Belfast, Northern Ireland — According to a report published in this week’s New Scientist magazine, nearshore waves offer much better prospects for wave energy development than previously thought. The article quotes scientist Dr. Matt Folley of Queen’s University, Belfast, who has calculated how much energy can be extracted from all wave types. He has found that nearshore waves offer almost as much exploitable energy as offshore waves.
Folley’s research, according to the article, shows that waves from 0.5 to 2 kilometers from the coast carry 80-90% of the usable energy of waves further out. His calculations reportedly show that offshore waves carry exploitable power at a density of around 18.5 kilowatts (kW) per metre-slice, compared with about 16.5 kW for nearshore ones.
Standard figures have historically overestimated the utility of offshore waves for two reasons, Folley told New Scientist. They allowed severe storms to push up the average power figures, however in reality wave power devices generate little power in such storms because they may have to switch into a self-preservation mode.
Previous figures also assumed that offshore waves have a prevailing direction, Folley goes on to say in the article, in the same way that nearshore waves tend to move towards the coast. However it is now understood that offshore waves come from a greater range of directions meaning that some harvesters in an offshore wave farm would be blocked by others. Nearshore farms could be strung out in lines to avoid that, says Folley.
The findings are good news for wave energy developers including Aquamarine Power, which said that its Oyster technology is designed specifically to harness the energy found in nearshore waves. The company has identified 8GW of exploitable nearshore energy in UK and Irish waters – enough energy to power around seven million homes.