Using Energy Storage to Optimise Delivery of Renewables

The US state of Hawaii has experienced rapid uptake of renewables in recent years, with some islands producing up to 300% of their local electricity demand from solar and wind power. Traditionally the most expensive state for electricity, Hawaii is benefiting from its renewable energy abundance to drive policy change and reduce both curtailment and fossil fuel use during peak hours. Hawaii was the first state to set a 100% renewable portfolio standard (by 2045) and reached 29.8% renewable generation in 2019.

The decommissioning of the largest fossil fuel plant on the island of Oahu has prompted the state's electric utility to work with customer-owned energy advocates on a programme to pay households upfront cash plus a monthly credit to install a battery alongside their rooftop solar. Policies supporting feed-in tariffs have fluctuated in recent years, but households are now paid to store excess solar production throughout the day and to release it to the grid for two hours during the evening at premium electricity rates.

Hawaii's utility also introduced pilot programmes to provide bus owners with no-cost charging infrastructure for electric buses and special rates for daytime charging when renewables are producing the most. Special time-of-use rates for EV charging also are available for medium- to large-sized commercial customers on the islands of Hawaii, Maui and Oahu, helping them save anywhere from 7% to 58% on electricity rates during these periods.

Source: See endnote 15 in chapter 06.

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