4 ms·
Earth receives about 1.3 to 1.4 kW per square meter from the sun (and that's before the atmosphere absorbs and reflects a huge chunk of that) - which is effecti
by jbri 16y ago
Earth receives about 1.3 to 1.4 kW per square meter from the sun (and that's before the atmosphere absorbs and reflects a huge chunk of that) - which is effectively an upper bound on the energy that can be produced by any solar power source. A playing-card sized device is going to take more than a day to produce a day's worth of electricity for a current developed-world lifestyle, even if it were 100% efficient.
- pshapiro 16y agoI think the point is that it can use that small amount of energy to break the hydrogen bond in the water, releasing more energy than was used. Edit: Apparently I made a mistake. See the correction, which I was the first to upvote.
- jbri 16y agoBreaking bonds does not release energy. Bonds are the way the are because they are (locally) the lowest-energy configuration for the atoms that are taking part. You need to put energy in to get out of a low-energy configuration. The device appears to use water->hydrogen as an energy storage mechanism, to solve (at some efficiency cost) the issue of energy demand generally being out of sync with the supply from the sun. You put energy in to convert water into hydrogen+oxygen, and then you can get that energy back out by converting it back into water.
- runningdogx 16y agoSince most reactions do not end up with all the constituent atoms as free ions, the real question is how the sum of bond energies of the reaction product(s) compares to the sum of bond energies of the starting molecule(s). In the case of water, 2 H20 -> 2 H2 + O2 is endothermic, but reactions do not have to be endothermic, or else chemistry would be very boring and cold.
- corin_ 16y agoPisses me off that comments like the one I'm replying to get downvoted. He expressed his understanding of the science, if he's wrong then by all means explain why and upvote those who have explained why - but don't downvote just because somebody made a mistake, it's surely better to have the discussion than for nobody to bring it up.
- BoppreH 16y agoI won't upvote GP because it contains a factual error and you can't upvote only parts of a comment. If it was edited to include a note about the mistake, thus dismissing the error, I'm sure it'll get get some votes.
- corin_ 16y agoI'm not saying upvote incorrect comments, but there is a place inbetween punishing and rewarding.
- Natsu 16y agoI sometimes vote such comments towards one, especially if they're only one vote away.
- michaelchisari 16y agoyou can't upvote only parts of a comment Well, that's an interesting UI idea...
- corin_ 16y agoSolar panels are already good enough that they are used in developed countries such as USA and UK. Are they perfect? No, they cost too much, and they don't generate enough electricity, but they are used none-the-less. By the sound of it, this new creation would be more efficient, either in price, electricity generation, or both, than traditional solar panels - if that wasn't the case, why on earth would any project use them in third world countries, when they could instead use solar panels. So, based on those two facts, surely anyone who would be using solar panels ought to look to be using this product in the next few years? (And, depending on how much better than traditional solar panels it is, possibly more people/companies would want to use it than are willing to use solar power right now.)
- berntb 16y ago>>Solar panels are already good enough that they are used in developed countries such as USA and UK. Are they perfect? No, they cost too much, and they don't generate enough electricity, but they are used none-the-less. Does no one follow energy news, except for oil prices and the Polywell project?! :-) Many estimates talk about soon reaching "grid parity" in large parts of the world. If this leaf isn't good enough, there will be some other solar variant soon. http://en.wikipedia.org/wiki/Grid_parity http://en.wikipedia.org/wiki/Grid_parity It seems to go faster than this prediction from 2009: http://news.bbc.co.uk/2/hi/8386460.stm http://news.bbc.co.uk/2/hi/8386460.stm (Kurzweil argued in 2008 that solar energy will take over http://www.livescience.com/4824-solar-power-rule-20-years-futurists.html http://www.livescience.com/4824-solar-power-rule-20-years-fu... )
- antihero 16y agoWhat if we covered our houses with them? Instantly I'm dreaming of lush, green cities, covered with the stuff :)