Case Study:

Charting the course to 100% Renewables in Hawaii

Video Presentation by Dr. Gary Dorris

Download PDF

2,282 MW

Total Capacity






2016 Renewable Energy


Hawaii is blazing the trail for 100% renewable energy, pairing ambitious goals with Ascend Analytics' modeling software and services.

Hawaii has been called the 'Silicon Valley of clean energy' and rightfully so, given the state has far more rooftop solar per capita than any other and equally ambitious legislation to match.  The Hawaiian legislature passed a bill mandating a 100% renewable energy supply by 2045, the most aggressive renewable energy goal of any in the country.  As islands that must import nearly all their fuel, Hawaii's goal is an attempt to eliminate import-dependence, diversify the supply mix, reduce fuel costs, and curtail carbon emissions.

Integrating renewables on a large scale is incredibly challenging.  Solar and wind generation, both highly dependent on fickle weather conditions, introduce dramatic fluctuations to the energy supply which can be hard to counter-balance.  Faced with this and many other challenges of renewable integration, Hawaiian Electric Industries Inc. (HECO) asked Ascend Analytics to evaluate the company's long-term resource plan and help it meet three main objectives:


  • Calculate the optimal resource mix needed to become 100% renewable by 2045,
  • Model load and renewables on a sub-hourly timescale to determine flexible capacity needs, and
  • Determine optimal battery deployment.

























Ascend analyzed various, HECO-proposed resource plans, comparing a thorough range of portfolio characteristics:


  • Costs.  Ascend calculated the total net present value (NPV) of each plan, accounting for capital, production, risk, and unserved energy costs.


  • Optimal renewable mix. By optimizing the mix of renewables in each plan, Ascend helped HECO understand the tradeoffs between additional solar and wind production.


  • Flexible generation needs.  Minutely weather variations lead to constant uncertainty in production needs; Ascend addressed this uncertainty by detailing exactly how much flexible generation HECO would need under each power supply plan.


  • Storage.  Ascend determined that Hawaii could reach its goal of 100% provided HECO adds significant battery storage to its resource mix.



Prior to working with Ascend, HECO had difficulties adopting a planning process that accounted for the extreme variability of renewables at the hourly and sub-hourly scale. Rather than evaluating pre-formulated portfolio scenarios, Ascend accounted for the variability of renewable generation by stochastically simulating a full range of possible weather conditions in our PowerSimm software.  The graph below is output from PowerSimm; it shows how flexible, fast-ramping generation drastically fluctuates from about 8am to 6pm when the sun is out and solar generation peaks.  Using this and other detailed figures on how renewables would impact generation needs, HECO can plan for its future resource needs down to the minute.


On July 14, 2017, after multiple attempts and much stakeholder input, the Hawaiian Public Utilities Commission accepted HECO's Ascend-advised PSIP.  According to Todd Kanja, System Planning General Manager at HECO, this success, "...certainly could not have [been] achieved....without the efforts and contributions from the team at Ascend."


By providing HECO with the optimal combination of renewables, thermal generation, and battery storage, HECO can begin to:




Global Headquarters

1877 Broadway, Suite 706

Boulder, Colorado 80302

p.  1.303.415.1400



Montana Office

222 E Main, Suite 201

Bozeman, Montana 59715


California Office

440 Grand Avenue, Suite 420

Oakland, California 94610


©2018 Ascend Analytics, LLC

All rights reserved

Privacy Policy 2018