What if the energy we lack came from the sea?

What if the energy we lack came from the sea?

When we imagine a renewable energy source, we look up towards the sun. The time has come to look straight at us too: towards the sea. Capturing the kinetic energy of waves and tides has long been a low-yield, high-cost investment. In the last few years, various technological innovations in the field are making marine energy a concrete option: the latest comes from Italy. Pewec 2.0 is the name of the new device developed by Enea and Politecnico di Torino. The latest version of the Pendulum Wave Energy Converter (the full name summed up by the acronym Pewec) is a device specially designed to exploit the waves of the Mediterranean.

The final version will have a power of 525 kW, will measure 15 meters long, 23 wide and 7.5 high with a weight of over 1,000 tons (including ballast). And it promises two advantages: not having a drastic impact on marine fauna and flora, like many similar converters, and fighting the erosive phenomena of the beaches, by reducing the energy of the waves breaking on the coasts. The device - based on the oscillation of a pendulum that allows electricity to be produced from the sea by exploiting the waves - has shown in the test phase to withstand even extreme conditions: one of the great limitations of devices of this type. Here is the water test of the new device (Naples, October 2021) through a 1:25 scale model, aimed at studying the survival and arrangement of moorings during extreme events:

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Test on PEWEC 2.0 in the Naval Basin of the Federico II University of Naples - Credits: ENEA

The next step will be to develop a 1 to 1 scale model and test it in the two coastal areas that most of all lend themselves to the collection of this type of energy in our peninsula: western Sardinia and the Sicilian Channel. According to Gianmaria Sannino, head of the Enea laboratory for climate and impact modeling, Pewec 2.0 could be immediately useful for small Italian islands:

"In our country there are more than 50 smaller islands with an average population of about 2,500 inhabitants, an average per capita consumption of 6 kWh / d and a very high cost of energy. A dozen of these devices could produce electricity for a country of 3 thousand inhabitants "

Marine energy: definition, types and problems Europe wants global leadership by 2050 In Europe in 2021 installations will grow What happens in the rest of the world Marine energy: definition, types and problems 70% of our planet is covered by water: of this percentage, 97% is made up of oceans. It is therefore natural that man has been looking for a long time at the possibility of extracting energy from the sea: the French Girard were the first to think about it in a structured way, who filed a patent to extract energy from the sea in the very distant 1799. Marine energy contained in waves (Wave Energy) comes from the force that the wind exerts on the surface of the sea, forming ripples on the surface of the water.

Storing energy at the bottom of the sea Various projects are making their way through technologies in the field of renewables that use the seabed as storage tanks for electricity This renewable source does not produce waste and is truly unlimited, but up to a few year retained the bad name dictated by its great limitations: expensive to extract and maintain, negative for maritime habitats, useful only for sites close to the coasts. Furthermore, the salt water is corrosive and storms can damage the machinery that must be tested in the open sea: thus the experimental phases require a lot of time and money. There are different types of marine energy extraction which translate into technologies linked to different elements of the sea:

Currents: as for wind energy, the blades moved by the sea create mechanical energy; Tidal wave: the rhythmic rise and fall of the sea level is captured by turbines; Wave motion: devices capable of capturing the kinetic energy released by the waves; Thalassothermic: the temperature variation between the sea surface and the depth is captured; Salt gradient: the different concentration of fresh and sea water is used to create the chemical energy in a salt gradient. In any case, the movement of the waves is certainly the type on which the most insisted. In general, the entrapment of the kinetic energy of the sea occurs through the WEC (Wave Energy Converters) which capture the energy from the waves using different physical principles. Generally very expensive devices, difficult to install and maintain, especially characterized by modest performance. At least until today.

Europe wants global leadership by 2050 In the last thirty years, renewable energy drawn from the sea has returned to the center of interest in the scientific and business world. Unfortunately, the invented prototypes always showed various problems in the marketing phase: too expensive and underperforming, too impactful for the seabed, not very resistant to the unpredictable impetuosity of the sea. The confirmation that instead the new technological developments have made this source a real alternative comes from the plans of the European Union.

The Old Continent is a world leader in tide and wave technologies, largely thanks to policies and early investments that helped lead them towards commercialization. Over the past decade, Europe has invested more than $ 414 million in ocean energy research, development and innovation through a variety of funding programs.

And now it is ready for the leap: the Union aims to reach 10% of its energy needs from the sea by 2050. A condition that could satisfy the needs of 94 million families a year, supporting the EU sustainability objectives in terms of decarbonisation, energy independence and creating 500,000 new jobs.

In Europe in 2021 the number of installations is increasing Even to reach 10% of its energy needs from the sea by 2050, the 'Union aims to invest 1 billion euros between 2021 and 2025. This is not a random date: once a first phase of development has been completed, the five-year period 2025-2030 intends to be the moment for the operational installation of the devices. According to ENEA, 127 technological projects of this type are currently financed in Europe: 60% of these to capture wave energy and one in five of the total is practically ready for the commercial phase.

It is always the countries of Northern Europe that are the masters in this sector and in fact in 2021 new devices have been deployed along the Atlantic, the North Sea and others in the Mediterranean. According to the latest report by Ocean Energy Europe, the largest network of ocean energy professionals in the world, the installations related to the energy exploitation of the tides in the Old Continent have grown by 10 times between 2020 and 2021, reaching 2, 2 megawatts in total. A huge leap, marked by the slowdown in installations in 2020 due to the pandemic. But it was not taken for granted that after the first wave of Covid investments and objectives for this renewable type remained unchanged. Similar speech for the installations that capture the power of the waves, which tripled between 2020 and 2021 to reach 687 megawatts overall. Devices located mainly in Scottish, Dutch and Iberian Peninsula waters.

Source: Ocean Energy - Key trends and statistics 2021 (March, 2022)

The competence of European companies in this field is thus recognized that the turbines of some of these companies were also installed in Canada and Japan in 2021. Two of the countries outside the EU are among the most interested in exploiting marine energy.

What happens in the rest of the world Canada, China and the United States are the main markets for ocean energy at outside Europe: this is confirmed by the 2021 data, which also describe how these countries have stabilized public support mechanisms in this sector. In addition to these countries, last year saw the growth of new installations in Australia, Japan and Chile as well.

The effects of sea level rise in the United States will not be the same everywhere A new report illustrates the projections relating to the rise of water in the country, highlighting how the repercussions on the communities concerned will vary greatly depending on various factors.In particular, the United States is very interested in this new energy source, given that about 50% of the US population lives within 50 miles from the coast. In 2021, the United States significantly increased investment in the sector, adding public support measures of $ 200 million in a single year.

Developing just one-third of the wave energy available near Pacific Ocean states with US-made equipment could support 33,000 jobs and meet up to 30% of West Coast electricity demand. The goal is to try to become the first world market for this alternative source, but the gap with the European Union still seems very deep both in terms of megawatts installed, and in terms of outlook and technologies developed. In any case, this growing interest - also manifested by the investments planned by Canada and China in 2022 - testifies that marine energy really has important opportunities for development in the short term.

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