Browsing by Author "Kempton, Willett"
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Item Influence of Battery Energy, Charging Power, and Charging Locations upon EVs’ Ability to Meet Trip Needs(Energies, 2023-02-21) Kempton, Willett; Pearre, Nathaniel S.; Guensler, Randall; Elango, Vetri V.One year of high-resolution driving data from a sample of 333 instrumented gasoline passenger vehicles are used to create a trip inventory of U.S. vehicle travel requirements. A set of electric vehicles (EVs) is modeled, differing in battery size (kWh), recharging power (kW), and locations for charging when parked. Each modeled EV’s remaining energy is tracked while traversing the entire sample’s trip inventory in order to estimate how well each EV meets all U.S. driving requirements. The capital cost of refueling infrastructure is estimated per car, for gasoline and for each analyzed combination of charging station locations. We develop three metrics of the ability of different EV characteristics to meet trip requirements: the percentage of trips successfully met by each modeled EV, the number of days that the driver must “adapt” EV use to meet more demanding trip requirements, and the total driver time required for refueling. We also segment the market of trip patterns per car, finding that 25% to 37% of the vehicle population could meet all their drivers’ trip needs with a smaller-battery EV combined with community charging. This potential combination of EVs and charging would enable lower-price EVs and lower-cost recharging power, and would broaden EV availability to groups for whom today’s EVs and charging configurations are less accessible.Item Marshaling ports required to meet US policy targets for offshore wind power(Energy Policy, 2022-02-16) Parkison, Sara B.; Kempton, WillettWe analyze infrastructure needed for offshore wind power targets set by U.S. state and federal policies—specifically, manufacturing, vessels, and offshore wind ports. By examining cost-competitive turbine and project sizes and infrastructure challenges, we identify marshaling ports as a key bottleneck. Through elicitation of requirements from supply chain, port, and vessel experts, we identify the necessary attributes for marshaling ports and calculate the area needed to meet policy targets. US marshaling ports are currently insufficient to meet either state or federal power targets. We calculate state commitments from state contracts and policies: in sum, 40 GW by 2040. Federal targets from the Biden Administration are 30 GW by 2030 and 110 GW by 2050. Either target yields more demand for marshaling area than is currently available or planned. The shortage of marshaling area supply has incorrectly been attributed to lack of suitable U.S. locations. Instead, we attribute it to developers having built ports to support early, smaller projects, and having located them to incentivize state power contracts rather than developing ports for long-term, large-scale, and economically-efficient use. Additional land suitable for marshaling ports exists, but it requires commitment from port authorities and port investors to develop it for this purpose.