Rare-earth-free generators for wind and tidal power
CategoriesSustainable News

Rare-earth-free generators for wind and tidal power

Spotted: The scarcity of rare earth elements (REE) is a challenge for the wind and tidal renewable energy sector. These minerals are lanthanides (Lanthanum-Lutetium in the periodic table plus Yttrium and Scandium) and are vital in the conventional production of wind and tidal turbines, specifically in the magnetic cores of these generators. Contrary to their name, they are not rare in the Earth’s crust, but they are rarely found in high concentrations, which makes mining them difficult. And even after being mined, it is necessary to refine them. China currently has a near monopoly in the global trade of these materials, with 90 per cent of all the REE entering the market produced in the country. The EU, meanwhile, has to import almost all of its REE.

This is where UK company GreenSpur comes in. Its generator replaces the need for REE in the magnets of wind and tidal turbines. The company uses far more abundant and easily available ferrite (Iron derived) magnets, and surrounds these with aluminium coils rather than conventional copper ones. The company is able to make these sustainable material substitutions due to a design innovation in the generator itself.

Conventional generators use moving magnets placed around static coils of wire arranged in concentric circles. The movement of the magnets (in this case via wind or tidal energy) produces an electric charge or energy in these wire coils.

The GreenSpur design, by contrast, relies on ‘axial architecture,’ in which disks of aluminium coil are stacked on top of disks of ferrite magnets. This means that the magnetic field flows parallel to the axis of the generator, which results in a higher ‘magnetic flux’ (essentially magnetic strength) and allows for the alternative materials to be used.

The benefits of using these REE alternatives are clear: lower cost of materials, cheaper cooling than conventional REE generators, and greater strength in supply chains for materials. The new design is also more environmentally friendly as harmful REE byproducts are no longer mass produced and low-risk alternatives are used in their place.

Springwise has also spotted hi-tech anodes for the next generation of batteries as well as one company that uses shades screens as a renewable source of energy.

Written by Archie Cox

Reference

Underwater kites harness energy from predictable tidal currents
CategoriesSustainable News

Underwater kites harness energy from predictable tidal currents

Spotted: Tidal energy is a source of renewable power in which energy is harnessed from either the natural rise and fall of ocean tides or the movement of tidal or ocean currents. Although not yet widely used, tidal energy has a huge potential for future electricity generation. Unlike wind and solar energy, tidal streams and ocean currents are predictable and continuous. First-generation tidal technologies tend to require strong tidal flows in order to be commercially viable. However, a new approach could greatly expand the energy potential of tidal flows.

Startup Minesto has developed a ‘kite’ with a turbine that ‘flies’ underwater to generate electricity from predictable tidal streams and ocean currents. The device is attached to a tether and uses the hydrodynamic lift force created by the underwater current to move. An onboard control system autonomously steers the kite in a figure-of-eight trajectory. This motion pulls the turbine through the water at a water flow several times higher than the actual stream speed – and this faster speed generates more power.

The tether contains cables for communication and power and is connected to the seabed foundation by a connector that can be easily latched and unlatched for installation and recovery. Electricity generated is sent to the grid using a power cable within the tether.

Minesto claims that its use of a wing design and its underwater ‘flight’ makes this technology more efficient than other tidal energy technologies. On its website, the company explains that, “This means that when the kite multiplies the relative speed which the turbine is pushed through the water, the electricity produced by the generator is several times greater compared to if the turbine would be stationary. By adding this step of energy conversion, Minesto expands the global tidal and ocean currents’ extractable potential.”

Other recent renewable energy innovations that harness the flow of water include a floating platform that harvests energy from rivers and a new design that could allow wave energy to be harvested from the open ocean.

Written By: Lisa Magloff

Reference