Does an Island Approach to Higher 

Penetration Renewables Make Sense 

for the Mainland?

Robi Robichaud, Senior Engineer

ASES Solar 2018 Conference

August 7, 2018

NREL/PR-5000-72213
NREL | 2

Island Approach to Higher Penetration Renewables

Outline

• Where Are We Now?

• Higher Renewable Energy (RE) 

Penetration Challenges 

• Stakeholders—Island vs. Mainland

• Advantages of “Island Approach”

• What “Island Lessons Learned” Can 

Be Applied to Mainland Applications?
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The energy sectors

• Electric Power (38%)

• Transportation 

(29%)

• Industrial—Process/ 

HVAC/Other (22%)

• Commercial/ 

Residential (11%).

Challenges of Higher RE Penetration
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The energy sectors

• Electric Power (38%)

• Transportation (29%)

• Industrial—Process/HVAC/Other (22%)

• Commercial/Residential (11%).

Coal (34%)

Natural Gas (26%)

Nuclear (23%)

Renewable Energy (17%)

 Wind 6.2%

 Solar 1.8%

 Hydro 7.4%

DOE’s Wind Vision cites a penetration goal of 20% wind by 2030. 6.2% equates to 89 

gigawatts (GW) by end of 2017. To get to 20% the U.S. will need 287 GW by 2030.

DOE’s SunShot program does not cite deployment or penetration goals by 2030.

They cite energy cost goals: $0.05/kilowatt-hours (kWh) for residential PV; $0.04/kWh 

for commercial PV and $0.03/kWh for industrial PV. It is anticipated that at those 

levelized cost of energy (LCOE) levels, photovoltaic (PV) penetration rates across each 

market will be high.

Source: https://www.eia.gov/totalenergy/data/monthly/pdf/flow/css_2017_energy.pdf

Challenges of Higher RE Penetration
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Stakeholders

• Any utilities expecting reduced revenues or 

fewer customers

• Any generator seeing declining percentage or 

declining capacity from existing generation

• Any transmission owners that will see drop in 

use of their transmission lines and revenue

• Landowners impacted by new installations of 

wind, solar, pumped storage hydro, 

geothermal, or biomass

• Environmental orgs seeing new development 

impacting endangered or threatened species.

Challenges of Higher RE Penetration
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• Most of us were not alive when many of today’s 

nuclear, coal, and hydro plants were permitted 

and installed

• Same with many of the transmission lines (though 

2005–2020 has new capacity in regions; very little 

capacity additions added late 1980’s–2005 due to 

deregulation uncertainty)

• In the 1930’s (except for impact of Great 

Depression—economic stagnation/shrinkage) 

Public Works Administration drove installation of 

large hydro

• 1940’s, 50’s, and 60’s—the economic pie was 

always getting larger; generation needs always 

growing; regulated utilities planned for growth 

and got more generation, transmission.

What Is Different Today?
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Kaua’i Island Utility Co-op (KIUC) has 140 employees.

Rural electric co-op exists solely to provide electricity to its members and:

• Provide safe, reliable, fairly and competitively priced power

• Encourage conservation and efficient use of resources

• Increase sustainable power supply and environmental stewardship.

Source: http://kiuc.coopwebbuilder2.com/sites/kiuc/files/PDF/annualreport/AnnualReport2017.pdf

2008: Renewable Energy Goal 50% by 2023

2010: 92% of energy from imported oil

Kaua’i Island Utility Cooperative (Co-op) Profile
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33,000 customers 439,000 megawatt-hours (MWh) $0.33/kWh

Source: https://www.eia.gov/state/print.php?sid=GQ

Kaua’i Island Utility Co-op Profile 

2016 Utility Bundled Retail Sales - Total

(Data from forms EIA-861- schedules 4A & 4D and EIA-861S)

Entity Customers 

(Count)

Sales 

(Megawatthours)

Revenues 

(Thousands Dollars)

Average Price 

(cents/kWh)

Hawaii Electric Light Co Inc 84,609 1,067,398 309,521.3 29.00

Hawaiian Electric Co Inc 304,261 6,660,195 1,466,224.8 22.01

Kauai Island Utility Cooperative 32,967 439,088 143,007.0 32.57

Maui Electric Co Ltd 70,724 1,117,742 306,766.9 27.45

OneRoof Energy, Inc. 290 2,971 353.3 11.89

SolarCity Corporation 3,810 55,514 7,063.7 12.72

Spruce Finance 160 1,826 375.5 20.56

SunEdison LLC 16 5,063 1,116.4 22.05

SunPower Capital Services, LLC 180 2,129 506.7 23.80

SunPower Capital, LLC 659 8,540 1,608.1 18.83

Sunnova 316 3,159 646.2 20.46

Sunrun Inc. 3,883 34,993 7,209.0 20.60

Vivint Solar, Inc. 4,341 38,529 8,399.9 21.80
Source: http://kiuc.coopwebbuilder2.com/sites/kiuc/files/PDF/annualreport/AnnualReport2017.pdf NREL | 9

Kaua’i Island Utility Co-op Profile 

91.5 Megawatts(MW)/44%

156.5 NW/80%

Total Renewable Energy in 

Service 2017

Potential Renewable Energy in 

Service 2025
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Source: http://kiuc.coopwebbuilder2.com/sites/kiuc/files/PDF/annualreport/AnnualReport2017.pdf

Kaua’i Island Utility Co-op Profile 
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2017: New RE penetration goal—70% RE by 2030

Source: http://kiuc.coopwebbuilder2.com/sites/kiuc/files/PDF/annualreport/AnnualReport2017.pdf

2017: 

• Solar plus storage: 20 MW of storage for 5 hours—> 100 

MWhs of solar for meeting peak evening demand

• Power purchase agreement (PPA) for 14 MW of solar PV 

with 70 MWhs of battery energy storage systems (BESS) at 

Pacific Missile Range Facility—Barking Sands.

PPA price for each was ~$0.11/kWh for 25 years

2017: 44% RE—hydropower, biomass, and solar PV

For KIUC, they are actually experiencing a downward pressure on 

rates due to cost of renewable PPA’s.

Kaua’i Island Utility Co-op Current Projects 
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Landowners on Kauai with thousands of acres of fallow agricultural land 

who were eager to collaborate on projects in order to put some of their 

land to productive use.

In 2005, KIUC commissioned a study to identify viable renewable 

technologies:

• Wind, biomass, hydroelectric, landfill gas, and waste-to-energy rose to 

the top.

KIUC indicated that: a) state tax incentives for solar coupled with b) 

federal tax incentives have been big factors in utility scale projects.

Having good relationships with local, state, and federal elected officials is 

one key to success.

Biomass was the first to be completed (6.7 MW; 10.4% of load).

KIUC Success Factors in Higher RE Penetration
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https://www.eia.gov/state/print.php?sid=GQ

Guam Power Authority Profile
Source: http://www.guampowerauthority.com/gpa_authority/about/gpa_fact_sheet.php and GPA staff. NREL | 14

• 2008 set RPS goal of 25% RE by 2035

• GPA will have met Guam’s Renewable Portfolio Standard 

(RPS) of 25% a decade early 

• New goal is 50% by 2028

• Per current plans, will likely achieve by 2025.

Guam Power Authority (GPA) Background and Beginnings:

· Established May 1968 by the Guam Power Authority Act of 1968

· GPA is a public corporation and an enterprise fund of the Government of Guam

· GPA's governing board is the Consolidated Commission on Utilities (CCU) consisting 

of five elected commissioners. 

Major Plant Assets 

· 525 MW Gross Generation Capacity 

· 175 Miles of Transmission Lines 

· 646 Miles of Distribution Primary Lines 

· 28 Substations.

Employees and Customers 

· 512 Employees (9/30/14) 

· 49,297 Customers (9/30/14).

Guam Power Authority Profile
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GPA completed a Renewable Integration Study. 

Executive Summary findings include:

Risks of not implementing these improvements include 

inverter cessation during disturbances, increased load 

shedding, and possible system collapse.

Guam Power Authority Study Results

• Existing system cannot accept renewables due to several main issues:

o Non-responsive and non-flexible generation

o Low short-circuit currents

o No automatic generation control (AGC) 

o Slow 34.5 (kiloVolt) kV and 115 kV fault clearing

o Fault-induced delayed voltage recovery.

• With improvements, GPA system can accept renewables up to the economic 

limit of the renewables, not technically limited

• Required immediate improvements are:

o 115 kV relay upgrades/communication

o 34.5 kV relay upgrades.
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Guam Power Authority Study Results

Executive Summary findings include (continued):

• Required immediate improvements are:

o Flexible generation plant

o Malojlij – Agana 115 kV transmission line

o Energy Storage System (ESS) transient grid support.

The future:

• System with new generation and Phase III & IV renewables was studied 

out to 2029

• Required improvements for Phase III PV

o Transient grid support from Phase II ESS

o Synchronous condensor at flexible generation plant

o Temes/Yigo/Macheches synchronous condensor upgrades 

o Load-shifting/grid support ESS

• Required improvements for Phase IV & beyond

o Load-shifting/grid support ESS.
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Specific Recommendations include:

• Synchronous condensers 

• BESS

o Contingency batteries 

o Energy shifting batteries

o Batteries all contribute to system contingency response

o GPA 40 MW/22MWh BESS

o Flexible, highly efficient new generation

• Retirement of Cabras 1&2 (diesel)

• Upgraded system protection for all transmission lines

o Five-cycle clearing far and near end 

o High-speed fiber communications for relays

• With Phase I, II, III renewables, GPA will be 25% RE production

o Phase II is 120 MW with BESS to control ramp ups/downs to one percent 

o Phase III will be 40 MW solar plus 40 MW/ 160MWh energy shifting BESS

• Automatic generation control to manage batteries, conventional generation. 

Guam Power Authority Study Results
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Description 2016 2017

2018 

(Today) 2025

Energy Source (% Electricity) (%) (%) (%) (%)

Fuel Oil 90.8% 90.2% 89.9% 67.2%

Solar 9.2% 9.7% 10.1% 32.8%

Wind 0.1% 0.1% 0.1% 0.0%

Generation Mix (MW) (MW) (MW) (MW) (MW)

Net Metering (NEM) (MW) 13.7 16.5 18 28

NRG Solar PPA (MW) 25.7 25.7 25.7 25.7

Wind (MW) 0.3 0.3 0.3 0.3

Existing Generation (MW) 390 390 390 258

New Flexible Generation Plant (MW) - - - 180

Phase II - Solar (MW) - - - 120

Phase III (MW) - - - 40

Phase IV (Approx 250 MW cumulative to 2028) - - - 250

Generation Mix Type (MW) (MW) (MW) (MW) (MW)

Fossil Fuel (Oil/Natural Gas) (MW) 390 390 390 438

BESS Supported Solar (MW) 39.4 42.2 43.7 213.7

Wind (MW) 0.3 0.3 0.3 0.3

Total (MW) 429.6 432.4 433.9 651.9

NEM by year (Incremental MW) 5.4 2.8 1.5 10

Guam Power Authority Energy Future Profile
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Buy-in is less expensive than burning fuel. 

Rooftop solar is challenging from a utility perspective. 

Utility-scale PV has lower costs and more benefits.

Between solar PV, new more efficient generation, and natural gas, GPA 

should be able to significantly lower power rates.

GPA intends producing 50% of its energy from renewables, mainly solar 

PV, by 2025.

Risks of not implementing these improvements include: inverter 

cessation during disturbances, increased load shedding, and possible 

system collapse.

GPA completed a Renewable Integration Study that provided detailed 

information on what was needed to transform existing grid into a high 

penetration RE grid. 

GPA Success Factors in Higher RE Penetration
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• All stakeholders can sit at the table and be 

part of the discussions—their case can be 

made, their voice can be heard

• A “Systems Approach” is necessary—and it 

becomes possible “on an island” because 

• All parties have to focus on agreed 

outcomes—higher penetration RE

• There is one utility, one owner of 

transmission/distribution, one primary 

generator, evolving via request for proposals 

(RFPs) for PPA

What Advantages Do Islands Have?
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• Existing global status quo will have great 

impact on a number of islands

• Everyone is impacted in some way with each 

decision—EVERYONE IS A STAKEHOLDER

o Island electricity is typically more expensive, so 

alternatives such as solar, wind, and storage have 

a smaller impact on ratepayers

o Where to locate new transmission or distribution

o Where to site new PV or wind or biomass or 

nuclear or pumped storage hydro (PSH)

What Advantages Do Islands Have? (Continued)
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• Start with representatives of the stakeholder 

groups (generation, transmission, 

environmental, landowners, ratepayers (all 

classes), etc. 

• Work to establish societal goals that the 

energy stakeholders play such a crucial role 

in attaining—focus on goals, not current 

position.

How Can the “Island Approach” Apply to the Mainland?
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• Work to identify the larger goals of the community 

(e.g., improved resilience, reduced CO2, higher 

penetration of RE technologies, better balancing of 

all generation technologies)

• Find strategies that everyone can agree moves 

towards that goal

• Find lower-cost strategies for solar, wind, and 

storage—will vary by region, resources, and cost

• Find ways to reduce/mitigate impact to the 

stakeholders most negatively impacted 

o Job training for displaced workers

o Opportunities to enter the market with new 

technologies.

How Can the “Island Approach” Apply to the Mainland?
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Questions ??

Robi Robichaud

Senior Engineer, NREL, Wind & Water Deployment

robi.robichaud@nrel.gov

Special thanks to Guam Power Authority and its partners:

A.E. Balajadia Consulting:

Andriano E. Balajadia, PE Principal

Electric Power System, Inc.:

David Burlingame, PE Principal

Guam Power Authority (GPA): 

John J. Cruz Jr., PE (Project Lead) Assistant General Manager, Engineering & 

Technical Services (AGMETS)

Jennifer G. Sablan, PE SPORD Manager

Lorraine O. Shinohara, PE Special Projects Engineer

Roel A. Cahinhinan, PE Special Projects Engineer

Francis J. Iriarte, PE Special Projects Engineer

Joven G. Acosta, PE Manager of Engineering

Irwin B. Loyola, PE Engineering Supervisor

Special thanks to Kauaʿi Island Utility Cooperative
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APPENDIX—Additional Info

Wind Vision: 20% Wind by 2030

The report’s conclusions include:

• Reaching 20% wind energy will require enhanced transmission 

infrastructure, streamlined siting and permitting regimes, improved 

reliability and operability of wind systems, and increased U.S. wind 

manufacturing capacity

• Achieving 20% wind energy will require the number of turbine 

installations to increase from approximately 2,000 per year in 2006 

to almost 7,000 per year in 2017

• Integrating 20% wind energy into the grid can be done reliably for 

less than 0.5 cents per kWh

• Achieving 20% wind energy is not limited by the availability of raw 

materials

• Addressing transmission challenges such as siting and cost allocation 

of new transmission lines to access the nation’s best wind resources 

will be required to achieve 20% wind energy.

Source: https://www.energy.gov/eere/wind/maps/wind-vision
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APPENDIX—Additional Info

SunShot Initiative: Wide-reaching U.S. Department of Energy (DOE) program 

partnering with research labs and industry to bring down the cost of solar PV 

significantly by 2030.

SunShot Progress and Goals

Source: https://www.energy.gov/eere/solar/sunshot-initiative
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APPENDIX—Additional Info

Source: https://www.eia.gov/totalenergy/data/monthly/pdf/flow/css_2017_energy.pdf