Enhancing the resilience of energy systems: Optimal deployment of wave energy devices following coastal storms

Abstract

Isolated coastal areas and remote islands may be particularly vulnerable to damage from powerful storms, storm surges, and flooding. Because wave energy converters are designed to survive rough seas and can be transported by sea, they could potentially play a role in poststorm operations and contribute to power-grid recovery. To that end, this paper addresses questions such as how many devices would need to be deployed and in what sequence, in order to optimize some performance index that includes, as functions of time, both, the energy needed and the energy converted by the device units. In this work, the wave-by-wave dynamics of the devices are controlled to optimize mean power conversion over 20 min, assuming sea-state stationarity over that period. Sea-state variations between 20 min and 13 h are found to be small (relative to variations between 13 and 60 h) for a candidate deployment site near a Caribbean island. Targeting deployment over 5-7 days, two optimization schemes are considered: (i) maximization of the power conversion capacity over a specified time interval and (ii) minimization of the time taken to deploy the desired conversion capacity. With the wave energy devices controlled for optimal conversion over successive 20-min periods, the optimization is carried out over the number of converter units added as a function of time. The results indicate that optimal deployment sequences can be evaluated for given conversion capacity/recovery-time targets and the type of recovery desired [strategies (i) or (ii) above]. However, depending on the energy richness of the "normal" wave climate at the deployment site, cost-effective recovery may require closer consideration of the trade-offs among device configurations, size, and number of units needed for desired capacity. The potential for wave energy devices to power early recovery operations and to support power-grid black-start could be worth considering further as a means to enhance the resilience of coastal and island energy systems.