Mikaela C. Freeman

In the United States (US) Caribbean Sea, Puerto Rico and the US Virgin Islands (USVI) are planning to transition to renewable energy. Being surrounded by water, the use of marine energy within Puerto Rico and the USVI represents an opportunity to increase renewable energy usage. Marine energy includes wave, tidal, and current energy as well as thermal and salinity gradient energy, and has a large potential to provide reliable and efficient power. While marine energy is usually perceived to bring power to the grid, it can also be used to power activities at sea, particularly offshore aquaculture. In the US Caribbean islands, the development of co-located offshore aquaculture and marine energy could help boost the ocean economy. This study highlights a real-world assessment of the suitability to co-locate offshore integrated multi-trophic aquaculture (IMTA) and wave energy off Puerto Rico and the USVI. The feasibility for co-location was determined through a spatial analysis to identify suitable areas for co-location, field work to collect environmental data, and a readiness analysis of wave energy devices. Combining key environmental, regulatory, and logistical parameters, the spatial analysis identified potential suitable areas for co-location off the coast in the northwest corner of Puerto Rico, northwest of Culebra, east of Vieques, and north of St. Thomas in the USVI. Wave energy was identified as the most limiting parameter for co-location in the study area. The wave energy data collected were comparable to the model predictions, showing the usefulness of fine-scale environmental conditions from wave models to assess the feasibility for co-location. Through the combination of spatial analysis, environmental monitoring, and information on wave energy device readiness, several key components for the technical feasibility of co-locating offshore IMTA and wave energy have been demonstrated in the US Caribbean islands.

Marine renewable energy (MRE) harnesses energy from the ocean and provides a low-carbon sustainable energy source for national grids and remote uses. The international MRE industry is in the early stages of development, focused largely on tidal and riverine turbines, and wave energy converters (WECs), to harness energy from tides, rivers, and waves, respectively. Although MRE supports climate change mitigation, there are concerns that MRE devices and systems could affect portions of the marine and river environments. The greatest concern for tidal and river turbines is the potential for animals to be injured or killed by collision with rotating blades. Other risks associated with MRE device operation include the potential for turbines and WECs to cause disruption from underwater noise emissions, generation of electromagnetic fields, changes in benthic and pelagic habitats, changes in oceanographic processes, and entanglement of large marine animals. The accumulated knowledge of interactions of MRE devices with animals and habitats to date is summarized here, along with a discussion of preferred management methods for encouraging MRE development in an environmentally responsible manner. As there are few devices in the water, understanding is gained largely from examining one to three MRE devices. This information indicates that there will be no significant effects on marine animals and habitats due to underwater noise from MRE devices or emissions of electromagnetic fields from cables, nor changes in benthic and pelagic habitats, or oceanographic systems. Ongoing research to understand potential collision risk of animals with turbine blades still shows significant uncertainty. There has been no significant field research undertaken on entanglement of large animals with mooring lines and cables associated with MRE devices.

Marine renewable energy (MRE) is under development in many coastal nations, adding to the portfolio of low carbon energy sources that power national electricity grids as well as off-grid uses in isolated areas and at sea. Progress in establishing the MRE industry, largely wave and tidal energy, has been slowed in part due to uncertainty about environmental risks of these devices, including harm to marine animals and habitats, and the associated concerns of regulators and stakeholders. A process for risk retirement was developed to organize and apply knowledge in a strategic manner that considered whether specific environmental effects are likely to cause harm. The risk retirement process was tested against two key MRE stressors: effects of underwater noise from operational MRE devices on marine animals, and effects of electromagnetic fields from MRE electrical export cables on marine animals. The effects of installation of MRE devices were not accounted for in this analysis. Applying the risk retirement process could decrease the need for costly investigations of each potential effect at every new MRE project site and help move the industry beyond current barriers.