Energy Yield Assessment from Ocean Currents in the Insular Shelf of Cozumel Island

Abstract

Marine renewables represent a promising and innovative alternative source for satisfying the energy demands of growing populations while reducing the consumption of fossil fuels. Most technological advancements and energy yield assessments have focused on promoting the use of kinetic energy from tidal streams with flow velocities higher than 2.0 m s−1. However, slower-moving flows from ocean currents are recently explored due to their nearly continuous and unidirectional seasonal flows. In this study, the potential of the Yucatan Current was analysed at nearshore sites over the insular shelf of Cozumel Island in the Mexican Caribbean. Field measurements were undertaken using a vessel-mounted Acoustic Doppler Current Profiler (ADCP) to analyse the spatial distribution of flow velocities, along with Conductivity-temperature-depth (CTD) profiles as well as data gathering of bathymetry and water elevations. Northward directed flow velocities were identified, with increasing velocities just before the end of the strait of the Cozumel Channel, where average velocities in the region of 0.88–1.04 m s−1 were recorded. An estimation of power delivery using horizontal axis turbines was undertaken with Blade Element Momentum theory. It was estimated that nearly 3.2 MW could be supplied to Cozumel Island, amounting to about 10% of its electricity consumption.

Effects of the Stony Coral Tissue Loss Disease Outbreak on Coral Communities and the Benthic Composition of Cozumel Reefs

“…However, we can speculate on three possible causes of the outbreak that are not mutually exclusive. First, given that SCTLD was present on the eastern coast of Cozumel since at least September 2018 (Alvarez-Filip et al, 2019; Figure 1), it is possible that the outbreak circled the island, aided by the predominant currents that run from south to north (Alcérreca-Huerta et al, 2019). Another potential source for the outbreak may be that recreational divers or divemasters brought the disease to SW Cozumel from the mainland.…”

“…Given that dive gear can harbor and proliferate pathogenic bacteria, which may survive for extended periods and can be transferred among reefs (NOAA, 2019), by remaining damp and trapping water, it is plausible that if equipment was not rigorously disinfected between dives, divers may have helped to spread the disease throughout the MPA. In addition, strong coastal currents and eddies that are formed when oceanic currents approach the coast (Alcérreca-Huerta et al, 2019) can also aid in the rapid waterborne transmission of SCTLD across and between reef sites. Regardless of whether the disease was rapidly transported by divers and/or currents, once SCTLD arrived to the reefs, it is possible that the abundant and diverse coral reef communities that were present in most sites also aided in rapid withinsite transmission.…”

Design of a Horizontal Axis Tidal Turbine for Less Energetic Current Velocity Profiles

“…This differs from the Philippines case, where periodic increases and decreases of tidal velocities are observed. ADCP measurements obtained from a spatial variability analysis [25] provide snapshots of the flow within the current as opposed to being time-series measurements. Three 10-m windows ( Figure 5) with relatively flat bathymetry were selected for analysis.…”

“…The simulated power outputs were generally low since the turbines were made to be only 4 m in diameter. However, it has been shown [25] that an increased number of smaller turbines in an array can still generate considerably large power. The perceived benefits in terms of lower load magnitudes and less fatigue may not be realised when larger diameter turbines are adopted, since larger diameters would lead to slower rotational speeds.…”

“…The Yucatan channel in Mexico is a passageway that has current velocities with an upper bound of 2 m/s [23,24], but much of the passing current is limited to below 1.4 m/s [25]. Nonetheless, continuous operation is possible since the Yucatan current is a constant marine current as opposed to the periodic tidal current present in the previously mentioned sites.…”