Beyond Generation: The Grid Innovations Hawaiʻi Needs Next

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Naturally, just when Hawaiʻi’s decarbonization pathway starts to look complete, another chapter occurs to me. After the generation mix, the island-by-island resource story, the transport implications, and the logic of electrification, what remains is the part of the energy transition that fossil systems used to provide almost by accident. Hawaiʻi can build a renewables-heavy electricity system. The harder question is what keeps that system stable when the old fossil machines stop doing the work that spinning metal used to do for free. That is the next stage of the Hawaiian energy transition. It is less about adding more megawatts of clean generation and more about replacing the behaviors that conventional generators supplied by default, including inertia, voltage support, fault current, frequency response, and operating reserves.

That framing is consistent with work I have published over the past years on inverter-based resources, high-renewables grids, and grid-enhancing technologies. In my conversations with Cornelis Plet, now CTO of GE Vernova’s Grid Systems Integration division, the discussion centered on how modern power electronics, especially voltage source converter technologies, are changing what grids can do and how asynchronous systems can be managed. In my discussions with Mark O’Malley of Imperial College London, the focus shifted to what happens when grids become dominated by inverter-based resources, with his recurring point that grid-following and grid-forming are not a simple either-or but a continuum in which operators have to find the right system-specific balance. My recent series on grid-enhancing technologies made the same broader point from a different angle. Every constraint has its own tool. Advanced conductors solve one class of problems. Dynamic line rating solves another. Power flow control devices solve another. Buffering batteries solve yet another. None of them is magic, and none of them should be treated as interchangeable. Hawaiʻi is a place where that distinction matters a lot.

The reason it matters so much in Hawaiʻi is that the state is not dealing with one big synchronous grid in the way a continental system does. It is dealing with several island systems of different scales, each with its own mix of resources, its own transmission constraints, and its own dependence on rotating fossil machinery for ancillary services. On the mainland, when engineers talk about system strength, frequency stability, or reactive power support, they are often talking about problems spread across a broad interconnected network with large neighboring regions to lean on. In Hawaiʻi, every island has to live with its own balance. That makes the state more exposed, but it also makes the engineering cleaner. Weak assumptions show up faster. The services that matter become more visible. A fossil plant on one of these islands is not only an energy source. It is often still a voltage source, a fault-current source, a spinning reserve source, and a stabilizing mass in the system. Replacing its energy is one task. Replacing all of those functions is another.

Hawaiian Electric’s own materials make that explicit. The company says ancillary services were historically provided by conventional generating assets and increasingly can be provided by storage and demand response. That one sentence captures the transition. The old model was accidental. Burn fuel, spin metal, and get a package of useful behaviors along with the electricity. The new model is intentional. Design in the services one by one using batteries, advanced controls, inverters, demand-side systems, reactive power devices, and selective rotating support where it is still needed. Hawaiian Electric’s 2025 renewable portfolio reporting and related filings show the system in the middle of that transition. On Oʻahu, Schofield’s conventional plant was still called on for spinning reserves after wind units tripped. On Hawaiʻi Island, a battery storage state-of-charge problem after an unexpected CT3 outage contributed to underfrequency load shedding. Those are not theoretical edge cases. They are reminders that when conventional generators are reduced, the remaining grid has to be able to carry the stability burden itself.

The older planning documents are even clearer. Hawaiian Electric’s integrated grid planning materials noted that inverter-based generators historically could not provide the fault current required for protective relays, so those services came from conventional fossil-fueled units. That is not a small footnote. It tells us that the transition to renewables is also a transition in protection philosophy. If the relays, breakers, and protection schemes assume large synchronous fault current, then someone has to keep enough synchronous machinery online to provide it. If the grid is going to move past that, the answer is not simply to wait for more solar farms. It is to redesign the system around devices and protection methods that do not require fossil machines to remain spinning for the sake of grid physics. Hawaiʻi’s future grid is not just cleaner generation attached to the old operating model. It is a different operating model.

Kauaʻi is the clearest proof case that the new model is starting to work. KIUC has already been using a GE LM2500 gas turbine in synchronous condenser mode, with renewable energy from the grid keeping the machine spinning so it can provide stability services without burning fuel. That has allowed the cooperative to operate at 100% renewable on many sunny days. The fuel is reduced, but the rotating support is still there. That on its own is useful, because it shows that even legacy thermal equipment can be repurposed as bridge infrastructure. But the more interesting development is what comes next. Hawaiʻi’s State Energy Office and the U.S. Department of Energy backed two KIUC demonstration projects under the GRIP program. One adds advanced grid-forming inverter capability plus a 12 MW battery to each of two existing 12 MW solar plants. The other adds grid-forming capability to an existing generator at Port Allen. The state and DOE describe the goal in plain terms: frequency regulation, reactive power, voltage control, and operating reserves supplied by a renewables-heavy system rather than by fuel-burning plants. DOE projected immediate savings of about $300,000 from replacing fossil-provided grid services with renewable-backed alternatives. NREL has already reported that when a large generator tripped on Kauaʻi in 2023, the electrical disturbance that previously would have triggered oscillations did not do so because grid-forming controls had been added to the inverters. That is the future becoming visible on an actual Hawaiian island, not in a lab model.

Maui is the next frontier, and in some ways the most interesting engineering case. NREL has described Maui as potentially the first interconnected power system of its size, around 200 MW peak, to operate with 100% inverter-based resources during some periods. That is a major statement because 200 MW is large enough to matter and small enough for system behavior to remain legible. NREL’s electromagnetic transient analysis for Maui found that even changing a single resource from grid-following to grid-forming materially improves stability metrics in cases that would otherwise be unstable. That result matters beyond Maui. It suggests that the transition does not require every inverter on an island to become grid-forming at once. It requires enough of the right devices, placed in the right places, with the right controls. That fits Mark O’Malley’s point that the answer is not binary. It is about finding the right share and coordination of grid-forming and grid-following behavior across the system. Hawaiʻi is not trying to flip a switch from one world to another. It is trying to move to a different stability regime without losing service along the way.

That makes grid-forming batteries and hybrid renewable plants the center of the Hawaiian toolkit. Hawaiian Electric’s current procurement language already points there. For storage-equipped facilities, the utility requires grid-forming capability, autonomous operation after loss of the last synchronous machine where no reference is available, damping of adverse interactions among inverter-based resources, and black-start capability where applicable. That is not experimental language. It is procurement language, which means the concept has crossed from research into normal system planning. Oʻahu’s near-term grid needs assessment says the island will rely on wind, solar, battery storage, advanced inverters, and renewable firm generation. Hawaiʻi Island’s assessment says grid-forming capability is commercially feasible now from standalone storage, paired storage, and STATCOM devices. In practical terms, this means Hawaiʻi’s next wave of clean projects should not be judged only by how many MWh they produce in a year. They should be judged by how much of the old fossil stability package they can replace. A 100 MW solar plant that needs fossil spinning reserve behind it is less useful than a somewhat smaller or more expensive hybrid facility that contributes real grid support.

At the distribution edge, the cheapest and fastest stability gains come from requiring more of customer and community resources. Hawaiian Electric maintains a qualified equipment list for Rule 14H and IEEE 1547-2018 compliant advanced inverters, last updated on February 27, 2026. The utility’s technical materials identify the functions that matter: voltage and frequency ride-through, volt-VAR control, frequency-watt response, and volt-watt response. These features do not turn rooftop solar into a substitute for bulk system strength, but they do keep distributed resources from behaving like passive injections that disappear or misbehave when the grid is stressed. In a place like Hawaiʻi, where customer-sited solar is already a major share of renewable supply on several islands, that matters. Oʻahu’s 2024 renewable mix included 15.5% customer-sited renewables. Maui County was at 19.8%. Hawaiʻi Island was at 18.0%. If a fifth of delivered energy is already coming from customer systems, then the performance of those systems during disturbances is not a niche technicality. It is a core grid behavior question. Requiring and expanding grid-supportive inverter functionality across the DER fleet is low-hanging fruit compared with building new transmission or retaining more fossil reserve.

This is also where Hawaiʻi’s transition starts to look less like a supply problem and more like a controls problem. Once enough solar and batteries are on the system, the challenge is no longer just generating enough low-carbon electricity over the year. It is coordinating fast devices across milliseconds, seconds, and minutes. Grid-forming batteries can establish local voltage and frequency references. Grid-supportive rooftop systems can ride through disturbances instead of dropping offline. Demand response can shed or shift load faster than a thermal unit can ramp. Synchronous condensers can provide bridging support while the rest of the architecture matures. Protection settings can be revised so the grid no longer assumes a big fossil unit is always there. None of these changes is glamorous in the public imagination. But they are what turn a collection of renewable plants into a functioning high-renewables power system.

Synchronous condensers remain part of that picture, and Hawaiʻi should not be shy about that. The question is not whether spinning metal is bad. The question is what job it is doing, whether anything else can do that job better, and how long the transition is likely to take. Hawaiian Electric’s technical advisory panel noted that properly configured grid-forming inverters can provide benefits similar to a synchronous condenser, but with much lower fault-current contribution on a nameplate basis. That matters because fault current remains one of the sticking points in fossil-free operation. A synchronous condenser is not a clean-energy dead end if it is replacing fossil energy production with rotational support while the grid transitions to new protection schemes and inverter control architectures. But it is also not the final answer. It is bridge infrastructure. Hawaiʻi’s current use of synchronous condenser mode on Kauaʻi is a sign of maturity, not backsliding. It means the islands are willing to separate the useful behaviors of rotating equipment from the fuel consumption that used to accompany them. Over time, the aim should be to reduce how much of that support still depends on legacy rotating machines, but there is no reason to pretend the bridge is unnecessary.

Beyond inverters and spinning machines, Hawaiʻi also needs a second group of tools that sit in the voltage and system-strength category rather than in the energy category. STATCOMs and other dynamic reactive power devices are among the clearest examples. Hawaiian Electric’s 2021 stability framework puts grid-forming inverters, synchronous generators, synchronous condensers, and STATCOMs on the same broad support spectrum. Hawaiʻi Island’s recent grid needs study gets more concrete. It points to east-side voltage issues that could be addressed by adding or converting synchronous condensers, by adding a STATCOM, or by reconductoring the L6200 line. It also says south Hawaiʻi needs new dynamic reactive power sources closer to the area of concern. That is a reminder that many grid problems in renewables-heavy systems are not about insufficient MWh. They are about local voltage collapse risk, weak-grid conditions, and the inability to hold stable operating points when a disturbance occurs. In those cases, the right answer is not another solar farm. It is a device that can inject or absorb reactive power in the right place fast enough to matter.

The grid-enhancing technologies (GET) conversation fits here, but not as a grab bag. Hawaiʻi needs a filtered GET palette, not the whole catalog. My recent writing on the topic made that point repeatedly. Advanced conductors are useful where the right-of-way and towers exist but the wire itself is the thermal bottleneck. Dynamic line rating is useful where weather-driven thermal limits actually bind and where the rest of the path is not constrained by transformers, breakers, or voltage stability. Power flow control devices are useful where there are multiple circuits or network paths across which flows can be redistributed. Buffering batteries are useful when the constraint is time, especially in solar-heavy systems where the problem is not the daily energy volume but the midday surge and evening deficit. Hawaiʻi should not adopt these tools because they are fashionable. It should adopt them when they fit the actual constraint on a given island and circuit.

Oʻahu is where the classic GET toolkit matters most. It has the largest load, the densest built environment, and the most substantial corridor and substation constraints. Hawaiian Electric’s renewable energy zone work identified reconductoring and new-line needs around Wahiawa and Waiau, and found that a 345 kV Kahe-Wahiawa-Waiau loop could eliminate all identified 138 kV line upgrades for REZ groups 1 through 8. Whether that specific loop is the answer is less important than what it proves. Oʻahu’s bottlenecks are not just about having enough renewable generation in total. They are about moving electricity through constrained corridors and maintaining reliable flows into the largest load pockets. In that setting, advanced conductors make sense where wires are full. Corridor batteries make sense where solar surges can be buffered instead of forcing line upgrades. Selective power-flow control may make sense where the network topology offers alternatives. Oʻahu is the island where the mainland-style GET conversation has the strongest relevance in Hawaiʻi, because it has the closest thing in the state to a meshed transmission problem.

Maui is a different case. The island has meaningful transmission and substation constraints, but its more interesting challenge is showing that a mid-sized isolated grid can remain stable with very high instantaneous inverter penetration. That means controls and voltage support matter more than the headline GET devices. One grid-forming resource, properly placed, can materially improve stability. A few more can change the operating envelope of the island. Dynamic reactive power support and good inverter coordination are likely to deliver more value per dollar than broad deployment of DLR or power-flow devices. Maui still benefits from reconductoring and selected network upgrades where resource zones are remote from the main load, but its real importance is as a control-room proof case. If Maui can operate comfortably at very high inverter shares, it becomes one of the world’s most useful demonstrations that medium-scale isolated systems do not need fossil spinning mass to remain stable.

Hawaiʻi Island requires a different emphasis again. It has more resource room than the other islands, more wind and solar potential than Oʻahu, and geothermal as a major local pillar. But that does not simplify the grid challenge. It changes it. Hawaiian Electric’s studies indicate that the island needs geographically balanced generation and new dynamic reactive power sources, particularly on the east and south sides, because local voltage and system strength are limiting factors. That makes the right toolkit less about squeezing another few percentage points out of conductor ratings and more about placing system-strength devices where the network is weak. Grid-forming batteries, dynamic reactive support, selective reconductoring, and targeted synchronous condenser use where protection and fault current still need it all make sense here. A Big Island strategy built around the most fashionable GET acronym would miss the point. The real problem is a geographically stretched, weak-grid island with valuable local resources that have to be integrated without losing stability.

Kauaʻi, by contrast, is the live demonstration. It has already shown that renewable-heavy operation with synchronous condenser support and grid-forming controls can work. The logical next step is to make more of those services electronic and renewable-backed rather than relying on repurposed thermal machinery forever. That is not a criticism of the cooperative’s current approach. It is what success looks like. First use the gas turbine as a synchronous condenser so the island can stop burning fuel while keeping its stability. Then add grid-forming batteries and smarter inverter controls. Then reduce how much the island still depends on legacy rotating support. Kauaʻi is important because it turns the abstract debate into an operations story. The future grid is not an all-inverter leap in one motion. It is a sequence of substitutions that preserve reliability while the services migrate from fuel-backed equipment to electronically designed ones.

Molokaʻi and Lānaʻi point to another truth about GETs and inverter-based systems. On very small grids, the best answer is often not a transmission trick at all. It is stronger controls, a higher proportion of grid-forming storage, carefully designed reserve margins, and conservative operating procedures. In the island-by-island analysis, both Molokaʻi and Lānaʻi emerged as systems where a few megawatts of retained firm generation still materially affect reliability outcomes. That suggests these islands will benefit more from a stability-first approach than from a capacity-first approach. Strong inverter requirements for any new solar or storage, batteries capable of grid-forming operation, well-designed airport and harbor charging buffers, and perhaps selective rotating support where needed are likely to matter more than DLR or power-flow control. A small grid can be highly renewable without being cavalier. In fact, the smaller the grid, the less room there is for bravado.

That is also why buffering batteries deserve a larger place in Hawaiʻi’s future than they usually get in standard grid discussions. In my March 2026 writing on buffering batteries, I argued that they are often the cleanest way to solve a time-based grid constraint. A line is overloaded at noon because solar is flooding one part of the system. Another part of the same network needs that energy later in the day. Instead of immediately reaching for a bigger wire, place storage near the constraint, charge it when the corridor is crowded, and discharge it later when the corridor is free. In Hawaiʻi, where solar is central on every major island and where several systems are small enough that midday surges can be operationally meaningful, this is likely to be one of the most valuable tools in the box. It also fits the broader logic of the state’s energy transition. Hawaiʻi is already becoming a battery state, not just through EVs and utility-scale storage, but through the way batteries can substitute for both peakers and wires in the right context.

Dynamic line rating is more limited in Hawaiʻi than some enthusiasts might hope. My own article on DLR made the case that the tool is real and useful, but only when weather-sensitive thermal ratings on the conductor are the actual bottleneck. Hawaiian Electric’s technical advisory process echoed that caution. In solar-dominant systems, DLR may not add much value because the times of peak solar output do not always coincide with the most generous ambient conditions, and the limiting element may not be the line at all. If the true bottleneck is a transformer, a breaker, a voltage support issue, or a single radial path, DLR solves the wrong problem. Hawaiʻi should use DLR where the facts support it, but it should not build a strategy around it. Advanced conductors and buffering batteries are likely to have wider application.

Power flow control devices occupy a similar category. They can be highly useful in meshed networks with parallel paths and large power transfers where flows need reshaping. But on a radial or weakly meshed island network, there may not be enough alternative paths for those devices to matter much. That is why Oʻahu is the main candidate for them, and why the smaller islands are not. The right lesson from the GET series is not that every island needs every tool. It is that each island should use the minimum set of tools that fit its real problem. Hawaiʻi’s grid innovation palette should be wide, but its application should be selective. The most expensive mistake in grid modernization is solving the wrong constraint elegantly.

In the end, the grid story for Hawaiʻi is a shift from a system stabilized by fuel consumption to one stabilized by design. That is the real transition taking place beneath the public conversation about renewables. Solar panels and wind turbines change where the energy comes from. Batteries, inverters, reactive-power devices, advanced controls, and selective GETs change how the grid behaves. Fossil plants gave the islands stability as a side effect of burning oil. A renewables-heavy Hawaiʻi has to provide those same services on purpose, using devices engineered for the task. In a sense, that makes the future grid more honest. Its stability is not accidental. It is planned, procured, tested, and placed where it is needed.

That also means the order of operations matters. The first step is requiring and expanding advanced inverter functions at the grid edge, because customer solar and batteries are already too large a share of the system to be treated as passive. The second step is making grid-forming capability standard in new utility-scale storage and hybrid renewable plants, because that is where the largest share of future system services will come from. The third step is keeping synchronous condensers and other rotating support where protection and fault current still require them, but treating them as bridge infrastructure rather than a reason to preserve fossil generation. The fourth step is adding dynamic reactive support such as STATCOMs where local voltage weakness is clear. The fifth step is using GETs surgically, with advanced conductors and buffering batteries first, DLR where thermal ratings truly bind, and power-flow devices where the network is meshed enough for them to help. That is not a flashy roadmap. It is an engineering roadmap. It also happens to be the one that fits Hawaiʻi best.