Readers may be interested in my “The Renewable Energy Coincidence Theory.”
The premise is that regardless of how many intermittent inputs, there will always be nulls that are coincident with at least one other, two others and so on, including them all.
Much of the hyperbole surrounding the renewable energy industry centres on the so-called ‘energy mix’ giving misplaced justification for destroying pristine wilderness areas by erecting larger and larger wind turbines.
Working on full capacity outputs from an energy mix from, say, solar, wind, wave and tidal stream, we can calculate the probabilities of coincident nulls occurring in a typical year.
Annually, at Shetland’s latitudes, solar generates at full capacity for an average of 1 hour each side of local noon annually, so the probability of a null is 92%, the probability of generating at plated output from a wind turbine on the Scottish Mainland is around 16% but we can attribute 25% to Shetland’s wind regime making the chances of a null 75%. So can I say that the probability of a null with just these two in the energy mix is 69%?
Waves that are big enough, must be in line with wind at 25% reducing the probability of a coincident null to 52%. The chances of a marine turbine generating at full capacity annually must only be ~30% making the chances of a tidal stream full capacity null, 70%.
So with these four renewables in the energy mix, Shetland has the probability of a coincident null 36%. So for 3,153 random hours a year, Gremista will have to provide 100% backup to keep the lights on in Shetland.
Recently, the Crown Estates, suggested that it was perfectly ‘feasible,’ following my suggestion in SN’s Letters page a few years ago, to lay a HVDC link to the Scottish Mainland.
Question is, how can an interconnector be justified when it will lie dormant for 36% of the year with four renewables in the energy mix?
What Shetland needs is a non-intermittent electrical supply from a reliable intermittent energy source like tidal stream. Sending base load electricity, from Gentec venturi, down the interconnector would make it feasible.
Nothing short of this is good enough!
Andrew H Mackay
Greenheat Systems Limited
14 February 2008
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