Solid Oxide Fuel Cells

FuturePundit prompted me to speak to Professor Ignatiev about the new advance in fuel cells.
I hope you'll excuse me using industry insider knowledge to provide a little perspective on this announcement. There aren't that many who work in this field and I may be the only one with a blog.
My work in this field is from the day job, the delightfully named "The Low Hanging Fruit Company Ltd", where we supply much of the world's usage of scandium. (Don't worry, it's just a metal and yes, very few people have heard of it.) /advertising off.
Over the past few years we've been in contact with a number of fuel cell people as scandium seems to solve some of the problems people were having with Solid Oxide Fuel Cells (SOFCs). Over the years the specific problem has changed. First it was making sure that the SOFC actually produced electricity at something close to the theoretical limit for the technology, some 60 - 65 %. This was achieved by using Yttria Stabilised Zirconia (YSZ) as the electrolyte. Don't worry too much about what this is but yttria is yttrium oxide, (about $30 a kg in bulk) and zirconia is zirconium oxide, a cheaper material. While there are some costs in making the compound, it isn't, as these things go, all that expensive.
However, operating temperatures of 900 - 1,000 oC mean that all of the supporting structure needs to be made out of comparatively expensive materials.
The next stage was to see if a slightly different electrolyte could be in itself more efficient, allowing the cell stack to run at a lower temperature. Scandia Stabilised Zirconia (ScSZ) allows this, operating at about 800oC. This seemingly small change means that much cheaper materials, simpler steels, can be used as the supports and surrounds. Great, except scandium oxide is much more expensive than yttria, about $500 a kg in bulk. Still the first large scale manufacturer of SOFC power plants went the scandia route : Toho Gas. There is also a problem with ScSZ, in that it can crack during the heat up/cool down cycle. Toho fixed this with an addition of ceria (cerium oxide) and Professor John Irvine in Scotland (who is the head of the EU investigation into all of this) used a ScYSZ electrolyte.
OK, so far so good, we've got a lower operating temperature, thus lower component costs, still at or near theoretical limits of efficiency, but at the expense of a much dearer electrolyte.
(If you want to see other players, have a look here. There's all sorts of interesting ideas out there, like Rolls Royce intending to run turbines off the waste heat from large plants to people who will sell you an operating plant today.)
The next stage, about 18 months ago as I recall, was to try and thin the electrolyte so as to reduce costs. The first group to leap up and down in excitement were these guys at Lawrence Livermore. Their aim was to get material costs down below $400 per kilowatt, something they could achieve with their process for 500 nanometre layers of electrolyte (that figure came from Professor Ignatiev this afternoon, sorry, I've forgotten what Steve Visco told me). Thinner electrolyte also meant less heat to disperse, further lowering temperatures and the cost of alloys needed for all the surrounds and supports.
All of this leads us to Prof Ignatiev and his team. Their electrolyte layers are down to 100 nanometre. This they do by a one stage lithography process, something that is cheaper, way cheaper, than the manufacture of silicon chips. Again, the thinning of the electrolyte layers has led to a reduction in operating temperatures, meaning that again all of the surrounding materials can be of yet cheaper manufacture. This is a bit of a guess but I would be willing to put money on the idea that you would not even need stainless steel, not even 18/8 at this point. Good old carbon steel at $400 a tonne should do it.
I think you can see that this isn't some leap in the dark, some out of the blue occurence. It's good science and engineering being done well, getting to one point, evaluating the problems then solving those, then around for another iteration.
This latest development means, from my worm's eye view, that the cost constraints on SOFCs are really and truly gone. We know how to do one stage lithography (although currently Prof I is using crystal nickel upon which to deposit, still distressingly expensive) cheaply and easily and all the materials come in well under the $400 per kWatt level.
Great, we've solved all our problems?
Not so fast. SOFCs are not, for technical reasons, well suited to use in transport. These new lower operating temperatures might make them so but I'm not at present in a position to say. Local generating plants? Oh yes. Combined Heat and Power? For a theoretical efficiency above 80%? Bring It On!! Transport? Someone else will have to determine that.
There is also the problem of fuel. SOFCs can use methane, methanol, ethanol without too many problems. They can also use hydrogen without it having to be excessively pure (this is what "internal reformer" means, I think), yet we still need to work out where we're going to get any of these things from. Given the greater efficiency of the unit over simply burning the stuff, natural gas usage would reduce emissions. Yet we've only really solved the problem when we have a non fossil fuel method of creating any of the above and hydrogen would be best.
Cheap efficient SOFCs are, from what I can see, now only an engineering/manufacturing problem. How about we run the windmills and the solar cells to electrolyse water (getting round their problem of inconsistent output) and use hydrogen as the battery, the SOFC as the means to turn the hydrogen back into power. Yes, inefficient, but the cumulative inefficiencies seem to be less than those of the fossil fuels we use right now.
Here's an interesting calculation:
Insolation is at roughly one horsepower per hour per square yard for seven equator equivalent hours per day just about anywhere with extensive human habitation. That's 5 or so KWatts per sq yard per day. What's the size of the average American houses' roof? 1,000 sq foot? 100 or so sq yards? 500 Kwatts a day? Solar cells with 30% efficiencies are out there (Berkeley, GaAs/GaN/InN). 150 KWatts. As I don't know the efficiency of a process to separate the hydrogen from the water, I'll assume 50%. OK, we've got 75 KWatts of usable power now. Our SOFC produces electricity at 60% efficiency: 45 KWatts per day of storable power. From land that's already in use for something else. Average US household daily electricity usage? 30 KWatts.
OK, OK, there's a number of leaps in those numbers but we are getting there, we really just on the cusp of being able to power a household from the ground it already occupies.Anyone who wants to correct me on the above please do.
Now all I have to do is to convert Professor Ignatiev from his use of yttria stabilised zirconia to scandia stabilised. I did plant the idea this afternoon and he says it is on his list of things to do. Just how cool would it be to be part, in however a small way, of the solution to global warming?
(If it's happening of course, and if it's not the sun itself. I do read TCS after all.)