Think B.I.G. Hawaiʻi · Energy Self-Reliance (ESR) framework · Maui County
How Maui County’s power grids got here, where today’s plans take them, and what 95% self-reliance would take
Every major power plant on Maui, Molokaʻi and Lānaʻi since 2000, sized by capacity and colored by fuel. The three islands have separate grids, all run by Hawaiian Electric (formerly Maui Electric). Play the history, then the buildout of projects under contract. Below the map, a simulator lets you choose what to build and how fast, to see when the county could get 95% of all its energy — electricity, cars and trucks, boats, interisland flights and industry — from island sources.
Share of electricity sales by source
Hawaiian Electric, 2005–2025.
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, not yet built, or never built. Contours are schematic (simple cones for each volcano), not survey data. Kahoʻolawe has no grid. 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 Maui Electric planned, and what happened
Renewable share of Maui County’s electricity: plans vs. actual
Actual: share of sales to 2021, share of generation from 2022 (Act 240). The PSIP and statutory targets were set for all of Hawaiian Electric’s islands together. Hollow points are estimates.
The plans, in brief
Aug 2014 PSIPs: about 65–67% renewable by 2030 across Hawaiian Electric’s three utilities, with LNG as a bridge fuel. LNG was dropped; Maui County reached 41.6% in 2025.
2016 PSIP update: 48% by 2020 and 72% by 2030 utility-wide. Maui County was at 51% of sales in 2020 but has hovered there since.
Kahului retirement: first set for 2024, then 2028. In May 2026 the EPA partly rejected the state’s haze plan, leaving the date unclear.
2018–2021 solar contracts: five Maui projects approved by the PUC; four were terminated (including Paeahu, Nov 2023). Only Kūihelani (60 MW + 240 MWh, 2024) was built.
Stage 3: Kūihelani Phase 2 (40 MW, 2028), Pūlehu Solar (20 MW, 2027), the Waena battery (2027), a Kaheawa Wind repower (2027), and 40 MW of fuel-flexible ʻŪkiu engines (2028).
IGP RFP (2026): the approved first round covers Oʻahu and Hawaiʻi Island; Maui’s next resources are expected in a later round.
Molokaʻi and Lānaʻi have their own small diesel grids, included in the Maui County totals here.
2035 on current plans
Kūihelani Phase 2, Pūlehu and the Kaheawa repower lift the grid to the mid-to-high 50s by 2030. With nothing more contracted, it stalls around 60%, and Māʻalaea keeps burning oil. Cars, trucks, boats, planes and industry still run on imported fuel, so all-energy self-reliance stays under a fifth.
Simulator: what gets Maui County to 95% self-reliance?
Choose what to build and when. Results update as you move the controls. Start from a preset, then adjust.
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
Item
This scenario
Reality 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 in the county: 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.
One county, three grids. Maui, Molokaʻi and Lānaʻi have separate grids; the model treats them as one county total, so it understates how hard the two small diesel grids are to convert.
Grid dispatch is annual, with a simple day/night split: wind and any new firm plant 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 fill the rest. Surplus solar is curtailed unless e-fuels are switched on (50% conversion). A planning sketch, not a reliability study.
2025 starting point matches Hawaiian Electric’s 2025 RPS report for Maui County: 41.6% of 1,440 GWh (rooftop ~20.3%, wind ~13.3%, utility solar ~7.9%).
Key assumptions (low confidence flagged)
Base demand +0.5%/yr before electrification (Lahaina rebuilding could add more).
Road fuel: 62.0M gal gasoline + 6.2M gal highway diesel (DoTax CY2024, Maui County). 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 1,149 GWh-eq (Maui County’s 24% share of state aviation fuel applied to the ESR workbook’s interisland total) and marine 130 GWh-eq (18% of the state estimate) (low).
Propane ~6M gal and off-road diesel ~4M gal outside power plants (low).
The Kaheawa repower adds ~20 GWh/yr over today’s output (low); new wind at a 35% capacity factor.
ʻŪkiu engines count as fossil unless the biofuel slider supplies fuel.
2024 generation-basis share (41%) is estimated. Pālāʻau and Miki Basin capacities are approximate.
Sources
Hawaiian Electric, historical RPS data by island 2005–2024 (“historical_03_RPS”), sales basis.
NREL (2021), Assessment of Wind and Photovoltaic Technical Potential for the Hawaiian Electric Company; Think B.I.G. ESR Framework workbook (sector scope).
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.
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