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Xcel and NREL Unveil Wind2H2 Project

18 December 2006

The Wind2H2 project. Click to enlarge.

Xcel Energy and the US Department of Energy’s National Renewable Energy Laboratory (NREL) unveiled a pilot facility that uses electricity from wind turbines to power electrolyzers to produce hydrogen, which is then compressed and stored at 3,500 psi.

The Wind2H2 project is designed to examine the system integration issues with wind-hydrogen production, compression, storage, and use. The project integrates wind turbines directly to the electrolyzers testing both AC and DC connections. The hydrogen is used to power a Hydrogen Engine Center (HEC) genset. (Earlier post.) A hydrogen fueling station for vehicles is planned for the future.

Today we begin using our cleanest source of electricity—wind power—to create the perfect fuel: hydrogen. Converting wind energy to hydrogen means that it doesn’t matter when the wind blows since its energy can be stored on-site in the form of hydrogen.

By marrying wind turbines to hydrogen production, we create a synergy that systematically reduces the drawbacks of each. Intermittent wind power is converted to a stored fuel that can be used anytime, while at the same time offering a totally climate-friendly way to retrieve hydrogen, to power our homes and possibly cars in the future.

—Richard Kelly, Xcel Energy chairman, president and CEO

Currently, there are limitations to both wind power and hydrogen. Wind farms only generate electricity when the wind is blowing, which is about one-third of the time in the United States. This creates the need for backup generation, which is usually fossil-fueled. Hydrogen production currently relies on the reforming of natural gas, or on electrolysis of water—energy-intensive processes that result in greenhouse gas emissions (depending on the source of the electricity).

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.

The project allows our researchers to compare different types of electrolyzers and work on increasing the efficiency of a wind to hydrogen system. And, it has the potential to point the way to a completely emissions-free system of making, storing and using energy.

—Dan Arvizu, NREL director

NREL and Xcel Energy expect to offer a public update on the operation of the project around the middle of 2007. Results will also be shared with the Hydrogen Utility Group, made up of Xcel Energy and nine other utility companies interested in hydrogen’s future role in the utility industry.

The Xcel-NREL Wind2H2 project is one of several projects in the US sponsored by the DOE to investigate the combination of wind power and hydrogen production. (Earlier post.)


December 18, 2006 in Hydrogen, Power Generation, Wind | Permalink | Comments (27) | TrackBack (0)


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Some would say the best use for wind or solar electric is to put it on the grid. However, time shifting the energy can be done with pumped hydro, flywheels, batteries or other methods. This should quantify the electrolyzer efficiencies. It is my understanding that they can be efficient, if run at an optimum level.

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.

Yes. Feed all the electricity that is available from wind into the grid first. If there is power available but no call from the grid, then backup the power. However, wind is providing a very small proportion of the power that the grid requires. Therefore, could someone please explain why backup is needed. Backup might be needed if wind became a high percentage of the grid. But I don't see this happening in the U.S. for decades, if ever.

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.

Hydrogen is still the "Darling Child" of Greenwashing.
Flywheel storage can address this issue today.

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.

Vanadium redox flow batteries already provide about 75% round trip efficiency (much better than flywheels that idle for any length of time). I doubt any hydrogen electrolyzer /compressor / fuel cell can get anywhere near that.

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.

Rise of the humongo battery...or capacitor. Alternatively, ther could be a large number of battery sites to go with all the wind farms.

The only upside to H2 production is for chemicals.

Most economical usage of wind electricity is to provide backup power generation by means of diesel (or H2-ICE)generators for local heat and electricity co-generation.
Many smaller units of diesel (or Hydrogen-ICE) generators can be turned on or off rapidly in response to varying in wind electrical output without shortening durability unlike gas turbine power plants that will experience shortened life span with frequent shut-down or power down.
Diesel with efficiency 42% or higher with turbocompounding, and H2-ICE with efficiency of 45-50% can compete with even combine-cycle gas-steam turbine power plants because the smaller distributed generation genset provide 110-220 volts directly at the site of consumption. This can avoid the 8-10% loss from the use of power transformers to step up and step down the voltage for long-distance power transmission, with some line losses as well.

Now then, if you wanna make transportation-grade fuel (H2) from wind, nothing can beat high-temp electrolysis with electrical efficiency of 140-150%. The high-temp heat greatly reduce 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.
Thus, 1.5 x .6 (from SOFC) = .9, or 90% efficiency wind electricity to H2 and then electricity again. No other energy storage device can beat that!

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 :)

Roger, I'm having trouble understanding "1.5 x .6 (from SOFC) = .9, or 90% efficiency..." Could you elaborate? Maybe you could provide some references too? It sounds like you're assuming "free" heat from some other source. If so, that's not a fair comparison.

I still think the flow battery is currently the best solution for leveling the power flow from solar and wind. Allen has a good point, though. It might make sense to produce H2 if there is a goal other than generating electricity.

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

If you are using CO2 from coal, it is not CO2 neutral, you are just using the CO2 twice. If you used the CO2 from ethanol fermentation, it would be CO2 neutral, because the plant absorbed the CO2 as it grew.


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.

The changeover to HEV's is inevitable. Toyota is already claiming that all of its vehicles will be HEV's after 2010. In order to achieve decent fuel economy the HEV or BEV drivetrain is a No-Brainer. To change from an HEV or a BEV to a PHEV is a triviality. An extra $1000 to $2000, tops, mostly for the batteries. Will easily be made up for by the greatly reduced driving costs.

There are many methods of producing liquid fuels efficiently for longer range driving needs (> 100 km per day). Various means of methanol production, LPG, Ethanol, Biodiesel, SynGas etc. With HEV technology an average fuel economy of > 60 mpg is entirely feasible, and likely upwards of 100 mpg can be achieved, for consumer vehicles. 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. Why must the taxpayer fund to the tune of probably in excess of $1 trillion, a switch to a Hydrogen economy, when cheap readily available alternatives are here now. Ever wonder why the Bush Oil Slave Government, Big Auto and Big Oil push Hydrogen so vehemently, while they are still trying their level best to Force the consumer to consume large quantities of gasoline unnecessarily in oversized, gas guzzling vehicles and by blocking EV technology (like Chevron killing the NiMH battery for EV's). Because they know that they can make big profits, funded by the taxpayer, on hydrogen powered vehicles and production & distribution of this particularly ornery fuel source. And since the feasibility is still way in the future they can continue to pretend they support green technology, while in reality they are doing almost everything they can against it.


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.

That is why you use concentrated solar thermal heat energy with SOFC electrolyzers, multijunction PV and wind. You can time shift the power release for baseload or create hydrogen for cars, if they ever figure out a good way to store it on the car. If you were to create hydrogen for cars, you would want to do it at the fueling station and not transport it by truck or pipeline. I agree that the present administration pushes FreedomCar hydrogen because it is decades away and not a solution for now. Exxon would not have taken $36b in profit in 2005 if we had 70 mpg PNGV diesel hybrid vehicles.

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:

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

There have been several articles on here about SOFC electrolyzers. As a fuel cell, they give off heat, as an electrolyzer they take in heat. Most articles have been heat from nuclear plants, but there is no reason you could not use concentrated solar thermal. You can obtain 1000C from the sun.


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

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.

You can pretty much generate anything you want, whether it has to be done in your back yard is a matter of opinion. The technologies are available. Multijunction PV cells at 40% efficiency, SOFC fuel cells at 60% efficiency. I just want to see the U.S. get off the dime and get with it, instead of wasting money and lives on war.


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.

u should read this about hydrogen!

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