If everything falls in place for him and his fellow researcher, Professor Arun Majumdar says a villager in India may be able to produce electricity for his home from a chullah, or a stove that uses wood, coal, dry leaves, or cow-dung to make fire.
During winter, instead of turning on heaters, a person anywhere in the world would be able to use a simple power-jacket utilising his body heat to stay warm. The same body heat could even be used to recharge a cell phone.
If this sounds farfetched, you need to find out from Majumdar why he believes that day is not too far.
For years, Majumdar and fellow investigator Peidong Yang have been trying to see if energy routinely lost as heat during production of electricity could be harnessed using silicon nanowires.
About a year ago, Majumdar and his colleagues discovered it is possible to achieve substantial improvement in thermoelectric energy efficiency at room temperature in silicon nanowires. The high performance thermoelectric capability in silicon, Majumdar says, opens up tremendous possibilities for human welfare and cost savings.
"To give you an example," Majumdar said, "90 per cent of the world's power is generated by heat, whether it is steam turbines, coal-fired power plants, or gas turbines. It is all heat-to-power conversion. These engines operate at approximately 30 to 40 per cent efficiency which means that about 60 to 70 per cent of the heat is lost.
"If we could convert even 2-3 per cent of that lost heat into electricity," he continued, "the number would be absolutely staggering. It is almost half the United States' electrical capacity."
He said thermoelectric materials that have the ability to convert heat into electricity could be used to capture much of the heat that is currently wasted.
"These devices can be used both as power generators and also as refrigerators or air-conditioning devices. So the same devices, if you hook them up to a battery, will become a refrigerator. Thus if your jacket is filled with these devices on a
hot and humid day, you can carry your own air-conditioning in your jacket," Kolkata-born Majumdar, who came to the US in 1985 after a BTech in Mechanical Engineering from the Indian Institute of Technology- Bombay, said.
Majumdar, who holds nine patents and has authored a book and over 150 articles in journals, said the Berkeley Laboratory is not the only one doing such research.
"There are others like MIT [Massachusetts Institute of Technology] who are also into this. We are a community," he said.
He said a whole series of work started in 2001 and then he and his team observed something that pushed them to do further research and confirmed their findings over and over again until the discovery some months ago.
The results of the discovery were published in an article written by Majumdar and chemist Yang in the scientific magazine Nature in January.
There is a challenge though in the otherwise bright prospect for the use of the new technology -- how to make it cost efficient and performance efficient. "It is actually a combination of performance and cost. The cost has to come down in order of magnitude. Right now if you buy one of these units -- which is about an inch by an inch -- it is about $10. This has to come down to $1 or less than a dollar, and the performance has to double. So, it is not easy," Majumdar said.
But the professor, whose research interests are in the broad area of energy conversion and storage in solid-state materials and devices, heat and charge transport in nanostructured materials, and electrochemical and bimolecular phenomena in micro- and nano-fluidic devices, is pretty hopeful about the future.
Asked what gives him confidence, Majumdar said the fact that one can do it in silicon gives rise to optimism. "Silicon has $10-billion industrial infrastructure, which is producing chips or electronics. If you can take that infrastructure and turn part of it towards energy, you do not have to do much.
"Silicon wafers are already cheap. The packaging and processing conditions are all known. The fact that this is happening in silicon is a big deal. That is a big promise," he said.
Majumdar, who got interested in nanotechnology about 20 years ago and for whom the 'profession has become a passion,' says that the thermoelectric capabilities of silicon open up new vistas for making life easier and comfortable, especially in developing countries like India.
He says technology can enable people in rural areas to use local resources to generate electricity, citing the fact that there are many in India who are off the electricity grid.
"If you take a chullah for cooking and wrap a thermoelectric device around it, you would generate electricity. Similarly, if you take a kerosene lantern, which although is a very inefficient way of generating light, and wrap a thermoelectric
device on the top from where the heat goes up and use that waste heat, you can generate electricity for your home," Majumdar said.
"That is very much possible, if the cost costs come down and it becomes scalable," he said.
Majumdar does not want to specify how long one has to wait before the technology can be commercialized although he says there is somewhat of a pressure on them to start a company.
"But we are backing off a little at this stage because we want to do a little more research. From the promise of a material to reality of systems takes at least about 10 years," he said.
"When I said reality of systems, I mean that someone has to manufacture it, someone has to sell it and people have to use it. From that perspective a lot of work is still to be done," Majumdar said.
The research at the Berkeley Lab, which is a Department of Energy national laboratory, has been funded by the DEO's Office of Basic Energy Science.
Majumdar is a member of the Nanotechnology Technical Advisory Group to the President's Council of Advisors on Science and Technology. He served as the founding chair of the ASME Nanotechnology Institute, a former member of the Council of Materials Science & Engineering of the Department of Energy, and is currently Chair, Advisory Committee of the Engineering Directorate of the National Science Foundation.
(Above) Professor Arun Majumdar.
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