Researcher Quantifies Water Requirements for Transitional Hydrogen Economy; A Significant Impact on A Critical Resource
18 October 2007
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| Annual water consumption as a coolant and as a feedstock for generating 60 billion kg of hydrogen as a function of the fraction that is produced by thermoelectrically powered electrolysis and for a range of electrolyzer efficiencies. Click to enlarge. |
A researcher at the University of Texas has provided the first analysis of the water intensity of a transitional hydrogen economy. Michael Webber, Associate Director at the Center for International Energy and Environmental Policy at the University of Texas at Austin, quantified the direct and indirect water requirements to annually manufacture 60 billion kg of hydrogen partly by thermoelectrically powered electrolysis.
While the hydrogen economy is expected to be in full swing around 2050 (according to a 2004 report by the National Research Council [NRC]), a transitional hydrogen economy could occur in about 30 years, around 2037.
The analysis, which is published in the open-access journal Environmental Research Letters, determines that up to 143 billion gallons of water would be directly consumed as a feedstock, with a total consumption including evaporation of cooling water at power plants of 0.5–1.7 trillion gallons annually.
Total water withdrawals for thermoelectric cooling (most of which is not consumed) are expected to increase by 27–97% from 195,000 million gallons/day used today by the thermoelectric power sector to generate about 90% of the electricity in the US. The amount of the increase depends primarily on the aggregate efficiency of electrolyzers that will be in place and the portion of hydrogen that is produced by thermoelectrically powered electrolysis.
On a per unit basis, thermoelectric power generation for electrolysis will on average withdraw approximately 1,100 gallons of cooling water and will consume 27 gallons of water as a feedstock and coolant for every kilogram of hydrogen that is produced using an electrolyzer that has an efficiency of 75%.
...if the hydrogen economy includes thermoelectrically or hydroelectrically powered electrolysis as a prominent source of hydrogen, then we can expect significant increases in water withdrawals and consumption for fuel production over today’s use of gasoline. Given that water withdrawals have remained steady for decades, these increases in water use represent a significant potential impact on a critical resource.
If minimizing the impact of water resources is a priority and electrolysis becomes a widespread method of hydrogen production, it is likely that the power for electrolytic hydrogen production will have to come from non-thermoelectric, non-hydroelectric and non-irrigated renewable sources. Consequently, almost all the new electricity generating capacity for hydrogen production would need to be from hydrogen production pathways that do not use much water (such as wind or solar), or effective water-free cooling methods (e.g. air cooling) will need to be developed and widely deployed.
Resources:
Webber, Michael E. “The water intensity of the transitional hydrogen economy.” Environmental Research Letters, 2 (2007) 034007
It is not practical nor efficient to generate electricity via a power plant and then use that electricity to produce H2. It would be far cheaper and twice as efficient to produce H2 directly via gasification (and water-gas shift reaction) of the fuels that will go into the power plant.
The amount of water that will be used for high-temp electrolysis will be minuscule in comparison to the amount of water used daily for home, industry ( eg. petroleum refining) and irrigation. The water produced from FC can be recycled for home use as well.
Posted by: Roger Pham | 18 October 2007 at 07:51 PM
Yet another reason to quit messing with hydrogen for consumer vehicles and build battery powered EVs
Posted by: | 18 October 2007 at 08:11 PM
Yet another reason to quit messing with hydrogen for consumer vehicles and build battery powered EVs
How's the Kool Aid? Grape flavor today?
Posted by: jack | 18 October 2007 at 08:24 PM
What, Jack's a hydrogen weenie? I thought he was an environmentalist. Really, Jack, if you care about the environment, H2 is not the way to go.
Posted by: George | 18 October 2007 at 08:35 PM
What, Jack's a hydrogen weenie? I thought he was an environmentalist. Really, Jack, if you care about the environment, H2 is not the way to go.
Another great argument presented. Good job.
Posted by: jack | 18 October 2007 at 09:05 PM
I didn't catch your argument, jack. May you recall it ?
Posted by: François | 18 October 2007 at 10:09 PM
"While the hydrogen economy is expected to be in full swing around 2050 (according to a 2004 report by the National Research Council [NRC]), a transitional hydrogen economy could occur in about 30 years, in 2037."
By 2037 expensive oil will have already pushed us into one alternative or another (probably electricity). The only thing left for hydrogen will be niche markets and range extension. If hydrogen backers can't get their product to market a whole lot faster, they'll have missed the boat.
Posted by: Neil | 18 October 2007 at 11:20 PM
"A researcher at the University of Texas" ...
"
On a per unit basis, thermoelectric power generation for electrolysis will on average withdraw approximately 1,100 gallons of cooling water and will consume 27 gallons of water as a feedstock and coolant for every kilogram of hydrogen that is produced using an electrolyzer that has an efficiency of 75%.
"
pretty bullshit
Posted by: itsme | 19 October 2007 at 01:50 AM
Producing 1100 gallons of (hot) cooling water needs an enormous amount of heat. I wonder how you achieve a 75% efficiency when you need to 'heat' that amount of cooling water to produce one kg of H2.
The actual crude arrives in the west mostly by boats. If we locate the H2-production sites in those harbors, there is plenty of water.
The problem is not lack of water, but wasting of energy.
Most of the H2 will probably be produced by electrochemical processes. There is no need to first make electricity, so you need no steam turbines, no cooling towers and no inefficient electrolysis needing expensive catalysers.
Additionally, if there still is 'waste'-heat, it shouldn't be wasted in a cooling tower. Many industrial processes need heat (for instance ethanol production), so building these installations close to a power station allows to reuse the 'waste'-heat.
--> Much higher 'overall efficiency' and no need for cooling water.
Posted by: Alain | 19 October 2007 at 03:35 AM
hey itsme you have a problem with university of texas?
have you even graduated from high school? your post does not show even the slightest hint of intelligence. after all, anyone can take a statement and just say "thats (some word that shows your limited vocabulary)"
why don't you try what an intellectual would do and formulate an argument based on facts, that contradict the facts presented you see as false. that is, if you want to talk to real people here in the real world.
Posted by: marc | 19 October 2007 at 05:32 AM
Jack,
Give it a rest. Either clean up your act or get off this site.
Posted by: sjc | 19 October 2007 at 02:56 PM
Give it a rest. Either clean up your act or get off this site.
You funny.
Posted by: jack | 19 October 2007 at 03:35 PM
When they first come commercial fuel cell cars will only need about 2x the total energy as a pure ev and then only when in range extender mode. They will have greater range.
By 2025 much of that energy oremium will be gone and the range will be even better.
In 10 years h2 will likely be cheaper then gasoline. They already used it to MAKE your gasoline...
H2 used to cost 250 a kilo not all that long ago... it now costs less then chocolate.
Posted by: wintermane | 19 October 2007 at 04:28 PM
Fresh water consumption becomes a non-issue if you use the waste heat from a steam-based power plant to thermally distill salt water in a high vacuum. You'll lose some efficiency in the electricity production, but in such systems, you need to look at aggregate efficiency.
Mind you, all I'm saying is that water isn't going to be an insurmountable problem for the hydrogen economy. Political opposition to wind farms (NIMBYs), to wasting NG and/or to producing radioactive waste plus, the difficulty of distribution and storage and, the cost of automotive fuel cells are all more daunting challenges.
If the Li-ion battery manufacturers make good on their promises, there won't be a market for fuel cell vehicles and the hydrogen highway will be stillborn. Not that politicians will stop throwing money at it any time soon...
Posted by: Rafael Seidl | 19 October 2007 at 04:50 PM
Jack, you act as if trite dismissals are a substitute for detailed analysis. They aren't.
George, sjc and François are right; you should clean up your act or take it elsewhere.
Posted by: Engineer-Poet | 19 October 2007 at 08:15 PM
Jack, you act as if trite dismissals are a substitute for detailed analysis. They aren't.
Not every comment needs to be a detailed analysis. Suggestion: you write your own posts and I'll write mine.
George, sjc and François are right; you should clean up your act or take it elsewhere.
You should go back to your blog and then you can determine the rules.
Posted by: jack | 19 October 2007 at 08:45 PM
We'll see what Michael Milliken thinks of you.
Posted by: Engineer-Poet | 19 October 2007 at 11:03 PM
We'll see what Michael Milliken thinks of you.
Ooh. Shall I go get all your one-liner posts and nasty insults and forward them to him as well?
Posted by: jack | 20 October 2007 at 12:39 AM
"Rafael, do you even read what you write?"
"You'll feel differently when you get past high-school level work and start doing real analyses, wintermane. Or should I say, if you get past it"
"I wonder what you got your degree in; you are very, very good with the sophistry. Law? Or could you be a seminarian?"
"You think the Second Law of Thermodynamics is just a matter of insufficiently clever engineers? If so, the low opinion of economists held by so many other professions is well-earned."
Just from doing a quick pass of your posts, seems you have trouble getting through a thread (especially one regarding hydrogen) without getting belligerent.
You know what they say about casting stones.
Posted by: jack | 20 October 2007 at 12:53 AM
Of course since we are dealing with people... wich car tech wins likely will boil down to functionality issues rather then anuthing else.
If the fuel cell car can fill up fast cheap enough and copsts cheap enough.. it will win simply because people wish to fill up as inoften as possible and no one has room in thier harage for a car that needs to be recharged all night long.. much less 2.
Posted by: wintermane | 20 October 2007 at 10:50 AM
Stupid cars. They're dumb. Space travel! That's what we need. I hear there's gold on Mars. Lunar vegetable farms? Think about it. I'm going for a walk now.
Posted by: Wells | 20 October 2007 at 01:49 PM
This is a "How many angels can dance on the head of a pin" argument.
Posted by: DS | 20 October 2007 at 02:45 PM
Even more blunt.
Unless that electrolyzed hydrogen comes from a power plant with less pollution than a Natural Gas Combined Cycle power plant, then it's actually going to create more Greenhouse emissions than petroleum.
http://greyfalcon.net/hydrogen2.png
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Furthermore, it's not really possible for a hydrogen car to use any less than 3-4x as much electricity than a comprable electric car.
http://greyfalcon.net/hydrogen.png
http://greyfalcon.net/hydrogen4.png
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Whats more, if it comes from Steam Reformed Natural Gas, then it's practically no different than just burning the natural gas in the first place.
And by comparison, a hybrid is greener.
http://greyfalcon.net/electriccars2.png
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Which means a lot since if an electric car driving on coal electricity is comparable to hybrid in emissions.
http://greyfalcon.net/plugins3
And only half the US grid is coal.
Posted by: GreyFlcn | 20 October 2007 at 04:29 PM
Ag I see where you got the wrong idea.. those numbers for h2 are several years out of date.. they look in fact like 2002 data. They have greatlu improved every one of those numbers since then.
Also remember in the same timeframe they cut the cost of making h2 from nat gas by 40%.
Posted by: wintermane | 21 October 2007 at 10:48 AM
"On a per unit basis, thermoelectric power generation for electrolysis will on average withdraw approximately 1,100 gallons of cooling water and will consume 27 gallons of water as a feedstock and coolant for every kilogram of hydrogen that is produced using an electrolyzer that has an efficiency of 75%."
The author designates both numbers at least in part as "cooling" units. And, if the process is high temperature electrolysis, how much cooling is needed to maintain efficient reaction?
The only models demonstrated at this point are predicted to operate at a max of 50% efficiency. And those models are based on heat derived from nuclear which already uses large amounts of cooling water.
However if these models can extend the energy capable output of a modern nuclear plant to produce H2 for renewable power generation elsewhere (thereby eliminating further nukes) - it may become politically viable.
Posted by: gr | 21 October 2007 at 06:04 PM