I’m not real certain just what the process is for the Crown Estates in the UK about leasing tidal areas, but it seems to be competitive for at least two companies to battle to have their ocean current designs installed at Pentland Firth, off the coast of Scotland.

Pentland Firth is in the UK’s far north and has been described as the “Saudi Arabia” of marine power.

The considered leading candidate is Marine Current Turbines Ltd, who confirmed that it intends to apply for a lease from the Crown Estate to deploy its “world-beating” tidal technology in Scotland’s Pentland Firth.

Atlantis Resources Corporation chief executive Timothy Cornelius said the area that the company hoped to develop in Scotland is also the Pentland Firth in the country’s north, too. The company is confident it will win a contract to build 500 underwater turbines in the sea off Scotland.

One wonders how big this Pentland Firth place is, now with so much interest.

SeaGen In Operation

SeaGen In Operation

Marine Current Turbines has a project underway called SeaGen deployed in May of this year, a tidal project in Northern Ireland’s Strangford Lough, the world’s first commercial-scale grid-connected tidal stream energy system. At 1.2MW capacity, SeaGen, which is in the final stages of commissioning, will generate electricity onto the grid to meet the average needs of 1000 homes. Martin Wright, Managing Director of Marine Current Turbines adds, “Harnessing the power of the Pentland Firth will be challenging and there are still substantial issues, in particular financing and grid connection, which will have to be addressed. However, the move by the Crown Estate is a significant and welcome step forward if the UK is to harness the sea’s energy potential on a truly commercial basis.”

SeaGen works in principle much like an “underwater windmill” with the rotors driven by the power of the tidal currents rather than the wind. Strangford Lough has a highly energetic tide race and so is recognized as one of the main tidal “hotspots” in UK and Irish waters.

The Aussies at Atlantis Resources Corporation have developed turbines that can generate electricity from the sea’s movement, too. The deep-water Solon turbine “is a story of a group of young Australians doing wonderful things on a global scale.” Cornelius said.

The Solon Ducted Turbine

The Solon Ducted Turbine

Cornelius said, “This young guy from Townsville, in 12 months, has gone from concept to building this turbine.” The deep-water Solon turbine designed by 28-year-old Dr. John Keir is considered by many to be the world’s most efficient underwater generator.

The thrifty and frugal Scots have their naysayer in Scottish engineer Tony Trapp who told The Scotsman newspaper that tidal power was not reliable enough to generate the power levels that Atlantis is suggesting. Dr. Trapp says, “The trouble is, it isn’t the solution. Tidal and wave [power] are trivial in the world energy picture. The overall conclusion is it’s silly – it’s not a sensible use of intellect or financial resources.”

Cornelius counters saying, “The tides are completely reliable, so much so that you can predict them 20 years in advance. That is exactly the kind of information energy companies are looking for. We can be highly accurate on our outputs to the electricity grid.”

I’m with Cornelius on this. There is a huge amount of momentum in tidal flows ready for the harness if the details and economics can be worked out. It seems that the Crown Estate and Marine Current Turbines think so, too.

Now as you’ve noted, these two companies are using what can be described as conventional turbine technology of blades levering a shaft. A new take on this is a near shocker – using vortex-induced vibrations, actually making them to work in slow moving water – is counter intuitive as vortex induced vibrations are something engineers avidly seek to avoid. These vibrations are the bane of moving things; they wear, fatigue and destroy equipment and installations to great damage and harm. The idea of inducing them and pulling out the energy is just – innovative in the extreme.

A University of Michigan engineer, Michael Bernitsas, a professor in the U-M Department of Naval Architecture and Marine Engineering designed VIVACE, which stands for Vortex Induced Vibrations for Aquatic Clean Energy. VIVACE is the first known device that could harness energy from most of the water currents around the globe because it works in flows moving slower than 2 knots (about 2 miles per hour.) Most of the Earth’s currents are slower than 3 knots. Turbines and water mills need an average of 5 or 6 knots to operate efficiently. A paper on it is published in the current issue of the quarterly Journal of Offshore Mechanics and Arctic Engineering.

Vortex induced vibrations are undulations that a rounded or cylinder-shaped object makes in a flow of fluid, which can be air or water. The presence of the object puts kinks in the current’s speed as it skims by. This causes eddies, or vortices, to form in a pattern on opposite sides of the object. The vortices push and pull the object up and down or left and right, perpendicular to the current. The vortices push and pull the passive cylinder up and down on its springs, creating mechanical energy. Then, the machine converts the mechanical energy into electricity.

Professor Bernitsas estimates that array of VIVACE converters the size of a running track and about two stories high could power about 100,000 houses. Such an array could rest on a riverbed or it could dangle, suspended in the water. But it would all be under the surface. Because the oscillations of VIVACE would be slow, it is theorized that the system would not harm marine life like dams and water turbines can.

Bernitsas says VIVACE energy would cost about 5.5 cents per kilowatt-hour. Wind energy costs 6.9 cents a kilowatt-hour. Nuclear costs 4.6, and solar power costs between 16 and 48 cents per kilowatt-hour depending on the location.

Here is a hard truth and some study based facts on the power in tides and currents. “There won’t be one solution for the world’s energy needs,” Bernitsas said. “But if we could harness 0.1 percent of the energy in the ocean, we could support the energy needs of 15 billion people.

That would be a lot of power and the professor is thinking a tenth of one percent of the power available for his assertion.

It might behoove the Crown Estates to do a little further research before they commit to leases. The installed cost, the rate for kilowatt-hours to the consumers and the longevity of the initial investment with good operating cost estimates needs prime attention.

Those tides and currents aren’t likely going anywhere soon. But a bunch of capital investment will be involved for a multi decade or even longer useful lifetime. Realistically, as amazingly sensible as tide, current, wind and solar are, it will be the cost for ratepayers that matters. Great ideas need great development work and a sense of application of skills that brings more, better and cheaper. None of the resources are going to disappear or deplete. Getting it right, getting the most efficiency for the best price can take a little extra time. Harvesting systems need to get much better, and cheaper than the fueled production systems are today.

Competition has an important role here, as the best will be found and everyone will benefit. It’s a sure thing that some of the currents and tides will get into a harness.


2 Comments so far

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