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MIT chemistry professor Daniel Nocera has devised a novel way of storing solar power using inexpensive materials. He says its the first step to creating a hydrogen generating synthetic "plant", critics say his claims are overstated.   (Source: Christopher Harting )

Professor Nocera imagines a system where solar panels or articial leaves collect solar energy and turn it tinto electricity. From there his catalyst would use the electricity to split water, forming hydrogen fuel.  (Source: Bryan Christie )

Professor Nocera's novel system for hydrogen generation uses cobalt, an inexpensive catalyst previously dismissed due to its high solubility.  (Source: Bryan Christie )
Is Professor Nocera's solar brew a savior or a wishful thinking?

Solar power's efficiency is advancing at a steady rate, and with improvement such as concentrated cells and novel materials the question is not so much if solar can be cheaper than coal power someday, but rather when.  However, when this scenario does eventually arise, solar faces some remaining challenges, the most significant of which is the intermittent nature of the power source. 

In short, without something to store solar power efficiently, it’s infeasible as a primary electric power source.

Batteries and ultracapacitors are frequently discussed as possible means of solar power storage, but they are very expensive.  Other novel storage methods have also been explored, but they seem uncertain prospects at best.  Some scientists point out that there is already a system that takes solar power and stores it -- photosynthesis in plants.

When it comes to imitating nature's hydrogen producing system (remember, sugar is only the secondary product of photosynthesis, driven by the production of the primary product -- hydrogen ions -- from using sunlight's energy to split water), many scientists have tried.  However, the electrocatalysts needed to split water into hydrogen and oxygen are typically even more pricey than batteries.  However, one MIT professor has discovered a possible alternative using cheap materials that he says may help keep the dream of solar power (and solar storage) alive.

Daniel Nocera PhD, a professor of chemistry at MIT, devised a catalyst system using strips of cobalt, nickel, and phosphate, all relatively inexpensive chemical compounds.  By eschewing expensive catalysts like platinum, the cost of the system is kept low.  So why didn't others think of this efficient system?  Well, he says that it is commonly known that cobalt dissolves relatively easy in water, making it typically a poor electrode material, and typically earning it a quick dismissal.  To remedy this, Professor Nocera chose a somewhat creative approach, instead adding dissolved cobalt directly to the solvent and relying on a thin cobalt film which formed on the electrode.

The success of the result surprised even its creator.  He describes, "Here's the luck.  There was no reason for us to expect that just plain cobalt with phosphate, versus cobalt being tied up in one of our complexes, would work this well. I couldn't have predicted it. The stuff that was falling out of the compounds turned out to be what we needed."

Now he is looking to improve upon his lucky break.  He states, "Now we want to understand it.  I want to know why the hell cobalt in this thin film is so active. I may be able to improve it or use a different metal that's better."

However, he also wants to move towards a production system.  He states, confidently, "We were really interested in the basic science. Can we make a catalyst that works efficiently under the conditions of photosynthesis?  The answer now is yes, we can do that. Now we've really got to get to the technology of designing a cell. "

Some are skeptical about Professor Nocera's big claims.  They say that his system is cheap and promising in some respects, but that he is overstating its potential for commercial scale hydrogen production.  By an important metric, the peak efficiency current density (the higher this number, the faster the rate of hydrolysis), his best reported result of 10 milliamps per square centimeter is only a hundredth of the current commercial electrolyzer rate of 1000 milliamps per square centimeter.

Even one of his teachers is taking issue to Professor Nocera's alleged hyperbole; Thomas Meyer, who has been a mentor to Nocera, states, "The claim that this is the answer for artificial photosynthesis is crazy.  [This] could prove technologically important [as a] research finding, [but]  there's no guarantee that it can be scaled up or even made practical."

John Turner, a research fellow at the National Renewable Energy Laboratory in Golden, CO, adds, "At least what he's published so far would never work for a commercial electrolyzer, where the current density is 800 times to 2,000 times greater."

While some say he is wasting his time and should refocus on batteries, Professor Nocera continues his research and his big talk.  He's teaming up with Professor Michael Grätzel of the  École Polytechnique Fédérale in Lausanne, Switzerland to make a full solar cell and catalyst system which produces hydrogen.  Professor Grätzel invented a unique dye that gives off electrons when exposed to sunlight.  Professor Nocera hopes to merge the two inventions to create an artificial, fuel-generating leaf, what he sees as the future of electric power generation.

One thing's for sure -- Professor Nocera's work and rhetoric will likely continue to draw rebukes from colleagues, but it’s hard to argue the temptation of emulating nature's most successful energy fixing design and storing power by a simple equation -- "sun + water = fuel".

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RE: So...
By randomly on 11/24/2008 8:03:02 PM , Rating: 2
Yes it's electrolysis.

The problem is electrolysis sucks for energy efficiency at only around 50%. This makes it noncompetitive as a fuel storage/transport medium. By the time you pull the energy out with a fuel cell you have lost 75% of your starting energy in the process. This makes it 4x more expensive than the original cost of the electricity. Modern battery chemistries on the other hand are better than 90% efficient as an energy storage medium.

There is currently no cost competitive way to produce hydrogen other than reforming natural gas.

Without an economical source of hydrogen that does not use fossil fuels a hydrogen economy makes no sense.

The only good candidate for cost effective hydrogen production is very high temperature nuclear reactors using the Sulfer/Iodine cycle. That's 20-30 years away from commercial deployment. At least.

He's trying to improve the efficiency of electrolysis to make it more efficient and thus cost competitive as an energy storage medium.

RE: So...
By FishTankX on 11/25/2008 2:40:28 AM , Rating: 2
Actually, not entirely true.
The significance of his breakthrough is that he can achieve electrolysis without using expensive catalysts like platinum and such. This allows for much cheaper electrolyzers, allowing much cheaper hydrogen stations, in theory.
Normal hydrogen stations have to have their tanks made out of the same metals as the electrodes and have to use expensive catalysts. Not very cheap.
However, with the hydrogen generation per surface area so abysmally low, even if it's 100x cheaper per catalyst, it's still going to be 8x-10x more expensive, at current efficencies/rates.
GM was trying to do the same thing with their plastic tank electrolyzer, if I do remember correctly.

RE: So...
By Suntan on 11/25/2008 1:39:00 PM , Rating: 2
Normal hydrogen stations have to have their tanks made out of the same metals as the electrodes and have to use expensive catalysts. Not very cheap.

Odd, that's not how we did it in college. We just dipped an electrode and an anode into a pirex glass of water (laced with acid to make it more conductive.) Your talking fud if you think you need a tank made of platnum for electrolysis.


RE: So...
By Solandri on 11/25/2008 8:39:07 PM , Rating: 2
The rate at which you're driving the electrolysis depends partly on the surface area of the exposed metals. So either you dip big platinum sheets into the solution (sheet = lots of surface area), or you use the same amount of platinum to line the inside of the tank. The latter setup is generally cleaner and less prone to short circuiting. So no you don't have to use tanks made out of the metal, but it's usually the most cost- and time-efficient if you do.

RE: So...
By FishTankX on 11/26/2008 7:50:02 AM , Rating: 2
The thing is, when you use other catalysts for the electrolysis, they degrade. Some more rapidly than others. As far as I know, platinum does not degrade in electrolysis.

And I'm sorry, I mis spoke

When I said that I was misinterpreting what I read.

Infact, a big part of the capital costs that make the electrolyzers expensive is the need to build alot of the machines out of metal that is resistant to the strongly alkaline sollutios used in the electrolyzing process.

The new GM system, refrenced in the article in which I misinterpreted the information, uses a plastic that fits the bill just as well.

However, i'm not sure if this breakthrough negates the need to use platinum as a catalyst. However, the GM breakthrough certainley brings down the capital costs to build comercial electroloyzers.

RE: So...
By Bongwater on 11/26/2008 9:02:34 AM , Rating: 2
The problem is electrolysis sucks for energy efficiency at only around 50%.

OK, fine. If we can have a type of solar cell that has close to 20% energy conversion efficiency, and couple that to an electrolyzer, we still get a total efficiency of close to 10%. The Gratzel cells are cheap and stable, and their efficiencies are getting close to 20%. All the b.s. about losing 75% etc. doesn't matter. As long as you have sustainable fuel production out of solar and water, with higher efficiency than photosynthetic biomass production, that is all you need.

RE: So...
By Suntan on 11/26/2008 1:34:40 PM , Rating: 2
So it doesn't matter that we have to cover 95% of the land with solar cells to make up for the inefficiencies because 1% of free sun is still free? Sorry, I do like trees and grass too.


RE: So...
By Natfly on 11/26/2008 4:23:11 PM , Rating: 2
Right, as long as it is cheap enough, and sustainable. Even at 1% efficiency you wouldn't need 95% of the land, and who says we need to use 100% solar anyway. The point of all this is that you put your solar capturing devices where it works best, deserts or wherever, and by converting it into hydrogen you can take it to where the energy is needed.

RE: So...
By Bongwater on 11/27/2008 2:19:55 AM , Rating: 2
95% of the land?! Where did you get that number? Actually, only 2% of the land is needed at an efficiency of 10%.
The problem with biofuels is that not only is photosynthesis inefficient, but the biomass you get (trees, sugarcane etc) has to be refined before you use it as fuel, making the efficiency even worse. *And* when you grow the crops used for biofuels you still have to wait for them to, well, grow. With direct hydrogen production from solar, on the other hand, you will have the product instantly.

"And boy have we patented it!" -- Steve Jobs, Macworld 2007

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