Fuel cells produce nothing but energy and water vapor, right. But this is new water, not water that has been part of the water cycle since … whenever. Doesn’t the addition of massive amounts of new water vapor to the system do something to the ecosystem? I would think it would produce more cloud cover. Would this increase global warming, or block sun energy and result in cooling, or would the effects neutralize?
Turns out that regular old internal combustion engines also make new water vapor, in comparable amounts to fuel cells. So we’ve been doing this. Does anyone know of a source that has modelled the effect of new water in the water cycle on the climate?
Why do you think that the fuel cell’s water is new water? It is not like they are tapping Montana’s vast hydrogen mines to get the H to combine with the O to get water. To get hydrogen water is separated into H and O and then combined back at the fuel cell to get electricity.
There are some fuel cells that can run off of natural gas but to the best of my knowledge that has been in the water cycle at some time.
But the main thing is that water in and of itself wouldn’t cause problems. I don’t think we use enough energy to raise the seas by a measurable amount if we got all our power by creating new water.
Well, I’m glad somebody else asked this, because I was curious, too. It seems like cracking water to get the hydrogen out would eventually use up all the water in the earth’s oceans, so that would be a Crisis, and then burning the hydrogen would create more water vapor which would increase Global Warming, so that would be another Crisis…
I’m still working on the El Nino Crisis, three crises ago. Then when I get that done, there’s Artificial Intelligence taking over the world, and Invasive Nanotechnology (“atomic robots live in your bloodstream!”) to worry about, and finally, when I get done with those, I can worry about The Dangerous Deterioration of The Nation’s Bridges.
The point of the hydrogen economy is to use hydrogen donors like natural gas or gasoline (Montana’s mines) … if you used water to create the hydrogen, you’d need to use energy to do it (electrolysis), and end up more in the energy hole than when you started.
If the hydrogen from these sources was in the cycle at one time (say, like an oil source), then it was a very long time ago and is now being released relatively quickly.
I’d be happy to not lose sleep over it if some knowledgable climate modeller has calculated roughly how much water is produced per year by either internal combustion and/or would be by fuel cells and can calculate how much additional water in the system would cause what result. So far, all I get is the “It’s just water” answer. Less than satisfactory…
Note, that in stationary fuel cell applications, the water will probably condense and be drained off. In vehicles, most people would probably want to have it remain a vapor.
It would not take much work to get it to condense, in fact, quite the opposite. A very efficient heat extraction system would already put it near the condesation point. Upon hitting a cool exhaust duct, it would condense on the sides and can be gravity drained off. This is in fact what happens with my high efficiency gas furnace. Water vapor is an unintended byproduct of the combustion; it collects in the PVC pipe that subs for a chimney and drains off. Note that this liquid water comes from a gas that was on fire a few seconds earlier. Amazing, and its just a PVC tube.
Where do you think the oxygen in the air comes from in the first place? From photosynthesizing plants who get it from [sub]wait for it[/sub] water! So, we are just returning water to the environment that the plants have unceremoniously removed.
Pretty much anything that uses up fuel of any sort produces water. Horse-drawn carriage? The horse is converting sugar in hay and oxygen in the air to water and carbon dioxide. Internal combustion engines? Water, again, as you noted above. Us? You guessed it.
Basically, the role that all these machines are playing in the environment is that of just another animal.
The car, emitting CO2, must be just another animal to you too then. No need to be concerned about its emissions …
The point is that climatologists are very concerned with “carbon sinks” and that no one seems to have even done a basic consideration of any potential consequences of an ongoing addition of water to the cycle. (water sinks? nah.)
What have I calculated so far? I don’t have the figures to do the calculation. The best info I can find, at www.fuelcells.org, is
This doesn’t tell me how much water 0.005% of natural evapotranspiration is (I think that this could be a lot, especially over a period of years) and how much additional water would be required to have an environmental impact on phenomena such as global warming. If the calculations are out there I’d like to know, that’s all.
If ya’ll don’t know, fine. Again, fuel cells are still better than internal combustion, but I suspect that a significant factor is not even being considered in the calculations because it is just water. Very unsexy.
To put it in the crudest terms, the most economical way of producing hydrogen (at least at this point in time) is by stripping hydrogen atoms off hydrocarbons- oil and gas.
It is likely that any major hydrogen project anytime in the foreseeable future will be based on oil and gas, not on electrolysis of water.
You have two possible greenhouse gas sources then - the carbon (which will come out as CO2) that is left over after you remove the hydrogen from hydrocarbons and water vapour produced in a fuel cell or from direct combustion of the hydrogen.
The water vapour can be dealt with mainly through condensation (cooling towers on industrial facilities, exhaust pipes on cars etc). The extra Carbon (CO2) will be much more difficult. To be greenhouse friendly, you would have to look at options like subterranean seqrestration which is extraordinarily expensive.
The point is that both the condensed water and the CO2- because they are coming from oil and gas which has been under the ground for millions of years- will effectively be new greenhouse gases.
It would be interesting to see if anyone had done a Life Cycle Analysis of hydrogen produced from hydrocarbons.
Chronos, allow me to push your point a little harder. Every single combustion reaction involving hydrogen produces water. Your car’s exhaust is already mostly water vapor. When you burn hydrocarbons, you release the exact same amount of water you would were you to use it in a fuel cell. This chemistry is inescapable. I guarantee you that fuel cells will change nothing that hasn’t already been changed by IC engines. Why are you worrying about this only in terms of fuel cells?
Well, not exactly. It depends on the relative efficiencies of the hydrogen remover and the IC engine. It is concievable that a fuel cell vehicle would actually release less water than a combustion type engine.
As for DSeid’s question about water sinks. Yes, they do exist. They are more commonly known as oceans. They are vast and water in the air can readily reach them. This is in contrast with CO[sub]2[/sub], with which there is significant lag time between being released into the air and reaching a sink.
As Dr. Lao pointed out, “additional water in the water cycle” is simply going to raise the level of the oceans 5 nanometers or so per octillion vehicle miles. [sub]Note: this statistic was made up.[/sub] No biggie.
!! “.005% could be a lot, especially over a period of years?” No, it will be .005%, no matter how many years. What that means (assuming it is correct, and that distribution of fuel cell engines and plants are uniform) is that by using fuel cells, the water “added to the water cycle” will be .005% of what would have been put in the water cycle anyway.
You may be under the impression that if you add .005% to the atmosphere in year 1, that that means that it will remain in the atmosphere and in year 2 we’ll thus have .01% more water than we did in year 0, and so on. However, once the water is in the ocean there is no reason it would lead to accelerated evaporation from the ocean.
Now, what may be a concern is concentrating water vapor generating engines in areas normally not used to water vapor generation. In other words, what happens when distribution of engines differs drastically from distribution of plants?
I think if there were any mileage to be gained from it, people would be screaming about this already. “Runaway sauna effect!” read the headlines…
I think it has been considered, and I think that it is not a problem because of these giant pools of water that live between the continents.
Well, Dr. Lao, I’m only arguing that fuel cells generating water is not some brand new problem. We’ve been releasing water from fossil fuels since we first figured out that coal could be burned. I’m not concerned with the efficiency of the system, only the end result of the oxidation of hydrogen which takes place in both cases. I still don’t see why a water-based objection to fuel cells as opposed to ICEs makes any sense.
If there ever is a problem with excess water in the ecosphere, it will not be due to fuel cells, because they cannot conceivably produce an amount of water equal to IC engines and coal-fired power plants for many decades. As Dr. Lao pointed out, fuel cells are likely to put much less water for the amount of energy produced due to increased efficiency, thereby offering themselves as a temporary solution rather than a larger problem.
They take CO[sub]2[/sub] out of the atmosphere and store the carbon as biomass.
They “hold” it until they are cut down and burned, or until they die and rot.
Note that a lawn or a mature steady-state forest is not a carbon sink. Only while the amount of biomass is increasing is there a net removal of carbon (e.g. newly-planted forest). Actually lawns are worse than concrete, because they take up carbon dioxide, then after cutting, the clippings are stored in heaps where they rot anaerobically and produce methane, more than 10 times as potent a global-warming gas.
I have to admire DSeid for sticking with his question in the face of a string of ill-considered posts that failed to address his points. As DrLao and douglips have explained, the answer is that the (very real) excess water ends up in the sea and there will be no global build-up of water in the atmosphere.
I agree, but I want to point out that that is not what the OP is trying to do. He states:
My impression is that it was the fuel sells that got him thinking about this, and from there he discovered it’s been going on for centuries. Now he is asking if that steady leaking of water vapor into the air could have had any overlooked enviromental impact. The answer, apparently, is “no”, because the oceans have an immense ability to soak up water.
And I think that may be right. Does it? Is it just an infintessimal rise in sea level (oceans as the water sink), or does a new equilbrium form? I think the ocean resevior is likely correct. Does the vapor contribute to local effects?
Thanks to those like hibernicus and Manda JO, who understood the question. And eventually Dr Lao.
Aside: even some growing trees are not good carbon sinks. It depends on the rate of decomposition of its root structure and leaf litter too.