Offshore wind power: EDP’s 5 floating wind turbines

The wind power generator, which cost 20 million euros ($25.3 million), floats over deep ocean waters, unlike previous offshore wind farms built in shallow waters and attached to the ocean floor.

EDP and Seattle-based Principle Power, partners in the project, said the pilot produced 1.7 gigawatts of energy per hour (GWh) on average since its blades started turning six months ago, enough to supply power to 1,300 families.

"This was a great success, our calculations have proved right, and the unit performed as predicted. But this was a conservative design. Next time we will be more optimistic," Principle Power Chief Executive Alla Weinstein told Reuters.

The pilot sits six kilometres off the coast of the windy town of Povoa do Varzim, close to Porto in northern Portugal.

It is 54 metres tall and weighs 1,200 tonnes, with a turbine from Denmark’s Vestas and backup from Repsol and other local partners.

Its capacity at 2 megawatts (MW) is just below the average of offshore wind turbines in Europe, which was 3.6 MW at end-2011, according to the European Wind Energy association.

Construction of a bigger windfarm park now awaits EU funding.

"We have applied for a European Commission funding scheme that creates a tariff-like funding mechanism when you produce energy. It is provided through the monetisation of carbon credits," Weinstein said.

Construction and testing would then commence on a larger scale.

"After the prototypes are fully tested, we start with the commercial phase in two years’ time, with the objective of starting to have some return on the investment," Pedro Valverde, the project manager at EDP, said.

The first wind turbine is connected to the grid through cables that run on the ocean floor and are linked to an onshore sub-station. If the distances are much greater than 6 kilometres, the plan is to build mid-ocean substations.

Why did you decide to install the wind tower in Povoa do Varzim?

This area had already two projects testing wave energy and had a substation, and had a submarine network to connect the earth. EDP ​​joined the substation EFACEC to buy this and use it in this wind power project.

How long will this phase of testing?

The wind tower works for five and a half months with excellent results and take a year and a half. We will use it to solve problems that arise and, for example, the response to erosion.

After this phase, they will do?

We want to move to the next edition with five floating wind turbines. Construction began in late 2013 to take the wind turbines operating in 2015.

Each wind tower has a capacity of 2 MW and the wind farm will have five wind turbines and 10 MW in total. But this is under study. The production of this wind tower can supply more than a thousand families.

By José Santamarta, www.evwind.com