CSIR Current Affairs

CSIR scientists develop artificial leaf create hydrogen fuel from sunlight, water

CSIR scientists have developed an ultra-thin wireless device that mimics plant leaves to produce energy using water and sunlight. The artificial leaf absorbs sunlight to generate hydrogen fuel from water.

In advance, this artificial leaf may provide clean energy for powering eco-friendly cars in the future. It can serve ultimate solution for our energy and environment problems.

Need for such technology

At present, hydrogen is produced from fossil fuels by steam reforming. In this process large amount of carbon di-oxide (CO2) – a greenhouse gas is emitted which promotes global warming. So in view of pressing energy and environmental issues, it is important to produce hydrogen from natural resources such as sunlight and water. India is also blessed with plenty of sunlight throughout year that is not exploited significantly to produce energy or hydrogen.

Key Facts

The artificial leaf or the wireless device consists of semiconductors stacked in manner to simulate natural leaf system. The device has an area of 23 square centimetres. When visible light strikes semiconductors, electrons move in one direction and produce electric current.

The current almost instantaneously splits water into hydrogen – making it one of cleanest forms of fuel as its main byproduct is water. It can produce 6 litres of hydrogen fuel per hour.

To improve light-absorbing efficiency of artificial leaf, researchers had used gold nanoparticles, titanium dioxide and quantum dots. Quantum dots are semiconductor crystals of nanometre dimensions with properties that depend on the size of dots.

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CSIR-NIIST develop new technique to produce bioethanol from cotton-stalks

Scientists from CSIR’s National Institute for Interdisciplinary Science and Technology (CSIR-NIIST), Thiruvananthapuram have developed new technique to produce bioethanol from discarded cotton-stalks. The technique uses combination of chemical and biological techniques.

The new technique will help to produce bioethanol, a clean fuel from cotton stalk wastes. Converting the agro-residues such as cotton stalks and wheat and rice husks etc to ethanol reduces the food vs fuel competition.

India has about 9.4 million hectares under cotton cultivation and every hectare generates 2 million tonnes of cotton stalk wastes.

New Technique

In new technique, cotton stalks first are treated with acid, alkali and different enzymes to breakdown its complex organic polymers. The acid treatment remove hemicellulose, a polymer of cell wall and alkali makes easier to extract lignin, a binding matrix in cell wall, made of complex phenolics.

These treatments exposes cellulose of cotton stalks made of glucose to the action of enzymes. It converts glucose into final product bioethanol by the process of fermentation using a novel yeast strain.

The novel yeast strain used was Saccharomycescerevisiae-RRP-03N, obtained from a rotting wild fruit we found in the Silent Valley National Park, Kerala.

Significance

The Saccharomycescerevisiae-RRP-03N yeast performs better than distiller’s yeast strains commonly used in fermenting the cotton stalk hydrolysate. It has glucose conversion efficiency of 76% and it utilised entire glucose in just 24 hours and converted into alcohol.  The final alcohol obtained after distillation can be made to fuel grade bioethanol (>99% purity).

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