Scotland could realistically generate nearly half of the electricity that it currently uses solely with the tidal energy available in Pentland Firth, according to new research from Oxford University. Tidal turbines stretched across the region could provide a maximum of somewhere around 1.9 GW of electricity, with a more practical target for the area being 1 GW of capacity.
The researchers note that their estimate of 1.9 GW is a good bit lower than some previous estimates put out there mostly by politicians, some over 10 GW — regardless, though, the region is still potentially one of the best sites in the world for tidal energy. 1.9 GW is nothing to sneer at, especially from such a small country.
The reasons for Oxford’s lower estimates are that they actually take into account a number of factors which weren’t taken into account with earlier estimates — such as construction feasibility, interactions between/within groups of turbines, and diminishing returns. Also, the new estimates average out the variations caused by the daily and seasonal cycles of the tides.
The new research does show that the extraction of the first 500 MW of energy would be very cost-effective — beyond that first 500 MW, though, the increasing difficulty of extracting more and more energy makes 1 GW the most reasonable goal.
“Pentland Firth promises to be one of the best sites in the world for tidal power, what our research shows is that it could potentially generate power equivalent to almost half of Scotland’s annual electricity consumption,” stated Dr Thomas Adcock of Oxford University’s Department of Engineering Science, and primary author of the new research paper.
“Our study provides the first robust data about how much energy it would be feasible to extract, it also suggests that to be efficient any scheme would have to be ‘joined up’ so that, for example, individual tidal turbines do not cancel each other out and provisions are made to store the greater energy produced by spring tides and feed these back in at neap tides.”
The researchers also note that, for any potential Pentland Firth tidal energy systems to be cost competitive, “the energy generated by each tidal turbine would have to be greater than that of off-shore wind turbines, due to the higher loads they would have to endure and higher maintenance costs.” Otherwise, offshore wind energy would prove more economical.
Another potential issue addressed by the researchers is the way that different rows of turbines would possibly interact with each other, perhaps even limiting the energy available to their neighbor turbines. For this, the researchers utilized mathematical models, “working out how to arrange them so as not to ‘steal’ each other’s tidal energy, and calculating how power generation for the overall scheme might be maximized.”
“Building handfuls of tidal turbines in ‘plots’ of ocean leased out to individual developers is not going to extract the maximum energy from Pentland Firth,” stated Dr Adcock. “To make the most of this unique site the placement of turbines would need to be carefully planned.”
Either way though, the tidal energy potential of Pentland Firth — while substantial — is nowhere near the figures that were put out there previously. Any talk of potentially exporting excess energy generated by tidal energy to other parts of Europe should die down now with the release of this research. “There’s a huge amount of tidal power there but it’s certainly not the case that Scotland will be able to export its tidal energy.” Dr Adcock concluded.
However, Scotland itself will still be able to benefit greatly from this substantial resource and could very well reach its goal of receiving 100% of its electricity from renewable energy sources by 2020.
The new research was recently published in the journal Proceedings of the Royal Society A.
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