Mar
29
Half of Artificial Photosynthesis Invented
March 29, 2011 | 11 Comments
The American Chemical Society press release headline runs, “Debut of the first practical “artificial leaf””, which is a little more than some extra on what has happened. The prolific and wide ranging skills of Dr. Daniel Nocera have come up with an “artificial leaf” of sorts. By that they mean Dr. Nocera has built a low cost water splitting solar cell. Now that’s news. But first . . .
Photosynthesis is the plant kingdom’s way of using water and carbon dioxide in reforming the molecules into useful building blocks of plant life. Spitting out the hydrogen and oxygen from water is done to get free H2. Splitting out the CO2 gets the carbon and both release the necessary O2 providing plants the element building blocks for the starches, sugars, proteins and fiber, which in turn the animal kingdom needs for its’ metabolism – which makes CO2 again. It’s a cycling system.
What makes the Nocera announcement big news is the water-splitting half is being touted as a major accomplishment – which at the engineering level – it is. Here’s why:
MIT’s Daniel Nocera, Ph.D., who led the research team 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.”
Nocera’s new solar cell overcomes these problems: 1. It is made of inexpensive materials that are widely available. 2. Works under simple conditions. 3. And it’s highly stable. It seems to be a major improvement on news about two years ago.
In laboratory studies, Nocera showed that an artificial leaf prototype could operate continuously for at least 45 hours without a drop in activity.
The foundation of the new cell comes from Nocera’s recent discovery of several powerful new, inexpensive catalysts, made of nickel and cobalt. The new catalysts are capable of efficiently splitting water into its two components, hydrogen and oxygen, under simple conditions.
As the technology sits at lab status, Nocera reports the new cell is about 10 times more efficient at carrying out water splitting photosynthesis segment than a natural leaf. He’s optimistic that he can boost the efficiency of the artificial leaf much higher in the future saying, “Nature is powered by photosynthesis, and I think that the future world will be powered by photosynthesis as well in the form of this artificial leaf.”
Nocera notes the prior credit in the artificial leaf business. John Turner of the U.S. National Renewable Energy Laboratory in Boulder, Colorado developed the first artificial leaf more than a decade ago. 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 device bears no resemblance to real leaves on real green plants. Scientists have used as the leaf as a model for their efforts to develop a fuel producing form of solar cells. The MIT cell is about the shape of a poker card but even thinner, the device is fashioned from silicon, electronics and catalysts, the substances that accelerate chemical reactions that otherwise would not occur, or would run slowly.
Here’s the press release bold quote, “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.”
What common sense suggests is that the new cell produces Browns Gas (aka oxyhydrogen), the vernacular name for the hydrogen gas and oxygen gas that flows from splitting water. The press release makes no mention of separating these two gases. Left together they are a very, and your humble writer means very, ignitable hot burning fuel mix. Storage over the course of the day is going to need considerable and innovative engineering skills to be affordable. One will want to use the Browns Gas up quickly and have as little mass around as possible.
Then you would need a fuel cell to recombine the hydrogen and oxygen releasing the electrons as electricity. Lots of headway is being made on fuel cells, but industry is far from making them cheap enough for the third world household.
There remains the cheap CO2 split side of photosynthesis. That’s a major target as well. Having free carbon, hydrogen and oxygen makes most of the energy part of organic chemistry available for engineering back to energy stores in liquids or gases without the oxygen premixed with the fuel. Back to carbon based products would be much safer, very much so.
On the other hand . . . A few of the new cells, or many perhaps, used to make Browns Gas immediately, used in an economical fuel cell which loads to an economical battery might be much safer and cheaper . . . with equal or better chances of being viable sooner.
Meanwhile a deal has already been cut.
The point, investment in Nocera and his catalyst research is paying off handsomely. New ground is being broken. If the new cell is cheap enough, lasts long enough and systems develop to use the products efficiently and safely, the announcement is a very big deal. It’s a very big new first step.
Comments
11 Comments so far
Feedburner
Reddit
Stumbleupon
I really enjoy this blog. As a non-engineer, all I can do is hope some of these wonderful technologies come to commercial fruittion.
Keep up the great work, engineers and scientists of the world!
You don’t need a fuel cell to convert hydrogen and oxygen into electricity. A simple internal combustion engine can do the job at third world prices. It isn’t the most efficient, but it is the most practical.
The internal combustion engine is a very inefficient way of converting power. Wouldn’t it be nice if we could develop a system that would use the fuel efficiently and free the third world (and ourselves) from the internal combustion engine? It has many downsides. It uses oil for one. We need to think in a way that frees us all from oil.
Chris makes a good point that the internal combustion engine could be used to burn the above mentioned brown gas, and not oil as Don thought. However Don is right about freeing the third world of oil as much as possible. Let’s hope this idea works as well as it sounds, way to go Dr. Nocera.
Perhaps, RO type systems with H2 molecular size pores but smaller than O2 and H2O could do the trick separation and render combining with a fuel cell possible. Again, a whole series of techno-engineering and space related problems would definitely require to be solved, but Nano technology break-throughs are now routine. Wonder, what is the diameter of the thinnest carbon nano tube?
Watch the youtube video to get a better idea of how it all works. The breakthrough here is the catalyst that lowers the energy required to break apart the hydrogen and oxygen molecules of the water. Browns gas is formed if 2 electrodes aren’t used. When 2 electrodes are used, oxygen separates into one collector and hydrogen into another, just like you did in Jr High physical science class. There is nothing new here about fuel cells. Just the catalyst for lowering the energy to separate H and O molecules. This is just a way to fuel something continuously with PV cells even when the sun is not shining. Has nothing to do with photosynthesis.
Also check out the numerous “Water for Fuel” websites where anecdotally, lots of people have been doing this for years.
I would like to say “wow” what a inspiring post. This is really great. Keep doing what you’re doing!!
We’ll always use oil. We use nearly 40% of every barrel to make plastics. But hopefully, the oil the US produces would be enough to satisfy that demand.
However, I agree, moving our country away from foreign oil dependance to a more healthy, green living mindset, while improving the quality of life in poor areas of the planet, should be our goal.
I was just having a conversation over this I am glad I came across this it cleared some of the questions I had.
Great read. Thanks for the info!
Of course, what a great site and informative posts, I will add backlink – bookmark this site? Regards, Reader