SoylentNews is people
SoylentNews
Scientific American has a story on recent developments made by scientists in solar fueled vehicles.
Experts have long been experimenting with techniques to create solar fuels, which allow all the advantages of conventional fossil fuels along with the environmental benefits of renewable energy. However, this requires a "photoanode" — a sort of catalyst that can set the ball rolling — and researchers have had a tough time identifying them in the past.
Now, scientists from the Department of Energy's Lawrence Berkeley National Laboratory and the California Institute of Technology think they've found a better way. If their experiments bear fruit, the results could revolutionize the renewable energy landscape. [...] Photoanodes are key to this procedure.
"The job of the photoanode is to absorb sunlight and then use that energy to oxidize water — essentially splitting apart the H2O molecule and rearranging the atoms to form a fuel. And because this photoanode material needs to have the right sunlight absorption and catalytic properties, they're very rare," explained Gregoire.
In fact, photoanodes are so rare that in the last 40 years, scientists have only been able to find 16 of them.
[...] Gregoire and his colleagues have come up with a new way to hunt for the catalysts, however, and it's much more effective. In two years, the scientists have already pinpointed 12 new photoanodes.
The technique used to identify the photoanodes uses a combination of theory and practice — the scientists worked with a supercomputer and a database of around 60,000 materials, and used quantum mechanics to predict the properties of each material. They then selected the ones that seemed most promising as photoanodes and used experiments to determine whether their calculations were right.
"What's special about what we have been doing is that it's a fully integrated approach," said Jeffrey Neaton, a physics professor with the University of California, Berkeley, and director of the Molecular Foundry. "We come up with candidates based on first-principle calculations, then measure the properties of the candidates to understand whether the criteria we used to select them are valid. The supercomputer comes in because the whole database we're starting with has about 60,000 compounds — we don't want to end up doing calculations on all 60,000."
This technology allows scientists a road map to find catalysts and eventually use them to create solar fuel. The final product, Gregoire said, would look something like a solar panel and involve three components: the photoanode, a photocathode, which forms the fuel, and a membrane that separates the two.
(Score: 2) by MrGuy on Wednesday March 15 2017, @03:44PM (8 children)
This sounds like a solution in search of a problem to me.
I get wanting to use renewal energy (such as solar) to create combustable fuel, for example by splitting water into oxygen and hydrogen (though I'm more than a little suspicious about hydrogen as a long-term motor fuel option).
And, from TFA, that seems to be what they're trying to do:
The thing is, electrolysis of water is something we can do today. Put some water in a tank, apply two electrodes, and generate hydrogen at one of them. You can use a solar cell or any other source of electricity to generate the power to do this. This is something we can already do.
What it sounds like they're trying to do is to do this as a single step, WITHOUT the electricity being generated outside - have the sunlight directly split the water with no wires required. They're not talking about making solar cells more efficient in general. They're talking about building a specific new type of solar cell that is custom designed for this one specific purpose.
That sounds like a cool and challenging engineering problem. But the article is a little light on why this specific solution is necessary to the long-term future of solar-sourced fuels.
(Score: 3, Interesting) by VLM on Wednesday March 15 2017, @04:01PM (3 children)
I admit to the same mystification, but medium length hydrocarbons are just another boring organic chemical so presumably some later engineering breakthru would result in direct conversion of sunlight into THC or LSD or perhaps into synthetic meat. "Honey turn the dials on the solar panels to steak; we're grilling tonight"
There is a huge problem BTW with solar - electric - fuel pipeline economically which is a plant running electric - fuel will dominate the industry. It can be perfectly green if it runs off a hydro plant or nuke. Just the source of the electricity almost can't be solar for certain capital cost reasons because hooking up the same gadget to the output terminals of a hydroelectric dam will instantly double the annual production because it'll run at night.
My guess is their hope is to make an "artificial plant" that'll live where normal plants can't live and will cost less than just using a greenhouse.
Obviously the best solar to fuel system is crude oil, perhaps a thermal depolymerization plant could take a few million years off the reaction time. Or just manufacture charcoal and do interesting organic chemistry things to the solids liquids and gasses that boil out. Which is almost the same as the previous line.
The second best solar to fuel system is biodiesel recycling used veg oil into delicious synthetic diesel fuel.
The third best solar to fuel system is running diesel engines off plain old veg oil the way the Diesel brothers originally intended.
The problem with the artificial plant is we're pretty good at agriculture today, so if you want to run a diesel engine we already can do that cheaper than an artificial plant.
So the situation is just weird.
(Score: 1) by khallow on Wednesday March 15 2017, @06:47PM (1 child)
The problem with the artificial plant is we're pretty good at agriculture today, so if you want to run a diesel engine we already can do that cheaper than an artificial plant.
No. Plants aren't so good at convert solar power into complex organic molecules. I believe the typical estimate is that about 1% of the solar energy falling on an agricultural plant gets converted into into chemical energy. Then you have to convert that chemical energy into chemical energy that you can burn in an engine.
There are roughly six billion joules in a barrel of oil (gasoline would have a similar energy content). If we can come up with a process that can convert solar to oil at a 10% efficiency rate, that would mean about a sixth of a barrel per square meter per year. At the current price of over $48 per barrel, that means roughly $8 per square meter or $80k per hectare, $32k per acre. That's not bad revenue for land use (agriculture usually doesn't have that much return IIRC), but of course, that just means it'll depend more on what infrastructure (light catching arrays, pipes, etc) has to be put in to make it work and the cost of maintenance on this infrastructure.
(Score: 0) by Anonymous Coward on Wednesday March 15 2017, @09:26PM
Don't forget externalities! Having a self-sustaining system is a pretty big bonus as well.
(Score: 1, Funny) by Anonymous Coward on Wednesday March 15 2017, @07:16PM
presumably some later engineering breakthru would result in direct conversion of sunlight into THC or LSD
...
So the situation is just weird.
Yeah, I think that's a statement about where your head is at, not where the researchers are at.
(Score: 1, Informative) by Anonymous Coward on Wednesday March 15 2017, @04:52PM
I think they are striving for gains in total efficiency & cost-effectiveness, from https://en.wikipedia.org/wiki/Electrolysis_of_water#Efficiency [wikipedia.org]
There are two main technologies available on the market, alkaline and proton exchange membrane (PEM) electrolysers. Alkaline electrolysers are cheaper in terms of investment (they generally use nickel catalysts), but less efficient; PEM electrolysers, conversely, are more expensive (they generally use expensive platinum-group metal catalysts) but are more efficient and can operate at higher current densities, and can therefore be possibly cheaper if the hydrogen production is large enough.
Reported working efficiencies were for alkaline in 1996 lying in the 50–60% range for the smaller electrolysers and around 65–70% for the larger plants.[21] Theorical efficiency for PEM electrolysers are predicted up to 94%.[22] Ranges in 2014 were 43–67% for the alkaline and 40–67% for the PEM, they should progress in 2030 to 53–70% for the alkaline and 62–74% for the PEM.[19]
If the process was direct solar to hydrogen it might be higher efficiency and compete with the standard way of making hydrogen from natural gas.
Also from, https://en.wikipedia.org/wiki/Electrolysis_of_water#Applications [wikipedia.org]
About five percent of hydrogen gas produced worldwide is created by electrolysis. The majority of this hydrogen produced through electrolysis is a side product in the production of chlorine and caustic soda. This is a prime example of a competing side reaction.
2NaCl + 2H2O → Cl2 + H2 + 2NaOH
The electrolysis of brine (saltwater), a water sodium chloride mixture, is only half the electrolysis of water since the chloride ions are oxidized to chlorine rather than water being oxidized to oxygen. The hydrogen produced from this process is either burned (converting it back to water), used for the production of specialty chemicals, or various other small-scale applications.
(Score: 2) by NewNic on Wednesday March 15 2017, @04:54PM
Yes, but at a low efficiency.
lib·er·tar·i·an·ism ˌlibərˈterēənizəm/ noun: Magical thinking that useful idiots mistake for serious political theory
(Score: 4, Interesting) by bob_super on Wednesday March 15 2017, @04:58PM
Electrolysis is very inefficient, so they're trying to find ways to improve it, in this case by cutting away the electrical middle-man.
If they get a jump in efficiency at a cheap cost/low maintenance, it will be great for hydrogen production.
In the meantime, the ability to use solar panel electricity when not running electrolysis, or an improved electrolysis process to dump overcapacity into, is something that integrates better into the existing electricity-driven modern world.
(Score: 2, Insightful) by Anonymous Coward on Wednesday March 15 2017, @05:37PM
It is the computationally winnowing of candidate compounds for the big productivity win that is the cause for note. This one potential application needlessly distracts from how massive the labor savings they realized actually is.