The Energy Storage Report 2024

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AES withdraws hybrid solar-plus-storage project from Hawaiian Electric procurement


AES Corporation has withdrawn one of its solar and battery storage hybrid facilities from Hawaiian Electric Co’s (HECO’s) latest renewable energy procurement.

The solar-plus-storage project was originally included in the US island state utility’s final award group announced in December last year as reported on

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In a heavily redacted filing submitted with the regulatory Hawaii Public Utilities Commission (PUC) on 31 May 2024, AES explained that although it had been able to secure site control to develop the hybrid facility, it had been unable to secure the land to interconnect the project to HECO’s electricity grid.

AES submitted separate notices with the PUC cancelling a System Impact Study (SIS) and Feasibility Study (FS) which were underway as part of the interconnection process. 

The Puu Hao Solar and Storage project has also been removed from HECO’s project status board that tracks the progress of renewable energy projects which the utility has power offtake deals with.

In the filing lodged with the PUC, AES added that it “remained committed” to meeting the energy needs of the county of Maui through the development of its Kuihelani Phase 1 + 2 Solar and Storage facilities.

Phase 1 of the project, which includes a 60MWac solar farm co-located with a 240MWh BESS, was brought online 31 May 2024, according to HECO’s project status board.

Puu Hao project part of 2.1GWh Hawaiian Electric procurement

The Puu Hao Solar and Storage facility was slated to comprise a 20MWac solar farm co-located with an up to 80MWh battery energy storage system (BESS) approximately 1.9 miles southwest of Kula in the county of Maui, Hawaii.

According to a website set up by AES, the project would have connected to the local grid via the Kealahou Substation owned by one of HECO’s subsidiaries Maui Electric Co. AES expected to commence construction on the project in 2026 and was targeting a commercial operation date (COD) in 2027.

The Puu Hao project was selected alongside 14 other developments as part of Hawaiian Electric’s Stage 3 Request for Proposals for Renewable Dispatchable Generation and Energy Storage. The utility opened negotiations with the selected projects in December 2023. Of the 14 remaining projects, nine are expected to incorporate BESS facilities totalling 2.06GWh of capacity across Oahu, Maui and Hawaii Island.

Longroad PPA declared null and void ahead of resubmission

One of the 14 selected projects is being developed by Longroad Energy in the County of Oahu and will incorporate a 120MWac solar farm co-located with a 480MWh BESS. An agreement between Longroad and Hawaiian Electric for the offtake of power from the Mahi Solar facility had already been negotiated as part of a previous procurement but was ultimately declared null and void in March 2022.

In order for the project to remain viable for Longroad Energy, it proposed amendments to the original PPA which HECO brought to the PUC for approval in February 2022. Amendments included a delay to the guaranteed commercial operation date (GCOD) from the end of 2023 to March 30th 2024 and a 19.3% increase in the unit price paid by HECO.

The Hawaiian PUC declined to approve these amendments in March 2022 after it argued the proposed unit price increase and delay to project schedule were not in the public interest.

As part of the latest procurement, Longroad is targeting a COD in the fourth quarter of 2027 for its Mahi development.

Hawaii Clean Energy Initiative: 100% renewables by 2045

The Hawaii Clean Energy Initiative (HCEI) was first launched in 2008 by the US Department of Energy (DOE) and the State of Hawaii with the goal of achieving 100% renewable energy by the year 2045.

HECO announced in February of this year that 33% of the energy it generated across Maui, Hawaii Island and Oahu came from renewable sources which was a 1% increase on the year before. HECO has an intermediate goal of generating 40% of its electricity from renewable sources by 2030.

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