Hawaiian Electric Industries subsidiary Hawaiian Electric Company (HECO) is seeking proposals for large-scale energy storage systems to help manage and add more renewable generation to the Oahu grid.
Large-scale energy storage a necessity
Hawaiian Electric Industries is on the look-out for storage system solutions that will be able to store 60 to 200MW for up to half an hour. This request is the biggest to date from a single utility, outside of the state-mandated procurements targets that California has initiated.
As for storage technologies, the utility describes itself as agnostic. There are a number of different technologies that could be deployed-these include batteries, mechanical flywheels, capacitors, compressed gas systems, pumped hydro storage or a combination of the above.
Oahu has experienced a major boom in utility-scale wind and solar projects, as well as rooftop solar. Over 11% of Hawaiian Electric customers now have rooftop panels and this figure is growing due to the high costs of grid electricity. Some neighborhoods are so solar-heavy that they’re causing backward power flows at the sunniest times of the day -- a situation that has forced Hawaiian Electric Company to put a stop to new photovoltaic interconnections. The utility is facing system-wide pressures, as its already-expensive oil-fired power plants are being forced to ramp down production during solar's midday peaks, making their power even more expensive.
This increase in renewables has forced the utility to install energy storage solutions in order to deal with the sudden changes in availability of these variable natural energy resources.
Reliability and auxiliary services
When renewable power suddenly drops, energy storage systems can help maintain a reliable service by avoiding customer outages as fast-starting firm generation units are brought online. Energy storage can provide not only electricity but also so-called "auxiliary services," such as sub-second frequency response (near-instantaneous changes to keep power quality at 60-hertz) and minute-to-minute load following (power output adjustments as demand for electricity fluctuates throughout the day), to operate the grid.
Selected projects, costing US$2.5 million will need to go through the Hawaii Public Utilities Commission (PUC). Hawaiian Electric Company intends to complete and file energy storage agreements with the Hawaii Public Utilities Commission by the end of 2014. The energy storage system should be in place by the first quarter of 2017.
Hawaiian Electric Company’s new storage proposal comes after the utility received severe criticism from the state’s Public Utilities Commission, which rejected its integrated resource plan. The Commission demanded that the utility improve its approach to solar photovoltaic integration, develop a demand response plan, and improve grid reliability.
Currently, the absence of energy storage solutions is one of the key elements preventing the Hawaiian Electric Company from achieving its goal of integrating high levels of variable renewable energy sources like solar and wind.