Out of all the major forms of renewable energy, wind energy has been around the longest and is perceived to be the most monolithic. While fast paced progress in materials sciences have us accustomed to seeing new developments in solar almost on a weekly basis, wind is largely seen as being unchanging. However that belief couldn’t be farther from the truth, as there are many exciting advances taking place in the sector that have the potential to change how we produce wind energy in the coming years.
Floating wind turbines:
One of the most important developments of the last years is the creation and installation of floating wind turbines. This isn’t a new technology per se, but its adoption is still very limited and its growth will open up many new regions for wind energy exploitation.
Currently, wind comes in two flavours depending on location: onshore wind and offshore wind. Floating turbines have the potential to vastly increase our offshore wind generation capacity because they can be placed in much deeper waters than ground mounted ones. Consider that up until now, most turbines that are built over water are actually fixed to the ocean floor. In areas where the floor is stable and not too deep this works out fine, but there are many regions that are perfect for wind energy exploitation where the ground is not adequate to support giant metal structures weighing hundreds of tonnes, or the ocean floor is simply too deep to be able to reach it.
Many expert analyses agree that deeper waters, further from the shore have the highest potential because the wind blows more consistently there than it does nearer the coast. Additionally, if turbines can be installed many miles off the coast in waters that are hundreds of meters deep they won’t be visible from land, reducing visual pollution and opposition deriving from it. This would be an especially attractive perspective for the UK because its national waters are widely considered to be the best in Europe for wind energy.
Floating turbines function using a floating platform that is connected to the sea bed with cables and some form of anchors, which hold them in place, stabilise them and keep them from drifting away. Since wind turbine structures are so large (some are over 100 meters tall), the ballast needed to stabilize them is enormous, sometimes in the millions of kg. There are two main configurations for these types of turbines: tension leg mooring systems, in which the cables are attached to the sea bed directly below the turbine an are in constant tension, keeping the structure stable; and catenary mooring systems, in which the cables are spread out around the structure and hold it in position but don’t exert as much tension or stabilise it.
Turbines with no blades and turbines that fly:
Currently, the most powerful ground-mounted turbine systems produce multiple MWs, stand hundreds of meters tall (when factoring in the blades) and the blades and the equipment to which they are connected weight in at tens or hundreds of tonnes. Building such massive equipment, creating strong and reliable support towers to hold it up, putting it all together, and maintaining it when needs repairs costs a lot of money. Engineers around the world are looking for ways to attack this problem and over the last few years we have seen the birth of new systems that promise to reduce costs and offer other benefits.
One such system is the Vortex wind turbine, designed and developed by Spanish startup company Vortex Bladeless. Vortex’s founders were inspired by the Tacoma Narrows Bridge incident, where the entire bridge collapsed because of wind-induced oscillations that weakened its structure. After studying the incident while in school it occurred to them that they could harness the same effect to generate energy. The turbine, which looks like a giant white cone protruding from the ground, is designed to vibrate in the wind. The internal mechanism of the turbine captures the energy from these vibrations and transforms it into electricity. According to Vortex, manufacturing and operation of their device will be 50% cheaper than traditional wind turbines, and while each individual device is less efficient than traditional turbines their lower cost and smaller profile in space means that more of them can be installed in an area.
Another radically different design that is being tested currently is for flying turbines, which will float hundreds of meters up in the air where they will be able to capture energy from much stronger and more consistent wind currents. Google is very psyched about the technology, and earlier this year they announced they were to begin testing an 84-foot long model of their flying turbine machine. The device,which looks like an airplane or a glider of some sort, is launched into the air and rises like a kite. When it gets very high the many small propellers mounted on its front side turn rapidly in the wind, producing electrical energy which is sent back down to the ground via its tethering cable.
But Google isn’t the only company working on flying wind turbines. Boston based Altaeros Energies is working on its own design with very specific use-cases in mind. Their Altaeros BAT (Buoyant Airborne Turbine) is a flying wind turbine that uses the same technology as blimps to float in the air, that is, it is a helium-inflated floating structure that contains turbine blades. The company is now testing the model near Fairbanks, Alaska, and says that a single unit can produce 30 kilowatts of energy, enough to power 12 homes. The BAT has been designed with a different use-case than other wind turbines. It is easy to deploy and requires virtually no other infrastructure investment, making it ideal to power remote communities that don’t have access to the regular electrical grid. In places like Alaska, where many communities depend on Diesel generators for their electricity, the opportunity to shift to cheap, renewable wind.