Posting in Energy
MIT researchers want to give solar energy a rain check with a rechargeable heat battery. In search of materials to chemically store the sun's energy, they give nanotubes a try.
A major concern for renewable power industries is storage. Figuring out how to save that energy for those rainy, windless days and nights would benefit bottom lines, grid stability, and ultimately, the Earth. For solar's sake, MIT engineers have been making inroads in chemically storing the sun's energy as heat rather than electricity. The idea is to develop a thermal battery that can take in and release solar energy on demand, and do it over and over again.
Last November, a research team led by Jeffrey Grossman demonstrated how this could be done with help from ruthenium, a very expensive metal that isn't easy to find. So they've been on the lookout for a suitable substitute, a nice and cheap substitute.
They may have found it: a combination of carbon nanotubes and azobenzene.
Publishing this week in Nano Letters, Grossman and Alexie Kolpak, a post doc, describe how the material stores 10,000 times more energy within the same amount of space than its predecessor, the ruthenium compound. According to the researchers, its energy density is akin to that of a lithium-ion battery. And like lithium-ion batteries, the potential device would be rechargeable.
The material performs by switching between two stable energy states, one that brings in the charge and one that releases it. When sunlight strikes the nanotubes, it changes their molecular structure. The new shape can hold steady for long periods of time, storing the energy within its molecular bonds. Though the structure is stable, flipping the switch and releasing the heat needs only a little push. A catalyst, even just a flash of light, the researchers say, could do the trick. Add sunlight to repeat.
Grossman says in a statement:
You’ve got a material that both converts and stores energy. It’s robust, it doesn’t degrade, and it’s cheap.
The practical applications are significant. The energy stored could heat water and homes or produce steam to generate electricity. While promising, however, this research is at its dawn. The solar industry will likely see many nights pass before the production of such nanotube batteries is perfected.
In the meantime, Grossman and his team so they will continue their search for material with similar properties.
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Jul 14, 2011
There is no requirement that this HAS to release this energy explosively. If these nanotubes are of a heterogeneous fine structure and dispersed in a matrix, they could release the stored energy in a progressive manner, and most likely we're not talking about extremely high power densities anyway.
Storage for non-productive times is the Achilles heel for RE- for the large installation. If we maintain the continental (mostly) power grids we have, small installations have virtually NO storage problem if they are a good mix of technologies (and they are and will continue to be such)- just feed excess power into the extended grid. Once again, the large-scale producers have set the terms of a false argument. This new development is perfect to defuse their opposition to the rapid replacement of fossil-fuel tech. Even without this, were the commitment there, a few large trans-oceanic power lines would be sufficient to implement a global grid.
We could have panels of this stuff under insulated glass, exposed to light during the day, and at night exited to give up its stored heat. OR, if the stuff is somehow liquifiable, it could be pumped between the collectors and storage (better). Interesting factor: Presumably, the stuff could also be pumped or shipped in its charged state, which practice could provide extreme versatility in using the stored energy... And be very, very dangerous. Given the practical intelligence of human animals operating in groups, I'd expect this to become the norm... And NOT beside the point, but doesn't this create a new sort of "explosive?" Given that the impetus to discharge can be so slight, it might be supplied by the discharge of the molecule next door, and...
of solar and wind power generation. In some places pumping water to run hydro stations is an option. Others have proposed producing hydrogen or ammonia with excess energy to be burned in turbines when wind and sun are not present. Maybe this idea works out. There will likely be no one size fits all solution, but what ever it is, it has to be cost effective to implement and operate.
The storage of energy is the way we have to go into the future. Untill we find a way to tap into zero point energy.