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    Taiwan's Feng Chia University has succeeded in boosting the production of hydrogen from biomass to 15 liters per hour, one of the world's highest biohydrogen production rates, a researcher at the university said Friday. The research team managed to produce hydrogen and carbon dioxide (which can be captured and stored) from the fermentation of different strains of anaerobes in a sugar cane-based liquefied mixture. The highest yield was obtained by the Clostridium bacterium. Taiwan News - November 14, 2008.

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Tuesday, December 02, 2008

Fraunhofer researchers make bioplastic from liquid wood

Bioplastics made from cellulosic biomass, such as forestry or crop waste, offer a smarter way to use biomass than turning it into liquid biofuels. Per hectare of crops grown or per quantity of biomass, cellulosic bioplastics offset more petroleum and GHG emissions than liquid cellulosic biofuels (previous post). Most of these next-generation bioplastics, which no longer rely on easily extractible starch or sugar like that found in corn or sugarcane, are made from a limited range of feedstocks and research is still in an early stage. However, German engineers from the Fraunhofer Institute have already added a new feedstock for bioplastics and show the final product is ready for market. The plastics are made from what's called 'liquid wood', a lignin-rich product.

Most plastics are based on petroleum. A bioplastic that consists of one hundred percent renewable raw materials helps to conserve this resource. Limiting its use also reduces greenhouse gas emissions. The researchers have optimized the new wood-based plastic in such a way that it is even suitable for products such as Nativity figurines. Toys have to put up with a lot of rough treatment: they are sucked by small children, bitten with milk teeth, dragged along behind bobby cars, and every now and then they have to survive a rainy night outdoors. Whatever happens, it is vital that the material does not release any softeners or heavy metals that could endanger children.

Toys can be made of the new feedstock, called 'liquid wood', in the future. The advantage is that this bioplastic, known as 'Arboform', is made of one hundred percent renewable raw materials, more specifically lignin-rich biomass, and is therefore neither depenent on fossil oil or easily extractible starches, vegetable oils or sugar from crops.

Researchers at the Fraunhofer Institute for Chemical Technology ICT in Pfinztal and the Fraunhofer spin-off TECNARO GmbH have developed the material. But what exactly is liquid wood?

The cellulose industry separates wood into its three main components – lignin, cellulose and hemicellulose, explains ICT team leader Emilia Regina Inone-Kauffmann. The lignin is not used in papermaking, however. Researchers at TECNARO mix lignin with fine natural fibers made of wood, hemp or flax and natural additives such as wax. From this, they produce plastic granulate that can be melted and injection-molded.

Car parts and urns made of this bioplastic already exist, but it is not suitable for toys in this form: To separate the lignin from the cell fibers, the workers in the cellulose industry add sulfurous substances. However, children’s toys should not contain sulfur because, for one reason, it can smell very unpleasant.

Now the scientists were able to reduce the sulfur content in Arboform by about 90 percent, and produced Nativity figurines in cooperation with Schleich GmbH. Other products are in the planning stage, says TECNARO’s managing director Helmut Nägele.

This is a challenging task: sulfur-free lignins are usually soluble in water – and therefore unsuitable for toys. On no account must they dissolve if they are left out in the rain or if children suck them. With the aid of suitable additives, the TECNARO scientists were able to modify the bioplastic in such a way that it survives contact with water and saliva undamaged.
A big question is: can the material be recycled?
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To find that out, the researchers produced components, broke them up into small pieces, and re-processed the broken pieces – ten times in all. They did not detect any change in the material properties of the low-sulfur bioplastic, so that means it can be recycled, says Inone-Kauffmann.

It will be interesting to study the energy and carbon balance of products made by this new process. If they were to show a strongly positive balance, they could become a green resource capable of reducing a considerable amount of petroleum. Lignin is considered to be, worldwide, the largest but most under-utilized biomass feedstock available for bioenergy and bioproducts.

The question is whether the liquid wood bioplastics will be able to compete with potentially more lucrative lignin-based products, such as carbon fiber composites, which are currently under study.

Image: Nativity figurines made of 'liquid wood' called Arboform. Credit: TECNARO GmbH and Fraunhofer-Gesellschaft

Biopact: Researchers find bio-based bulk chemicals could save up to 1 billion tonnes of CO2 - December 17, 2007


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