I am all for using wind power to produce hydrogen for industrial purposes. Let's replace all the natural gas we can.

However, I do not see hydrogen as the miracle that solves the problem of intermittency of renewable resources. The efficiency is just too low (google Ulf Bossel if you want more info). Furthermore, from the schematic it appears that power above the capacity of the electrolyzers is fed to the grid. If that is true, they have only increased the variability of wind power on the grid, which is exactly the opposite from what they set out to do. I have heard from other sources that electrolyzers do not work well with strong variations in power. From a peak-smoothing point of view, the electrolyzers should only run when there is surplus power on the grid, irrespective of wind output.

I still maintain that it is much better to organize power consumption such that non-essential consumers switch of when the price is high. By non-essential I mean PHEVs, freezers that are cold enough, air-conditioning (cold enough), water heaters, etc. All it takes is minute-by-minute metering and prices of electricity and appliances that switch of automatically would become price competitive.

NREL assessed the economics of wind-powered hydrogen production and concluded that while the near-term cost is around $4.03 per kg of hydrogen, long-term costs could drop down to $2.33/kg hydrogen.

NREL also concluded that it would be feasible to produce 154 billion kg of hydrogen per year from Class 4 and higher wind in the United States. Current transportation fuel usage is around 140 billion gallons per year.

What they seem to be implying is that the hydrogen highway would be lined with windmills. I do not see that likely to happen.

I wonder if the price per kg includes selling the oxygen. It would have been good if they had used a fuel cell or better yet, a reversible PEM.

I think you are right. Even if the hydrogen can be created and compressed with 80% efficiency and the electricity can be generated with an SOFC and turbine at 60% efficiency, that would be .8 x .6 = .48
I look at this as between batteries and pumped hydro. Even though pumped hydro is more than 70% efficient, it is hard to find suitable terrain and can not scaled down easily. Batteries may be more efficient, but can not be scaled up for cost and replacement reasons. As far as the hydrogen highway, we will see.

The only upside to H2 production is for chemicals.

How about high grade concentrated solar thermal heat. A dish than can generate 1000C along with an SOFC electrolyzer should make that hydrogen highway real smooth :)

You are all missing the boat here. The real use for wind h2 is in to the Fischer-Tropisch process. Wind h2 in conjunction with co2 from coal fired production plants can be combined to make affordable high quality fuel. The bonus is that it is a 100% co2 neutral process. It consumes the same amount of co2 as it produces. No need for fuel cells, transmission lines, new engines or fuel transportation systems. F-T fuels will run in any diesel or jet engine made today. When co2 credits are used the fuel can be produced for under $2 a gallon
http://www.greencarcongress.com/2006/03/a_proposal_for_.html

Steve,

If wind + flow battery to PHEV is more efficient than wind + Fischer-Tropisch to ICE, then how is it that we're "all missing the boat"? Whichever uses the wind generated electricity more efficiently, wouldn't that be the way to displace more fossil fuel, and reduce CO2 more? I don't see how we can disregard efficiency.

As for ease of deployment, wind + Fischer-Tropisch to ICE would require a huge invesment in F-T plants, whereas wind + flow battery to PHEV would require a huge shift to PHEVs. Honestly, I don't know which is more do-able. Has anyone compared the two? You may have a point there.

netscrooge,

Roger was indeed contemplating the use of external heat. As he wrote in his earlier post:

"The high-temp heat greatly reduce[s] the electrical power input, thus making electrical efficiency greater than unity. The source of heat can come from the free heat of stand-alone gas turbine power plants."

Basically, he envisions the use of waste heat from fossil plants that are already in operation as part of the hydrogen production cycle (though I don't see why this can't be extended to nuclear plants).

I don't have any references handy which I could use to evaluate this claim. For instance, we would need to know the optimum operating temperature of a high-temperature electrolysis unit, and whether the waste heat coming from a typical fossil plant can get you most or all of the way to that ideal temperature.

Furthermore, when evaluating the resulting H2 for its "carbon footprint," we have to acknowledge that some of the energy embodied in it came from heat that was generated with fossil fuels -- it is not strictly carbon neutral hydrogen. If the fossil plant is going to run anyway, then it practically resulted in the release of no extra CO2. But the better way to account for the carbon would be to consider the electricity produced by the plant to be somewhat less carbon intensive than before, with the difference assigned to the hydrogen production. That way, when long-term plans are made regarding which kind of plants to build and which kind to decomission, the impacts and outputs of each are identified clearly.

It works something like this:

Plant X (coal or natural gas fired) currently produces 10 megawatts of power, a bunch of waste heat which is dumped into a lake where it kills all the fish, and 5 megaunits of CO2 over the course of a year. Each megawatt-year of electricity has a carbon footprint of 0.5 megaunits of CO2.

A windmill and high-temperature electrolysis unit is then build next to the plant. Now it generates 10 megawatts of power plus provides half the energy (or whatever the actual proportion is) embodied in a quantity of hydrogen gas, produced over the course of the year, which contains the energy equivalent 10 megawatt-years of electricity. It still produces 5 megaunits of CO2 over the course of that year. In this case, each megawatt-year of electricity or hydrogen equivalent has a carbon footprint of 0.33 megaunits, instead of 0.5.

By using the carbon more intensively/efficiently, we reduce the size of the footprint of each unit of output -- but each unit of output bears *some* footprint.

Warren Heath said:

"With the already demonstrated capabilities of BEV's and PHEV's, the advantage of Hydrogen fuel goes to nil, and it's inherent and unavoidable disadvantages drives it to a point of absurdity."

Well said Warren. We already have an energy distribution system in place that is capable of transporting renewable energy to green cars (the grid). Why in the world would we want to build a new and wildly expensive distribution system for hydrogen? Who would benefit? Follow the money.

The existing grid can tollerate a lot more solar and wind generated electricity, but as the percentage grows, at some point, we'll need to store/buffer the intermittent output.

When natural geologic formations are available for storage, utility scale projects will favor pumped air or hydro. There are several technologies to consider in other circumstances. SJC, correct me if I'm wrong, but it sounds like you're advocating SOFCs:

"That is why you use concentrated solar thermal heat energy with SOFC electrolyzers, multijunction PV and wind."

That's an interesting suggestion, but I thought concentrated solar systems only ran at about 200 to 300 degrees Celsius. Solid oxide regenerative fuel cells (SORFC) need to be at about 800 or 900 degrees Celsius to work efficiently. Is someone actually working on using solar this way? (Even if this is possible, I'm concerned about the long term durability of such high temperature systems.)

I still think the vanadium redox flow battery is a great technology for converting solar/wind into "spinning" capacity. They are durable, and can be scaled from residential to utility size systems. Check out what VRB Power Systems Inc. is doing:

http://www.vrbpower.com/

And in case you're wondering, I have absolutely no connection with this firm. (I work at a hospital in Columbus, Ohio.)

SJC,

Thanks for the reference. It contained a link to a presentation about hybrid solar concentrators:

http://www1.eere.energy.gov/solar/pdfs/mcconnell.pdf

You've answered my question. Yes, people are actually working on using solar generated heat to help produce hydrogen. Unfortunately, it doesn't look like they're anywhere near putting these systems into production.

At the top of your link, the main article's headline trumpets that a record 1,000 hours of high temperature electrolysis was achieved. 1,000 hours isn't much. Compare that to the decades of nearly maintenance-free operation that can be expected from both photovoltaic systems and vanadium redox batteries.

Durability is key to widespread adoption. Let's focus on technologies that can be deployed in everyone's backyard. Otherwise, energy will remain under the control of a few, giant corporations.

On the other hand, it would be great if we could replace all the hydrogen that's used in industry with hydrogen from renewable sources. But once that market is satisfied, use the heat that's split off the concentrator dishes to generate electricity rather than hydrogen.

netscrooge,

Hydrogen can supplement battery as the ultra-clean and efficient future transportation fuel. There may not be sufficient raw materials for hundreds of millions of BEV's battery packs. Battery takes a long time to charge and weights a lot and takes a lot of valuable space. Look at the Tesla Roadster, with a large area behind the front seat devoted to house the Li-ion battery. If this is a gas car, these space can be use for a row of rear seats. Battery's performance and durability can deteriorate with too hot or too cold climates.

Hydrogen, even though bulky to store, takes less space than battery for the same range. Take a look at the Honda's latest FCX hydrogen vehicle. Hydrogen tank can be filled in minutes intead of hours for BEV. Hydrogen vehicle can have comparable efficiency to BEV from source-to-wheel calculation. Distributing H2 is inefficiency over a long distance, but H2 can be easily produced locally within the same city as the point of consumption. Distributed locally, H2 distribution is more efficient than electrical transmission from power plants to high-voltage power lines and then transformed into lower voltage to feed into the home socket. H2 infrastructure will take a lot less investment to serve a given number of vehicles than the cost of purchasing battery packs for the same number of vehicles!

What is there not to like about H2 as future transportatin fuel? H2-ICE direct injection can have higher efficiency than diesel or gasoline (GDI) engines, while having almost no PM, HC, CO, or CO2 exhaust emission. NOx can be far lower than diesel's. H2-ICE can be designed to run on CNG stored in the same tank. This can triple the vehicle's range for long-distance cruise, when necessary, while increase the flexibility of fuel supply logistic where H2 is not available. CNG initially can be much more available because of widespread NG pipeline network. Millions of vehicles world-wide are now running on CNG, paying a lot lower for fuel cost. NG usually is a lot cheaper for a given BTU amount than gasoline or diesel fuels. H2 and NG produced from waste biomass or coal will also be a lot cheaper than synthetic gasoline or diesel fuels derived from biomass or coal via F-T synthesis.