Energy harvesting: gathering momentum

Jon Lawson

Louise Smyth meets the inventors of an innovative motion-to-energy technology that could shake up the renewable energy sector

Energy harvesting concepts have been hailed as heroes of the renewable energy sector for many years now. Yet the commercial fruits of projects in this arena have so far been fairly disappointing.

The main barriers to success here are both technical (particularly when it comes to scaling up initial concepts) and financial.

However, a UK-based company is setting out to tackle both of those hurdles head-on with a motional energy technology that its inventors believe to be both completely scalable and affordable.

Witt Limited has developed a technology called the WITT, which converts motional energy into electricity.

Mairi Wickett, co-founder & director, recalls how the initial concept came about by explaining how her husband and co-founder adapted the technology from a rather different idea. “It began through a series of transmission design projects by Martin Wickett. The first unit was for bicycles, and instead of having to do a full circle of motion, you could drive the bike forward by rocking motion back and forth (like a pedalo). The bike industry was not interested, but Martin then spent months developing the unique transmission and by building two, discovered that it could take all motion and turn it into electricity, harvesting more power than any other system – i.e. clockwise, anti-clockwise, up and down, back and forth – very chaotic! The acronym we came up with, WITT, stands for Whatever Input to Torsion Transfer - or the fun name is What Is That Thing?”

So what exactly is it then?

Contained within a sealed unit, a WITT uses two pendulums connected to a flywheel to generate electricity.

Movement causes the pendulums to swing, and they are attached to a shaft that then turns a flywheel in one direction. The flywheel is connected to a generator, which produces electricity.

The unit harvests chaotic motion, fast, slow or erratic, turning it into useable power. The company claims that no other device captures energy from all six degrees of motion. Where most energy harvesting devices are point absorbers, taking up-and-down or side-to-side motion and turning it into useable power, the WITT takes all motion.

Part of what makes the WITT so compelling for investors (the company has attracted £2.38 million of private investment from crowd-funding) and tech-heads alike is that the technology is not just designed for creating one type of energy. It’s not just a marine-based tool, for instance; a unit could be placed on a backpack for consumer applications, or a bigger version could be used to capture wind power.

The intellectual property is more associated with the transmission concept itself than a nuts-and-bolts product. Therefore, this concept can be adapted for many different application environments.

Mairi Wickett explains: “The WITT is a unique transmission and will work as an affordable solution especially when produced in large production runs. We are working with aerospace precision manufacturers to ensure we have robust parts ready for testing the prototypes in the marine sector because our first deployment will be in a navigational buoy. The WITT has a series of patents: the complete transmission has a granted patent and we also have follow-on patents, which will be ongoing as we go through different design arrangements. There is an opportunity to have different WITT systems for different sizes and different applications. We are currently working on three robust prototypes: a 5W unit, a 15W unit and a 200W unit.”

Getting to grid-scale 

Those prototypes will be used across a variety of applications.

As well as small marine power applications and vessels and buoys, there will be personal consumer units such as those backpack-sized units mentioned above and eventually, grid-scale ocean power and wind power units are planned. The company is working with partners such as Schaeffler to get the technology to the production level.

“As the WITT can be built in sizes from centimetres to metres, it is obvious that one of the next steps would be to meet with organisations that would like to license the technology – and we are already talking to several interested parties,” reveals Wickett.

This scalability will be a deciding factor in determining the success of the WITT within the renewable energy sector.

Wickett predicts that, “For the marine renewable sector we can see WITT units ranging from 3 to 10m in an array, harvesting energy 24/7. The units can be deployed easily and can also be maintained quickly; a real bonus in these harsh conditions.”

She hopes that the technology will ultimately make a real mark on the renewable power industry. “We believe the impact will be high. We have quite a few USPs – for instance, when it comes to wave power, we have a sealed unit with no blades or parts that are exposed to the harsh, salt-water environment.”

The ocean-based WITT units will be able to harvest wave power from surge and pitch, sway and roll, with no shock load.

The company believes this offers twice the capacity for wave power conversion than other devices. It is currently working with various industry partners on feasibility studies regarding generating offshore grid-scale power.

The inventors also envisage seeing the technology put to use capturing wind power from any direction too. “We see the WITT as providing a future wind harvesting technology that could be developed for a global market,” confirms Wickett, although the company will focus on the marine sector first.

When it comes to quantifying just how much grid-scale power could be generated by any of these applications of the technology, Wickett says that it’s still a little too early to make accurate predictions. “But we want to demonstrate the WITT in real situations with a clear indication of the energy it can generate. In the next six months, when we finish our next batch of testing, we will have lots more data. So watch this space!”

Marine prototypes all at sea

Bearings expert Schaeffler is working with WITT Ltd on R&D to develop the marine version of the WITT. In this version, the energy device is fitted into a completely sealed 1.5m unit. The first working prototypes of the device were tested recently on a 6 degree of motion shaker table at Southampton University – the tests were deemed extremely successful. A smaller WITT prototype has had its first week of sea trials with help and support from Plymouth Marine laboratory.

Schaeffler UK is supplying a variety of bearings for the marine WITT. These include roller bearings, ball bearings and one-way clutches. As Stewart Davies, principal applications engineer at the firm states: “There are approximately 25 different bearing locations on the 200W marine WITT device, some of which are bespoke to meet the restricted design envelopes in the application.”

As the marine WITT is a totally enclosed, sealed unit, Schaeffler UK was able to select standard bearings for most locations, which helped to minimise the cost per kW of the device.

Popular with the crowd

In contrast to many small companies looking for investment in renewable energy concepts, WITT Ltd decided to use crowdfunding to enable its technical development.

This proved a great success, as the Crowdcube campaign became the largest equity-funded cleantech campaign ever, raising just under £2.4 million. “We had first round investors who immediately saw the potential, and we felt we had a good package to offer,” says Mairi Wickett, modestly. In fact, the technology had already won three Innovate UK awards, as well as winning US$100,000 from the Ocean Exchange.

Wickett says: “We had investment from every continent, and the shares were from £10 up to £100,000 plus!”

As well as people seeing the technical potential of the WITT concept, Wickett believes there’s also a more altruistic side to the financial backing, which demonstrates how people genuinely want to help in the renewable energy sector.

“The fact that the WITT can harvest energy from water – be it sea, river or tidal – and also from wind, human or even animal motion makes it a compelling technology for many people who have been willing to invest their hard-earned money to say ‘we are getting behind a technology that will help the planet’,” she adds.

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