New Solar Cell Harvests Hydrogen From Water 222
Engadgets is reporting that researchers at Penn State have built a new kind of solar cell that can harvest hydrogen directly from water. "The folks at Penn State have now developed a process that more closely mimics the photosynthesis process in plants, and while we won't pretend to understand all the nitty gritty of dye usage and other such nonsense, we do know that such a system could eventually attain 15% or so efficiency, providing a nice and clean way to gather power for that fuel cell car of the future."
TFA is worthless. (Score:5, Informative)
The original article [sciencedaily.com] was on Science Daily [sciencedaily.com] a few days back.
Re:TFA is worthless. (Score:5, Informative)
Re:TFA is worthless. (Score:5, Informative)
2. Only light in the range 400-700 nm can be used. This amounts to 43% of total solar incident radiation.
3. Canopy limits absorption to 80 %
4. Respiration required for translocation and biosynthesis requires about 33% of the energy stored which leaves 67%
The overall efficiency is then
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Not that hydrogen cars [daughtersoftiresias.org] are a realistic solution to our current problems anyways.
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However, I don't believe in feeding page views to a site that does nothing but summarize someone else's article, poorly.
15% efficiency (Score:2, Interesting)
Re:15% efficiency (Score:5, Insightful)
Re:15% efficiency (Score:5, Informative)
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40% is still in the lab. It remains to be seen if we can get anything like that out in the real world, though if we can, there is certainly a hell of a lot that we could do with it. Even if we do get it though, this technology would still have a place.
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As for battery/capacitor breakthroughs, there are now no fewer than three of them trying to make t
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Also note that that the article states that they could *theoretically* get this hydrogen cell up to 15% efficient. Hard to get excited when the theoretical max of a new idea can't even match the practical (if uneconomical) maximum of existing technology.
-matthew
Re:15% efficiency (Score:5, Insightful)
mod up (Score:2, Troll)
This is the biggest problem with solar/wind power, the power generated often needs to be supplemented with conventional generation technologies to ensure constant energy supply. Production of stored energy source like hydrogen solves this issue.
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According to http://en.wikipedia.org/wiki/Electrolysis#Electrolysis_of_water [wikipedia.org], electrolysis of water to produce hydrogen has an efficiency of more than fifty percent, at least theoretically. If that's true, then you might be better off using the 40% efficient cell to generate hydrogen at 20% efficiency, rather than using this new cell to generate hydrogen directly at 15% efficiency.
Of course, there are lots of other factors which might make using the new one more attractive. In particular, it certainly s
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Perhaps if you didn't have some other source of chemical fuel, absolutely had to have it, and already had enough electricity. But other than that I wouldn't waste the electricity making potential. You'd be a fool to do so. You can do a lot more with electri
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Transporting electricity is more efficient. We lose only about 5% due to transmission in this country (total) and it could be reduced even further.
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Re:Wrong. (Score:5, Insightful)
Go ahead and try. Electricity is far more valuable than chemical fuels. You can do so much more with it with much more efficiency. Electric cars, for example, run at, what, 90% efficiency? Electric heat pumps can actually get more heat in your home than they use to do it. You can produce light very efficiently as well. Ever try to light your home with natural gas? Electricity is the universal form of energy with the highest value, joule for joule.
I'm repeating myself in this thread, I know, but this point is very important:
The ONLY reason that chemical fuels seem valuable now is because we essentially get them for free. Or rather, all the work has already been done to store the energy. We just need to dig it up, refine it a bit, and get it where it is needed. If there ever came a time when there was no natural hydrocabons available, we'd very quickly realize just what a waste chemical fuels are.
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They also have substantially higher energy density today than the theoretical limit of chemical batteries. That counts for an awful lot.
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True, but if the energy didn't come free with the fuel, the cost of making it would make the energy density moot.
Here's a little hypothetical. Which option would you choose:
1) Fill your gas tank with 10 gallons of gasoline at, say, $30/gallon (because it has to be synthesized
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You have presented a false dilemma. In fact there are many more choices. Also, the total energy consumption of the vehicle must be considered. It's possible to make engines which take far less energy to produce than current models (because they lack the huge castings.) But the energy cost of making batteries is quite high and can only be reduced so much (although it CAN be reduced significantly.) The only reason Hybrids are affordable at all is because their high production cost is subsidized by raising th
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Heat pumps as the name implies aren't generating heat, they're moving it from one place to another and heat pumps using chemical fuels (like natural gas) also get more heat into your home than they use to do it. I doubt converting electrical energy to heat via resistive heating is any more efficient than converting a chemical to heat via combustion. (Certainly not when you consider that most of that electricity is generate
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I've never heard of a natural gas heat pump. But I'll take your word for it that they exist. How efficient are they?
Well of course converting electrical energy
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Wait, first you compare electricity and hydrogen, and then you swap in gasoline? How about this:
Imagine how much hydrogen you would need (and how you would store it) if it had to provide energy for 250 miles lon
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I know your point was about liquid fuels in general. And I pointed out why it isn't valid. Yes, gasoline is very convenient and compact as far as energy storage. But that is only part of the equation. There's a cost associated with the energy itself and how it is collected or generated. My point was that if you had to actually make the gasoline or hydroge
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All consumer grade solar cells easily produce more power than they use.
Only the super high efficiency 40+% cells used by NASA and the like are even close to using as much energy to create as they will generate. This is do not just to the manufacturing techniques but to the harsh, highly radioactive environment they are in which decreases the life expectancy of the cell.
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It allows energy storage (in the form of hydrogen) for later use. Maybe it's not as efficient as using compressed air [sciam.com], as was described in the cover story in January's issue of Scientific American, but it's still worth investigating.
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The thing that's cool about this is the conversion efficiency; converting water to hydrogen and oxygen using traditional methods isn't itself all that efficient. If they could get t
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$/watt is more important than eficiency (Score:2)
Who cares if the efficiency is 10% and you have to cover your whole house in the stuff?
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However, the whole idea is pretty stupid when you consider that with today's technology you could just generate electricity, charge a battery, and run an electric car. The whole process would be much more efficient than the 15% advertised by this system, and even the 15% is just a theoretical number. Sadly, hydrogen cars are basically a scam brought about by oil companies to distract
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Don't forget about BMW's $1 billion dollar participation in this scam
They are? (Score:2)
Sadly, hydrogen cars are basically a scam brought about by oil companies to distract attention and funding away from gasoline alternatives that are actually realistic.
I don't believe oil companies would fund with that in mind because it seems terribly counter productive.
If an oil company were to fund an alternate non-fossil fuel, don't you think they would want to back the one that already matches their existing infrastructure? If hydrogen became the next big thing, they'd have an awful lot of new equ
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I don't believe oil companies would fund with that in mind because it seems terribly counter productive.
The answer is painfully obvious. If the oil companies control the hydrogen production, distribution, and fueling infrastructure, then they can get rich by buying energy, making hydrogen, and selling it at a markup - which people will pay, because their car will run on it, and they will need it, and they can't make it themselves cheaper (because you have to compress the hell out of it and that equipment is expensive.)
Remember, oil companies aren't in the oil business - they're in the energy business. It's just that currently the easiest way to get energy to the customer is through oil. They'd happily switch to anything else just so long as it made them a buck.
That's the point exactly. There currently exist feasible alternatives to gasoline which
Re:15% efficiency (Score:5, Interesting)
Now, what concerns me about this system is that usually the dyes used in these things are rather short lived and tend to break down after hardly any time at all. Maybe this should be one of the first real uses of biotech, we should engineer some microbes that produce this dye and live off O2 and water (and various proteins naturally), then we just harvest the excess hydrogen.
need to get hydrogen engines??? (Score:3, Informative)
If you own a four stroke, spark ignited, internal combustion engine, you have one now. The conversion to run on hydrogen gas instead of liquid gasoline is quite trivial.
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The conversion to have the fuel tank to store hydrogen is anything but. The damn thing has a habit of oozing straight through metal, due to the small molecule size. You can't store the gas under pressure, since the gas tank in your car is not designed to hold any pressure (and in fact is open to air, since otherwise the gas wouldn't flow
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Re:15% efficiency (Score:5, Interesting)
Then the power can be generated on the grid. If that is nuclear, coal, hydro, solar, or wind power - it can be whatever makes sense for the region. What ever is used, the filling station grabs the electricity from the grid and charges up batteries or capacitors. I swap mine out for a charged one and pay for the service.
Seems to me that this is something we could do now. Seems to me this way we could adopt newer, cleaner sources of power much quicker than waiting the life span of the auto.
Re:15% efficiency (Score:4, Interesting)
For one, there is no standard battery pack, nor could there be without making all the systems similar enough. How would you like to own an electric sports can that has the same battery pack as a single seat local commuter vehicle? There's also the need to invest in sufficient numbers of battery packs by the stations to meet consumer need. Many gas stations server over 1k customers a day! Even counting that the batteries are being charged and then re-used, you'd have to have 250 packs to service a station open for 16 hours/day with a 4 hr. mean charge time.
There's also the issue of battery life. Since every battery eventually needs to be replaced, you have to have a way to track and credit or debit the customers for bringing in new or almost defunct batteries. That means every battery would have to have a battery life indicator on it, and a complex formula worked out for pricing. You: "I need recharged batt-paks." Service station attendant: "I only have once-recharged, and your's are at end-of-life, that'll be $1285.60, plus tax." You: "But I only need to go 50 more miles, I have brand new ones at home!"
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I'm not sure I understand why my car needs to have a power plant in it. Why can't it just have a large capacitor or bank of batteries, which I can swap out at the filling station? Obviously I am not going to wait for charging at filling time, but why not just swap out the uncharged capacity for charged capacity much as we change out propane tanks?
1) The fact that all batteries may not have a standard housing or load rating for every model
2) The fact that swapping the batteries probably isn't something any Joe Blow can (or would want to) do on his way to work.
3) They take up a lot of space!
Do you have any idea how many cars a service station fills up in a given day? The service station would pretty much need a large warehouse just to house all the batteries. Gasoline is nice, because you pull it from an underground tank and pour it into your gas t
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Your Fact =
Your claim = his fact is denial because your facts are more obvious!
Energy from water... (Score:2, Funny)
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That's actually how I'd prefer my body to be disposed of when the med students are done with it. Burying corpses is so wasteful in the grand scheme of things.
=Smidge=
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the cockroaches that inherit the earth will burn you in their Cadillac Roachmobile LeSabres
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As a concept it's pretty straightforward: "Cook" the biomass until it turns into oil. I think it's one of the multitude of technologies we'll need for sustainable, "green" energy.
=Smidge=
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I'm reminded of a mediocre Niven/Pournelle novel where dramatic climate change was blamed on inhabitants of a space station needing to be resupplied with oxygen from time to time. What will burning all the water do to the planet? Won't someone please think of the fishes??
photosynthesis (Score:5, Interesting)
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Even in plants, which have had millions of years to evolve this, those systems last about 30 minutes before they're destroyed.
Far, far easier and more robust to use a conducting element to separate your two excited systems. Think of the battery as a remote photosystem II, it could easily be replaced with a photovoltaic cell.
could eventually (Score:5, Funny)
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Isn't "could eventually" one of those warning phrases that tells you something is dubious, like "up to twice as long" or "she has a great personality" or "you're violating our patents but we don't want to tell you which ones"?
Or "we'll develop it and then an 'energy company' which is a front for an oil conglomerate will swoop in and buy up all the intellectual property and sit on it."
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Isn't "could eventually" one of those warning phrases that tells you something is dubious,
Sure. It think it's really more like communicating an upper limit. The more interesting number would be cost/watt.
15% (Score:2)
And then begins the energy intensive liquification stage. Having those carbon atoms attached to your hydrogen is just a huge advantage.
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15% would be pretty good (Score:5, Informative)
Here is one calculation showing ~6.6% photosynthesis efficiency
It takes into account things like canopy shading, which wouldn't necessarily apply to this, but here's the link:
http://www.upei.ca/~physics/p261/Content/Sources_Conversion/Photo-_synthesis/photo-_synthesis.htm [www.upei.ca]
I tried to find a peer reviewed one, but can't find one right now(I'm at work, break almost over...
What they know (Score:4, Insightful)
So they don't even pretend to understand how it works, but they know it can eventually attain 15% or so efficiency.
...about those hydrogen cars (Score:5, Interesting)
Here's why:
In regards to using liquid H2 in vehicles:
- It's too dangerous. You're driving a bomb. Every car using liquid H2 is a has-mat vehicle by legal definition. Imagine the terrorists glee where they don't have to rent a car and then build a bomb because the rental car IS a bomb.
- it must be trucked in liquid form - can't be pipelined, and therefore we'll have to deal with massive supply issues, thouands more has-mat trucks on the roads, and reduculous logistics.
- fuleing requires extensive safety measures and extremely specialized and expensive equipment
- you either have MASSIVE pressurized tanks (taking a very large portion of your vehicle space and weight) or you have to have the H2 actively cooled to extremely cold termurateres, requiring the car to be powered 100% of the time.
For metal infused H2 gas vehicles:
- well, it's much safer... but:
- maximum range uning even theoretical technologies is about 220 miles per fill up, assuming you leave enough seating room in a large SUV for 5 people and no luggage.
- the tank is huge, and weighs hundreds of pounds, eating at vehicle efficiency and space (too big for those small commuter cars in Europe)
- IT TAKES UP TO 8 HOURS TO FILL UP, and requires active cooling to prevent explosions while doing it.
H2 in general:
- it's dangerous to use a vapor gas as a fuel. Imagine auto shops all over the country having to worry about gas being spilled during repairs? Spill hydrocarbon, just avoid dropping a spark in the liquid until you soak it up with sawdust. Cause an H2 leak and you have to evacuate the building, no different than a natural gas or propane leak. Also, if liquid H2 leaks, you not only have to worry about combustion, but vapor expansion and extreme freeze issues.
- It costs 3-5 times more energy to make it that it would to simply run the car on electricity
- It's expensive. best estimates, you go the same distance on H2 for 2-4 times the cost of gasoline, and that's with all the current government funding lowering the costs.
- Where do you plan to store all the H2? Large scale containers are very difficult to make assuming you're storing it in liuquid form. We simply don't have enough room to store it in gaseous form.
- Fuel cells don't get repaired, they get replaced. The repair costs will be immense, collision insurance even worse (not to mention the danger issues insuring rolling bombs).
- burning H2 directly in ICEs is barely more efficient than burning ethanol.
- minimum car price. You can forget about those $7,000 cars. Minimum price for a fuel cell vehicle will be in the 20K range once the government subsidies stop becoming affodable.
no, we can't power every vehicle on earth on ethanol
yes, we will run out of oil, sooner than you like to admit
yes, we havre to do something, but what?
What is the answer? Super conducting electrical grids (which we can make today with existing technology at reasonable costs), fed by renewable energy in target locations around the world (wind farms where it's windy, water where there's natural falls, solar in the deserts, etc). We use all that to recharge plug-in cars using batteries from Toshiba and others companies that have already been developed which have as quick as 90 second recharge times. For those of you who say we can't do it, that we can't run recharge units all around towns for people to plug into on the run, well look at how Alaska has done it, and many other countries in the fridgid north of Europe, where cars that don't have engines running need to be plugged so their heaters can prevent fuel lines from freezing. Every parking meeter in some coutries have power cables attached. We CAN do it. It's been done before. We'll still use ethanol as a backup to the battery using ethanol in ICEs until small turbines (like BMW uses in their motercycle) become more cost effective through mass production.
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However, I do think you're right that it's presently more a distraction than a reality. We get a lot of "promote or enforce use of alternative energy" legislation pro
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However, it just occurred to me that this could be useful for home heating -- and possibly replace propane for those of us who can't get natural gas, and even a fairly pricey initial setup could pay for itself in a hurry, given that water is cheap and propane costs a fortune (at its present price of $3.20/gallon, about $10/hour to keep your house at a frigid 62F). Wouldn't matter if it was inefficient, just make a bigger unit for home heating purposes (since
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If you transport the sodium borohydrate and not the hydrogen, you can do the conversion at a central location (at the solar or nuclear plant) and not have the refilling in the car, thus very different issues with cooling and heating cost in the conversion. Simply make the fuel a removable cartridge rather than a liquid or gas. The "tank" (or more accurately "tanks", to
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http://automobiles.honda.com/fcx-clarity/ [honda.com]
There's a video of Jay Leno and the Clarity which pretty much debunks most of your reasoning about hydrogen never being viable. Honda is obsessed with safety, if they didn't think it could be done they would not continue to pour money into the R&D.
http://www.hydrogencarsnow.com/blog2/index.php/celebrities/jay-leno-takes-honda-clarity-for-a-ride/ [hydrogencarsnow.com]
I'm not sure if the actual vid
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As opposed to current gasoline vehicles, which are non-flammable.
Every auto shop I've been too has very high ceilings, and big, wide open doors that can easily vent TONS of vapor.
When my idiot neighbor put a shovel through a natural gas line, the fire department didn't t
Screw cars (Score:2)
the singularity will consume all the water! (Score:2)
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Sandia solar Sterling engine hits 31.25% efficienc (Score:2)
31.25 percent efficiency rate topples 1984 record
ALBUQUERQUE, N.M. --On a perfect New Mexico winter day -- with the sky almost 10 percent brighter than usual -- Sandia National Laboratories and Stirling Energy Systems (SES) set a new solar-to-grid system conversion efficiency record by achieving a 31.25 percent net efficiency rate. The old 1984 record of 29.4 percent was toppled Jan. 31 on SES's "Serial #3" solar dish Stirling system at Sandia's National Solar Thermal Test Facility.
Each dish unit consists of 82 mirrors formed in a dish shape to focus the light to an intense beam.
The solar dish generates electricity by focusing the sun's rays onto a receiver, which transmits the heat energy to a Stirling engine. The engine is a sealed system filled with hydrogen. As the gas heats and cools, its pressure rises and falls. The change in pressure drives the pistons inside the engine, producing mechanical power, which in turn drives a generator and makes electricity.
Re:Yawnnn (Score:5, Informative)
Re:Yawnnn (Score:4, Informative)
Take a 40%-efficient solar cell and use it to feed power to a 50%-efficient electrolyzer, and you get a net total efficiency of 20%, which is better than the maximum estimated efficiency of this dye-based approach.
If they dye approach proves to be cheaper or can also be enhanced by solar concentrators or what have you, then it may have some value from an economic perspective, but I don't see anything 15% efficient providing dense solar power solutions compared to other technologies already available.
The other thing to keep in mind is that the output from this dye is hydrogen, not electricity. If you need electricity from one of these dye-based hydrogen generators, you'll need to marry it with a fuel cell or something long those lines which will further degrade efficiency. In terms of raw electrical output-per-square meter of deployed solar collectors, you'd be better off with conventional solar cells in the 15-20% efficiency range.
You don't need high efficiency though... (Score:5, Insightful)
The only time it would not work is during long highway trips. During these times some kind of accelerated process or hydrogen filling station would be needed.
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Re:You don't need high efficiency though... (Score:4, Insightful)
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Re: no free lunches (Score:5, Informative)
Let's take your average car. Not being picky, I'll surf over to Carmax and choose whatever pops-up first
- Engine: 2.4L 166-hp (~575kW) inline-4
- Outside dimensions: 172" x 72" (4.4m x 1.8m)
So you've got 7.92 sq.m. of available roof area. I'll assume you can cover that 100% with your solar converter, and I'll further assume you can keep it pointed normal to the incident light. Typical insolation [wikipedia.org] is 1000W/m^2, so your roof-mounted collector can harvest 7.92kW. Period (i.e. you don't get more energy than what is incident on the vehicle's cross-section.) You're collecting solar energy, and storing it in the potential reactive energy between hydrogen and oxygen. With a 15% efficiency, your converter stores 1.188kW while it's illuminated.
Getting back to our example Honda Element - 575kW engine
And therein lies the fundamental limitation. There isn't enough energy intercepted in a vehicle's cross section to make this structure viable. At 100% conversion efficiency, you just start to be able to power the econobox-class vehicles for around-town drives. Anything with distance or power requirements will need to be fueled by something much larger than the vehicle itself.
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Re: no free lunches (Score:4, Insightful)
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Most gasoline-fueled internal combustion engines, even when aided with turbochargers and stock efficiency aids, have a mechani
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Depends on how efficient the solar cell is. Since 15% effciency is the maximum projected for this photolysis process and solar cells are already up to 40% efficient, I'd put my money of regular solar cells + electrolysis in the long run
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Not sure I like the sound of this. A lot of areas are already having trouble with their water supplies -
The US per capita continuous total energy consumption averages out to about 10.5kW thermal (100e18 J annual national total/300M people). With hydrogen combustion at 286kJ/mol, it would take 62 liters of water per day per person to provide hydrogen for *all* the energy currently used in the US. Residential water consumption is already around 400 liters per person per day, industrial usage is more than that, and agricultural usage is many thousands of liters per day per person. IOW, this won't be a signifi
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It's more likely that the exhaust from these systems would be released into the atmosphere and effectively lost from the system.
Even if you do filter most of it back in, you still have to increase the capacity of your sewage/treatment plants and your pipelines (
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