Eduardo Madrid Navarro, CTN - Marine Technology Centre - Centro Tecnológico Naval y del Mar
#energy, #renewable, #marineenergy, #electricity
That energy is the main driver of our civilization’s development is undisputable and as such it is always a hot topic in governments and industries agendas. Energy consumption is also the main emitter of greenhouse gasses, which ultimately is causing climate change, one of the greatest challenges of humankind in the XXI century.
To put things in perspective, the total energy consumed by the world in the year 2020 was 557.1 exajoules, distributed in 83.1% (around a third of it coming from natural gas) and 16.9% of renewables and nuclear sources, a percentage still quite low despite the efforts taken in GHG emissions reduction. In Europe, these numbers were correspondingly 77.15 EJ, 71.2% (with 35.5% of natural gas) and 28.8%, with around 12% less of fossil energies consumed .
One of the reasons that non-renewable contribution is this high (even for Europe) in the share is that heating and transport still heavily rely on oil, natural gas and coal. If, instead, we focus on the global electricity generated in that year (26823.2 TWh), it comprises about the 17.3% of the world’s consumed energy but has a much higher share of nuclear and renewable sources in its mix: a 61.6%. In Europe the corresponding percentages are very similar, with 3871.3 TWh generated, around a 18% of Europe’s total consumed energy, and 62.3% of renewable energy share in the electricity mix . Therefore, one inevitable step towards GHG emissions reduction consists of electrifying the energy flows as much as possible, as electricity generation seems easier to decarbonize. In this sense, a good news is that the historically accepted coupling between economic growth and CO2 emissions has been proven to be breakable, as some recent articles have shown . Renewable energies increasingly cost efficiency and implantation is one of the drivers of such decoupling.
In this regard, among the renewable sources (excluding nuclear), hydroelectric, wind and photovoltaic are by a large extent the most important technologies in terms of installed capacity. Globally, in the year 2020, there were 10600 TWh of hydroelectric consumed energy, and 1591.2 and 855.7 TWh of wind and solar generated energy, respectively (these numbers are 1616.7, 510.1 and 178.9 TWh respectively in the case of Europe) . In order to strengthen the renewable mix, it is mandatory for each country to tap into their most abundant renewable resources, as well as diversify the mix so the energy generated is in line with the demanded energy.
In this context, marine energy is usually overlooked as a renewable energy (it is noticeable that it is completely missing in some of the most comprehensive annual energy reports), as it is still in development stage and few working plants are already operating. In fact, it generated only about 1 TWh in 2018 . The harsh conditions of the sea, the high variability of environmental conditions, and the inherent difficulty of operating at sea are some reasons that explain this significant delay in marine energy implementation . However, the ocean represents a great (and mostly untapped) potential, with a theorical resource potential capable of generating world’s annual electricity consumption [5, 6]. Some advantages with respect to other renewable technologies are the abundance of energetic resource, a high-power factor, high availability, and greater energy density, as well as proximity to most concentrated populations . Furthermore, it could be a crucial component in the electricity mix of countries with significant ratios of coastline length and surface area, such as islands or peninsulas. Under this perspective, it is no surprise that several countries are interested in the development of marine energy projects; in particular, the European Union has been historically at the forefront of this industry, with a planned 40 GW of marine energy cumulated capacity installed by 2050 .
There are various types of marine energy, including wave, tidal stream, tidal range and offshore wind, as well as ocean thermal, ocean current, run-of-river and salinity. Among these technologies, wave energy is one of the most promising, as is highly available, predictable and is considered the renewable energy with highest energy density . In addition, it has been relatively well tested, with the more advanced device developers progressing beyond single unit demonstration devices and proceeding to array development and multi-megawatt projects [9, 10].
Another related technology, while not purely marine (as the working fluid is the wind), is offshore wind power, which has taken advantage of the already advanced level of development of wind power technology and keeps growing steadily and quite fast. Its global cumulated installed capacity in 2020 was 35.2 GW . Its main benefits are that, in contrary to their onshore counterparts, it does not need land terrain, its visual and noise impacts are smaller (to humans at least), and winds are usually strong and constant in the marine environment.
Even solar photovoltaic technology is starting to go offshore during the very last years, although the technology is still in the start of development phase and current plants are basically pilots, much behind offshore wind energy .
All these kind of energy technologies (marine, offshore wind and photovoltaic), which can be encompassed as Blue Energy, will progressively constitute a more important part of the Blue Economy as their development progress, creating a vast place of opportunities and corresponding challenges that need will need to be faced to transition towards a more blue, sustainable future.
Author: Eduardo Madrid Navarro, CTN - Marine Technology Centre - Centro Tecnológico Naval y del Mar
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