A team of researchers from Israel and the United Kingdom has discovered that energy produced from the planet's oceans can increase twofold when novel methods for predicting wave power are used. Presented in the journal Renewable Energy, the results could help scientists drive and make marine renewable energy research an optimal source of power. The study was funded in part by the WAVEPORT ('Demonstration and deployment of a commercial scale wave energy converter with an innovative real time wave by wave tuning system') project, which has received more than EUR 4.5 million under the Energy Theme of the EU's Seventh Framework Programme (FP7).
The researchers from the University of Exeter in the United Kingdom and Tel Aviv University in Israel extracted energy that was more than double what is generated today by developing a way to accurately predict the power of the next wave. The outcome is much more efficient technology.
Experts postulate that while marine energy could provide twice the amount of power to the United Kingdom, the actual extraction and conversion of such energy is not up to par with solar or wind power. Marine energy is also not commercially competitive without subsidy. And while significant advances have been made in this area of research, scientists have been unable to ensure that devices are not damaged by the hostile marine environment. They have also been unable to enhance the efficiency of energy capture from waves.
This is where this latest study enters the picture. The British and Israeli researchers tackled the problem by enabling devices to accurately predict the power of the next wave and respond by extracting the maximum energy. They targeted point absorbers, which are floating devices with parts that move in response to waves. They produce power which they feed back to the grid.
According to the researchers, point absorbers are more efficient in the quantity of energy they produce if their response closely matches the force of the waves. And while past studies focused on boosting this efficiency, their study aimed at increasing the device's efficiency by predicting and controlling internal forces of the device caused by forthcoming waves.
They developed a system that gives the device the ability to extract the maximum amount of energy by predicting the incoming wave. So the data allows a program to actively control the response needed for a wave of a specific size. The chance of the device being damaged is lessened because it responds appropriately to the force of the next wave. The upshot, therefore, is that the device need not be turned off during volatile weather conditions, which is what happens now.
'Our research has the potential to make huge advances to the progress of marine renewable energy,' said first author Dr Guang Li of the University of Exeter. 'There are significant benefits to wave energy but progressing this technology has proved challenging. This is a major step forward and could help pave the way for wave energy to play a significant role in providing our power.'
For his part, co-author Dr Markus Mueller of the Environment and Sustainability Institute at the University of Exeter's Cornwall Campus said: 'The next step is for us to see how effective this approach could be at a large scale, by testing it in farms of wave energy converters.'
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Li, G., et al. 'Wave energy converter control by wave prediction and dynamic programming'. Renewable Energy, published online 27 June 2012.