Utility Hawaiian Electric is seeking proposals for large-scale energy storage systems to ease the integration of renewable energy sources, to be installed on the island of Oahu.

The island’s grid has seen what Hawaiian Electric describes as “continuing dramatic growth” of both utility-scale and rooftop renewable energy generation capacity, while Hawaii as a whole is one of the first US territories to mandate for energy storage to be deployed, along with California and Puerto Rico.

The company is now seeking out one or more projects that can store between 60MW and 200MW of energy for up to 30 minutes. The selected project, or projects, will be used to smooth out variations in electricity generated from renewable sources, which are mainly utility-scale solar and wind, and rooftop solar on Oahu. Hawaiian Electric wants companies bidding to provide engineering, procurement and construction (EPC) services, as well as testing, commissioning, start-up and performance verification.

The utility claims it will evaluate non-cost factors such as feasibility and operating flexibility as well as price when it comes to choosing a successful project. It says it will consider various competing technologies, both mechanical – such as flywheels - and electrical – such as flow batteries.

If a project proposal will cost over US$2.5 million, it will require approval from Hawaii’s Public Utilities Commission. Hawaiian Electric has set a deadline for proposals of 21 July this year, with agreements to be in place by the end of 2014. The ultimate aim is the deployment of large scale storage by the first quarter of 2017.