Solar cells that imitate plants
Every year, approximately 2.5 million exajoules of solar energy reach the Earth. That's about 5,000 times the amount of energy consumed by people each year. The trick is collecting it and converting it into electricity cheaply and efficiently. Plants do a good job of that. Turns out scientists have been working on ways to imitate nature's photosynthesis since 1912. And they're still at it. This week, the scientific journal Chemical & Engineering News posted two deep articles on the subject. The first is about the molecular mysteries of photosynthesis, including whether it's as efficient as one would expect from a process that has more than a couple billion years of evolution behind it. From the article, "Harnessing Light":
Water-splitting is key to the renewable production of hydrogen gas and other energy fuels, and doing so with inexpensive catalysts, as plants do a billion times per day, would be a huge step forward for solar power research. But the photosynthetic process has some other secrets, too, that scientists are only just figuring out, such as how photosynthetic organisms can tame light without suffering too much radiation damage, the plant equivalent of a sunburn...That's where biomimicry comes in. The companion article in C&EN describes research by Gust and others to build small molecular systems that imitate what plants do using a biological "machine" consisting of 20 proteins. From the second article:
(One) contentious area is the question of how efficient photosynthesis actually is..
One reason that plants don't store fuel efficiently is that "plants' goals are different than our goals," says (Devens Gust, a photochemist at Arizona State University). "The plant's goal is to live and reproduce, not to store energy for humans."
Even so, many researchers turn to photosynthesis for inspiration on how to achieve humanity's energy needs. They hope to mimic the early, energy-efficient light-harvesting steps of photosynthesis, but then direct the harnessed light energy entirely toward producing fuel instead of growing a plant.
"When we think about ways to harvest sunlight," Gust says, "it seems natural to look to photosynthesis for ideas. It has been around for the longest time, and it works on the largest scale."
The overall efficiency of photosynthesis for making sugar fuels is low--only about 2-3%--because plants' primary goal is to live and reproduce, not store fuel. But the first steps performed by (the plant's photosynthesis system) are much more energy efficient, about 30%. So researchers want to "take the basic chemistry and the basic physics of the photosynthetic reaction center" and build a molecular version in the lab, says Devens Gust, a photochemist at Arizona State University. In effect, they want to produce a molecular photovoltaic that, like (the plant's version), produces a current of electrons that could be used to split water and thus drive the production of a fuel such as hydrogen gas.Harnessing Light
Attempts To Mimic A Plant's Light-Harvesting And Water-Splitting Megamachinery
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No problem, if the war with the machines starts going badly we can always burn the sky. Where else would they find such an abundant power supply?
Not surprising, since plants don't actually do any "work", as humans would define it. Other than growing/branching out, plants just sit there, whereas animals are moving around, building shelters, mating, etc.
So when I'm sitting on the couch watching television, moving no other muscles but those that work the remote, I'm really "conserving energy."
What's with the GE logo at the bottom of the post? I don't remember seeing any other posts that were sponsored by a specific company. Are the linked articles actually interesting or did GE simply pay to have a post about their "research"?
I linked to this research here yesterday, tired or solar energy being labeled as unicorn farts. Glad to see this is getting the attention that it deserves. =D
"Great spirits have always encountered violent opposition from mediocre minds" -Albert Einstein.
It's not really accurate to call C&EN a "scientific journal" since it doesn't publish any original research. A better description would probably be "newsmagazine for chemists".
THE_LEISURE @3, As far as I know, GE isn't involved in the research discussed in the articles I link to. GE is just sponsoring a special section of our energy-related posts. They have no input into what we're going to write about. As always, I just post what I find interesting.
What's with the phrasing "2.5 million exajoules"?
That should be either "2.5 yottajoules" or "2.5 septillion joules". Maybe "2.5 quadrillion joules", in old British money.
There are situations where "million exajoules" would make sense; in particular, one might use consistent units to facilitate comparison. Normally, however, one should normalise, usually to prefix-only.
PHIKUS
Unicorn Farts.
Brilliant.
My Brother has been keeping me up to date on artificial photosynthesis over the last couple of years.It been tremendously uplifting really, as when things get too gloomy I remember where this stuff is going and it gladdens my black n bitter little heart.
There was some other pertinent info he mentioned about a Japanese research project that is using the full spectrum of light very efficiently and getting vastly higher energy compared to photovoltaic.
Sorry to be scant on details...I am the art guy , my bro' does the science.
@3
I have previously commented that posts have that 'ads disguised as content' feel. Xeni denied it, saying that all revenue for bb is provided by google adsense.
But, bingo, here's evidence that posts may have corporate sponsors. What's unsettling is that 1) which posts are sponsored and why is not disclosed, and 2) there's a post every other day on why intellectual property laws should be ignored. Railing against big brother is odd when big brother is paying the bills. Cognitive dissonance, anyone?
read the moderation policy
#9: "Bingo"? Random posts have had corporate sponsors for a while, or you've forgotten the whole Microsoft foofrah from last year.
Also, I question your leap of logic from "sponsored by" to "ads disguised as content".
Corporations often sponsor stuff that has nothing to do with their products. The extreme examples are stuff like food companies sponsoring motor racing teams, or just about any company sponsoring an arts and culture event.
only 5,000 times? thats kinda scary.
"The trick is collecting it and converting it into electricity cheaply and efficiently. Plants do a good job of that. "
Really? Never knew plants converted sunlight into electricity, much less cheaply and efficiently. The green narrative causes us to deal in unexamined cliches that sound nice (Can you say "Hope" and "Change?")
OK, let's grant that the writer meant "plants do a good job convert sunlighting into something useful." But even that is not true. They use sunlight about as efficiently as they use water. Which is to say that the sky dumps tons of it and they absorb about 1% and the rest runs off somewhere else. Ditto sunlight.
No doubt we can learn some secrets from plants, but our methods will produce far more toxins and waste that... well, burning oil. Solar, like wind is a dead end, and the GPS of intelligence will lead us back to nuclear.
The only problem I see is that the earth receives ONLY 5,000 times as much energy as we use. Knowing the nature of exponential growth of humanity (in ways other than just population), how long before we just literally and figuratively overshadow other bioorganisms who need the energy for, say, oxygen producing purposes?
"Every year, approximately 2.5 million exajoules of solar energy reach the Earth. That's about 5,000 times the amount of energy consumed by people each year. The trick is collecting it and converting it into electricity cheaply and efficiently."
This introduction irks me a little (just a little...) - I'm all for solar power, but people get the impression that it's "free energy", completely available for the taking, and thus, you can never have enough solar panels. I don't have to inform everyone that light has other roles to fulfill than to get converted into electricity.
I just meet a lot of people who see solar power as a readily available easy solution to everything. They're probably the people who only read the introduction to articles like these without finishing the rest. I'm definitely nit-picking here, the introduction is clearly meant as a 'layman's terms' summary to an otherwise really good article. But considering that "the solution to pollution is dilution" used to be a commonly accepted 'layman's terms' reduction, we need to mind our words. Solar energy is not as easy as that.
Upon re-reading, I'm totally being an ass, sorry. Good article. Does anyone agree, though?
@ #9 teufelsdroch,
I have previously commented that posts have that 'ads disguised as content' feel. Xeni denied it, saying that all revenue for bb is provided by google adsense.
I said no such thing! We receive sponsorship revenue in a number of ways.
Sometimes, a series of videos related to a specific subject matter -- for instance, games -- could be underwritten by one given sponsor. Or a series of items in our RSS feed with a given keyword might appear with an ad related to a specific sponsor's campaign. GE is attaching their ad to a series of posts related to a specific subject matter here, but they don't have any input on the content. Pesco didn't share his post with a GE gatekeeper before posting it, and we don't agree to any editorial limitations on what we put on the blog.
Also -- these posts aren't ABOUT GE.
dead end? Well, to you maybe, but that hardly changes reality. Ultimately the sun is the only workable source and we've barely spent a few decades
working on that. Tidal is coming along nicely and nuclear still has vast unresolved safety and waste issues.
Jerrill @11, Exactly. Thanks.
teufelsdroch @9, First of all, Xeni never said that all of BB's revenue comes from Google Adsense. That's ridiculous and obviously not true. Second of all, we make it absolutely clear when a sponsor is involved. For example, in this case the graphic saying "Section sponsored by GE" is a pretty good indicator, don't you think?
gadgets123,
I, as an environmental chemist, disagree with your assertion that: "No doubt we can learn some secrets from plants, but our methods will produce far more toxins and waste that... well, burning oil."
Name any toxic chemical 'invented' in the last 80 years.
It came from petroleum.
I find it tedious when the BB posters have to explain over and over again to every person who suddenly notices an ad on BB. Get over it. Read the Moderation Policy. Any time they have to spend on repetitious explanations comes out of their available time for creative efforts.
Gadgets, movements generate cliches ("small town values", "compassionate conservatism"). Maybe the biggest cliche of all is members from one camp tossing rocks from a glass house.
That said- your example has nothing to do with efficiency. Just because a sponge doesn't consume the ocean when you drop it in doesn't mean it is inefficient. The rest of your arguments from that point forward just make no sense to me. Incidentally, photosynthesis generates energy for a plant via an electron chain http://en.wikipedia.org/wiki/Electron_transport_chain .
I'm not certain what memes you are carrying that biases you towards nuclear energy, but you might want to ask yourself what your stake in it is. I'm somewhat open to nuclear energy myself, if it turns out to be the only power source with a sufficiently low carbon footprint- but nuclear waste is nasty, and nuclear power plants DO make me nervous in "a post-911 world". Furthermore, the more I try to match numbers of energy consumed by households and watt-hours generated by windfarms, solar, hydro, and geothermal, I'm not convinced that nuclear is necessary. You don't like hippies- I get that, but do you dislike them enough to bias yourself against better alternatives to nuclear power?
#13 gadgets123: Electricity is a phenomenon that involves the presence and movement of electric charge. Photosynthesis is all about moving electrons within and amongst protein complexes within the cell. QED.
OK, I looked back at the previous discussion and I did misunderstand the explanation--I apologize. BB is an ad-supported company, but the content is valuable to me, and there could be no confusion that GE is sponsoring this post.
However, I think there's some willful ignorance about advertising as content (also a NYT article here. )
As O'Reilly says,
"I suppose taking money to hawk products might put editorial integrity in question. The way around that is to put community response front-and-center. Or to have a clear relationship like 'Adobe hired us to show people how to use Photoshop Elements.'" (They haven't, but they should :-)
BB is awesome about response--that's what brings us back. But even after reading the moderation policy, your relationship with advertisers isn't clear, because you insist that money has no relation to posts. Corporations don't just take a fancy to paying for random blogs. Where you and GE share common interests and where the ads stop isn't clear, and it should be.
@Jerrill By way of arguing your point, you give several examples of PRECISELY what I'm talking about. Put yourself in the advertisers spot: what do they hope to gain from these events?
Meta-commentary, as always, belongs in the Moderation Policy thread.
Gadgets:
What are you talking about? Are you babbling? Why would this lead to us to produce more toxins and waste than oil?
Photovoltaic cells can already be about 20% efficient, with some third-generation experimental models hitting over 40% [1]. The total energy used in production of a cell, counting all the steps, is about 400-600 kWh/m2 [2]. If you ignore the high-efficient models mentioned above and assume a piddly 12% conversion factor and standard US sunlight, a cell will produce that much energy in under four years. If you assume 14% conversion, that drops to just 2 years [2]. Most solar cells have a life expectancy of about 30 years. This means that about 95% of the energy they produce over their lifespan creates absolutely no waste or toxins at all. That's 28 years of producing completely clean energy at over 200 kWh/m^2.
Now will this process add more waste? How? It could only possibly do so if it decreased the efficiency of the solar panels. But we already have solar panels acting at this efficiency, so we're not going to start buying solar panels that work worse.
Will it make the solar panels more efficient? I have no idea, but clearly the scientists working on this think so.
Great article, this affects us all and hopefully we're getting smarter in out consumption use.