Assessing the Technical Feasibility of
Integrating Renewable Energy Targets in the
India Energy Security Scenarios 2047 v2.0
Investment and Operational Insights from Grid Planning and Dispatch Analysis
Prepared for the NITI Aayog
Nikit Abhyankar
Amol Phadke
August 2015
1
Assessing the Technical Feasibility of Integrating Renewable Energy Targets in the
India Energy Security Scenarios 2047 v2.0: Key Findings from Grid Dispatch Simulations
Prepared for the NITI Aayog
Dr. Nikit Abhyankar, Dr. Amol Phadke
Lawrence Berkeley National Laboratory
In this document, we describe the methodology and the key results of the hourly grid dispatch simulation
for the financial year 2047 (April 2046 through March 2047). The main objective of this simulation exercise
is to assess the preliminary technical feasibility of some of the key energy pathways identified in the model
and broadly identify the storage and balancing electricity requirement for the grid integration of
renewable energy.
Methodology and Assumptions
We built a grid planning and dispatch model for India and simulated the hourly grid operation in FY 2047
by modeling generator unit commitment and dispatch for meeting the demand; the objective of the
model is to minimize the generation cost including the variable costs (fuel, variable O&M etc) and startup and shut-down costs.1 We enforced several operational constraints such as generator ramp rates,
minimum stable generation level, outages, minimum down time etc. No transmission constraints are
considered in this simulation. Based on the electricity demand and supply scenarios defined in the India
Energy Planning Tool, we run the simulation chronologically through all hours of the financial year 2047
(April 2046 through March 2047) in hourly intervals. In addition to the optimal grid dispatch, the
simulation also estimates the balancing electricity requirement for integrating renewable energy.
We conducted this exercise for the following four energy pathways identified in the Indian Energy Security
Scenarios (IESS) model (v2.0):
1.
2.
3.
4.
5.
6.
7.
Least Effort Pathway
Determined Effort Pathway
Aggressive Effort Pathway
Heroic Effort Pathway
Renewable and Clean Energy Pathway
Minimum Emissions Pathway
Maximum Energy Security Pathway
1
We built the model in Plexos, which is industry standard grid dispatch simulation software used by grid
dispatchers, policymakers, utilities and researchers across the world.
2
Note that this study tests only the preliminary feasibility of grid dispatch and broadly identifies storage
and balancing needs. A comprehensive study, which looks at transmission constraints and investments,
specific storage technologies, and flexible capacity needs, would be required to answer more specific
questions on the feasibility of grid dispatch and grid integration strategy of renewables.
Electricity Demand
IESS creates four levels of demand – each with different assumptions on the growth of electricity
consumption in the country and efficiency of electricity utilization. Using these demand levels, we
simulated an hourly demand curve for the financial year 2047 based on the historical hourly demand
patterns in the country, load growth, and projected urbanization. The following charts show the hourly
demand in the country for each demand level.
Hourly Electricity Demand (bus-bar) - GW
1000
Demand Level 1 (Peak Load = 921 GW; Energy Demand = 5548 TWh)
900
800
700
600
500
400
300
200
100
0
Apr-46 May-46
Jun-46
Jul-46
Aug-46
Sep-46
Oct-46
Nov-46 Dec-46
Jan-47
Feb-47 Mar-47
Apr-47
For demand level 2, the electricity demand reduces by nearly 10% because of the undertaken energy
efficiency measures, as can be seen from the following chart.
Hourly Electricity Demand (bus-bar) - GW
900
Demand Level 2 (Peak Load = 827 GW; Energy Demand = 4985 TWh)
800
700
600
500
400
300
200
100
0
Apr-46 May-46
Jun-46
Jul-46
Aug-46
Sep-46
Oct-46
Nov-46 Dec-46
Jan-47
Feb-47 Mar-47
Apr-47
3
In level 3, the demand reduces further by about 15%.
Hourly Electricity Demand (bus-bar) - GW
800
Demand Level 3 (Peak Load = 692 GW; Energy Demand = 4172 TWh)
700
600
500
400
300
200
100
0
Apr-46 May-46
Jun-46
Jul-46
Aug-46
Sep-46
Oct-46
Nov-46 Dec-46
Jan-47
Feb-47 Mar-47
Apr-47
The demand reduces further by about 5% in level 4.
Hourly Electricity Demand (bus-bar) - GW
700
Demand Level 4 (Peak Load = 654 GW; Energy Demand = 3941 TWh)
600
500
400
300
200
100
0
Apr-46 May-46
Jun-46
Jul-46
Aug-46
Sep-46
Oct-46
Nov-46 Dec-46
Jan-47
Feb-47 Mar-47
Apr-47
In all demand levels, the electricity demand peaks in the summer (April through June) mainly due to space
cooling load. It drops somewhat in the monsoon (July onwards) while the demand is lowest in the winter
(November – February). Because of the space cooling load, the demand in the summer is mostly afternoon
peaking. Winter demand, on the other hand has two distinct peaks – one in the morning (due to water
heating) and one in the evening (due to lighting). The following chart shows the average daily load curve
for summer (April-May) and winter (December through February) in FY 2046-47 for demand level 1.
4
Average Demand in Summer (April-May) (Level 2)
800
700
600
500
400
300
200
100
0
Average Hourly Demand (bus-bar) GW
Average Hourly Demand (bus-bar) GW
900
900
Average Demand in Winter (Dec-Feb) (Level 2)
800
700
600
500
400
300
200
100
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the Day
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the Day
Electricity demands for other demand levels would be lower, but will follow a very similar pattern.
Each of the selected pathway assumes a different demand level. The pathway and corresponding demand
level table is shown below:
Pathway
Demand
Level
Least Effort
1
Determined Effort
Aggressive Effort
Heroic Effort
2
3
4
Renewable and Clean Energy
2
Pathway X
3
Min Emissions
4
Max Energy Security
4
Installed Capacity
As defined in the selected pathways, the following table shows the installed capacities (GW) in 2047 by
technology for all pathways:
Coal
Gas_CCGT
Nuclear
Hydro
Biomass+Cogen
Hydro_Small
Wind
Solar
Electricity Imports
Waste to
Electricity
Storage
Total
Peak Load
Least
Effort
Determined
Effort
Aggressive
Effort
Heroic
Effort
Pathway
X
Min
Emissions
681
132
78
150
20
30
551
930
0
6
Renewable
and Clean
Energy
413
83
78
105
23
30
551
833
0
6
494
83
26
75
11
20
290
405
0
4
261
37
78
150
20
30
472
930
0
6
Max
Energy
Security
368
132
45
105
20
20
472
833
0
6
261
37
11
49
5
9
71
56
504
0
368
50
26
75
11
15
222
243
135
4
539
83
45
105
23
20
332
449
0
6
5
1008
921
25
1173
827
33
1635
692
43
2621
654
43
2164
827
33
1441
692
43
2026
654
43
2043
654
5
It can be seen that in several of the selected pathways, the generation capacity is significantly higher than
the peak demand for that pathway – except for least effort and determined effort pathways. For these
two pathways, the capacity reserve margin is very small and as explained subsequently, significant
additional balancing resources would be necessary to avoid electricity shortages.
Many pathways have very high renewable energy penetration, which could be seen in the following table
showing the share of each technology in total electricity generation in 2047.
Least
Effort
Determined
Effort
Aggressive
Effort
Heroic
Effort
Coal
31%
50%
48%
17%
Renewable
and Clean
Energy
34%
Pathway
X
Min
Emissions
Max Energy
Security
56%
18%
28%
Gas_CCGT
4%
6%
0%
1%
1%
0%
0%
1%
Nuclear
1%
4%
8%
14%
11%
4%
14%
8%
Hydro
2%
4%
7%
10%
6%
5%
10%
7%
Biomass+Cogen
1%
2%
0%
0%
0%
0%
0%
0%
Hydro_Small
0%
1%
1%
2%
2%
1%
2%
1%
Wind
3%
10%
15%
21%
18%
15%
21%
22%
Solar
2%
10%
21%
34%
28%
18%
34%
32%
Electricity Imports
8%
2%
0%
0%
0%
0%
0%
0%
Waste to Electricity
0%
1%
0%
0%
0%
0%
0%
0%
Storage
0%
0%
0%
0%
0%
0%
0%
0%
Additional Grid
Balancing Support
(Peaking plants etc)
Total
47%
12%
0%
0%
0%
0%
0%
0%
100%
100%
100%
100%
100%
100%
100%
100%
Operational Assumptions
The assumptions regarding operational characteristics of generating plants such as ramp rates, heat rates,
auxiliary consumption, outages etc are given in the following table.
Unit
Size
(MW)
Minimum
Stable
Level (%)
Heat Rate
(GJ/MWh)
Auxiliary
Consumption
%
Forced
Outage
Rate
(%)
Maintenance
Rate (%)
Maximum
Ramp up
(MW/min)
Maximum
Ramp
down
(MW/min)
Start
Cost ($)
Coal Super
Critical
Gas_CCGT
660
50%
9
8%
5%
5%
2
2
10000
250
40%
7
3%
5%
5%
1
1
10000
Nuclear
410
100
50%
0%
10
0
10%
1%
5%
5%
5%
5%
1
10
1
10
10000
0
Small Hydro
20
20
0%
0%
12
0
10%
0%
5%
5%
5%
5%
0.5
2
0.5
2
100
0
Coal_CCS
660
40%
9
10%
5%
5%
2
2
10000
Hydro
Biomass
6
Waste to
Electricity
Grid Balancing
Resource
(Open Cycle
Gas CT)
20
0%
12
10%
5%
5%
0.5
0.5
100
50
0%
12
2%
5%
5%
5
5
100
Renewable Energy
Hourly wind generation patterns (onshore) have been extrapolated from the historical actual wind
generation profiles in the key states like Maharashtra and Tamilnadu. Same pattern (with higher capacity
factors) are assumed for offshore wind. Solar PV generation profiles have been estimated using System
Advisor Model (SAM) of National Renewable Energy Laboratory. SAM takes the historical solar irradiance
data and projects the expected hourly PV output. Same irradiance pattern is used for CSP, albeit with
dispatchable storage. The following charts show the average seasonal profiles (normalized to the annual
average) of onshore wind and solar PV generation (national level). The same profiles have been used in
all the pathways.
4.5
Wind
2.0
Average Summer Day
Average Monsoon Day
1.5
Average Winter Day
1.0
0.5
Normalized PV Generation (Annual Average = 1)
Normalized Wind Generation (Annual Average = 1)
2.5
4.0
3.5
Average Summer Day
Solar
Average Monsoon Day
Average Winter Day
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0.0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
One can see that the wind generation in India peaks in Monsoon (June through August) and has a
favorable diurnal profile for meeting an afternoon peaking space cooling load. Moreover, in monsoon,
wind generation is significant for all 24 hours, which is not the case in winter and therefore has a major
impact on the integration costs/strategies. Solar generation peaks in the summer and the diurnal profile
does not change much across seasons. The seasonal complementarity between wind and solar generation
is also evident from the above charts. In summer, solar generation peaks while overall wind generation is
low; in monsoon, wind generation peaks while solar generation drops. Both solar and wind generation
drop significantly in winter; thus, for aggressive renewable energy penetration pathways, most of the grid
balancing support (storage, gas CT etc) is required in the winter.
Key Findings
Based on the simulation results, we find that all the pathways are technically feasible and the electric grid
can be reliably dispatched with support from additional grid balancing / flexible sources like open cycle
gas turbines, storage (batteries, pumped hydro etc) or smart grid /demand response etc.
7
Balancing Electricity for Renewable Integration
In general, when the grid has very high RE penetration, the system would need significant capacity of
flexible resources in order to integrate the renewable energy projects into the grid reliably. The key
services provided by the grid balancing sources are primarily: (a) capacity support during peak load hours,
(b) ramping support (ramp-up and ramp-down) particularly during morning and evening peak hours, and
(c) energy support during winter evening peak periods, as wind and solar outputs drop.
In case of Least Effort and Determined Effort Pathways, significant grid balancing support in the form of
additional hydro / gas turbine power plants would be required. Interestingly, in both scenarios such
additional resources are needed to meet the electricity demand reliably and not necessarily to integrate
the renewable energy. In all other pathways, there is significant over-capacity in generation with
conventional and dispatchable generation covering nearly 80-90% of peak demand. Therefore, there is no
need for additional flexible resources for grid balancing.
The following table shows the additional grid balancing requirement for each pathway.
Pathway
Additional Grid
Balancing Support
(GW) (storage,
peaking plants etc
PLF
Least Effort
Determined Effort
335
82
89%
84%
Aggressive Effort
0
0%
Heroic Effort
Renewable and Clean
Energy
Pathway X
Min Emissions
Max Energy Security
0
0
0%
0%
0
0
0
0%
0%
0%
In the Least Effort and the Determined Effort pathways, significant additional grid balancing support is
required. This is because the planned generation capacity is not able to meet the electricity demand fully.
Therefore, the grid balancing resources are used not only as flexible resources but also as energy
resources, which is evident from their high capacity factors (PLFs).
In all other scenarios, although the renewable energy penetration is very high, the conventional capacity
already available to balance such high RE penetration is also high and therefore, no additional flexible
resources are required.
RE Curtailment and Storage Requirements
In most of the pathways presented above, the renewable energy penetration is as high as 30-60% by
energy. In some pathways, the installed capacity of renewables is significantly higher than the system
peak demand. For example, in the Heroic Effort or Minimum Emissions pathways, renewable capacity is
more than 1400 GW and the system peak demand is 650 GW. Therefore, at times (particularly, during
8
peak RE seasons i.e. summer and monsoon), the total RE generation is more than the demand or the
conventional plants cannot back down anymore because of the system security constraints or minimum
flow constraints of the hydro power plants. In those hours, renewable energy needs to be curtailed. As
shown in the hourly dispatch charts (negative generation), the curtailment could be significant in summer
and monsoon (average hourly curtailment reaching as high as ~165GW in monsoon). For Heroic effort and
Minimum Emissions pathways, more than 15% of the energy generated by wind and solar projects needs
to be curtailed for a reliable grid operation.
Note that with aggressive RE penetration, winter requires significant energy support especially to meet
the evening peak. This implies that the cost-effective energy storage solution should be cross-seasonal i.e.
it should be able to transfer the energy from summer/monsoon to winter. For example, the total RE
curtailment in the Minimum Emissions pathway is more than 80% of the total hydro generation.
Battery storage or other diurnal storage technologies would help manage the diurnal capacity support
issues (like ramping, reserves, and other ancillary services) in summer or monsoon, but their support
would be limited in winter. Hydro projects (with optimized dispatch) could serve as the cross-seasonal
energy storage; however, their effectiveness would be restricted given the long construction lead times
and limited potential in the country. Therefore, aggressive demand response (for peak capacity issues)
and energy efficiency programs (for energy support) would be the key to the grid balancing solutions.
Hourly Dispatch
The following charts show the average hourly grid dispatch for each pathway in summer (April-May),
monsoon (June-August) and winter (December-February).
9
Least Effort Pathway
Key insight: Electricity Imports (from the Calculator) and Grid Balancing resources dominate the total
supply. Although renewables penetration is significantly lower than the other pathways, significant grid
balancing support is required – mainly as a base load energy resource.
Average hourly dispatch in each season
Least Effort - Summer (April - May)
900
Generation at bus-bar (GW)
700
500
300
100
-100
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
-300
Least Effort - Monsoon (June - August)
900
Generation at bus-bar (GW)
700
500
300
100
-100
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
-300
Least Effort - Winter (Dec - Feb)
900
Generation at bus-bar (GW)
700
500
300
100
-100
1
2
-300Nuclear
Other_RE
Storage
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
Coal
Wind
Grid_Balancing
Gas
Solar
RE Curtailment
Hydro
Electricity_Imports
10
Determined Effort Pathway
Key insight: Solar PV and CSP (with thermal storage) make significant dent in the summer afternoon peak,
while wind provides significant electricity in monsoon. However, grid still needs additional balancing
resources as a base load supply to meet the demand; solar thermal storage does help, but given its
installed capacity the grid needs additional balancing support.
Average hourly dispatch in each season
Determined Effort - Summer (April - May)
900
Generation at bus-bar (GW)
700
500
300
100
-100
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
-300
Determined Effort - Monsoon (June - August)
900
Generation at bus-bar (GW)
700
500
300
100
-100
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
-300
Determined Effort - Winter (Dec - Feb)
900
Generation at bus-bar (GW)
700
500
300
100
-100
-300
1
2
3
Nuclear
Other_RE
Storage
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
Coal
Wind
Grid_Balancing
Gas
Solar
RE Curtailment
Hydro
Electricity_Imports
11
Aggressive Effort Pathway
Key insight: Renewable energy generation increases. But there is enough conventional capacity in the grid
to integrate that. No RE curtailment is necessary.
Average hourly dispatch in each season
Aggressive Effort - Summer (April - May)
900
Generation at bus-bar (GW)
700
500
300
100
-100
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
-300
Aggressive Effort - Monsoon (June - August)
900
Generation at bus-bar (GW)
700
500
300
100
-100
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
-300
Aggressive Effort - Winter (Dec - Feb)
900
Generation at bus-bar (GW)
700
500
300
100
-100
-300
1
2
3
Nuclear
Other_RE
Storage
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
Coal
Wind
Grid_Balancing
Gas
Solar
RE Curtailment
Hydro
Electricity_Imports
12
Heroic Effort Pathway
Key insight: Significant increase in the RE capacity requires the conventional plants to back down to their
minimum during summer and winter. Given the large conventional capacity available, no additional grid
balancing is required but significant RE curtailment is necessary in all seasons. Solar CSP (with storage)
helps in meeting the evening peak demand in all seasons.
Average hourly dispatch in each season
Heroic Effort - Summer (April - May)
900
Generation at bus-bar (GW)
700
500
300
100
-100
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
-300
Heroic Effort - Monsoon (June - August)
900
Generation at bus-bar (GW)
700
500
300
100
-100
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
-300
Heroic Effort - Winter (Dec - Feb)
900
Generation at bus-bar (GW)
700
500
300
100
-100
-300
1
2
3
Nuclear
Other_RE
Storage
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
Coal
Wind
Grid_Balancing
Gas
Solar
RE Curtailment
Hydro
Electricity_Imports
13
Minimum Emissions Pathway
Key insight: Significant increase in the RE capacity requires the conventional plants to back down to their
minimum during summer and winter. Given the large conventional capacity available, no additional grid
balancing is required but significant RE curtailment is necessary in all seasons. Solar CSP (with storage)
helps in meeting the evening peak demand in all seasons.
Average hourly dispatch in each season
Min Emissions - Summer (April - May)
900
Generation at bus-bar (GW)
700
500
300
100
-100
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
-300
Min Emissions - Monsoon (June - August)
900
Generation at bus-bar (GW)
700
500
300
100
-100
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
-300
Min Emissions - Winter (Dec - Feb)
900
Generation at bus-bar (GW)
700
500
300
100
-100
-300
1
2
3
Nuclear
Other_RE
Storage
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
Coal
Wind
Grid_Balancing
Gas
Solar
RE Curtailment
Hydro
Electricity_Imports
14
Renewable and Clean Energy Pathway
Key insight: RE penetration is lower than the Minimum Emissions and Heroic Efforts Pathways. Therefore,
RE curtailment is significantly lower (~5%). The grid still has very large under-used conventional capacity.
Therefore, no additional balancing support is required.
Average hourly dispatch in each season
Renewable and Clean Energy - Summer (April - May)
900
Generation at bus-bar (GW)
700
500
300
100
-100
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
-300
Renewable and Clean Energy - Monsoon (June - August)
900
Generation at bus-bar (GW)
700
500
300
100
-100
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
-300
Renewable and Clean Energy - Winter (Dec - Feb)
900
Generation at bus-bar (GW)
700
500
300
100
-100
-300
1
2
3
Nuclear
Other_RE
Storage
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
Coal
Wind
Grid_Balancing
Gas
Solar
RE Curtailment
Hydro
Electricity_Imports
15
Maximum Energy Security Pathway
Key insight: RE penetration is lower than the Minimum Emissions and Heroic Efforts Pathways. Therefore,
RE curtailment is somewhat lower (~10%). The grid still has very large under-used conventional capacity.
Therefore, no additional balancing support is required.
Average hourly dispatch in each season
Max Energy Security - Summer (April - May)
900
Generation at bus-bar (GW)
700
500
300
100
-100
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
-300
Max Energy Security - Monsoon (June - August)
900
Generation at bus-bar (GW)
700
500
300
100
-100
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
-300
Max Energy Security - Winter (Dec - Feb)
900
Generation at bus-bar (GW)
700
500
300
100
-100
-300
1
2
3
Nuclear
Other_RE
Storage
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour of the day
Coal
Wind
Grid_Balancing
Gas
Solar
RE Curtailment
Hydro
Electricity_Imports
16