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Artificial Leaf Could Provide Cheap Energy

Posted by Soulskill on from the make-like-a-tree-and-catalyze-the-electrolysis-of-water dept.

sciencehabit was one of several readers to tip news of a sunlight-harvesting artificial leaf, writing: "Nearly all the energy we use on this planet starts out as sunlight that plants use to knit chemical bonds. Now, for the first time, researchers at the Massachusetts Institute of Technology have created a potentially cheap, practical artificial leaf that does much the same thing—providing a vast source of energy that's easy to tap. The new device is a silicon wafer about the shape and size of a playing card coated on either side with two different catalysts. The silicon absorbs sunlight and passes that energy to the catalysts to split water into molecules of hydrogen and oxygen. Hydrogen is a fuel that can be either burned or used in a fuel cell to create electricity, reforming water in either case. This means that in theory, anyone with access to water can use it to create a cheap, clean, and available source of fuel."

21 of 326 comments (clear)

  1. Vaporware by GabriellaKat · · Score: 5, Funny

    At last, true vaporware!

    --
    "Have you ever thought about just turning off the TV, sitting down with your politician, and hitting them?"
  2. So it's a solar cell.... by artor3 · · Score: 4, Insightful

    There's only so much insolation to harvest. If this is cheaper and higher efficiency than existing solar cells, then great. Based on the article, it's only 5.5% efficient, so meh. But even if it were 100% efficient, it's not some magical free energy machine, and never can be. While it's true that "nearly all the energy we use on this planet starts out as sunlight", a lot of that energy arrived at earth several millenia ago. In the long run, we're going to need to either use less energy (preferably by making things more efficient, not making do with fewer things) and/or get some near-unlimited fuel source, like fusion.

    1. Re:So it's a solar cell.... by timeOday · · Score: 5, Insightful
      No, actually there is plenty of sunlight to power all current needs and more, if we could capture it efficiently.

      Yup, I linked to a page claiming to "debunk" this "myth" on the basis it would take a solar panel the size of Georgia to power the whole earth. Big deal! Vastly more land is consumed by agriculture. Just reclaiming all the space on rooftops, roadways, and parking lots for solar would account for a lot of that, puttng power generation right where it's needed.

      And then there's there's the 2/3 of the earth covered by water nobody is making much use of. If cheap solar devices can produce hydrogen, it can be shipped long distances efficiently.

    2. Re:So it's a solar cell.... by bunratty · · Score: 3, Interesting

      Well, at the point solar power runs out, we'd have to find a new planet anyway. It would provide energy for billions of years rather than hundreds. For all intents and purposes, solar, wind, and biofuels never run out.

      Also, all forms of energy generation require human workers. Who do you think digs up the coal, oil, and uranium? Who do you think runs the oil refineries, nuclear power plants, and coal plants? Do you have any evidence that we'd need more workers per unit of solar power than for other forms of power?

      --
      What a fool believes, he sees, no wise man has the power to reason away.
    3. Re:So it's a solar cell.... by rubycodez · · Score: 4, Informative

      Actually, the deuterium in the oceans would provide fusion energy sufficient for billions of years, the sun would scorch the earth to by expansion first before we ran out. And there is lithium and boron, and we can make tritium. Fusion really is the holy grail of power generation if we can't make solar power work. http://www.engineeringchallenges.org/cms/8996/9079.aspx

    4. Re:So it's a solar cell.... by sunzoomspark · · Score: 3, Informative

      The big question I see with this is just how clean does the water going in have to be?

      The article said they'd been running it on water from the Charles River, so it doesn't have to be very clean.

    5. Re:So it's a solar cell.... by rubycodez · · Score: 3, Informative

      Deuterium is much more abundant than gold and far easier to extract from water (of any source, fresh or ocean doesn't matter). We've been producing and using deuterium for decades, for example as moderator in heavy water reactor. The energy cost is negligible even for fission reactor moderator, for fusion energy even smaller cost compared to yield.

    6. Re:So it's a solar cell.... by rubycodez · · Score: 4, Interesting

      Normal solar panels have albedo of 0.35, which is close to average of earth 0.30. We'd be far better off thermally using that than burning fossil fuel or fissioning atoms. However, comparing the energy input of the sun to what man generates, the fraction is so very tiny that the global direct thermal effects (not greenhouse gases which is another discussion) of our power generation in essentially zero.

    7. Re:So it's a solar cell.... by c6gunner · · Score: 3, Interesting

      Well, at the point solar power runs out, we'd have to find a new planet anyway.

      I was more concerned about the materials which go into panel production.

      Also, all forms of energy generation require human workers. Who do you think digs up the coal, oil, and uranium?

      The same types of people who dig up the materials needed to make your panels?

      You'd need more resources (ergo, more people working) to build the damn panels in the first place, and THEN you'd need to hire tens of thousands of workers to service the panels. There's a reason why solar power is currently THE most expensive source of energy on the market, and is between 2 and 3 times more expensive over the lifespan of the panels when compared to nuclear (and 4-6 times more expensive than oil/coal).

      Do you have any evidence that we'd need more workers per unit of solar power than for other forms of power?

      You know, I had a really long comment written up, with figures showing you'd need upwards of 10,000,000 man hours to do a single cleaning, and extrapolating that to X number of full time workers and comparing it to number of workers needed to run a nuclear power plant .... but then I went and checked and it turns out solar panels don't need to be cleaned all that often. So, suffice it to say, I don't have any solid figures, and I don't think anyone else does at this point. We'd have to figure out a mean rate of failure, which would be different for different panel types, AND we'd have to figure out how often they need cleaning, which would be different for each area. You'd also have to worry about unexpected things, like tornadoes and other extreme weather (which don't generally affect nuclear power plants), and you'd have to worry about man-made problems, like Billy Bob and his cousin Cletus figuring out that there's millions of free panels sitting there for the taking. I'd say that it's fairly obvious that they would, at the very least, require a similar number of personnel as other forms of power generation, but I suspect the number would be far higher.

    8. Re:So it's a solar cell.... by Anonymous Coward · · Score: 3, Insightful

      People keep claiming that something the size of Georgia is a sane amount of the earth's surface to cover. You know that agricultural land isn't completely covered with manufactured material, right? Even if it were, how is doubling the human footprint on the planet reasonable? That article really is a successful debunking.

      You're talking about mining enough resources to cover Georgia in something manufactured every N years, perhaps N = 30. Think about how bad that is. It's not road bed, either, it's something expensive and chemical-intensive to produce.

      I'm completely for solar energy research, and it can totally make sense for some applications, and why not cover an otherwise unused roof when solar cells are cheap enough. But you just have to look at the energy densities of various energy sources to understand that nukes are it. Nukes are much more sustainable than anything that requires to cover 0.01% or more of the earth's surface with anything manufactured. Nukes aren't perfect, but they're by far the most sustainable, safest, cheapest source of energy, if we could ever act rationally as a species.

      I mean, energy density (http://en.wikipedia.org/wiki/Energy_density) isn't the whole story, but even the most pedestrian nuke fuel is four orders of magnitude denser than the most exotic chemical fuel. Five would be a realistic comparison, and then another order of magnitude for more refined fuel, and then another three orders of magnitude when fast breeders become really practical. We're talking about eight orders of magnitude denser energy!

      Uranium isn't cheap to mine, but it almost doesn't matter, and silicon is not so cheap to refine, either.

      So, I'm no expert, and I'm happy to hear some detailed arguments refuting my back-of-the-envelope ones. But even the most cursory glance at the issue from an engineering perspective says nukes are quite safe enough to be the most sustainable form of energy, even if you use TMI technology and just blow up a nuke plant every 10 years. The energy density, and therefor logistical considerations, are just ridiculously lopsided.

      Again, I'm all for developing everything, and I'm working hard on residential-scale solar myself as a hobby. But basic physics says there will not be a fairytale ending for solar, wind, biofuels, or fossil fuels. Certainly, there will be local niches where each of these will be the right tool for the job, but at the planetary scale, we can do better than evolution. We have harnessed the power of the atom. WTF is wrong with us.

    9. Re:So it's a solar cell.... by joocemann · · Score: 4, Interesting

      You should consider:
      1) The energy harvested by solar would hit the earth anyway, and thanks to laws of thermodynamics, we can't get 'more' from it than would already arrive.
      2) The energy harvested using fossil fuels hit earth millions of years ago and was stored in chemical bonds that we break with combustion. If we otherwise did not choose to release this energy via combustion, it would stay in chemical form.

      There is a difference. There is also no excess blanket of CO2 being produced, where carbon that has been absent from the atmosphere for millions of years is now reintroduced, and as it is a heat storing gas, it aides in global warming.

      There is a difference.

  3. This is how it goes by alex_guy_CA · · Score: 4, Insightful
    See cool science article.

    Get excited.

    Read comments.

    Excitement crushed.

    --
    San Francisco Photographers
  4. MIT invents everything by RabidRabbit23 · · Score: 3, Informative

    I saw a presentation on exactly this technology a few years ago at a conference, not from an MIT researcher. It's a strange phenomena, but within science MIT is just one of many research institutions doing great work, but to the public it has the most significant and frequent press releases. I mean, this isn't even a leaf, it's a silicon wafer which happens to be green and splitting water using catalysts is very old. The only innovation I'm seeing here is a new catalyst, which is pretty common in these fields. I also like the token quote from Bob Grubbs who won a Nobel prize in catalyst research and thus is interviewed in every catalyst article.

  5. Benefit to Georgia by Anonymous Coward · · Score: 4, Funny

    Plus as some one who lives in Georgia I can tell you that is is hot! A solar shade for the state might work well!

  6. Re:10x more efficient than photosynthesis?! by loshwomp · · Score: 4, Informative

    I'm amazed that the foundation of life on earth is so inefficient (one tenth of 5.5% is only .55%!). Is this right?

    Somewhere on that order, yes.

    Also, if this is true, then isn't this a major reason against using biofuels?

    Exactly. Plants are ~1% efficient at harvesting solar energy, and we have much better collectors (photovoltaics) that are much more efficient (15-20% in mass production) and generate energy in a more versatile form (electricity).

  7. Re:Isn't it better with traditional electrolysis? by im_thatoneguy · · Score: 3, Informative

    It's made from copper and cobalt instead of a lot of the more exotic materials used in standard photo-voltaic cells.

  8. Re:Isn't it better with traditional electrolysis? by loshwomp · · Score: 3, Insightful

    So, unless there's a pretty substantial price benefit to the cell, where's the benefit?

    As you have discovered, the economics are precisely the key to solar energy. The power density (Watts/m^2) is unimportant, except for installations with unique constraints (e.g. spacecraft). For terrestrial applications, Watts/$ is the most interesting term.

    Similarly, for economic reasons, I don't think electrolysis (or H2) is likely to succeed on a wide scale. The dirty secret of the H2 "economy" is that the hydrogen fuel cell cycle has a round trip efficiency of about 25%. A fuel cell is effectively a battery, and we already have substantially better batteries at a tiny fraction of the cost.

  9. Re:10x more efficient than photosynthesis?! by Anonymous Coward · · Score: 5, Informative

    Plants limit their photosynthetic efficiency largely because raising it too high starts raising the internal temperature, which raises the rate at which they lose water. Basically, they are tuned to gather 'enough' energy without wasting water (which is rarer for them than sunlight) rather than extracting as much energy from the sun as they can. Biofuels are usually suggested not because they are efficient, but because they are cheap and work fairly well with our existing infrastructure.

  10. Re:no free energy by Black+Gold+Alchemist · · Score: 3, Informative

    If you have solar panels capture the energy, they simply suck the energy up, store it, and when it returns as heat in the friction of the objects it moves, the lights it powers, etc. Without the solar panels, the light would just be heat. So it is free.

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    Virtue is a temptation
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  11. Re:no free energy by shermo · · Score: 4, Insightful

    The second law of Slashdot:

    "No matter how obvious you make the joke, someone will feel the need to correct it for you."

    --
    Insanity: voting in the same two parties over and over again and expecting different results
  12. Re:What about night and bad weather? by LBU.Zorro · · Score: 3, Informative

    Ok, so I found 3 Humboldt Countys in California, Iowa and Nevada, but based on size it appears you mean the CA one, of course it only really has 2.2million acres of land, the rest is water.

    According to this report (http://postcarboncities.net/humboldt-county-ca-energy-element-background-technical-report) Humboldt county (apologies if I got the wrong one or anything) used 940 GWh of electricity alone in 2003, which comes out to around 2500MWH averaged daily - that is a heck of a jump from your 100MWH, 25 times as much. And that doesn't count usage growth over the last 8 years, nor the natural gas heating, cooking and hot water (about 45million therms) nor transportation energy costs.

    I'm pretty concerned by your numbers now, but even taking your 25 acre 5MW station at face value, and even allowing that it's a molten salt plant and stores enough energy to provide that 5MW continuously day and night with backup storage to last several weeks and to provide that 5MW during the local solar minimum you would need 12500 acres to provide just the electrical energy. 10 cubic meters of molten salt can provide 1MWH of storage, since you'd need 2500MWH of storage for a single day, and several weeks of storage you're talking about 350k cubic meters of molten salt, a heck of a lot.

    Sure all of this is relatively minor compared to the actual size of Humboldt county but I'd guess the cost of manufacture of a 5MW plant to be around the $20million mark (unaccurately based on http://www.power-technology.com/projects/Seville-Solar-Tower/ and scaling down), so if you have to build 500 of them just to handle the electrical load you're talking about $10billion to manufacture (and remember this is for purely the electrical generation of 2003, not transport or natural gas). The population of 2008 is estimated at about 130k (http://mapzones.org/Humboldt_County_California.html) meaning that would cost about $77k per resident. The same report shows that the average per-capita income of Humboldt county residents is $17k annually - or 4.5 times the cost.

    I don't know about you but I'm a little puzzled as to how you're going to pay for all of this? Not to mention over doubling it for powering hydrogen/electrical vehicles and replacing natural gas completely - something you'll have to do to have this green revolution of yours.

    What you, and everyone who thinks that "popular pundit b.s." is just "b.s." seem to fail to understand is that this is a huge engineering, financial and technological issue to overcome. There are many reasons why it hasn't happened already, and aside from energy density and reliability the biggest reason is cost, are you really willing to have an additional 50% tax on all income in your state for the next 10 years to pay for constructing the plants necessary? Think of what that would mean, can you cope with 50% less money every payday?

    Just as a comparison a 320MW natural gas power station costs about $150million dollars (http://www.power-technology.com/projects/laverton/), so you're looking at about the equivalent of 8 of them, or $1.2billion dollars - your solar plan is an order of magnitude more expensive. If you're saying that they should be built with loans and then amortised over the lifetime of the plant with the cost being the energy, you're still looking at about 5 times more expensive electricity (yes I know the fuel costs are minimal - mirror maintenance is a pain but you don't have to buy gas) unless you subsidise it somehow (in which case it's still 5 times as expensive but you're pretending it's not).

    If you're going to have statements like "Now you see where the science behind green makes sense, and the popular pundit b.s. that is constantly echoed is just exaggerated doubt and nonsense claims." then you had really better match that with actual verifiable numbers and facts. Rather than just repeating what you've heard without really understanding it - it is completely possible, but then again so