Slashdot Mirror

← Back to Stories (view on slashdot.org)

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."

11 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 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

    3. 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.

    4. 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. 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!

  5. 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).

  6. 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.

  7. 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