The second round of open sea testing is about to begin for something called the Arrecife project. Originally the brain child of José Javier Doria, a professor in fluids mechanics for over 25 years, he and his son, Iñigo Doria and their business partner, Oscar Villanueva have developed the concept, which is attracting a lot of attention in the scientific community.
Prof. Doria noticed how efficiently rows of coral reefs absorbed wave energy and he theorized that by placing direct-action turbines in series, each with as many blades on as possible, he could create a device that could absorb the energy equally as well, in a similar fashion: killing the wave, so to speak.
In 2015, they applied for a series of patents and began testing small, 1:10th scale prototypes in a wave tank at the University of Cantabria, on the northern coast of Spain. They soon discovered that the principle worked and the turbines, or freewheels, absorbed the wave energy. The research also helped the team determine where the freewheels should be placed and the optimum design of the outer framework, so that it could easily cope with waves up to five meters in height.
"Arrecife consists of a horizontal floating platform provided with multiple cross-flow turbines that are strategically disposed to oppose the waves and break them emulating the coral reefs," Iñigo Doria, CEO of Arrecife Energy Systems told Forbes. "The process maximizes the capture of the wave's energy density."
The success of this led to interest from the Massachusetts Institute of Technology (MIT) and the rumblings of investor funding. Consequently, this enabled another 1:10th scale prototype to be built for open seas testing. Unlike the earlier prototype however, this one was an exact replica of what the final version, it is thought, would look like – a three-boom, trimaran-style configuration.
Testing took place off the Bilbao coast in northern Spain, in the Cantabrian sea, which itself forms part of the Bay of Biscay. Once again, the experiment was successful and the team proved it could work successfully offshore, with a simple anchor mooring and survive significantly rougher weather than the conditions required for optimum operation. All while generating power.
Many existing wave energy converters (WEC) require waves of between 5 to 8 meters in height. Arrecife is designed to generate power with the more common types of waves of between just 1 to 5 meters in height, which are found to occur 98% of the time, according to Arrecife. This means that WEC can work at full capacity for longer.
It's able to do this because its unique design means it captures energy from both horizontal and vertical wave movement, in others words, kinetic and potential energy. The Arrecife WEC naturally aligns itself by way of the direction of the waves themselves. It's provided with an immersion system that will be operated in storms; the system submerges partially and thus avoids getting damaged and it can be adapted to any sort of mooring: single anchor, dead weight, chain, jackets or pilots among others.
The MkII prototype has officially been recognized and rewarded within the industry: the idea won the Marine Technology Entrepreneurship in Boston 2017, it was a finalist at the MIT Water Innovation Prize 2018 in Boston and Richard Branson's start-up competition, the Extreme Tech Challenge, announced Arrecife as the Sustainability Vertical Winner this year. The project was also awarded the Seal of Excellence SME Instrument Phase 2 "recommended for funding" by the European Commission this year.
The next phase of the project is already well under way. A full scale MkIII prototype is under construction and the company's headquarters in Bilbao, Spain. However, this will be a catamaran-style configuration instead of having three booms. The reason is simply to save on construction costs as this final round of testing focusses much more on being able to transfer the generated electrical energy from the WEC over "a grid" to its intended target.
Current testing is around the 75kW range and the MkIII will raise that to about 150kW, but the projected output of a full-sized, fully functional Arrecife is 2,000kW and that's twice as much as many – if not most – of any other WEC concepts that currently exist. That's enough to power 1,000 homes.
The current plan is that providing the next series of tests are successful, a third round of investment will be required and then the team can move on to the final mock-up, a full-scale, three-boom 2mW variant in 2021 with an aim to begin production for widespread commercial use in 2022.
In a somewhat ironic circumstance, the team has been approached by an oil company that is interested in adopting this technology to provide electrical power to their offshore drilling platforms, since in addition to every other advantage, the Arrecife system has no depth limitations.
"We are right now well in discussions with an oil and gas company to install in one of their oil and gas platforms because they're using diesel generators and they are spending a lot of money," Iñigo Doria says.
"So they want us to connect our system to their platform. The problem is we need to manufacture the system because for them 75 kilowatts is not enough. So we were offering them to install another 10 turbines and increase the system to 150 kilowatts. And they say that they want more than two megawatts. So we are right now discussing if maybe we can find a way to manufacture our system to them."
You can follow the progress of the Arrecife project here.
