http://www.physorg.com/news87494382.html

I wonder if it will pay to off-line any available wind-turbines used to electrolyze hydrogen from water? The best efficiencies for electrolysis are like 84%. Are the transmission losses for wind generated electricity higher?! If the wind-turbines are used to generate electricity for hydrogen production through electrolysis, rather than to supply power to the grid, then won"t the grid demand burn more fossil fuel? Seems to me, the wind-based electrolysis needs to have a direct market (for gaseous hydrogen and oxygen), that will offset with greater revenues, the expense of the fossil fuel used instead, because the wind-turbine
is not supplying the grid. And then how would this be "clean" hydrogen. It is only not directly made from fossil fuel energy, but preventing a wind-turbine from supplying electricity will surely mean more use of fossil fuel (or nuclear), so the hydrogen does not really save or prevent using fossil fuel, does it? Maybe wind during a "no-demand" period could be used, but when is there ever a "no-demand" period or even deand lower the wind output capacity?

This is great research and of great practical value. What holds back alternative energy is its intermittant nature and unreliability. While this is not at all obvious to the casual observer, Xcel is all too aware of this issue as they have to deal with it on a daily basis. All of the wind turbines you see installed to date do not reduce the number of fossil fuel power plants required at all. The number of fossil fuel power plants required is dependent on peak load and alternative energy souces cannot be relied upon to meet peak load. Take Denmark with over 6000 wind turbines, even with all that investment they have not been able to shut down one fossil fuel plant. And what was Denmark's output of electricity from wind generators in the month of Feb 2005 - 0. Wind fluctuates a great deal. It can cause instability in the electrical grid as the other sources cannot be ramped up or down quickly without causing increased pollution and/or lower efficiencies. High wind times rarely coincide with peak load times. There is a good reason Xcel is funding this type of research and it is good to see.

I'm unconvinced that this is the breakthrough they are making it out to be. I think your point about Hydrolysis inefficiency is accurate, and in every step of the process, generating the hydrogen, using the generator to compbust it etc, entropy is going to suck the efficiency out of this. I recently read an article in the New Scientists supporting flow batteries as a brazen alternative to hydrogen and it seems sound to me. The electrolyte solution they are employing now in flow batteries off of australia have already cut back diesel generator use by almost half in initial experimentation, effectivley tripling the power of wind and solar. The best part is, since it can be built to scale, the flow battery culd be used to store electricity while coal blants are burning to maintain threshhold capacity overnight, effectivley boosting efficeincy in energy reserves for the next day. So the impetus to develop this technology seems to me to bear better under scrutiny since the application is broader and the results are already more fantastic. Why is everyone so Hydrogen obsessed?

We considered both batteries and hydrogen for a remote site project. We used HOMER -- the same software NREL used to design this Xcel -- to model different approaches. Fuel cells aren't anywhere close to economical, yet, so hydrogen combustion was examined. HOMER estimates hydrogen ICE efficiency at a measly 9%. Throw in loss from electrolysis and compression for storage, and there isn't much left. No matter how we fiddled with other parameters -- even making the storage and electrolyzer cost zero -- HOMER couldn't find a way to make economical use of hydrogen.

Note that the purpose of this Xcel/NREL project is mostly research. No one pretends that the Xcel project is economical or efficient, or will be any time soon. NREL's own analysis suggests that it if it ever makes sense at all, most of the hydrogen produced will be sold rather than stored and burned.

Batteries can make sense, however, if you're far enough from the grid. We looked at Vanadium Flow batteries. They aren't cheap. The high marginal cost of electrolyte ($120-280/kWh) means that long-cycle storage is out of the question. It can be useful for rapid-cycle, short term (4-8 hours) load-leveling and peak shaving, however.

Dr. Zoikelstein writes:
"The electrolyte solution they are employing now in flow batteries off of australia have already cut back diesel generator use by almost half in initial experimentation"

I believe the doctor is referring to the King Island project:
www.vrbpower.com/applications/remote-area-power-supply.html

They did reduce diesel consumption by half. According to the battery manufacturer, going from diesel-only to wind-diesel-battery can cut diesel fuel use as much as 95%. However, the economics seldom support that. You'd need very good wind and very high diesel prices. In our case, HOMER optimized the system to 56/36/8% wind/gas/diesel.