Scientist Creates Biofuel From Discarded Peanut Shells
By Kate Ravilious*
One person’s rubbish is another person’s gold. Peanut shells may not hold much value to most of us, but to K C Das, from the University of Georgia, US, they are a valuable resource.
By burning the peanut shells at low temperatures Das is able to create a charcoal-like substance, known as biochar, which can be used as a fertilizer on land, as well as a hydrocarbon oil, which can be used as a biofuel.
The process has multiple environmental benefits. It uses up a waste product and prevents it going to landfill; it produces a biofuel, and the biochar fixes as much as 50% of the carbon in the peanut shells, preventing it from entering the atmosphere and contributing to climate change.
Das is not the first person to produce biochar. Indigenous tribes living in the Amazon rainforest used to produce a rich black compost for their soil by slow burning of unwanted plant material. Archaeologists have found evidence for production of this compost – called Terra Preta – as far back as 9000 years ago.
Compared to ordinary plant material biochar is very resistant to being broken down. “It locks up carbon for at least several decades – probably much longer,” Das told environmentalresearchweb.
During the last few years Das and his colleagues have been developing a process that maximises the way biomass, like peanut shells, is used.
By experimenting with pyrolysis (burning without oxygen) techniques at differing temperatures, they have developed a system that produces both biochar and hydrocarbon oil from biomass that would otherwise be thrown away.
After condensing, the oil can be used as a fuel, blended with conventional hydrocarbon oils. Or it can be burned and used to produce electrical power and heat.
Currently the oil is not directly useable as a fuel because it is acidic and contains lots of water and oxygen, but Das and his colleagues are investigating ways of improving the process to produce a better quality oil.
“We are looking at different catalysts which may help produce oil with a better composition,” said Das, who presented his findings at the International Biochar Initiative Conference in Newcastle, UK in 2008.
Pilot plants are capable of burning up to 20 tonnes of biomass per day, but eventually Das hopes the process will operate at a much bigger scale. “Soon it could be used by large manufacturing operations, such as paper mills, which already deal with biomass waste,” he said.
And eventually he envisages electrical power plants using this process to produce energy and fertiliser from biomass waste such as forestry brash and crop residues. “The scaleability of the technology is what is holding us back at the moment,” said Das.
*Kate Ravilious is a contributing editor to environmentalresearchweb.
Image credit: viZZZual.com/ Flickr
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