I try to keep abreast of the developments in the alternative energy field and am always surprised with how fast new developments are happening. Yesterday I read about 2 interesting developments in the field of Solar energy. Both where developed by The Strano Group a team of scientists and researchers led by MIT’s Charles and Hilda Roddey Associate Professor of Chemical Engineering Michael Strano.
The two developments were nanotube solar funnels and self healing solar panels, both are ground breaking developments in the field of nanotechnology and Solar energy. The team has managed to mimic a leaves ability to r
The articles that caught my eye were the following:
Imagine Solar panels that take lesser space and are more efficient? That is exactly what the researchers at MIT have created! A team of researchers under the leadership of Associate Professor Michael Strano have developed technology which concentrate solar energy 100 times more than a regular PV cell. Such nanotubes could form antennas that capture and focus light energy, potentially allowing much smaller and more powerful solar arrays.
Photovoltaic cells generate electricity by converting photons or light energy into an electric current. The nanotube antenna created by the MIT research team led by Associate Professor Michael Strano, boosts the number of photons that can be captured and transforms the light into energy that can be funneled into a solar cell. “Instead of having your whole roof be a photovoltaic cell, you could have little spots that were tiny photovoltaic cells, with antennas that would drive photons into them,” says Strano.
The antenna consists of a fibrous rope about 10 micrometers (millionths of a meter) long and four micrometers thick, containing about 30 million carbon nanotubes. Strano’s team built, for the first time, a fiber made of two layers of nanotubes with different electrical properties – specifically, different bandgaps*.
Strano and his students describe their new carbon nanotube antenna, or “solar funnel,” in the Sept. 12 online edition of the journal Nature Materials. Lead authors of the paper are postdoctoral associate Jae-Hee Han and graduate student Geraldine Paulus. Solar cells that incorporate carbon nanotubes could become a good lower-cost alternative to traditional silicon solar cells.
While the cost of carbon nanotubes was once prohibitive, it has been coming down in recent years as chemical companies build up their manufacturing capacity. “At some point in the near future, carbon nanotubes will likely be sold for pennies per pound, as polymers are sold,” says Strano. “With this cost, the addition to a solar cell might be negligible compared to the fabrication and raw material cost of the cell itself, just as coatings and polymer components are small parts of the cost of a photovoltaic cell.”
*Bandgaps – is an energy range in a solid where no electron states can exist.
Plants have been successful at utilizing solar energy efficiently for eons and scientists have been trying to mimic the process for decades. Now a group of MIT Scientists have succeeded in mimicking a key aspect of that puzzle. The Sun rays are destructive to most materials and degrade most of the systems man has created till date. Plants on the other hand have a system where they constantly breakdown their light capturing molecules and reassemble them from scratch there by making the basic structure to capture sunlight new daily!
The Strano Group has managed to imitate that process by creating a novel set of self-assembling molecules that can turn sunlight into electricity; the molecules can be repeatedly broken down and then reassembled quickly, just by adding or removing an additional solution. Their paper on the work was published on Sept. 5 in Nature Chemistry.
Strano says the idea first occurred to him when he was reading about plant biology. “I was really impressed by how plant cells have this extremely efficient repair mechanism,” he says. In full summer sunlight, “a leaf on a tree is recycling its proteins about every 45 minutes, even though you might think of it as a static photocell.”
In the case of the molecules used for photosynthesis in plants, the reactive form of oxygen produced by sunlight causes the proteins to fail in a very precise way. As Strano describes it, the oxygen “unsnaps a tether that keeps the protein together,” but the same proteins are quickly reassembled to restart the process.
The system Strano’s team produced is made up of seven different compounds, including the carbon nanotubes, the phospholipids, and the proteins that make up the reaction centers, which under the right conditions spontaneously assemble themselves into a light-harvesting structure that produces an electric current.
“We’re basically imitating tricks that nature has discovered over millions of years” — in particular, “reversibility, the ability to break apart and reassemble,” Strano says. The team, which included postdoctoral researcher Moon-Ho Ham and graduate student Ardemis Boghossian, came up with the system based on a theoretical analysis, but then decided to build a prototype cell to test it out. They ran the cell through repeated cycles of assembly and disassembly over a 14-hour period, with no loss of efficiency.
BBC article here