..STRAIGHT FROM THE HORSES MOUTH

D. Lienemann

 UNL Extension Educator,

Webster County

February 15, 2012 Edition

As I filled up with $3.50+ gas today, I was thinking, amongst other things, that maybe I needed one of those electric cars, but wasn’t sure if I could get batteries big enough to get me to all of my destinations. Perhaps a bicycle would do me a lot better, but imagine just going to Red Cloud. Ok, maybe alternative fuels may be a better bet for my personal safety and well-being. I was thinking of not just getting run over, but the implications of the old beater.
Actually I was thinking of all kinds of alternative energy that may someday be available to us, let alone tapping the resources we already have. I got to thinking of that green leaf, full of chlorophyll that is so crucial to the total energy of the natural world. If you think about it, if some scientist could invent a solar cell that could mimic photosynthesis, wouldn’t that be a game changer for alternative energy. I know the leaves are not even on the trees yet, but that did not keep me from thinking about them. Call it wishful thinking. Each day we are getting closer.
Nature is amazing. Take that humble leaf, it's capable of absorbing the sunlight and converting it into the chemical energy that fuels the growth of plants. As smart as human beings can be, nature almost always does it better, possibly because nature has had hundreds of millions of years to get it right. Why would we be so arrogant to think we could even match nature? Take photosynthesis for example. Plants with green leaves are able to capture the sun's energy and turn it into useful chemical fuel in a process that is much, much more efficient than anything we have devised up to this point. Photosynthesis is one of the fundamental forces of life, and it's far superior to our technological efforts to harness sunlight. Scientists have however been pushing for a form of artificial photosynthesis that would create electricity that would then be harnessed to produce hydrogen for use in fuel cells. That's only one way to harness photosynthesis. There are others. For instance, a photovoltaic solar panel can transform sunlight to electricity, but right now that power is difficult to store without expensive batteries, which limits the potential of solar energy. The sugars produced by photosynthesis, though, can be tapped by a plant for energy whenever it's needed. That is where nature has us. We can’t ever seem to really mimic nature, or perhaps the margarine commercial had it right. Don’t fool with Mother Nature!
As it turns out, we may be getting closer to having an artificial leaf and mimicking photosynthesis. In a recent copy of Science Magazine, I stumbled on an article that piqued my interest. It seems Massachusetts Institute of Technology (MIT) professor Daniel Nocera and his colleagues announced the development of an effective, relatively inexpensive "artificial leaf", a solar cell that can turn sunlight directly into chemical fuel. This playing card-sized device is made up of cheap materials, mostly silicon, cobalt and nickel, and when placed in a container of water and exposed to sunlight, it generates bubbles of oxygen and hydrogen. Those gases can be collected and stored, much more easily than the electricity produced by a photovoltaic solar cell, and then used to generate power through a fuel cell.
Now I am envisioning my pickup covered with artificial leaves. I bet that would get some stares driving around Blue Hill, Red Cloud or any other destination. I am not sure how air dynamic it would be, but it is certainly intriguing. Aesthetics aside, how does it work? Nocera indicated in a companion article that his device directly mimics nature: It's doing exactly the same thing as a leaf. It's sunlight in; hydrogen and oxygen out. And you can use the hydrogen and oxygen at some later time. Not all that much different than a real leaf.
Nocera and other scientists have been working on the artificial leaf for some time. Many call it the "Holy Grail" of renewable electricity. If they can get everything worked out, it is possible that this invention could make solar power affordable and viable for poor, off-the-grid locations. From the description laid out by Dr. Nocera, the artificial leaf is basically very simple, no excess equipment, no expensive materials. Ideally, the cell could produce enough electricity to power a house in a developing country with just sunlight and a gallon of water. That may be the reason why an Indian conglomerate, Tata, has helped finance research on this project. What isn’t there to like with this potential technology. I wonder if it will also work for cell phone reception?
As I understand it, in order to keep his cells cheap, or at least inexpensive, Nocera needed to sacrifice some efficiency; basically, how much sunlight his cell can convert into energy. The standard commercial solar photovoltaic cell has an efficiency rate of about 10% and the artificial leaf right now is closer to 2.5%. That's still significantly more efficient than the average actual leaf, but of course, human beings need a little more power than trees or grass. The artificial leaf also has to be durable enough to last for thousands and thousands of hours. It interested me that an older prototype, developed more than a decade ago by John Turner of the U.S. National Renewable Energy Laboratory lasted barely a day. Nocera's leaf has operated continuously for at least 45 hours, but it will need to do better. Still, at a moment when most of the attention on renewable energy is being directed towards "scandals," like Solyndra, it's a good to see what a smart and dedicated scientist can do to change the way we power our lives. Maybe we can fool Mother Nature-- I certainly hope so!
The preceding information comes from the research and personal observations of the writer which may or may not reflect the views of UNL or UNL Extension. For more further information on these or other topics contact D. A. Lienemann, UNL Extension Educator for Webster County in Red Cloud, (402) 746-3417 or email to: dlienemann2@unl.edu or go to the !website at: http://www.webster.unl.edu