Aerogels – a material with multifold potential for greening the world

Aerogels are translucent solid materials, created by slowly extracting liquid from gels and replacing it with gas. This makes them one of the lightest materials on Earth but also brings a series of other benefits, such as low thermal conductivity. They can be derived from a wide range of materials, most commonly silica, but carbon or graphene have also been used as starting materials. Aerographene (graphene aerogel), for instance, is about seven times lighter than air but immensely robust. Application opportunities are countless.

Aerogel (Image credit: massenpunkt)

Being excellent insulators, aerogels have been used for outdoor clothing and in the construction industry for years. They have a great potential to improve energy efficiency of the housing stock.  

Apart from NASA having used aerogels to protect the MARS Rover and the US Navy experimenting in using aerogel-based insulation for protect divers in extreme sea temperatures, MIT researchers have recently developed transparent aerogels, which could also be used tfor well-insulated windows – researchers expect that double-glazed windows with aerogels between panes to be much cheaper, while offering better insulation than triple-glazed windows.

Transparent aerogels could also significantly improve the efficiency of solar thermal systems, as it can trap higher temperatures than conventional solar collectors.

Aerogels are great at sound proofing; and also highly efficient at adsorbing pollutants, making them ideal to remove heavy metals or oil from water, or utilised for water purification.

One of the major drawbacks of aerogels today is their brittleness, although researchers have been working on addressing this issue with new approaches, such as polymer aerogels.

Also, they are quite expensive for everyday use but with widespread use and economies of scale, the cost is expected to come down.

Water from thin air

Access to clean water is a major global issue, especially for those who need to walk long distances to fetch some water, in cases several times a day, while they still might end up with contaminated water.

VICI-Labs has developed a new device called WaterSeer that basically condenses water from the air in an underground container, from where clean water can simply be pumped up. It does not need an external power source or potentially harmful chemicals.

WaterSeer has a turbine above the ground that is turned by the wind, and the air goes down to the chamber below the ground. Due to the temperature difference on its way down, water vapour is condensed and collects in this chamber. It is claimed that WaterSeer is able to produce about 37 litres of water per day – the average daily water use in many African countries today.

Similar solutions are already available on a commercial scale. An example are the products of Israeli company Water-Gen, which technology also utilises condensation by stacking a series of plastic ‘leaves’ that create a specific airflow and act as a sort of ‘dehumidifier’, while storing the moisture. This devices requires an electric plug and it is claimed to be more energy efficient that other similar, existing alternatives. It is available in three sizes: the smallest version, aimed at homes, can produce about five gallons (approx 22 litres) a day – while industrial users can benefit from the device offering 800 gallons (approx 3637 litres).

Photos: WaterSeer/Treehugger and Water-Gen

 

Cutting edge ways to utilise buildings for electricity

Tesla and SolarCity-owner Elon Musk has just revealed their latest product, called the ‘Solar Roof’, which is essentially tiles with integrated, high-efficiency solar cells behind tempered glass.

The new solar tiles are stylish as one can choose the most matching look for any building from the four different styles available (textured glass, slate glass, Tuscan glass, smooth glass tile). By using glass, the durability of tiles is increased and might even outlast the building’s life as claimed. There is a slight loss of efficiency (they work at 98 per cent), but the company is working on improving this rate.

Tesla claims the new roof could be more affordable than conventional ones when calculating utility costs as well, and when bundled with Tesla’s Powerwall ‘personal battery solutions’, households of the future shall be able to generate most of the power they would use.

Meanwhile researchers are also working on how to utilise windows to generate electricity. Scientists at the Los Alamos National Laboratory, New Mexico, have published a paper in Nature Energy claiming that a thin film layer of ‘quantum dots’ added to existing windows could enable low-cost window-based solar photovoltaic (PV) systems, which could reach higher efficiency (up to six per cent) than current systems. Quantum dots are nanometre-sized semiconductors, which enable scientists to set which type of light is absorbed. The layer is easy to apply, and the silica-protection protects against oxidation, for enabling durability.

Photos: Tesla Solar and Los Alamos National Laboratory, New Mexico

Let’s go fly a kite…

Wind turbines are becoming an increasingly controversial topic: many people oppose them claiming to spoil the landscape, whilst others praise them for bringing clean energy. Wind power is still abundant and as related costs are on the way down, it is one of the best renewable resources available today. Despite claims of it being unreliable, wind does have calculable and predictable patterns, which can be utilised to our advantage.

A number of companies are now working on how to harness wind energy at an even higher level – up in the skies.

Kite Power Solutions  is working on the concept of flying kites over the sea in formation. The idea is to anchor three kites, which could then fly in a circular path – similar to the tips of the turbine blades. The kites pull a winch on the ground that is linked to an electric generator, and the circular motion of the kites helps generating electricity.

© Kite Power Solutions Ltd 2015

Makani also believes in kites for harnessing electricity and their “energy kites” would be connected to the ground station through a tether, and it would also be supplied with an intelligent computer system to reach maximum output.

A similar approach is to use glider planes (Ampyx Power), again pulling on the tether and hence generating electricity on the ground.

Kites have already been trialled for lowering the consumption of ships, but using them on a wider scale of energy generation could bring more efficiency than conventional wind turbines –  at the fraction of the expenses.

Some solutions could eliminate the costs for expensive concrete and the use of specialised construction boats for installation, and could just be attached to a floating platform. Also, flying kites could reach heights with more powerful winds than current wind turbines, therefore harnessing more energy.

These innovations come with integrated sophisticated technology and computer systems, which can design the best set-up for the most efficient operation at any given time, while reacting faster to suddent changes in the weather or environment – for example by detecting approaching storms.

And those, who still believe in wind turbines – Altaeros Energias has been testing a floating wind turbine, where a helium-filled shell houses the turbine and which can be lifted up to 600 metres – about twice as high as the tallest current wind turbines. 

Image sources: Altaeros Energias and Kite Power Solutions

See-through solar cells

Solar cells are mostly thought of as covering a roof or a large field of reflective solar panels in the middle of the desert. But recently researchers at Michigan State University developed a solar cell that is transparent, and so could bring amazing possibilities. Being transparent means that these cells could be used in many more places than traditional solar cells – including windows and other glass surfaces like phone screens – without interruption to doing their job of collecting the sun’s energy. 

As the basic principle of solar cells is to absorb the sunlight in order to turn it into electricity hence shouldn’t let it through (which means they shouldn’t be transparent), this novel solar PV cell in fact is a so-called transparent luminescent solar concentrator (TLSC). It includes special organic salts than can transform certain types of non-visible wavelengths of light (UV and infrared) into a different type of non-visible light (also infrared) and this is then beamed to the traditional solar PV cells located on the rim of the solar cell.

The current efficiency is about one per cent (with expectations to increase it to five per cent) but it can be scaled up when applied at building windows, or it could be used to extend the battery life of mobile devices.

Prior similar solutions were mostly coloured, but the new technology allows them to be fully transparent, opening up a range of new surface options.

Michigan State University scientists are not the only ones trying to utilise large glass surfaces.

SolarWindow Technologies took another approach by having developed a see-through liquid coating that can be applied to glass that can harness solar energy. The materials used are organic, offer great performance and it’s claimed to be working well even in shaded areas and in artificial light!

Ubiquitous Energy is another company focusing on the development of transparent solar cells. Their solution technology is a film that lets visible light through but filters and absorbs ultraviolet and near-infrared light, which it turns into electricity. They claim that the efficiency can be more than ten per cent.

With so many different approaches to the same idea, see-through solar cells might be here soon.

Image credit: Michigan State University