Could Bamboo Replace Steel & Graphene Boost Solar PV Panels?

A laboratory in Singapore is working on bamboo as an alternative to steel for reinforced concrete applications in developing countries, where close to 90% of the cement and 80% of the steel is consumed by the global construction sector. And in an experiment that could nearly double the rate of solar energy conversion from 32% to 60%, scientists in Switzerland have used the super-material graphene to produce an electric current, which means it could be used as a photovoltaic material to add high-efficiency to solar panels. Read More

Nathan Johnson reports (17 February, 2015):

Could bamboo replace steel reinforcement in developing countries?

Singapore’s Future Cities Laboratory is working to tap into the potential of bamboo as an alternative to steel for reinforced concrete applications in developing countries.

Currently, steel-reinforced concrete is the most common building material in the world, and developing countries use close to 90 per cent of the cement and 80 per cent of the steel consumed by the global construction sector.  However, few developing countries actually produce their own steel or cement and are thus forced into exploitative relationships with sellers in the developed world.

The Future Cities Laboratory believes that the social, economic, and material benefits of bamboo combined with its high-tensile strength could make a composite version of it the ideal replacement for steel in reinforced concrete applications.

The key ingredient is the very light but tension-resistant fibre in the bamboo culm which is able to bend in extreme ways without breaking and is superior in its ability to withstand tensile forces, even to reinforcement steel.

Bamboo is also a highly renewable and eco-friendly material, grows much faster than wood, is usually available in great quantities, and is easy to obtain.

It is also known for its unrivalled capacity to capture carbon and could play an important role in reducing emissions.

A team of young researchers is now exploring new types of composite bamboo material by extracting the tension-resistant fibre and transforming it into a manageable industrial product so that it can be introduced as a viable building material and an alternative to steel and timber.

The Laboratory says Bamboo composite material can be produced in any of the familiar shapes and forms in which steel and timber are produced, and can be used to build wall structures for houses or any other buildings.

They also say that it will be used in reinforcement systems in concrete or beams for ceilings and roof structures because of the material’s tensile strength.

Source: www.architectureanddesign.com.au/news/could-bamboo-replace-steel-reinforcement-in-develo

Graphene could double the rate of solar energy conversion

For the first time, scientists have managed to feed a single light particle – or photon – into a graphene structure to produce multiple electrons – a phenomenon that could revolutionise the solar energy industry.

By the BEC CREW  on Science Alert ( 26 January 2015):

In an experiment that could nearly double the rate of solar energy conversion from 32 to 60 percent, scientists in Switzerland have used the super-material graphene to convert a single photon into many electrons to produce an electric current.

The team, from the Swiss École Polytechnique Fédérale de Lausanne (EPFL), demonstrates how graphene could join cadmium telluride, copper indium gallium selenide/sulphide, and various silicon structures as one of the few known photovoltaic materials – high-efficiency, solar energy-producing materials.

They achieved this by placing a sample of graphene – a thin layer of pure carbon that’s around 100 times stronger than steel and a very efficient heat and electricity conductor – into an ultra-high vacuum chamber. The graphene they used was ‘doped’, which means electrons were added or subtracted chemically before the experiment.

The graphene was then blasted with a super-fast pulse of laser light, which ‘excites’ the electrons floating around in the graphene and puts the whole material into a higher energy state than before the laser blast. In this state, says Michael Byrne at Motherboard, an excited – or ‘hot’ – electron might “pop loose from its atomic home”, and when it very quickly falls back into its regular state of energy, it excites an average of two more electrons as a knock-on effect. This phenomenon can then be conducted as an electric current and used for power, and it all happens in a matter of femtoseconds, so a few quadrillionths of a second.

The team observed this phenomenon for the first time by recording the energy of each electron at different points in time, over and over again, like “a kind of stop-motion movie of the conversion process”, says Dexter Johnson at IEEE Spectrum.

“This indicates that a photovoltaic device using doped graphene could show significant efficiency in converting light to electricity,” one of the team, materials scientist Marco Grioni, said in a press release.

The amount of energy you need to force an electron free depends on the material you’re using. If the amount of energy you need to achieve this phenomenon is too great, the material will be considered inefficient, because the leftovers will end up as wasted heat energy. But this new technique, known as carrier multiplication, uses that leftover energy to ‘pop loose’ more electrons so they can be harvested for power.

The results have been published in Nano Letters.

It’s pretty exciting stuff, because graphene is even better at conducting electricity than copper. But there’s one big problem – graphene isn’t great at absorbing light, which is pretty crucial if you want to make solar panels and the like out of it.

Michael Byrne explains at Motherboard:

“Being able to convert sunlight to electricity at very high efficiencies doesn’t much matter if the material wants to ignore the light in the first place. And there is also the question of how exactly to harvest current from graphene, the ​edges of which tend to have different conductivity properties than the central zones and are also quite reactive when exposed.”

But Grioni’s team would be all too aware of this fact, so I’m hoping they have some kind of solution up their sleeves. It would be truly amazing if they could double the upper-limit of solar energy conversion using a material as cheap to produce and great at conducting as graphene.

Sources: www.sciencealert.com/graphene-could-double-the-rate-of-solar-energy-conversion