Waves ahead

Fiona Bennett explores a new machine set to revolutionise wave energy technology

Wave energy remains the most enigmatic part of the whole renewable energy sector. Its potential benefits are obvious – an entirely ‘clean’ source of electricity which can be deployed in almost all marine environments, except perhaps those with the most violent weather conditions. Equally its major drawback – at least in the present – is equally evident. At the moment there is simply no generic design for an appropriate device that is accepted as the most efficient. Instead numerous possible hardware configurations are still competing to be the one or maybe one of the two or three that will win out when the inevitable ‘convergence’ occurs.

Concept
In fact more contenders are joining the field. One of the latest is 40South Energy, an operation set up originally in Italy in 2007 with a London base following in 2008. The company aims to develop and commercialise a design concept devised by founder and now chairman and CEO Michele Grassi – unusually, perhaps, a mathematician rather than an engineer. The devices work by exploiting the interaction of ‘upper’ and ‘lower’ members suspended beneath the surface of the water at respective depths of 1-12 metres and 15-25 metres.

According to Grassi, the configuration of the machines in which the key point of energy generation is well submerged means that they are unaffected by surface conditions. But he also says they boast several other quite specific advantages over many of their competitors. They are, for instance, built from standard components and are very easy to install. Maintenance, he adds, is a surface operation that requires little time to be spent offshore. As such they are suitable for operation in a wide range of coastal regions worldwide or indeed further out to sea with the sole proviso that they require a minimum water depth of 40 metres.

Prototypes
Grassi says that the concept has been proven both through simulation and extensive testing of half-scale prototypes in northern Italy. In fact he says that development work involving fullscale machines is now underway. Initial investment in the company, which came from Grassi and his family, has now been supplemented by support from the venture capital sector, though Grassi says that the precise figures involved remain confidential.

Ultimately Grassi says that he envisages two distinct, though related, ranges of machines being developed. The first – the D type machines – will involve a single upper member and will be rated at powers between 20-400kW, being named accordingly D20 up to D400. They are targeted at users that are poorly connected and possibly even totally disconnected from the main grid. Customers might therefore be isolated tourist resorts or hotels, remote villages and small enterprises in coastal locations such as desalinisation or water pumping plants. They would also be suitable also for small offshore rigs. The possibility of grid connection would also exist.

Targeted
Meanwhile the F type machines would have multiple upper members – between two and six – and would be rated accordingly between 40kW-2.4MW, with the nomenclature F40 up to F2400. They would be targeted at towns and larger enterprises, such as complete ports. Grassi says that when deployed in large numbers, they would certainly be suitable for wholesale production of energy to be sold through the grid.

So it seems that another contender to win the race for a commercially viable wave energy device has entered the fray. In this case it is a machine whose attributes include both physical robustness and operational flexibility. It seems to have what is necessary to prove a serious competitor.

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