Energy  |  Successes  |  12.12.2013

Innovation and renewables: wave energy

Converting sea and ocean wave energy is, alongside photovoltaic (PV) energy, one of the best options for the future production of renewable energy. This was the starting point also for Michele Grassi, who came up in 2005 with an innovative method for extracting energy from waves.


Michele Grassi, born in 1970, has a degree in Mathematics from Scuola Normale Superiore di Pisa and a PhD in Mathematics from the University of California Los Angeles. In 2005 he had an idea for an innovative method for extracting energy from waves.

After the initial preliminary studies, in 2008 he created 40South Energy Ltd in London to complete development of the Intellectual Property, to fabricate and to commercialise the machines globally. The Italian subsidiary 40South Energy Srl carries out some development and construction, mainly related to the mechanical components. The machines build by 40th South Energy aim to embody a generation jump with respect to the previous ones, in terms of survivability, reliability, load factor and cost.

The work of 40South Energy Srl has continued over the years, by perfecting technologies and developing new prototypes. Currently, the company is trying to extend its network of partners around Europe and India. Several converters are already installed and functioning: in the UK (Scilly Airport), in Italy (Punta Righini, Elba, Gorgona, Lavagna) and also in the Maldives (Vavvaru).

How do the 40South Energy Wave Energy Converters Work?

The 40South Energy wave energy converters comprise one fully submerged section – called Lower Member – and energy interceptors – called Upper Members – at different depths. The relative motion of the Lower and Upper members is converted directly into electricity on the machine. The depth of the machines is controlled automatically to respond dynamically to changing sea conditions.

This ability to vary depth dynamically and automatically in response to any changes in the state of the sea also guarantees that the same machines can operate across the globe. 

Italy – Punta Righini Wave Energy Plant (WEP) – the test site

This test site is located approximately 1.5Nm offshore Castiglioncello, in Tuscany. The wave climate is relatively mild, although there might be occasional rough event. Currently the site is not grid connected, but there is an ongoing evaluation to assess the possibility of laying a cable to it to put the test machines there in production. During the past few years extensive baseline and contextual environmental studies were conducted on the site.

In March of 2013 the authorisations for the upgrade were release and now the site can receive up to four machines. This test site of one of the very few in the world capable of hosting full scale wave energy converters in an offshore environment.

The area used for the WEP is extremely limited: approximately 300m x 250m, which might seem large on land but is completely negligible when 3 kilometers from shore. In particular it does not interfere at all with industrial fishing (it is located at 47m depth, where dragnets cannot be used), with commercial navigation (it is closer to shore than any commercial route) or with recreational navigation (not on any specific connection route between ports).

The site is still under development but the results gathered since now are very promising.

How to use the 40South Energy Wave Energy Converters?

Their flexibility and cost-effectiveness give the 40South Energy wave energy machines the potential to be used in many different ways. Here are just some examples of how they can be put to use:

  • IN GRID CONNECTED WAVE ENERGY PARKS, where they can produce energy to be sold through the electricity grid. These machines are meant to achieve a final energy cost in almost all wave conditions, which make them competitive with offshore wind.

  • IN FRONT OF HARBORS that adopt cold ironing to supply clean and cheap energy to the ships at berth.

  • IN ASSOCIATION WITH DESALINATION PLANTS – even in the absence of connection to the grid – to produce desalinated water. 

  • OFF-GRID In association with backup power sources, wave energy machines can provide all the energy needs of isolated communities in areas far from the grid. The use of fuel cells to produce energy from hydrogen when sea conditions produce insufficient wave energy and to produce hydrogen from water when wave energy is abundant, make it possible to create a closed loop configuration with no need for external fuel sources. 



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