Thanks, that was a really great talk for non-specialists. I’ll definitely pass it along to family and friends.
The one bit that was sort of unconvincing was when he argued that if we create an exponentially growing photovoltaic industry it will (implication: indefinitely) take more energy to build than it provides. But it’s silly to assume the exponential growth to be unbounded: the whole idea is that once we build enough capacity, we can stop making more of the things and after a few years we get energy coming out without so much further (energy/money) investment. He made it sound like building photovoltaics at scale would be overall detrimental.
Other than that though, really excellent introductory background to put papers like this current one in context.
I wish there was an efficiency vs cost of components chart here... Gives a bit more perspective on what technologies are just achieving better rates with just better components.
How much energy is required to compress the O2 or H2 for storage/transport or even use?
Pure O2 or H2 at atmospheric pressure isn't that useful. For example, it is very hard to use atmospheric pressure H2 to run an internal combustion engine.
It's easier to run an external combustion engine with atmospheric pressure H2, but said engine will have to be right on top of the H2 generator and since the engine needs a cooling source and the H2 generator requires sunlight, you may have enough of a temperature differential to run a heat engine directly, without the H2 intermediary.
Just to transfer solar energy to hydrogen, but there will be additional loss when converting to electricity, so it's way less efficient than conventional solar cells.
High end photovoltaic solar cells are over 40% efficiency for a while. Consumer solar cells are a little over 10% but comparing the best sample in lab conditions with a consumer level product is somewhat misleading.
While it is not new news in the sense that the artificial leaf has been mentioned before, this MIT press release is based off of a new Science paper from the Nocera lab where, in contrast to the previous papers, this "leaf" does both hydrogen and oxygen generation in the same device. So the breakthrough here is that a tandem PV was used (to supply the necessary voltage for splitting water) and both hydrogen and oxygen evolution catalysts were integrated with the PV.
The previous news had early versions of the device that used only a single junction PV. Thus, some external potential had to be applied for catalysis. Also, the device only had the oxygen evolving catalyst and relied on a buffer solution to supply the H+ ions. Therefore, the earlier versions of the device could not split water by itself when dropped into water.
Then you might be interesting in reading about this synthetic biology project to engineer an organism that can be used to inhibit or stimulate the freezing of water:
Neat packaging for electrolysis, but I'm trying to imagine where/how this would get used. Not as elegant once you add all the apparatus to capture and store the hydrogen.
everywhere where you need hydrogen for electricity generation and have some water and sunlight. combine it with a fuel cell and you've got a closed cycle, self-sufficient, localized power generation.
looking a bit further into the future, you might have a variant of this device produce petroleum or similar fuel for your car, with an added bonus of reducing the amount of carbon in the atmosphere.
If this can be scaled, it could be huge in terms of space exploration (Mars?). The ability to create oxygen using sunlight and silicon has huge potential to make uninhabitable places habitable. Granted this is all far in the future, but at least we can say this is true technological innovation.
Even if this becomes successful it will never be sustainable. What will happen when the Sun runs out of Hydrogen to burn? (in 5 billion years) We may have to find another star. Actually that is even less of a problem to worry about because the Sun will start burning Helium. Once it does the pressure pushing outwards from all the nuclear explosions (helium fusion is more efficient in converting mass to energy) at the core will be greater than the gravity pulling everything in, causing the star to expand into a red giant. The Earth will receive far more energy than it really needs and burn into ashes. So either way we are screwed!.....LOL
I agree. Of course I am being Facetious. With the right technology I can imagine a future where every home has solar panels and all cars are electric. We will use nothing but solar power to run our homes and fuel our cars. I did the math and this is all possible.
http://www.lsa.umich.edu/vgn-ext-templating/v/index.jsp?vgne...
video:
http://lecb.physics.lsa.umich.edu/wl/umich/phys/satmorn/2010...
his research lab:
http://www.umich.edu/~mgroup/research.html