See related imagePosted on 07/31/2008 5:48:38 PM PDT by sionnsar
PORTLAND, Ore. — Researchers at the Massachusetts Institute of Technology have combined a liquid catalyst with photovoltaic cells to achieve what they claim is a solar energy system that could generate electricity around the clock.
A liquid catalyst was added to water before electrolysis to achieve what the researchers claim is almost 100-percent efficiency. When combined with photovoltaic cells to store energy chemically, the resulting solar energy systems could generate electricity around the clock, the MIT team said.
"The hard part of getting water to split is not the hydrogen -- platinum as a catalyst works fine for the hydrogen. But platinum works very poorly for oxygen, making you use much more energy," said MIT chemistry professor Daniel Nocera. "What we have done is made a catalyst work for the oxygen part without any extra energy. In fact, with our catalyst almost 100 percent of the current used for electrolysis goes into making oxygen and hydrogen."
Nickel oxide catalysts are currently used to boost the efficiency of electrolyzers, and they worked equally well in MIT's formulation, Nocera acknowledged. He added that the toxicity of nickel oxide forces the use of expensive, hermetically-sealed water containers. MIT's patented catalyst formulation is "green," Nocera said, and can be used in inexpensive open containers.
"Nickel oxide can't be used around anything else in the environment because of corrosion -- even the carbon dioxide in the air will react with it to make carbonates," said Nocera. "But our catalyst uses abundant materials that don't react with environment."
MIT's patented formulation of cobalt phosphate was dissolved in water. When the electrical current is passed through it to initiate electrolysis, the catalyst attached itself to the oxygen electrode to increase its efficiency. When the electrical current was turned off, the cobalt phosphate dissolved back into water.
The simplicity of the process enables basic electrolyzers to be used, the researchers said.
"Because our catalyst is green, the machines that perform electrolysis can be much less expensive than they are today, since they don't need to be protected from environmental contaminants," said Nocera.
Currently, MIT is working with photovoltaic cell manufacturers to incorporate electrolysis using their catalyst into solar energy systems. By combining the two, excess capacity during the day could be stored as hydrogen and oxygen, then used in fuel cells at night when needed.
"Solar cell makers can add super-cheap electrolyzers to their system so that they work 24/7 -- during the day making hydrogen and oxygen, then at night recombining it in fuel cells to generate electricity," Nocera predicted.
Matthew Kanan, a MIT postdoctoral fellow, assisted in the research. Funding was provided by the MIT Energy Initiative, the Chesonis Family Foundation, the Solar Revolution Project and the National Science Foundation.
But, but, but I thought it was impossible. How can it be?
IOW ...a perpetual motion device. YUP!
“Almost 100% efficiency” is only a perpetual-motion machine if that “almost” exceeds 100%. Below 100% it’s lossy, and if you believe that’s “perpetual motion” I have a Ponzi scheme I’d like to sell to you.
This is a poorly written article. It’s very difficult to figure out what they have done that hasn’t been done before.
Thanks for confirming that this wasn’t up to the EE Times’ standards of a few decades back...
I always thought a perpetual motion device had to have a net gain in energy. That is certainly not the case here as PV cells are at the low end of efficiency. Nanosolar claims to achieve 15% efficiency.
Ok, so you took the scientist’s statement out of context to show a bit of ignorance. Here’s what you missed.
PV cells only function well during sunlight (although Unisolar claims their amorphous crystal gets a buzz from moonlight, albeit nothing to capitalize on). The Sun’s energy is converted via PV cells to DC current and converted to AC power via an inverter. An overall solar system is pretty inefficient at about most 10%. But the energy is from the Sun, so is considered free and infinite. 10% from something free and infinite can be better than something that is 100% efficient from something not free and finite.
What the electrolysis component in the system chain this scientist is referring to as 100% efficient is a small part of the overall system which is grossly inefficient. After converting current to H2 in a near perfect process, the Fuel Cell that converts the hydrogen back to electricity is also prone to inefficiencies.
So if we calculate the total efficiency of the system, we are going to fall short quite a bit. But at least this scientist has claimed to solve one of the more important parts of the whole problem here. Let’s hope he is successful at getting it out of the lab soon.
We gotta let it out
Ore. ping
Or not (just from Ore. paper)
Too many unanswered questions. Smacks of University of Utah’s cold fusion.
Article is worthless.
I don't know why but they sure are making a big deal about using this with PV. That's what makes me suspicious. It would be very beneficial to make it easier to split water on a huge scale with electricity from any source.
I wonder if this is any better than the large solar collectors that use molten salt to store energy.
for the renewable energy ping list
I usually don't see photovoltaics used with the phrase "excess capacity."
IMHO, I think you have it backwards. Wikipedia has a decent discussion of catalysis and catalysts. Catalysts just lower the energy of activation to get a reaction going forward. Photovoltaic cells capture the sun's free energy. Generating hydrogen from the electrolysis of water captures the energy for storage it in the form of hydrogen. It's just a storage medium. How you apply it is different. You lose energy anytime you convert it from one form to another according to the Second Law of Thermodynamics, IIRC. It will be lost as heat, so you may want to use the electricity from the PV cell as directly as possible, storing excess power as hydrogen.
Whaddya think?
IOW ...a perpetual motion device. YUP!
Check the first link in comment# 15. Catalysis is not perpetual motion. The photovoltaic cell just captures free energy from the sun that is otherwise lost. The elctrolysis of water stores that energy in the form of hydrogen.
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