naperlou, hydrogen storage technology may be more advanced than current batteries, BUT the logistics of handling quantities large enough to be worth the effort is a quite different story. Even at a modest 5000PSI it is no small deal to connect and transfer hydrogen as a gas. and the adsorbtion into hydrides is not an instant process, but rather more like filling a gas tank.
The most efficient way of obtaining it is separating it from natural gas when it comes from the well head, since that does not require adding energy to break any chemical bonds.
Using electrical power to dissociate water during the low demand periods still needs all of that power, and if lots of folks do it, the problem is still with us.
j-allen, you make some good points. What I think is useful is using that excess renewable energy. Becuase the demand for electricity does not follow the same pattern as winds, sun, etc. we do have an impedence mismatch between what can be produced and consumption. If we just ran the base load generators at a slightly higher rate and ran wind turbines more often, we could easily produce lots of hydrogen at low cost. I see wind turbines all the time that are not turning, even when there is sufficient wind, becuase there is not enough load. Hydrogen may not be terriably efficient, but making it does not entail moving lots of materil around. Water for electrolysis can be obtained in many places. The storage problem is a big one for the electric grid. I understand that in Japan many people are putting fuel cells in their homes.
I also like your idea of burning hydrogen, assuming the infrastructure could be set up, in an engine that could use multiple fuels. From what I have read, the hydrogen buring engine puts out 99% less CO2 than conventional engines. It would also help push the hydrogen distribution system needed for fuel cells as well.
You do have a point. Hydrogen is an energy storage medium, not an energy source. And it's a pretty inefficient one at that. When you calculate the 60-70% efficiency of electrolysis, 55-60% for the fuel cell (especially one small enough to fit in a car), and then the 10% or so to compress and handle the gas, the "round trip" efficiency is only about 1/3. However, if there are periods of excess capacity on a solar or wind installations, using this energy to make hydrogen is still better than letting it go to waste.
You can, of course, burn the hydrogen directly in an Otto cycle engine. This is less efficient than the fuel cell, but it would allow us to convert gasoline engines fairly easily. The same diaphragm carbureters that allow an engine to run on natural gas or propane can also handle hydrogen.
The safest way I have seen to store Hydrogen is by using hydrides. This keeps the Hydrogen in a form that will not explode on impact. Hydrogen fuel cells are the way to energy independence, but that doesn't please those who want to keep our wallets tied to the pump. The technology is here, now, today. It is a shame that fuel cell technology is not at the forefront of the battle.
Chuck, I tend to agree with you. On the other hand, one thing that has been of concern with BEVs is the strain they could put on the electric grid if used in large numbers. Creating hydrogen, which also uses electricity in most cases, is a different proposition. Since the hydrogen can (will) be stored, the power generators can run the process when load from consumers is down. This is just another way of stating the storage problem with BEVs. We have become used to having convenient stored energy with hydorcarbon fuels. Yes, there is a lot that goes into preparing them, but once prepared they are relatively easy to store and transport. Hydrogen comes closer to this than batteries.
Yes, there is a lot of activity in this area, naperlou. What I think it's signaling is that there's no agreement on which path is right. Some automakers have made it clear that they don't think the BEV is ready today; some are producing compliance cars. Others (Nissan, Tesla, for example), really believe that the BEV is the answer. But the bottom line is that by 2020, we'll have far more battery electric cars than hydrogen vehicles, and it will stay that way for many years to come.
Cap'n, there seems to be lots of activity in this area. What it might be signaling is that the battery technology is not going to get better soon enough to save that technology. Of course, to produce hydrogen one generally use electricity for electrolysis, so this is still an electric approach.
The real question is, is there a better way to dispense the hydrogen? As with batteries, this seems to be an intractable problem, very much like the battery. What about nuclear batteries? That was a concept a long time ago.
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