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MIT team claims development of first practical artificial leaf

In a presentation at the 241st National Meeting of the American Chemical Society today in Anaheim, Dr. Daniel Nocera of MIT said that his team has developed a practical “artificial leaf”—a type of solar cell that shows promise as an inexpensive source of electricity for the poor in developing countries. (Earlier post.)

The device is an advanced solar cell the size of a poker card that mimics photosynthesis, and uses catalysts derived from earth-abundant materials (e.g., cobalt and nickel). Placed in a single gallon of water in a bright sunlight, the device could produce enough electricity to supply a house in a developing country with electricity for a day, Nocera said.

A practical artificial leaf has been one of the Holy Grails of science for decades. We believe we have done it. The artificial leaf shows particular promise as an inexpensive source of electricity for homes of the poor in developing countries. Our goal is to make each home its own power station. One can envision villages in India and Africa not long from now purchasing an affordable basic power system based on this technology.

—Daniel Nocera

The first artificial leaf was developed more than a decade ago by John Turner of the US National Renewable Energy Laboratory in Boulder, Colorado. Although highly efficient at carrying out photosynthesis, Turner’s device was impractical for wider use, as it was composed of rare, expensive metals and was highly unstable, with a lifespan of barely one day.

Nocera’s new leaf overcomes these problems. It is made of inexpensive materials that are widely available, works under simple conditions and is highly stable. In laboratory studies, he showed that an artificial leaf prototype could operate continuously for at least 45 hours without a drop in activity.

The key to this breakthrough is Nocera’s recent discovery of several powerful new, inexpensive catalysts, made of nickel and cobalt, that are capable of efficiently splitting water into its two components, hydrogen and oxygen, under simple conditions. Right now, Nocera’s leaf is about 10 times more efficient at carrying out photosynthesis than a natural leaf. However, he is optimistic that he can boost the efficiency of the artificial leaf much higher in the future.

Nocera acknowledges funding from The National Science Foundation and Chesonis Family Foundation.

Comments

kelly

This sounds like an incredible life-saving appropriate technology for the third world. How will it be screwed up?

SJC

The third world has to have fresh water first.

kelly

Does the water have to be potable for this energy leaf conversion?

Water is something("Blue Gold..") people will fight 'corporation individuals' for.. http://www.youtube.com/watch?v=vLp1ZnjsIXc

HarveyD

Most of Sub-Sahara Africa, Asia and Latin America have plenty of water. Using some of it to produce hydrogen and electricity in a sustainable way could be a God send solution to fight poverty and under development.

ejj

My question is why can't it be for everyone? Why just third world?

Nick Lyons

Just to be clear: the 'leaf' is splitting water using sunlight instead of electricity, resulting in the release of H2 and O2. Not mentioned in the above, a fuel cell (or some other means) is still needed in addition to the 'leaf' in order to obtain electricity.

ejj

I'd like to see further development of the technology using seawater...perhaps coastal utility scale power plants could be possible, with freshwater created for thirsty areas like California's central valley? That could help them meet their irrigation needs without wiping out their aquifer....they desperately need more freshwater...I kind of feel sorry for them.

kelly

"..—a type of solar cell that shows promise as an inexpensive source of electricity.."

"Placed in a single gallon of water in a bright sunlight, the device could produce enough electricity to supply a house in a developing country with electricity for a day, Nocera said."..

is a pretty misleading way of saying releases H2 and O2.

DaveD

The question is how practical is this in the real world. It sounds great until you realize that you also need a fuel cell which is not cheap yet by any means. Also, "low cost" fuel cells are still really expensive and only about 40% efficient at converting the energy in the H2 to electricity.

End to end, which is more efficient:
1) The conversion of water to H2 and then using the H2 in a fuel cell with some type of H2 storage system
OR
2) solar panels directly converting sunlight to electricity with some type of battery?

As Kelly points out: Where does the water come from and does it have to be potable?

How do you store the hydrogen for use when the sun is not shining? H2 is notorious for leaking and damaging it's container unless you use expensive and specialized containers.

Great idea...but probably not practical at all regardless of how cheap and efficient you make the "leaf" itself.

HarveyD...I was totally under the impression that water shortages were one of the great problems facing much of the world. Do you have sources/links showing that Sub-Saharan Africa has plenty of water?

kelly

Call for definition: "enough electricity to supply a house in a developing country with electricity for a day."

What's the official first world definition of daily developing country electrical house needs?

danm

Nick Lyons, thank you. it was not clear that a fuel cell was still necessary. Why the emphasis upon 3rd world, in the article? A means to inexpensively produce H2 would be useful anywhere.

Reel$$

Dan Nocera announced this project a couple of years ago. The real breakthrough is the low cost catalysts. In order to make the whole thing look green Dan claims his source of electricity is solar. But the process works with wind, or hydro or other renewable electric inputs (even non-renewable. )

This IS interesting for the future of CHP systems running SOFCs. If Dan can get his "leaf" to split water more efficiently than straight electrolysis - he has created a source of local H2 fuel. A complete system would need to use some kind of FC and that cost must come down significantly.

As for the water - most electrolysis works best with de-ionized, fresh water. Probably not convenient in the sub-Sahara. A third world house might be rated for 2kWh/day?

SJC

They can make distilled water using concentrated solar thermal and generate electricity at the same time. If you use non potable water to cool the condenser in the rankine loop, it is clean and disease free for drinking.

There was a project from a university back east that went to the third world and created an array like this. They used a car power steering pump for the expander and got high enough temperatures from the tracking troughs to do refrigeration and cooling using adsorption.

Michael_R_Rose

I think many people are dismissing this innovation because of the perceived requirement of an expensive fuel cell in order to make electricity. A fuel cell is simply one way to do it. Although not ideal solution, a hydrogen combustion engine running a simple generator would also suffice. It is not as efficient and contains moving parts, but currently it is vastly cheaper. The hydrogen gas can also be used to power cooking and heating devices.

I think we all know the third world needs clean water first. But a device like this could generate the power needed to run more complex filtration and pumping equipment. Just because an artificial leaf may not directly solve the most pressing problem doesn't diminish its life changing potential.

Davemart

A couple of points.
This does not 'use' water, just borrow it. The waste from the fuel cell is the water which acted as a medium to trap the sunlight, so you just shift it around a bit.
Fuel cells are around 70% efficient, not 40%.

Roy_H

It doesn't sound like this device runs off electricity. "Placed in a single gallon of water in a bright sunlight, the device could produce enough electricity to supply a house in a developing country with electricity for a day, Nocera said. It does so by splitting water into its two components, hydrogen and oxygen."
There is another company rosestreetlabs.com that announced a similar invention over a year ago.
I do not see the value in this. It will be much easier and much cheaper to use inexpensive solar cells and batteries. I bought a few small (about 1 sq.ft) solar cells pre-wired for 12V for $15 each on sale.
The main thing these villages want is electricity, not hydrogen, and they have invented solar collectors (aluminum dish) to focus sunlight for cooking. They don't need to heat their house. What would they use hydrogen for? They do want lights for reading etc. in the night, and to power radios, cell phones, and even computers.

DaveD

Davemart,

Show me the reference for a cheap fuel cell that is above 50% efficient? And when I say cheap, I simply mean cheaper than average fuel cell costs which are still tens of thousands of dollars if not hundreds of thousands.

Yes, mass production will help bring those costs down to thousands of dollars one day, but that day is a long ways off yet.

As for "shifting the water around"...do you really get as much water back as you put in or even close??? My impression was a few drops would come dribbling out, but certainly not the same amount that was originally used. References here? I'm genuinely curious on this point and not claiming you're wrong...I would simply like to educate myself on that point.

SJC

Using the water vapor out of a fuel cell makes sense. It is like using that water for a gas shift reaction while reforming methanol to hydrogen. CH3OH becomes CO + 2H2. With H2O you get another H2 and the CO becomes CO2.

In essence you are turning water into fuel. In this case you are turning water into H2 and O2 and then turning it back into H2O to do it all over again minus evaporation which has to be made up with a small distilled water supply.

CelsoS


Last year they claimed to have developed a cheap catalyst to electrolyze [non-clean] water at room temperatures and pressures. The idea was to store energy as H2 at low pressure in big tanks in houses.

There are no news at Suncatalytix site.

What is new since last year claims ? Submersed PVs ?

Some old related links:
Dan Nocera: Personalized Energy for 1 (x 6 Billion): A Solution to the Global Energy (~1h18min)
http://www.youtube.com/watch?v=ZAkM_dV6CFs

http://web.mit.edu/chemistry/www/faculty/nocera.html

http://peswiki.com/index.php/Directory:MIT:Daniel_Nocera:Catalytic_Electrolysis

http://www.youtube.com/watch?v=WD9yr-Bf-Kw

http://www.suncatalytix.com/

2006 - Powering the planet: Chemical challenges in solar
energy utilization
Nathan S. Lewis*† and Daniel G. Nocera†‡
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1635072/pdf/zpq15729.pdf

2009 - POWERING THE WORLD WITH SUNLIGHT
A White Paper Describing the Discussions and Outcomes of the
1st Annual Chemical Sciences and Society Symposium (CS3)
Kloster Seeon, Germany, July 23-25, 2009
http://portal.acs.org/portal/fileFetch/C/CNBP_023077/pdf/CNBP_023077.pdf

http://solarfuelshub.org/

kelly

Recent: http://www.livemint.com/2011/03/23001656/Tata-signs-up-MIT-energy-guru.html

SJC

I saw a demonstration of this. The device was in a beaker of water in a dark space. They turned on the light and a lot of gas bubbles started rising to the surface. Considering the low power of the light and the amount of bubbles I was impressed.

kelly

Generating, separating, capturing, compressing, storing gases - then generating electricity in controlled amounts and voltage while maintaining proper water levels doesn't necessarily sound like a cheap, foolproof, slam-dunk 3rd world energy source.

SJC

The third world talk may be more for grants than reality. If you can grow switch grass and make cellulose ethanol, you create CO2. If you make H2 and O2 you can use the O2 for gasification of what is left after extraction for fermentation and distillation.

You use the H2 and O2 in an SOFC with output turbine at 70% efficiency. You use the electricity to combine with CO2 and H2 to make fuels. Once all the numbers are crunched the energy from the crops and sun just might work out to a tidy profit and some import reducing fuels with no sulfur and no benzene.

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