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Ka Lae (South Point). Photo: Wasif Malik, CC BY 2.0

Think B.I.G. Hawaiʻi · Energy Self-Reliance map · Big Island

How energy self-reliant is the Big Island?

More than half of our electricity already comes from the sun, wind, volcano heat and rivers. But once you count the gasoline, diesel and jet fuel too, only about one unit of energy in seven used on the island is made here. See how we got here, where today’s plans lead, and what 95% would take.

57%of the grid’s power is renewable2025, share of generation
14%of all energy used comes from island sources2025, every fuel counted
94%renewable grid by 2035 on current plansmodel projection
25%all-energy self-reliance by 2035 on current plansmodel projection
▶ Play the map Try the 95% simulator Plans vs. reality
Where we are

Electricity is only part of the picture

The Big Island’s grid draws on a mix few places can match: geothermal heat from Puna, trade winds at South Point and Hāwī, small hydro plants near Hilo, rooftop solar across the island, and new solar-plus-battery plants such as Hale Kuawehi. By the state’s official measure, renewables made 57% of the power generated in 2025. (The older share-of-sales formula would have given 74.5%.)

But the grid is only one slice of the island’s energy. Cars and trucks, boats, interisland flights and industry still run almost entirely on imported fuel. Count every fuel, and about 14% of the energy used on the island comes from island sources.

Renewable share of the grid57%
Island-made share of all energy14%
A row of wind turbines across green pasture at Pakini Nui Wind Farm, South Point
Pakini Nui Wind Farm at South Point: 14 turbines, 21 MW. Photo: Yoshi Canopus, CC BY-SA 4.0
How the model works

Every fuel, in the same units

The model starts from 2025 data, including the utility’s renewable-energy reports and state fuel-tax records for gasoline, diesel and aviation fuel. It converts every fuel to the same energy units, so electricity, transport, shipping, flights and industry can be added together.

A simple year-by-year model then adds the projects already approved or out to bid: the Puna Geothermal repower to 46 MW, Keʻāmuku Solar (86 MW with 344 MWh of batteries, 2030) and the utility’s next round of solar-and-storage awards, plus steady rooftop growth and gradual EV adoption. On those plans the grid passes 90% renewable in the early 2030s, but all-energy self-reliance only reaches about a quarter by 2035.

GeothermalWindHydroSolar + batteriesImported oil
Rows of solar panels under a cloudy sky with mountains behind, at a Hawaiʻi solar farm
A Hawaiʻi solar farm. Utility solar plus batteries is the fastest-growing source of island-made power. Photo: Reegan Moen, U.S. Department of Energy (public domain, source)
Where it could go

What 95% would take

The 95% pathway goes further: faster solar and storage, firm renewable power, electrified industry, island-made fuels for boats and planes, and EV sales climbing along an S-curve, from today’s 14% of new cars to about 63% in 2035 and 91% in 2040.

Because cars stay on the road about 22 years, that last step sets the pace: on this path the Big Island doesn’t reach 95% until after 2060. Add trade-ins of old cars and more island-made fuel, and the simulator gets there by 2037. Every grid is capped at 99% renewable, so some fuel-fired backup always stays on for caution. These are planning sketches, not utility forecasts; the assumptions and sources are listed below the simulator.

Try the simulator →
A wind turbine against an evening sky beside the Hawi Renewable Development wind farm sign
The Hāwī wind farm on Upolu Point, North Kohala, commissioned in 2006. Photo: Yoshi Canopus, CC BY-SA 4.0
2025

Renewable share of electricity, by source

2025

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Renewable share of grid
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All-energy self-reliance
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Battery storage
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Icons show the technology; the colored halo’s area = nameplate MW. Dashed halos: planned but never built, not yet built, or offline. Contours are schematic (a simple cone model of the five volcanoes), not survey data. Green dots: rooftop solar, one dot ≈ 3 GWh a year; grey dots: off-grid homes (estimate). Moving cars, planes and boats are colored by what powers them: green = electric, light green = island-made fuel, terracotta = imported fuel; their share of each color follows the model, not counts of real vehicles. EV shares before 2025 are approximate. Plant locations are approximate.

What the utility’s plans said, and what happened

Renewable share of Big Island electricity sales: plans vs. actual

PSIP-era targets were stated on the old sales basis, so actuals are shown on that basis too. The official RPS has used a generation basis since 2022 (Act 240); the hollow point shows 2025 on that basis.

Each plan for the Big Island, in brief

  • Aug 2014 PSIP (HELCO): renewables from 60% of sales in 2015 to 92% in 2030. Add 20 MW of wind (2020), 25 MW of geothermal in West Hawaiʻi (2025), Hu Honua biomass (2015) and batteries; deactivate all oil-fired steam units. None of the new wind, geothermal or biomass was built.
  • Apr 2016 PSIP Update: Big Island “could achieve a 100% RPS by 2040”; 20 MW of firm renewable capacity in 2022; Puna steam unit deactivated.
  • Dec 2016 PSIP Update: statewide 100% by 2040. Big Island 2017–21 additions: 30.3 MW rooftop, 5.7 MW feed-in-tariff solar, 10.6 MW demand response, 1 MW grid-scale solar, 22 MW wind.
  • Stage 3 RFP (2023–25 awards): Keʻāmuku Solar 86 MW / 344 MWh (2030) and Hāmākua Firm Renewable Energy 60 MW + batteries.
  • IGP RFP (filed July 17, 2026; PUC-approved Aug 2026): for Big Island, 435 GWh/yr of renewable energy, up to 115 MW of grid-forming resources, 30 MW of firm capacity and 20 MW for 6 hours in East Hawaiʻi, in service 2031–2034. The RFP notes new firm capacity could let older oil units retire sooner.

2035 on current plans

Approved and solicited projects push the grid past 90% renewable by the early 2030s. Cars, trucks, boats, planes and industry still run on imported fuel, so all-energy self-reliance stays near a quarter.

Simulator: what gets the Big Island to 95% self-reliance?

Choose what to build and when. Results update as you move the controls. Start from a preset, then adjust.

Goal
Firm renewable power
Million gallons a year. About 2.4 today at the Hāmākua plant.
Solar, wind and storage
Cars and trucks

EV share of new-vehicle sales over time: pick a curve, or shape your own.

The year sales are halfway from today’s 14% to the long-run share. Sales follow an S-curve: slow, then fast, then leveling off.

Not part of the Hawaii EV Association calculator, and off in every preset except “All levers”. It would take a trade-in (cash-for-clunkers) program: 1% of all cars a year is about 11,000 extra cars statewide.
Buildings and industry
Boats and interisland flights
Million gallons a year made on-island.
All-energy self-reliance in goal year
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Self-reliance over time

All energy used on the island, by where it comes from (GWh-equivalent)

What this scenario asks the island to build

ItemThis scenarioReality check
How this works, assumptions, and sources

Method

All-energy self-reliance = island renewable electricity actually used, plus off-grid solar and fuels made on-island, divided by all energy used on the island: grid electricity, road gasoline and diesel, marine fuel, interisland jet fuel, propane and off-road diesel. Energy-content basis, as in the ESR framework. Transpacific flights and shipping are out of scope.

Grid dispatch is annual, with a simple day/night split: geothermal, hydro and wind serve load around the clock; solar serves the daytime half of what’s left; batteries (one cycle a day, 88% round trip) move surplus solar into the night; biofuel and then oil plants fill the rest. Surplus solar is curtailed unless e-fuels are switched on (50% conversion). This is a planning sketch, not a reliability study. Backup floor: each grid tops out at 99% renewable. We assume fuel-fired backup plants still supply at least 1% of each year’s electricity (storms, outages, maintenance, long windless or cloudy spells), and that every island keeps some backup for caution and diversity.

2025 starting point matches HECO’s 2025 RPS filing: 1,381 GWh generated, 57.3% renewable.

Key assumptions (low confidence flagged)

  • Base demand +0.5%/yr before electrification.
  • Road fuel: 80.4M gal gasoline + 12.2M gal highway diesel (DoTax 2024). EVs use 7.3 kWh per gallon of gasoline replaced and 12 kWh per gallon of diesel. 3.6% of cars electric at the end of 2025 (DBEDT: 42,919 of 1,082,932 passenger vehicles by Sept 2026). Fleet turnover, using the same method as the Hawaii EV Association site calculator: about 50,000 new vehicles join each year and stay ~22 years; today’s EVs leave the road at ~6% a year; the EV share of new sales (13.8% in 2025, HADA) drives the fleet. Even 100% EV sales from 2027 leaves 10% of cars on gas until about 2046. Trucks and buses are assumed to lag cars by five years. “Current plans” holds EV sales at today’s ~14%; the ESR pathway’s EV sales follow the “Steady” S-curve (about 26% of new cars in 2030, 63% in 2035, 91% in 2040), with no early retirement. Island-made fuels go to boats and planes; a switch extends them to the remaining gas and diesel vehicles.
  • Interisland jet fuel 708 GWh-eq and marine 108 GWh-eq in 2025, from the ESR workbook’s statewide figures and Big Island shares (low).
  • Propane ~8M gal (20% of ~40M gal statewide) and off-road diesel ~9M gal outside power plants (low).
  • Off-grid homes ≈ 17.5 GWh/yr of solar, growing 3%/yr. There is no official count (low).
  • PGV returns to 2024 output in 2026 and reaches 46 MW at 90% capacity factor in 2027 (timing).
  • Hāmākua firm plant (2029) burns today’s amount of biofuel unless you add more. The IGP’s 30 MW of firm capacity adds reliability, not renewable energy, unless it burns biofuel.
  • IGP RFP energy (435 GWh/yr) is modeled as solar + storage ramping in 2032–33, with 460 MWh of batteries. Part of it is meant to replace expiring contracts; to test that, tick “Existing wind farms shut down”.
  • New rooftop solar comes with about 1 MWh of usable home battery per MW (low). Capacity factors: rooftop 20%, utility solar 24–25%, wind 38%, geothermal 90%.
  • Electrifying industry and boats uses 0.4 units of electricity per unit of fuel replaced; electric aircraft the same.

Sources

  1. Hawaiian Electric, 2025 Renewable Portfolio Standard Status Report (PUC Docket 2007-0008): 2025 generation by resource.
  2. Hawaiian Electric, historical RPS data by island, 2005–2024 (“historical_03_RPS”), sales basis.
  3. Hawaiʻi Electric Light, Power Supply Improvement Plan, August 2014 (Docket 2014-0183): 60%→92% plan, preferred-plan additions, generating-unit table.
  4. Hawaiian Electric Companies, PSIPs Update Report, April 1, 2016.
  5. Hawaiian Electric Companies, PSIP Update Report, December 23, 2016, Executive Summary.
  6. Hawaiian Electric, IGP RFP filing, July 17, 2026 (Docket 2024-0258), and PUC approval, Aug 2026. Big Island quantities from the draft IGP RFP (June 27, 2025, Exhibit 1), whose totals match the filed RFP.
  7. Hawaiian Electric, Renewable Project Status Board (updated Dec 23, 2025); HSEO CREDIT Task Force master schedule, May 2026.
  8. PGV Repower approval (38 → 46 MW), ThinkGeoEnergy / Big Island Now, 2025.
  9. Hilo Coast Power to close, Honolulu Star-Bulletin, June 2004; Keāhole ST-7 in service June 22, 2009, LUC filing.
  10. Hawaiʻi Department of Taxation, Liquid Fuel Tax Base, CY2024; LP Gas, Propane Fuels America: Hawaii (≈40M gal, 2019).
  11. Think B.I.G. Hawaiʻi, Big Island ESR Framework workbook (draft, May 2026): sector scope, aviation and marine inputs.

Export your results

Save the year-by-year numbers for current plans and the scenario now set in the simulator, as a spreadsheet or a short PDF report. The map picture shows the year currently selected on the map’s slider.