Clear The Air Energy Blog Rotating Header Image


World first for Shetlands in tidal power breakthrough

Nova Innovation deploys first fully operational array of tidal power turbines in the Bluemull Sound

A power company in Shetland has claimed a breakthrough in the race to develop viable offshore tidal stations after successfully feeding electricity to local homes.

Nova Innovation said it had deployed the world’s first fully operational array of tidal power turbines in the Bluemull Sound between the islands of Unst and Yell in the north of Shetland, where the North Sea meets the Atlantic.

It switched on the second of five 100kW turbines due to be installed in the sound this month, sending electricity on a commercial basis into Shetland’s local grid.

Existing tidal schemes use single power plants or installations rather than a chain of separate turbines. A French company, OpenHydro, says it too is very close to linking two tidal machines, off Brittany, to build a more powerful 1MW array.

After a series of commercial failures in Scotland’s nascent marine power industry, including the collapse of two wave power firms, Pelarmis and Aquamarine, Nova Innovation’s announcement was applauded by environmental groups.

Lang Banks, director of WWF Scotland, said: “News that power has been exported to grid for the first time by a pair of tidal devices marks yet another major milestone on Scotland’s journey to becoming a fully renewable nation.

“With some of the most powerful tides in Europe, Scotland is well placed to lead in developing this promising technology, which will help to cut climate emissions and create green jobs right across the country.”

The islands, which are not connected yet to the UK grid, get most of their electricity from a diesel-fuelled power station which is supplied by tankers, despite having some of the world’s strongest and most reliable wind, wave and tidal resources.

Shetland has also been the site of one of the UK’s most bitter disputes over renewable power. Thousands of islanders campaigned against an ambitious scheme backed by the local council to build the 370MW Viking windfarm, involving 103 turbines erected on the main island.

That scheme finally won legal approval in 2015 but construction has yet to begin; it is waiting for a UK government announcement on new energy supply deals and the installation of a national grid connection to mainland Scotland.

Nova Innovation said the two turbines installed so far were operating at 40% of their installed capacity. The company hopes its turbines, which were cofunded by the Belgian renewables company ELSA, will be sold worldwide now they have been commercially proven.

“We are absolutely delighted to be the first company in the world to deploy a fully operational tidal array,” said Simon Forrest, the firm’s managing director.

Chaotic Motion Device Aims for Scalability, Portability

The world is full of “chaotic motion,” in other words, continuous but non-uniform types of physical excitation that are nevertheless pervasive and commonplace. Ocean waves are a naturally occurring example. So is the movement of people as they walk or run in everyday life. What almost all have in common is that they represent a nearly limitless source of energy if only a means could be found to convert them into a reliable form of electric power generation.

Methods of doing so have long been a focus of engineering research. A UK-based company has come up with something different: a single type of device that could be scaled to provide useful, usable power from a few watts to hundreds of kilowatts depending on the scale of the motion source.


The company is WITT Energy based in Plymouth in South West England and founded by a husband and wife team, Martin and Mairi Wickett. Their aim was to find a means of converting bi-directional movement to rotation. Their initial idea has now been embodied into the design for a device that goes by the name Whatever Input to Torsion Transfer (WITT). It is claimed to be one of the first ever practicable pieces of equipment with the potential to translate multiple degrees of motion – up, down, backwards, forwards and rotation about an axis – into a single output able to drive a generator to produce electricity. (Watch a video of the generator in action.)

The basic principle involves the use of pendulums that react to external movement. These drive a flywheel and gearbox that in turn drive a conventional generator. The potential benefits could be considerable.

The first is its potential scalability from a wearable device to something that could be mounted in a boat to exploit its pitching and rolling motions. Second, all of the essential working parts can be sealed inside a housing pierced only by the wires carrying the electric current, thereby making it resilient to damage from external forces. Another is that it could be able to produce power across a wide range of excitation – a marine device, for example, should continue to operate in storm conditions. It also would be flexible in operation and could be used to charge batteries if there was no immediate need for power or if the source of motion was intermittent.

The company’s commercial director Nicholas Gill says that the device has already won at least one award for innovation – the 2013 Gulfstream Navigator Award worth $100,000 made by the Ocean Exchange organization, an international venture that seeks to recognize environmentally friendly innovation with a potential for global application. He says the device is also attracting interest from the German conglomerate Schaeffler, which Gill says has agreed to work with WITT to help refine the concept. Both the Indian and U.S. defense departments also have expressed interest, he says.

The defense departments’ interest has been stimulated in part by the device’s potential to be built into a soldier’s backpack. Gill says this would enable the device to provide a means of constantly recharging the batteries used to power electronic equipment that military personnel now carry. He says that a WITT device weighing two pounds and capable of generating 10W of power could feasibly be developed and would be sufficient to meet military applications.

A prototype of such a device has been tested and, Gill says, has achieved a “peak power” output of 5W. Further lightweighting of almost all its component parts could help boost power output towards that target figure. Moreover, Gill says that the company could exploit the need for the pendulums to retain some weight by making them incorporate batteries, which would contribute “net zero weight” to the device.

That possible application is likely to be beaten into real use by a larger version of the concept that is capable of generating as much as 200W. WITT Energy is developing that device in cooperation with UK precision engineering operation Gibbs Gears. Gill says that this device is intended for marine use although the company has also recognized that fixed floating objects such as marker buoys present a potential market. A prototype is scheduled to appear by “the third quarter of 2016” with a market launch possibly in 2017, he says.

Gill says that by late 2015 the company will launch a crowdsourcing push that aims to bring in at least $1.1-4.5 million.

Waving good buy? A hitherto-obscure piece of physics may be the secret to ocean power generation

THE idea of extracting energy from ocean waves and turning it into electricity is an alluring one. The first serious attempt to do so dates back to 1974, when Stephen Salter of Edinburgh University came up with the idea of “ducks”: house-sized buoys tethered to the sea floor that would convert the swell into rotational motion to drive generators. It failed, as have many subsequent efforts to perform the trick. But the idea of wave power will not go away, and the latest attempt—the brainchild of researchers at Oscilla Power, a firm based in Seattle—is trying to address head-on the reason why previous efforts have foundered.

This reason, according to Rahul Shendure, the firm’s boss, is that those efforts took technologies developed for landlubbers (often as components of wind turbines) and tried to modify them for marine use. The consequence was kit too complicated and sensitive for the rough-and-tumble of life on the ocean waves, and also too vulnerable to corrosion. Better, he reckons, to start from scratch.

Instead of generators with lots of moving parts, Oscilla is developing ones that barely move at all. These employ a little-explored phenomenon called magnetostriction, in which ferromagnetic materials (things like iron, that can be magnetised strongly) change their shape slightly in the presence of a magnetic field. Like many physical processes, this also works in reverse. Apply stresses or strains to such a material and its magnetic characteristics alter. Do this in the presence of permanent magnets and a coil of wire, such as are found in conventional generators, and it will generate electricity.

The core of Oscilla’s design is a bar made from an alloy of iron and aluminium, a mixture that is strongly ferromagnetic. Such bars need be compressed by only one part in 10,000 to have the desired effect. This means, to all intents and purposes, that the generator has no internal moving parts that can go wrong. But compressing a solid metal bar by even this tiny amount requires the application of a huge force. Fortunately, ocean waves are powerful enough to generate this force. Oscilla’s design, as the firm’s name suggests, does it by oscillation.


Its oscillating generators consist of two large objects connected by cables (see diagram). At one end of these cables, floating on the surface, is a buoy that contains the generating apparatus of alloy bars, magnets and coils, together with sets of hydraulic rams which can squeeze the bars as desired. At the cables’ other ends hangs a structure called a heave plate, which is kept stationary by a combination of inertia and the drag of the surrounding water. This arrangement means that, as the buoy rises and falls with the waves at the surface while the heave plate stays more or less put, the tension on the cables increases and decreases. That changing tension drives the rams. The whole system is kept in place by a second set of cables that moor it to the seabed.

A full-scale device, which Oscilla hopes to build by 2018, will be a foam-filled steel buoy 27 metres in diameter, six metres high and weighing 1,000 tonnes, tethered to a toroidal concrete heave plate 70 metres below the surface. It will carry 12 magnetostrictive generators within. Mr Shendure says that a single such buoy, placed a few kilometres offshore, should deliver an average of 600 kilowatts—about the same as an onshore wind turbine. A prototype four metres in diameter underwent a brief but successful open-ocean trial off the Atlantic coast of America last year.

Oscilla’s generators will, Dr Shendure acknowledges, be expensive to build and install. But their simple design, he says, should allow them to operate for decades with no more maintenance than an occasional scrub to remove accumulated barnacles. He calculates that the cost of producing electricity from them will be around ten cents a kilowatt hour. That compares with 16 cents a kilowatt hour for offshore wind farms and six cents for the onshore variety. A grid-connected fossil-fuel power station would be cheaper still—five cents or less. But ten cents represents a decent start for such a novel way of generating electricity.

East Delhi Commissions Hydropower Plant Powered By Sewage Effluent

Delhi is getting its first hydropower plant, but it’s not harvesting the energy of running water in the traditional hydroelectric model, as this new system uses falling water from a treated sewage effluent pipe to spin its turbine.

Recapturing some of the energy in flowing water that is generated by existing processes, such as municipal water supplies, is one non-traditional step for hydropower, and cities such as Portland have begun experimenting with this sort of ‘smart water pipe infrastructure.‘

The new hydropower plant, in East Delhi, India, is built onto the Delhi Jal Board’s 9 MGD sewage treatment plant at Chilla, and is said to be the first of its kind, not only because it’s being powered by effluent water, but also because it’s the first hydropower plant in the city. According to the Delhi Jal Board (DJB), this pilot project was set up “free of cost,” and the estimated annual 20,000 kWh of electricity produced by the hydropower installation will be used directly at the sewage treatment plant.

“The use of fossil fuels leads to the generation of carbon dioxide which in turn leads to Green House Effect and Global Warming. However no fossil fuel is being used in the generation of the power through Hydropower at Chilla, therefore this technology is termed as “pollution free technology.”” – Delhi Jal Board

The treated effluent water falls from a height of 4.8 meters at the sewage treatment plant, which is sufficient to spin the turbine and generate clean electricity, and this ‘Green Power Generation’ energy technology will help to reduce both air pollution and electricity costs. No additional specs, other than the estimated 20,000 kWh of electricity annually, for the installation were available. According to DJB, the Board is also looking to replicate this hydropower setup at its other installations in the future.