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# Western Wind and Solar Integration Study Phase 2

EPRI Cycling Webinar Debbie Lew, Greg Brinkman, Eduardo Ibanez – NREL Steve Lefton, Nikhil Kumar – Intertek APTECH Sundar Venkataraman, Gary Jordan – GE Energy September 11, 2013 NREL/PR

- 5D00

- 602492 wind

coal nuclear hydro Combined cycle Gas turbine PV CSP



# WWSIS1: The worst week of three years Can we integrate high penetrations of wind and solar into the Western Interconnection?
What do we need to do to accommodate this? 

# Western Wind and Solar Integration Study Phase 1

### Copyrighted page(s) removed. Copyrighted material is not available in Regulations.gov since it may not be reproduced without consent of the copyright holder. Removed pages can be viewed at the USEPA Docket Center, Public Reading Room.

Address: 1301 Constitution Ave, NW Room 3334 Washington, DC 20004 Telephone: 202-566-1744 Email: docket-customerservice@epa.gov4 

# Study Scope
Goal - Examine costs of cycling, emissions impacts of cycling, and compare wind and solar impacts

• We model the western grid based on transmission pl anning models and methodologies of the Western Electricity Coordinating Council (TEPPC 2020)

o 

## Results are specific to the grid and generator characteristics of the west



## • We examine grid op erations

o 

## This is not a transmission planning study

o 

## Reliability and stability are being examined in WWSIS -3



## • Used c ommercial software PLEXOS to model grid operations on 5 minute basis for year 20205 

# Ensured Technical Rigor

• Technical Review Committee met every 2 mo nths

o 

## Western Electricity Coordinating Council, Western Governor’s Association

o 

## DOE and other labs (Sandia, LBNL, NETL)

o 

## EPRI

o 

## Utilities (SRP, APS, PNM, TriState, WAPA, Xcel, Pacificorp, CAISO, BPA, NV Energy, ISO -NE, etc)

o 

## Other industry (NextEra, Energy Exemplar)



# • Working groups

o 

## Hydro (input from BPA, WAPA)

o 

## Reserves (input from reserve sharing groups)

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## Others



# • Nevertheless, any grid modeling has limitations6 

# Developed Emissions Data Set

• Measured hourly em issions from each fossil
- fueled plant in the U.S. for 2008

• CO 2 

# , NO X 

# , SO 2



# • For each plant:

• 

## Emissions rate as a function of generation

o 

## Additional emissions due to starts and ramps

0 20 40 60 80 100 120

1760 1765 1770 1775 1780NOx emissions (lbs/hr)

Hour of year Actual NOx Predicted NOx7 

# Developed Wear -and- Tear Cost Data Set

Upper and lower bounds developed for costs to reflect uncertainty ranges

Source: Kumar 2012, www.nrel.gov/docs/fy12osti/55433.pdf

.8 

# Scenarios Compare Wind and Solar

High Solar 8% wind 25% solar High Mix 16.5% wind 16.5% solar High Wind 25% wind

8% solar TEPPC

9.5% wind 3.5% solar CSP Plant Capacity (MW) 150 to 200 100 to 125 75 to 100 50 to 75 PV Plant Capacity (MW)

75 to 200 50 to 75 25 to 50 10 to 25 Wind Plant Capacity (MW)

710 to 1,650 250 to 710 140 to 250 70 to 140 10 to 709 

# Adding ~100,000 MW of Wind/Solar

PV (MW) CSP (MW) Wind (MW) Total (MW) TEPPC (9.5% wind, 3.5% solar) 7,074 4,352 27,900 39,326 High Wind (25% wind, 8% solar) 20,064 6,536 63,840 90,439 High Mix (16.5% wind, 16.5% solar) 40,374 13,997 43,118 97,489 High Solar (8% wind, 25% solar) 61,941 21,526 23,357 106,824



### • All wind and solar is sited in US portion of Western Interconnection. 2020 peak WECC load is 171 GW, of which 147 GW is in the US. TEPPC case uses same MW as TEPPC but all sited in US, giving 13% total VG penetration

• CSP has 6 hours storage

• WECC TEPPC 2020 PC1 case10 

# Spring Is Most Challenging for Operations11 

# No Renewables (0% Solar, 0% Wind)12 

# TEPPC (3.5% Solar, 9.5% Wind)

1213 

# High Wind (8% Solar, 25% Wind)14 

# High Mix (16.5% Solar, 16.5% Wind)15 

# High Solar (25% Solar, 8% Wind)

Solar is 60% PV and 40% Concentrating Solar Power with 6 hours thermal storage16 

# Coal Ramping Increases with Wind/Solar

Excludes must

- run gas combustion turbines which would distort statistics17 How much coal is committed

How much coal is dispatched 

# Little Impact on Coal Operation in Summer18 

# Spring: Wind Leads to Coal Shutdowns Solar Leads to Coal Rampdowns19 

# Renewables Displace Gas and Some Coal

Gas prices average $4.60/mmbtu20 

# How are emissions impacted by cycling?21 

# Emission Impacts of Cycling Are Relatively Small22 

# Wind
- and Solar
- Induced Cycling Can Have a Positive or Negative Impact on Emissions

0.00 0.50 1.00 1.50 2.00 2.50 3.00

0.4 0.5 0.6 0.7 0.8 0.9 1.0Average NOXemissionsrate (lbs/MWh)



### Fraction of maximum generation Coal CC CT GasSteam23 

# Average CO 2 

# Emission Rates From Coal Don’t Change24 

# Changes in NO X 

# Emission Rates Depend on Wind/Solar Mix25 

# Changes in SO 2 

# Rates Depend on Wind/Solar Mix26 

# How are wear -and- tear costs impacted by cycling?27 

# Electricity Costs Include Capital and Production Costs28 

# Production Costs Include Cycling Costs29 Cycling costs in these scenarios range from $271

- 800 million 

# Cycling Costs are 1% to 7% of Overall Production Cost30 33% High Mix has lower cycling costs than 13% TEPPC case Cycling costs increase by 13

- 24%Cycling cost (million $) 

# 33% Wind/Solar Induces $35 to $157 M/ yr of Cycling Costs31 

## Starts, not ramps, drive wear and tear costsCycling cost ($/MWh) 

## The average fossil

- fueled plant sees an increase in O&M of $0.47

- 1.28 per MWH generation 

# The Generator Perspective32 Cycling costs sometimes decrease

Gas CCs have a significant increase in cycling costs

Note: These are the lower bound cycling costsCycling cost ($/MWh) 

# Gas Combustion Turbines Bear Brunt of Cycling Costs33 

# From a System Perspective, Cycling Costs Are Relatively Small34 

### Production cost change of wind/solar ranges from $29.4

- $30.6 per MWh in the high penetration scenarios. Cycling costs reduce this by $0.14

- $0.67 per MWh of wind/solar 

# The System Perspective

Note: These do not include capital costs of construction of generation or transmission35 

# How do wind and solar impacts compare?36 

# Aggregation Reduces Variability37 

# PV Dominates Variability Extremes38 Removing the known path of the sun through the sky leaves us with weather/cloud variability which is significantly less 

# PV Variability Is Dominated by Sun Movement39 High Solar High Wind 

# High Solar Results in Less Transmission Use40 

# Solar Requires Less Reserves Than Wind

Scenario Contingency (MW) Regulation (MW) Flexibility (MW) No Renewables 3,361 1,120 0 TEPPC 3,361 1,158 1,193 High Wind 3,361 1,236 2,599 High Mix 3,361 1,211 2,035 High Solar 3,361 1,207 1,545 Contingency reserves are unchanged with wind/solar. High Wind/Solar requires up to 10% more regulating reserves than the No Renewables Scenario. High Wind Scenario requires Flexibility reserves of 3% of installed Wind/Solar capacity. This is reduced to 1% for the High Solar Scenario.41 

# Balanced Mix of W ind and Solar Reduces Curtailment42 

# Conclusions

• CO 2 

## , SO 2 

## , and NO x 

## emissions induced by cycling are a fraction of the overall reductions in emissions

o 

## Wind- and solar

- induced cycling can help or hurt emissions from a fossil plant, depending on plant type, wind/solar mix and penetration



## • Wind and solar increase cycling costs by $35 -157M /yr

o 

## From fossil perspective, cycling O&M increases by $0.47

- 1.28 per MWh of fossil generation

o 

## From system perspective, cycling reduces production cost savings by $0.14

- 0.67 per MWh of wind/solar



## • Wind and solar impact fossil plants differently but pr oduction cost savings is similar

• As with any analysis, conclusions specific to only to g rid footprint studied43 

# Contact Info.

• Debbie Lew

• 303
- 384
- 7037

• debra.lew@nrel.gov

• http://www.nrel.gov/wwsis44 

# Extra Slides45 

# What if gas prices change?46 

# Gas Price Has Greater Impact on Cycling Costs Than Wind and Solar Do47 

# With Low Gas Prices, Wind/Solar Still Displace Mostly Gas48 

# Adding Wind/Soar to $2.30 and $9.60 Gas Scenarios Results in Less Systemwide Cycling49 

# Adding Wind/Solar to $2.30 and $9.60 Gas Scenarios Results in Less Systemwide Cycling