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Effect of Electric Vehicles on Design, Operation and Cost of a 100% Renewable Power System
This report outlines the effect that electric vehicles could have on the cost of transport and electricity production in the context of a 100% renewable power system (RPS). Results presented here were produced using the SWITCH power system planning model, configured to choose a least-cost plan to achieve 100% renewable power on Oahu by 2045, subject to a 5% limit on biofuel usage.
Making an Optimal Plan for 100% Renewable Power in Hawaii
The State of Hawaii has adopted the unprecedented goal of building a 100 percent renewable power system by 2045. This report identifies some of the central challenges in achieving this goal and uses the SWITCH power system planning model to identify solutions to these challenges. A 100% renewable power system must balance electricity supply and demand on two main time scales: diurnal (providing enough power each hour of the day) and seasonal (providing enough total energy on each day of the year). The diurnal balance could be achieved by installing large amounts of primarily solar production capacity, then using batteries, demand response, biofuels or hydrogen production to shift power production and/or consumption between day and night. The seasonal balance may be more challenging. Energy demand during days or weeks with low sunlight could be met by building extra solar and wind capacity, using biofuels, or using hydrogen produced during sunny months. Demand response will likely be less expensive than the other options for day-night energy balancing, and customer-sited solar may be competitive with utility-scale solar; consequently electric utilities may need to become energy integrators and market managers, rather than bulk power providers.It is unclear how much biofuel the State could use without compromising other environmental and energy independence objectives; consequently hydrogen energy storage merits serious consideration. SWITCH or similar models can be used to identify optimal long-term plans; however, a new incentive system is needed to encourage the State's utilities to develop and implement such plans, regardless of who will own the generating equipment.
Efficient Design of Net Metering Agreements in Hawaii and Beyond
In Hawaii, like most U.S. states, households installing rooftop solar photovoltaic (PV) systems receive special pricing under net-metering agreements. These agreements allow households with rooftop solar to buy and sell electricity at the retail rate, effectively using the larger grid to store surplus generation from their panels during sunny times and return it when the sun isn’t shining. If a household generates more electricity than it consumes over the course of a month, it obtains a credit that rolls over for use in future months. Net generation supplied to the grid in excess of that consumed over the course of a full year is forfeited to the utility.