Marine ecosystems provide abundant resources and an enormous number of opportunities for economic growth. A sustainable Blue Economy can be achieved if economic activities are carried out in environmentally and socially responsible ways.
In this section, we focus on marine renewable energy (MRE) in the context of a Blue Economy.
MRE refers to energy generated from renewable marine resources such as wind, waves, tides, ocean temperatures, and ocean salinity.
- Wave energy is an abundant and renewable energy source. Electricity and power generation from ocean waves are made possible by wave energy converters that serve to capture the kinetic energy of ocean waves (Drew et al., 2009).
Despite its great potential, wave energy remains an underdeveloped energy source due to the challenges of designing economically viable and technologically resilient wave energy conversion (WEC) devices. These devices must be easy and cost-effective to deploy and maintain, resistant to extreme environmental conditions, and capable of efficiently capturing kinetic energy in various sea conditions (Roberts et al., 2021). - Tidal energy is generated by harnessing the power of tides, which are caused by the gravitational pull of the moon and the sun on the Earth’s oceans. There are two main types of tidal energy technologies (Polis et al., 2017). A “tidal barrage” is analogous to conventional hydroelectric dams in generating electricity but in an ocean setting. The other technology, tidal current energy turbines, was designed to capture the energy generated when elevation differences between high and low tides create strong currents (Polis et al., 2017).
One of the greatest advantages of tidal energy is the better consistency and predictability of power generation due to the predictability of tides. Tidal energy technologies are more mature than other ocean-energy technologies (Agarwala, 2022). However, the tidal energy industry hasn’t yet reached full commercialization due to a multitude of reasons, including 1) High costs associated with producing and maintaining hydrokinetic devices; 2) Uncertain durability of components in a saline environment; and 3) Public concerns over negative impacts on marine ecosystems and biodiversity.
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Offshore wind energy refers to the production of usable energy through wind turbines located offshore, which utilize the strong winds that blow over the ocean. Offshore locations provide several benefits compared to onshore sites, including 1) The ability to generate more energy due to stronger and more consistent wind; and 2) Fewer human disruptions (such as noise and shadow flicker) as they are located further from populated areas (Lamy and Azevedo, 2018).
On June 23, 2022, the White House and 11 governors from East Coast states formed a new partnership to help build up domestic supply chains for offshore wind farms and related infrastructure. This was a significant move toward accelerating the development of offshore wind facilities and creating jobs in the renewable energy sector. 
Floating solar power. A floating solar photovoltaic (FPV) system is an emerging technology in which a solar photovoltaic (PV) system is sited directly on the water. Compared to conventional PV systems placed on land or building rooftops, FPV systems generate higher energy yields because of the cooling effect of the water (Dörenkämper et al., 2021).
Offshore FPVs face similar challenges that many other MRE technologies face (e.g., high costs and reliability uncertainties under varying sea conditions). Therefore, it will be some time before their applications reach a larger scale.
Other examples of MRE include Salinity Gradient Energy (SGE), which is generated from the chemical pressure differential created by the differences in ionic concentration between freshwater and seawater, and Ocean Thermal Energy (OTE), which is generated from the temperature difference between cold ocean water and warm surface water. Similar to other sources of MRE, SGE and OTE have great potential as well as limitations and drawbacks. For example, the potential environmental impacts of SGE include disturbing the ecosystems where freshwater meets seawater by altering the balance of freshwater and saltwater and putting stress on freshwater resources in water-scarce regions. In addition, the construction and decommissioning of an SGE facility can cause disturbance to habitats and organisms due to factors such as noise, modification of land, and the release of pollutants (Seyfried, Palko, and Dubbs, 2019).
Biofuels generated from marine bio-resources are considered as a source of renewable energy. However, due to their bio-based nature, we will describe them in the next part of the article that focuses on bio-based fuels and products.
References:
Agarwala, N. (2022). Powering India’s Blue Economy through ocean energy, Australian Journal of Maritime & Ocean Affairs, 14:4, 270-296, DOI: 10.1080/18366503.2021.1954494
Dörenkämper, M., Wahed, A., Kumar, A., de Jong, M., Kroon, J., & Reindl, T. (2021). The cooling effect of floating PV in two different climate zones: A comparison of field test data from the Netherlands and Singapore. Solar Energy, 214, 239–247. https://doi.org/10.1016/j.solener.2020.11.029
Drew, B., A. R. Plummer, and M. N. Sahinkaya. 2009. A Review of Wave Energy Converter Technology. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 223(8):887-902. https://doi.org/10.1243/09576509JPE782
Lamy, J. V., & Azevedo, I. L. (2018). Do tidal stream energy projects offer more value than offshore wind farms? A case study in the United Kingdom. Energy Policy, 113, 28–40. https://doi.org/10.1016/j.enpol.2017.10.030
Polis, H. J., Dreyer, S. J., & Jenkins, L. D. (2017). Public Willingness to Pay and Policy Preferences for Tidal Energy Research and Development: A Study of Households in Washington State. Ecological Economics, 136, 213–225. http://dx.doi.org/10.1016/j.ecolecon.2017.01.024
Roberts, O., Henderson, J. C., Garcia-Teruel, A., Noble, D. R., Tunga, I., Hodges, J., Jeffrey, H., & Hurst, T. (2021). Bringing Structure to the Wave Energy Innovation Process with the Development of a Techno-Economic Tool. Energies (19961073), 14(24), 8201. https://doi.org/10.3390/en14248201
Seyfried, C., Palko, H., Dubbs, L (2019). Potential local environmental impacts of salinity gradient energy: A review, Renewable and Sustainable Energy Reviews,102(C), 111-120. https://doi.org/10.1016/j.rser.2018.12.003
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