Ocean Thermal Energy Conversion (OTEC), a process by which energy from natural temperature differentials in the ocean are converted to mechanical and electrical energy, is a renewable energy source that has experienced a resurgence in interest in recent years. As the lead licensing agency for OTEC facilities under the Ocean Thermal Energy Conversion Act (OTECA), NOAA’s Office of Ocean and Coastal Resource Management (OCRM) is responsible for evaluating the potential impacts and risks that the construction, installation, and operation of an OTEC facility poses to the environment. To understand these risks, a thorough understanding of the magnitude and extent of likely physical, chemical and biological impacts is required. In order to aid NOAA OCRM in the permitting process, a workshop was held to identify: 1) the baseline data and monitoring requirements needed to assess the potential physical, chemical and biological impacts related to the construction, installation and operation of a OTEC facility; 2) technology and methods to measure impacts; 3) research needed to adequately determine the degree of potential impacts; and 4) approaches to mitigate and/or avoid the impacts within the operational and design parameters of an OTEC system. The findings and recommendations of this report are based on assumed potential environmental impacts and should not be exclusively relied upon.
While it is certain that physical, chemical and biological impacts will occur during the installation and operation of an OTEC facility, the magnitude and extent of these impacts are not known. This workshop did not reach any conclusions in regards to cumulative or secondary impacts which, at this point in time, are largely undeterminable without long-term monitoring and additional research. It was recognized at the workshop that potential cumulative and secondary impacts may be more significant from an ecosystem perspective than immediate localized impacts from OTEC operations given expected operational lifetime of 25 - 40 years.
In order to better understand the risks that these impacts represent, a minimum temporal baseline is required prior to installation that includes monitoring for presence and abundance of large and small biota, as well as the physical and chemical characteristics of seawater in the region. For certain impacts, a longer baseline may be desired in order to capture multi-year variability. This will provide scientists and engineers with a better understanding of potential impacts and a basis for comparison to changes in the marine environment and ecosystem. Monitoring for changes to this baseline should occur during the installation and operation phase, and will provide information on how the facility is impacting the local environment. Many physical, chemical, and biological criteria should be monitored, including, but not limited to: temperature; salinity; dissolved oxygen; pH; trace metals; and abundance, diversity, mortality and behavioral changes in plankton, fish, marine mammals, turtles, and other biota.
Tables 1, 2, and 3 show specific information needed for baseline assessment, monitoring strategies, and modeling methods. The information contained in these tables, while useful, should not be relied upon exclusively in reaching conclusions regarding the development of baseline data, monitoring plans, sampling frequency and analytical methods. The extent and depth of discussion of the information contained in the tables varied among the break-out groups which developed them, and the information presented does not necessarily represent the consensus of the break-out groups.