional demand in Bangladesh triggers 

more coal generation in India, most of it on subcritical coal units. Figure 16 shows how resource 

utilization in India changes with a supply contract with Bangladesh, assuming Coordinated 

Operations between Nepal and India.

Figure 16. Major changes in generation by region and state with an added Bangladesh supply 

contract (TWh).

Note: Charts are based on Coordinated Operations and high buildout of hydropower in Nepal. Each region has its 

own vertical axis scale to illustrate scenario differences.

The largest single increase in coal generation occurs in Bihar, where generation from 

supercritical coal plants increases by nearly 3.5 TWh (69%). Jharkhand and West Bengal—on 

the path between Bihar and Bangladesh—increase generation from subcritical coal plants by 2 

TWh (2%).

Additional demand in Bangladesh has a muted impact on generation in Uttar Pradesh and the 

states in India’s Northern region. Total generation increases by about 1 TWh (<1%) in Uttar 

Pradesh, Haryana, Rajasthan, and Punjab. 

A related effect is a 2.2 TWh (0.4%) generation increase in the Western region, including the 

states of Maharashtra, Chhattisgarh, and Madhya Pradesh. These three states have some of the

lowest-cost coal resources in the country and are among India’s largest power producing regions, 

generating about 30% of the country’s electricity. The observed increase in generation is likely 

Category
33

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affected by the complex network of resources within India, as the system settles on a different 

equilibrium state with the additional load in Bangladesh. 

3.4.3 Energy Flow between Nepal, India, and Bangladesh

Adding a supply contract with Bangladesh (dispatched through West Bengal) has very little 

effect on the amount of hydropower generated in Nepal and sent to India. With the supply 

contract, exports increase by 0.02 TWh, less than 0.5%. The strongest effects occur within India, 

as generation and energy flows within India’s Eastern region are redirected to move 8.7 TWh 

into Bangladesh (Figure 17).

With the supply contract, exports from Jharkhand, Assam, Sikkim, and Uttar Pradesh are 

redirected to Bangladesh via West Bengal. West Bengal and Jharkhand both decrease exports to 

Bihar in order to supply Bangladesh. As a result, Bihar must increase its internal generation by 

3.5 TWh to meet demand.

Including Bangladesh did not impact the seasonal or daily patterns of trade between India and 

Nepal observed in Section 3.2.

Figure 17. Major changes to India’s internal annual interstate flows and generation after adding 

Bangladesh supply contract (TWh).

Note: Changes less than 0.5 TWh not shown, except for Nepal.

8.7 to 

Bangladesh 2.9

1.3

1.3 (to Assam)

1.0

3.5

0.5

1.0

0.6

-0.5 0.6 0.7

Increase in State’s Net Generation Additional Interstate Flow Reduced Interstate Flow

Additional generation in Nepal and exports 

to India: 0.02 TWh
34

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3.4.4 Transmission Congestion

Including Bangladesh does result in a small increase in the number of hours congested between 

Nepal and Bihar and Nepal and Uttarakhand. As in Section 3.2, transmission congestion between 

Nepal and India occurs only on the 132-kV lines, not on the larger 400-kV lines. Table 18 shows 

the number of hours transmission is congested congestion between Nepal and each Indian state.

Table 18. Transmission Congestion between Nepal and Neighboring Indian States, High Build–CO 

Scenarios with and without Bangladesh (hours)

Interface High Build–CO Bangladesh–CO

Nepal – Bihar 5,541 5,879

Nepal – Uttar Pradesh 0 0

Nepal – Uttarakhand 1,900 1,928

3.5 Full Regional Integration

As a final test, we compared some of the previous results against a scenario that is based on a 

theoretical independent system operator (ISO) comprising Bangladesh, Bhutan, India’s Eastern 

LDC region, and Nepal (BBIN). The purpose of this scenario is to provide an ideal and 

ambitious benchmark of least-cost generation dispatch for comparison. The other scenarios 

described previously in this chapter address issues arising in current and recent CBET 

discussions among India, Nepal and Bangladesh. This ISO scenario, which assumes full 

coordination (i.e., no hurdle rates) and full security-constrained unit commitment and economic 

dispatch within the BBIN region, helps compare the results of these other scenarios with benefits 

that are theoretically achievable with perfect coordination across the power systems. 

India’s Eastern LDC region includes the states of Bihar, Jharkhand, West Bengal, Odisha, and 

Sikkim. The region borders Nepal, Bangladesh, and Bhutan. Modeling these areas as a 

hypothetical ISO means that energy would flow among these countries and states as easily as it 

would if the region were one state with one independent grid operator. We operationalize this 

assumption in the model by removing all hurdle rates between countries and states within the 

BBIN region. The hurdle rates between all other Indian states remains the same (INR 1,000 per 

MWh), and is applied to transfers between the ISO and non-ISO Indian states. 

To evaluate how additional CBET benefits resulting from Coordinated Operations between 

Nepal and India compare with the benefits that might be achievable under full market 

integration, the relevant comparisons are with scenarios that include exports to Bangladesh. 

Table 19 summarizes the scenarios included in this part of the analysis. 
35

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Table 19. Scenarios in the Analysis

Scenario Hydro Buildout Hurdle Rates

India Wind and 

Solar Capacity Bangladesh

Bangladesh–BAU

High

(4,551 MW)

BAU

Bangladesh–CO Coordinated Operations 160 GW Included

BBIN ISO None within ISO

In the BBIN ISO scenario, Bangladesh and Bhutan are represented only as described in Section 

2.4—net imports from Bhutan and the 1,000 MW export to Bangladesh—not their full systems. 

More detailed modeling of these systems is possible but is beyond the scope of this analysis.

3.5.1 Electricity Production Cost

Table 20 summarizes the changes in total generation and total production cost progressing from 

current BAU to Coordinated Operations, and from Coordinated Operations to full market 

integration in an ISO. Here we consider the impact on BBIN countries and states independent of 

the rest of India to highlight changes within the ISO that may be obscured when considering all 

of India together. 

Table 20. Generation and Production Cost Differences between ISO Scenarios

Bangladesh–BAU Bangladesh–CO BBIN ISO

Change, 

BAU to CO

Change, 

CO to ISO

Total Generation (TWh)

BBIN 215 221 225 2.8% 1.8%

Rest of India 1,450 1,444 1,440 -0.4% -0.3%

Total Production Cost (USD million)

BBIN $7,458 $7,249 $7,301 -2.8% 0.7%

Rest of India $40,872 $40,574 $40,439 -0.7% -0.3%

Total Production Cost (USD per MWh)

BBIN $34.67 $32.78 $32.42 -5.4% -1.1%

Rest of India $28.19 $28.10 $28.09 -0.3% negligible

Moving from BAU to Coordinated Operations simultaneously increases generation and reduces 

total costs within the BBIN region. As detailed in Section 3.2, more coordination result in less 

hydropower curtailment in Nepal, the movement of more hydropower across the border from 

Nepal into India, and the replacement of relatively high-cost thermal generation in India.
36

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The additional step from Coordinated Operations to a full ISO leads to more production within 

the ISO and commensurately less generation in the rest of India. While the BBIN ISO’s total 

production cost increases because of this increased generation, its total cost per MWh generated 

falls 1.1% compared to Coordinated Operations. The additional increment of generation obtained 

by moving from Coordinated Operations to a BBIN ISO—slightly more than 4 TWh, or 1.8%—

costs $12.69 per MWh, compared to an annual average of $32.78 per MWh in the region with 

Coordinated Operations alone. Coordinated Operations and further integration to BBIN ISO 

reduces total generation costs per MWh everywhere, although the effect outside the BBIN area is 

comparatively small. 

These numbers suggest that Coordinated Operations between Nepal and India—arguably a less 

complicated proposition than creating an ISO—can capture most of the economic benefits that 

are theoretically achievable but currently unrealized. Measured in cost per MWh generated 

within the BBIN area, Coordinated Operations can achieve 5.4% of the theoretically possible 

6.5% in unrealized savings.

3.5.2 Electricity Generation by Resource

Similar to the Bangladesh scenarios, a BBIN ISO does little to increase the utilization of Nepal’s 

hydropower plants above what is observed under Coordinated Operations. Network congestion 

and seasonal capacity factors, rather than hurdle rates, limit Nepal’s hydropower exports. Given 

these constraints, further reductions in hurdle rates in the BBIN ISO scenario have no impact on 

Nepal’s hydropower generation and total exports. 

Figure 18 shows the change in annual generation between the Bangladesh BAU, Bangladesh 

Coordinated Operations, and BBIN ISO scenarios for dispatch regions within the ISO and the 

rest of India. While the magnitude of decreased coal generation in India remains constant across 

the Coordinated Operations and BBIN ISO scenarios, the actual plants that are being displaced 

are not the same. In the BBIN ISO scenario, consolidating operations among states in India’s 

Eastern region allows for greater utilization of the most efficient generators in that region. More 

expensive supercritical coal plants in Bihar are displaced by less expensive subcritical coal plants 

in Odisha and Jharkhand. Also, some subcritical coal generation from BBIN becomes cost 

effective enough to replace nearly 4 TWh of coal generation in the rest of India. 
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Figure 18. Change in annual generation for the BBIN region and the rest of India under different 

wheeling charge scenarios

3.5.3 Energy Flow between Nepal and India

Consolidation into a single market causes a net redistribution of about 5 TWh of generation 

among states and countries within the BBIN footprint. The result is a 12% increase in flows 

among these states and countries, accompanying the 4.1 TWh increase in generation shown in 

Table 20. Most of the shift in interstate flows—4.4 TWh—consists of additional transfers from 

Jharkhand and West Bengal to Bihar.

Overall, an ISO scenario puts the BBIN region in a stronger export position. Costs per MWh 

generated within the ISO decrease more than in the rest of India, making more BBIN resources 

economically competitive in India. While the BBIN region remains a net importer, the combined 

ISO increases its exports to the rest of India by about 4.4 TWh, or 20%. Nearly all of these 

additional exports are from Odisha, a state with low-cost coal, to its neighboring states in the 

Southern region—Andhra Pradesh and Karnataka. Net transfers to the BBIN region increase by a 

modest 2%, or 0.4 TWh. Flows from Chhattisgarh to Odisha and Jharkhand drop by 2.1 TWh, 

while flows from Assam to West Bengal and Bhutan increase 1.2 TWh. The BBIN ISO scenarios 

did not impact the seasonal or daily patterns of trade between India and Nepal as observed in 

Section 3.2.

3.5.4 Transmission Congestion

The largest increase in transmission congestion between Nepal and India occurs when changing 

from BAU to Coordinated Operations. Going further to a BBIN ISO adds slightly—4.6%—to 

the congestion within the ISO between Nepal and Bihar. Table 21 shows the hours of congestion 

across each interface between Nepal and India. As in other scenarios, the congestion is limited to 

the 132-kV connections between Nepal and India.

Category
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Table 21. Transmission Congestion between Nepal and Neighboring Indian States, All Scenarios 

(hours)

Interface Bangladesh–BAU Bangladesh–CO BBIN ISO

Nepal – Bihar 1,703 5,879 6,160

Nepal – Uttar Pradesh 0 0 0

Nepal – Uttarakhand 204 1,928 1,923
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4 Summary

The model results indicate significant opportunities for increased trade between Nepal and India, 

particularly for India’s Eastern and Northern LDC areas. Excess hydropower from Nepal tends to 

displace more expensive thermal generation in India. Future CBET will depend highly both on 

the level of Nepal’s hydro buildout and level of coordination for power exchanges between the 

two countries. 

Increased hydro buildout in Nepal. In the High Build scenario, where Nepal’s hydropower 

capacity is 4,551 MW, production costs in the combined India and Nepal system could fall by 

$106 million per year, or 0.3%. The increased hydro capacity would allow Nepal to increase its 

annual exports to India by 60%. Under existing levels of coordination, however, Nepal’s run-ofriver plants are not fully utilized. Nepal’s domestic load cannot absorb all of the increased hydro 

generation, and institutional hurdles between it and India make it uneconomic for Nepal to 

generate power for export during significant periods of the year such that 45% of available 

energy from hydropower is curtailed.

Coordinated operations. Nepal’s high-buildout hydro resources are almost fully used if 

operations between Nepal and India are more coordinated, such that trade with Nepal is 

institutionally no different than trades between Indian states. The increased generation from 

hydro translates to decreased total annual production costs. With both Coordinated Operations, 

annual production costs in India and Nepal decrease $356 million, or 1.0%, compared to the 

High-BAU scenario. Combining increased hydro buildout in Nepal with Coordinated Operations 

would allow Nepal to become a net exporter during the dry season as well as the wet season. 

Lower cost generation also expands economic opportunities for Nepal to compete with India’s 

Western region as a supplier of energy to the Northern region. As a result, in the High Build 

scenario with Coordinated Operations, coal generation in India’s Western region decreases by 

3.8 TWh, or 3.5% compared to the High Build scenario under BAU . 

Integrating India’s wind and solar resources. Greater hydro exports from Nepal to India appear 

to have little effect on integrating wind and solar in India, largely because most of the new hydro 

in Nepal is run-of-river hydro, which lacks storage. However, greater development of wind and 

solar resources in India can reduce the potential market for Nepal hydro unless institutional 

barriers to trade are reduced through coordinated operations. Wind and solar add zero marginal 

cost generation to India’s mix, which affects the periods when hydro exports from Nepal to India 

are economic under BAU conditions. However, this impact becomes negligible under 

Coordinated Operations, which enable Nepal’s hydro to compete economically despite the 

periods of lower marginal cost generation. As enabled by the hydro capacity in Nepal that does 

have storage, the profile of these exports tends to shift towards the evening hours to 

accommodate India’s additional solar generation. India’s curtailment of wind and solar at higher 

penetrations appears to be little changed by levels of trade between Nepal and India. 

Nepal hydro to Bangladesh. Including a supply contract with Bangladesh increases total 

production costs in the region due to overall greater levels of electricity generation but adding 

supply to Bangladesh does not materially change Nepal’s generation or exports under 

Coordinated Operations. Most of Nepal’s plants are already operating at their maximum 

allowable output, and only a small fraction are constrained by transmission congestion within 
40

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Nepal or between Nepal and India. Therefore, contractually obligating some amount of Nepal 

hydropower to Bangladesh essentially redirects power flows internally within India, particularly 

from added coal generation.

Consolidating system operations across Bangladesh, Bhutan, Nepal, and India’s Eastern region 

does increase savings compared to BAU operations. Costs per MWh in the region fall by 5.4% 

under Coordinated Operations, and by an additional 1.1% if operations are fully consolidated 

within an independent system operator. With greater internal efficiency, the BBIN region also 

exports more power to the rest of India.

This study examines the operational impacts of CBET between India, Nepal, Bhutan, and 

Bangladesh and finds significant opportunities for increased trade and production cost savings. 

Complementary analysis could identify policy and regulatory pathways to remove non-technical 

barriers to CBET and achieve these benefits. 
41

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