Nav: Home

Wave energy converters are not geared towards the increase in energy over the last century

July 20, 2018

Wave energy converters are specifically designed to produce the maximum output at the location where they are going to be placed, in other words, to ensure that they generate as much electricity as possible from the movement of the waves around them. The design and adaptation is made on the basis of historical data, past wave height and period. "However, the timescale taken into consideration tends to be quite short and, what is more, the year is regarded as typical in this period. So the converters are adjusted on the basis of how they are expected to behave during that typical year," explained Alain Ulazia, lecturer at the UPV/EHU's Faculty of Engineering - Gipuzkoa in Eibar.

Bearing in mind the changes taking place as a result of climate change with respect to temperature and other metrological parameters, Ulazia and another two UPV/EHU researchers in the departments of NE and Fluid Mechanics and Applied Physics II, and from the Plentzia Marine Station, in collaboration with the Irish Centre for Ocean Energy Research tackled a longer-term study. "In Ireland we conducted a study that we had previously done in the Bay of Biscay, given that Ireland is particularly active in terms of wave energy and we wanted to explore that energy as a resource. Using a simulation we calculated what response or behaviour a converter would have displayed when faced with the level of energy recorded during the last century, divided into periods of 20 years, given that the converters have a useful service life of 20 years on average," he said.

In this task their source of information comprised two datasets of the European Centre for Medium-Range Weather Forecasts (ECMWF): ERA-Interim and ERA20. Both of them are reanalyses, in other words, datasets fed by a whole host of observations and measurements. They are spatial networks that provide long time series in each of the eyes of the network, in other words, for each location. The better-known one is ERA-Interim as it brings together a multitude of data coming from satellites, but its limitation is that "it only has data on the last 40 years," explained Ulazia. "ERA20 is fed by far fewer data, is much more irregular from the time and spatial perspective but provides data on the whole of the 20th century."

In the research they calibrated one dataset against the other by making use of the overlapping period they have. And then they validated them against the measurements made in the buoys in the Atlantic. As Ulazia said, "we concluded that the data are acceptable, that they can be regarded as good, so we were able to simulate the levels of energy in which the converters were expected to have worked".

A 40% increase in wave energy

Taking the average 20 years' useful service life of wave energy converters as a reference, they divided the last century into five periods and adapted the converters for the level of energy corresponding to each of these periods. "We found that between the first time period and the last the level of marine energy saw an increase of more than 40%, and the biggest increase took place in the last 20 years (18 %)," highlighted the researcher. "We did not get involved in analysing what was responsible for this increase, but the main hypothesis would be climate change."

The fact that there are great variations in wave energy has direct consequences on the output of the converters; in the research they were able to see, for example, that "the converters did not take full advantage of all the energy they had available and, what is more, extreme events, such as periods of waves over seven metres high or phenomena like El Niño, became more frequent as the century progressed. As a result, the converters had to go more frequently into survival mode, or stop producing energy during these marine events," he said.

Ulazia says the information obtained should be useful in optimising the design of the converters. "As these devices are optimised on the basis of wave height and period, their design would need to be adapted to ensure they achieve maximum output in conditions that are increasingly more active".

Additional information

Three UPV/EHU researchers participated in this research: Alain Ulazia and Gabriel Ibarra of the Department of NE and Fluid Mechanics (the first in Eibar and the second in Bilbao), and Jon Sáenz of the Department of Applied Physics II. Ibarra and Sáenz also belong to the Plentzia Marine Station. They collaborated with the Irish Centre for Ocean Energy Research in view of its broad experience in machinery simulation, and for other reasons. There they had the participation of Markel Peñalba from the Basque Country.
-end-


University of the Basque Country

Related Wave Energy Articles:

New discipline proposed: Macro-energy systems -- the science of the energy transition
In a perspective published in Joule on Aug. 14, a group of researchers led by Stanford University propose a new academic discipline, 'macro-energy systems,' as the science of the energy transition.
How much energy storage costs must fall to reach renewable energy's full potential
The cost of energy storage will be critical in determining how much renewable energy can contribute to the decarbonization of electricity.
Shifts to renewable energy can drive up energy poverty, PSU study finds
Efforts to shift away from fossil fuels and replace oil and coal with renewable energy sources can help reduce carbon emissions but do so at the expense of increased inequality, according to a new Portland State University study
The new great wave
Radical Inkless Technology produces the world's smallest 'Ukiyo-e' and promises to revolutionize how we print.
First demonstration of antimatter wave interferometry
An international collaboration with participation of the University of Bern has demonstrated for the first time in an interference experiment that antimatter particles also behave as waves besides having particle properties.
Wave device could deliver clean energy to thousands of homes
A device that could convert wave energy into electricity has been demonstrated in scaled trials at the University of Edinburgh's circular testing tank, FloWave.
Putting that free energy around you to good use with minuscule energy harvesters
Scientists at Tokyo Tech developed a micro-electromechanical energy harvester that allows for more flexibility in design, which is crucial for future IoT applications.
Famous freak wave recreated in laboratory mirrors Hokusai's 'Great Wave'
A team of researchers based at the Universities of Oxford and Edinburgh have recreated for the first time the famous Draupner freak wave measured in the North Sea in 1995.
Wave-particle interactions allow collision-free energy transfer in space plasma
A team including researchers from Nagoya University finds evidence of collisionless energy transfer occurring in the plasma of Earth's magnetosphere.
MIT Energy Initiative study reports on the future of nuclear energy
In new MIT report, study authors analyze the reasons for the current global stall of nuclear energy capacity and discuss measures that could be taken to arrest and reverse that trend.
More Wave Energy News and Wave Energy Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Risk
Why do we revere risk-takers, even when their actions terrify us? Why are some better at taking risks than others? This hour, TED speakers explore the alluring, dangerous, and calculated sides of risk. Guests include professional rock climber Alex Honnold, economist Mariana Mazzucato, psychology researcher Kashfia Rahman, structural engineer and bridge designer Ian Firth, and risk intelligence expert Dylan Evans.
Now Playing: Science for the People

#541 Wayfinding
These days when we want to know where we are or how to get where we want to go, most of us will pull out a smart phone with a built-in GPS and map app. Some of us old timers might still use an old school paper map from time to time. But we didn't always used to lean so heavily on maps and technology, and in some remote places of the world some people still navigate and wayfind their way without the aid of these tools... and in some cases do better without them. This week, host Rachelle Saunders...
Now Playing: Radiolab

Dolly Parton's America: Neon Moss
Today on Radiolab, we're bringing you the fourth episode of Jad's special series, Dolly Parton's America. In this episode, Jad goes back up the mountain to visit Dolly's actual Tennessee mountain home, where she tells stories about her first trips out of the holler. Back on the mountaintop, standing under the rain by the Little Pigeon River, the trip triggers memories of Jad's first visit to his father's childhood home, and opens the gateway to dizzying stories of music and migration. Support Radiolab today at Radiolab.org/donate.