Thursday, April 12, 2007

Hydrogen Hype

There is an article in Culture Change about Hydrogen by Alice Friedemann that is a really good example of how someone who seemingly knows something about something in fact doesn't.

I know I should just let this go, but I hate it when bad thinking leads people to believe things that are the results of plain old specious reasoning.

So here goes.

According to the editors,
"It so happens our author has been a main factor in sinking the technofix illusion of hydrogen."

That may be true, but I would tend to give more credit to my friend Joe Romm, former Assistant Secretary of Energy under Clinton, and the author of The Hype about Hydrogen, which is one of the references in the story.

Ms Friedemann tends to conflate the Hydrogen Economy with the Fuel Cell economy. And she and Joe are both less than enthusiastic about the money that has gone into the so called Freedom Car initiative. As am I.

And I agree that making hydrogen out of coal or any other fossil fuel is not a road that we want to go down. But where I disagree is where it comes to making hydrogen out of wind or any other affordable renewable energy.

According to the author,

"Electrolysis is 70% efficient. To calculate the overall efficiency of making hydrogen from water, the standard equation is to multiply the efficiency of each step. In this case you would multiply the 30% efficient power plant times the 70% efficient electrolysis to get an overall efficiency of 20%. This means you have used four units of energy to create one unit of hydrogen energy."

This is true with electric plants with heat rates of over 10,000 BTUs/Kwh. However, our best combined cycle plants now have heat rates under 7,000 BTUs/Kwh which is almost a 50% efficiency. For those of you who don't know, there are 3414 BTUs in a Kwh.

And the best electrolysis units use less than 50 Kwhs per Kg of hydrogen produced. They are therefore a little better than 70 % efficient, some approaching 85%.

So using best practices and advanced technology, we would now be using 2.5 units instead of the author's 4 to create each unit of hydrogen.

But that is really not the point. What gets me is the next paragraph.

"Current wind turbines can generate electricity at 30-40% efficiency, producing hydrogen at an overall 25% efficiency (.35 wind electricity * .70 electrolysis of water), or 3 units of wind energy to get 1 unit of hydrogen energy. When the wind is blowing, that is."

This is where the author gives herself away I think. The statement that wind is 30 percent efficient is not only inaccurate, it is totally irrelevant here. Wind facilities in Texas have capacity factors between 30 and 40 %, but they are very, very efficient at extracting the power out of the wind that flows through their swept areas. The sophistry of the author's argument here is only slightly less mendacious than the ones we must endure from the current administration. Her solar argument is equally nonsensical.

The preferred way to look at this would be to look at the total imbedded energy that went into making the wind turbine and putting it into service. Most energy wonks estimate that wind enjoys a "energy out" to "energy in" ratio of at least 12 to 1.

If we used all that wind to make hydrogen at 85% efficiency, the ratio is now 10 to 1. Of course we won't do that because we only need to make as much hydrogen from wind as we must. We would rather use the high grade nature of electrical fuel in our computers, compact flourescents, and our plug in hybrid cars instead.

And that leads me to another favorite saying of those who like to try to discount the use of hydrogen in an advanced solar /hydrogen/electric future.

It takes more energy to make hydrogen that you get back.

With that as a standard, we would not make electricity either. There are always losses when you transduce something into something else.

The author states, "No matter how you look at it, producing hydrogen from water is an energy sink. If you don't understand this concept, please mail me ten dollars and I'll send you back a dollar."

However, using wind, we make 10 units for each one invested, even after conversion to hydrogen. If the wind costs 3 cents/Kwh, ( and I have contracts under that at my utility), then the hydrogen gas will run around 16.00 per MCF of natural gas equivalent, including the amortization of all my equipment. That's twice the cost of natural gas now, but there are no carbon emissions and there is no depletion of resource. If the hydrogen was used as a transportation fuel, it would be $2.40 gallon of gas equivalent without any taxes.

Now don't get me wrong, if the round trip of wind electric to hydrogen to electricity is only 35 % efficient, I don't want to do too much of that. But until I get an ultra cap, or a giant fleet of plug ins to help me increase my renewable energy fractions, that's exactly what we may have to do if we want to reduce emissions by 80% in the next few decades.

My dollar is enclosed.


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Anonymous Anonymous said...

Oz - you got this one exactly right. One last point to add, if we do not spend money on transmission lines for those wind farms in West Texas, then we will have to continue curtailing some of the production. This energy that has near zero cost (actually the small variable cost for O&M) because you can not get it out to the grid. It could be used to make hydrogen even more economically than your 3 cent, contract wind energy. It would be leveling the load on those overstressed tie-lines, too.

Nature's Electric Inc.

6:10 AM  

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