It is difficult to overstate the anger and sheer frustration felt in the islands this week, particularly those across the Minch.

The UK and Scottish governments published a report which considered “the evidence base for developing renewables projects on the Scottish islands”. In other words, how the hell are we going to realise the much-vaunted vision of creating an age of prosperity for the islands on wind, wave and tidal energy?

The report was clear on the economic potential of such a plan:

"Our analysis suggests that by 2020 up to 392 full-time equivalent jobs could be created on the Western Isles, 463 in Shetland, 416 in Orkney, and an additional 3000 FTEs could be generated in the rest of Scotland and elsewhere in the UK.

"By 2030, the number of jobs created could increase to over 3500 on the Western Isles, almost 2900 in Shetland, and over 4500 on Orkney, demonstrating the potential significance of the marine industry in the UK."

The numbers were a welcome confirmation of the sort of figures that had been mooted before. But the conclusions were depressingly familiar. By far the biggest cost associated with developing green energy projects in the islands would be in transmitting the energy to the mainland  for sale to the grid.

"The costs of constructing subsea cables between the islands and the mainland, and associated onshore reinforcements are very high. For example, the cost of the HVDC cable to Lewis alone is in excess of £700m," said the report.

The £700m figure was similar to the £775m figure that SSE revealed last November for the Lewis interconnector, a massive 65% increase on the £490m previously estimated.

But why on earth should it take £700m to lay a cable under the Minch?

Well, this week’s report explains. It says: "These transmission projects, and the associated onshore reinforcements that are required both on the islands and the mainland, are complex involving lengthy planning and engineering studies, and with their own environmental impacts."

This blog claims no expertise whatsoever in subsea engineering, but still, £700m? The ferry route from Stornoway to Ullapool is only 52 miles and much of grid-supplied Wester Ross is closer to Lewis than Ullapool.  Would it really cost about £14m for every mile of cable, however many onshore reinforcements are required?

Cometa is an undersea electric power transmission between mainland Spain and the island of Majorca. It consists of two bipolar high-voltage direct current (HVDC) cables with a capacity of 200 MW and an operating voltage of 250 KV of each, and a metal return cable.

The submarine cable is 149 miles long and the land cable is four miles. There are two converter stations. It became fully operational in August last year, a bit late but at a total cost of €375m or £316m.

Obviously, the Mediterranean is not the Minch, but the projects are similar. Cometa’s aims were to connect the Balearic Islands with the  mainland Spanish grid. But it cost less than half the price of a cable across the Minch, despite the distance being three times greater.

Meanwhile, the  science and technology website ExtremeTech published an article a year ago about cable laying. In this case it was cable for internet connections. The scale of projects discussed rather dwarfed the challenge of the Minch, but it made some extremely interesting points.

The article said: “Starting this summer, a convoy of ice breakers and specially-adapted polar ice-rated cable laying ships will begin to lay the first ever trans-Arctic Ocean submarine fibre optic cables. Two of these cables, called Arctic Fibre and Arctic Link, will cross the Northwest Passage which runs through the Canadian Arctic Archipelago.

"A third cable, the Russian Optical Trans-Arctic Submarine Cable System (ROTACS), will skirt  the north coast of Scandinavia and Russia. All three cables will connect the United Kingdom to Japan, with a smattering of branches that will provide high-speed internet access to a handful of Arctic Circle communities. The completed cables are estimated to cost between $600m and $1.5bn each.”

The article goes on to talk about the need for greater internet speeds for algorithmic stock market trading, where a difference of a few milliseconds can gain (or lose) millions of dollars.  “It is for this reason that a new cable is currently being laid between the UK and US - it will cost $300m and shave “just” six milliseconds off the fastest link currently available.”

So for £392m to £980m you can lay a cable from the UK all the way to Japan via the Arctic Ocean using ice breakers, and for £196m across the Atlantic Ocean to North America. But we are talking over £700m for a distance that an ageing car ferry can cover in two hours 45 minutes. Of course, it is not as simple as that, it never is. But neither can there be £700m worth of complexity.

Late last year the leader of Western Isles Council Angus Campbell warned there were just six months left to realise the opportunity to finally transform the fragile Westerns Isles’ economy through green energy production. But he said the dream would be worthless unless a contract could be signed to place an order by June or July for a subsea cable to take the power to the mainland.

On Wednesday, SSE subsidiary SHE Transmission said it awaited “a decision from the UK and Scottish governments on how to overcome the costs faced by renewable developers on the Western Isles, the placing of the multi-million pound cable contract by July is no longer achievable.  As a result it will not be possible to commission a link before 2017.”

Mr Campbell could not hide his disappointment and frustration to SHE's decision. He said: "This negative approach has been a characteristic of SHE Transmission's approach to the Outer Hebrides. Despite their excuses I think it is fair to say that SHE Transmission and their parent company SSE have totally failed the Outer Hebrides.

“In my view the organisation is no longer fit for purpose and we have to now seriously look at alternative transmission solutions for the Outer Hebrides.”

He said he would be writing to both National Grid and the regulator OFGEM to explore options around National Grid taking over the link or for the link to be put out to open competition. 

He said a case could be made that SSE's generation and transmission business should be "unbundled".

Indeed, but even that would need yet more reports, and in the meantime the green sun that was to have shone on Hebridean fortunes, will be in danger of setting for good.