Discussion on:

How to convert water into fuel using sunlight

I've seen these claims before, and they never got scaled up to generate enough fuel for a lawn mower, much less a car. If this is possible this time, it will be a real breakthrough, but I'm not holding my breath waiting.

.. I imagine the barrier to this and similar technologies from making it to fruition are the political incentives to keep fossil fuels alive and well for some time to come. I can't imagine a day where for a one-off $500 or even $5000 you will be able to buy a clean power source which is practically infinite and also free. The taxation system will have to change and the global patents will most likely be bought up by oil barons.

The economic cost of realising sustainable, eco-friendly, cheap/free fuels is greater than most governments, oil-sheik's and billionaire dynasties would be willing to bear.

We Tax Producers can control governments by voting for leaders who support Tax Producers and find ways to decrease Tax Consumers with cheaper energy to support businesses. Tax Producers would expand businesses and create more tax-producing jobs and thereby decrease tax rates for all.
Tax Consumers only think in terms of how to protect themselves. Europe wouldn't be in the mess today if they voted for more Tax Producers instead of more Tax Consumers.

Who you vote for is irrelevant. There is no government or opposition that would sanction free fuels and lose the taxation it brings in - not without implementing some other taxation system such as mandated black-boxes which show road-usage in all vehicles etc. In addition, I doubt the fossil fuel billionaires are going to sit by and watch oil get replaced. It's conceivable they'll use the oil for plastics etc, but in reality I think they will simply buy all the patents for the free-fuel technologies and sit tight on them until such time as the last few barrels of oil are consumed.

I doubt it. If this process is scalable and inexpensive, people & companies with a lot of $$, including oil and coal companies, will jump on it to be in on the ground floor. Those people that run the energy business aren't fools, and if this process produces hydrogen cheaply & plentifully, they'll be all over it. A cheap hydrogen source could also be used with CO2 from the atmosphere to make liquid fuels like diesel and gasoline, making these into a renewable resource.

You may be correct about the profit-seekers willingness to inhibit compeitive energy sources. But, as history tells us, ther is no keeping scientific discovery hidden; too many times it's been tried and now, with the Internet, I just don't see the possibility of keeping anything that gigantic "under wraps." Besides, as long as mechanical "things" have moving parts, the highest value of oil will be as a lubricant.

It doesn't matter if it's on the Internet or not, what matters is patent trolls and legislation. In a world that can conceive two mobile phone companies shelling out in a billion-dollar lawsuit for the use of a rounded-edge rectangle, I don't think it's a huge leap to envisage a technology that will benefit mankind but is kept artificially expensive/unimplemented. In some ways there are parallels that could be drawn with the pharmaceutical industry too.

I may be wrong, and I hope I am, but I can't see any viable technology being implemented which will dilute political and financial strongholds.

I'm not a scientist (but I did graduate in Mech. Eng.)...I'm not expert in the subject matter.

Sorry Janet, neither are you; there are several glaring technical errors.

"photosynthesis. Its how sunlight is converted into energy,"... Sunlight IS energy.

"energized electrons are then passed to the catalyst, which knits the hydrogen ions into hydrogen molecules."...Can't make hydrogen from nothing more that electrons. Nor can ions be converted to molecules.

"from a solution of water"....??

It would be interesting to see how much measurable energy from direct sunlight is required to produce a usable amount of hydrogen, compared to how much solar or wind derived electrical energy is needed to generate a similar amount of hydrogen through electrolysis?

Electrolysis generated hydrogen currently seems to be one potential solution to renewable-power generated electrical surpluses.

Power plants which cannot quickly throttle down their power output, also could benefit if their excess electrical output was directed to hydrogen production, rather than dumping electricity on the market well below production cost.

Article says "[Plants] capture photons of sunlight and use that energy to split water molecules into their constituents of hydrogen and oxygen ions. "

umm, no they don't. Plants use the energy from sunlight to combine carbon dioxide from the atmosphere and water (both from the atmosphere and the root system) to produce sugars of various kinds, which are used as fuel to 'power' the plant and as basic organic molecules to make fats/lipids to build its tissues. Hydrogen gas doesn't come into it, though hydrogen ions (from the water) are used. You can't make sugars without hydrogen (and carbon).

What's described might be a kind of photosynthesis, because it synthesises using light - but it's not "photosynthesis", which is peculiar to plants.

I'll tell IEEE seperately that they're being fools for a line like "in hopes of helping engineers more cheaply synthesize hydrogen gas to power hydrogen fuel cells and automobiles powered by them" Anyone who thinks we will ever use H2 as a consumer fuel is out of their minds. Anyone with high school physics should be able to see that.

We fill our fuel tanks based on volume. While hydrogen's Energy density is 33.3kWh/kg, this works out to 0.53 kWh/L at 20C and 20MPa (All values taken from the Physics FactBook). In comparison, gasoline has an energy density of 12.7kWh/kg and 8.76kWh/L at 20C and 20MPa. The important value for most of us is the kWh/L. 0.53 versus 8.76 is a BIG difference. The fact is, at standard temperature and pressure, because hydrogen has a low density, it has a very low energy density.Compressing the hydrogen will increase the energy density such that Liquid Hydrogen at -253C has an energy density of 2.36kWh/L, better but still a fraction of gasoline.

In industrial applications, where the hydrogen can be stored with appropriate safe guards, hydrogen would be a fine fuel. So I think this research is useful, but not in the way they are talking about it.

However, automobiles are consumer products and we cannot count on those kinds of safeguards being reliable when used by consumers. Just look at all the old clunkers on the road at the moment. New, each would have been fine, but it only takes 5 years before many of them are in need of the kind of work that would make the use of compressed hydrogen as a fuel unsafe. Imagine one of them with a compressed hydrogen fuel tank being ruptured during a minor fender bender. It'd be like the Hindenburg all over again. "Oh, the humanity!"

Simply put, free hydrogen (H2 in any state) is too impractical to be used as a consumer-grade fuel. Therefore, no H2-powered cars. A better solution would be to convert the hydrogen into some other kind of fuel, such as butanol. So any work on making cheap hydrogen should include the words "so it can be combined with CO2 in some fashion so as to form a safe liquid fuel suitable for use by" .

From Wikipedia:
The overall equation for the light-dependent reactions under the conditions of non-cyclic electron flow in green plants is:
2 H2O + 2 NADP+ + 3 ADP + 3 Pi + light 2 NADPH + 2 H+ + 3 ATP + O2

So the author's description of photosynthesis is not so far off as critics here are maintaining.

Janet.
You seem to have a number of self-appointed "experts", who lecture you on technicalities of which they clearly know very little to nothing.
As a retired lecturer in Plant Science it has been some years since I taught this stuff, but I shall check the textbooks on my shelf and try to not go too far astray.
Photosynthesis in green plants, and in several groups of algae, involves the capture of light photons by a "light antenna" (analogous to a dish antenna for a satellite signal). The captured energy of these photons is shuffled along to a reaction centre where the energy is transferred through a complex of reactions during which it strips water of its Hydrogen (with the accompanying electrons), with Oxygen as a by product. There are actually two successive series of energetic transfers, the older one coming from photosynthetic bacteria which use Hydrogen Sulfide as raw material rather than Hydrogen Oxide(water). All natural Sulphur deposits are the result of activity of such bacteria, just as the oxygen of our atmosphere result from photosynthesis of green plants and algae.
I'm getting out of my depth now and the books I have available are not much help, but to the best of my recollection, the light reaction results in transfer of electrons from H2O (along with the Hydrogens) to the energy currencies of the cell (NADP to NADPH and ADP to ATP. Oxygen (or Sulphur) are byproducts of these reactions. These energized products (ATP and NADPH) are then used to fix CO2 in one of several possible Carbon fixation schemes.
So, as the article is about the photolysis of water the only possible comparison here with photosynthesis is with the light reaction, as somebody has already pointed out. I do not, therefore, see any glaring technical mistakes that she has made.
A more important comparison here would, I think, be with the efficiencies. I don' t have the figures at hand, but my recollection is that in spite of its horrible complexities, the transfer of light energy to chemical energy is almost 100% efficient.
Dr. Arthur R. Berg

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