As a method for producing electricity from sunlight, this is hugely expensive. However, the process yields heat plus two valuable chemical products (hydrogen & oxygen).

The concentrated solar heat is perhaps best used to pre-heat the feed water of the solar concentrators via heat exchangers. This increases the throughput capacity of the solar ovens and cools the gases down so they can be handled more easily.

The hydrogen is best used locally to improve the yields of processes that generate liquid fuels, e.g. BTL, because those are much easier to distribute and fetch a higher price per kWh than electricty does.

Pure oxygen is a high-value input in a variety of industrial processes, including steelmaking and clean coal combustion. Or, it can be liquefied and shipped in bottles as an industrial gas for operating plasma torches etc.

Rafael, on what basis are you saying that this is a "hugely expensive" way to produce electricity from sunlight? You may well be right, but I didn't see enough information in the article to support that conclusion.

Are you perhaps thinking that any generation of electricity from hydrogen is expensive, due to the cost of fuel cells? That's presently true, but I'm not confident it will remain so in the future.

Nonetheless, I do agree that, given a source of hydrogen and oxygen, the most economically efficient use for it is the sort of thing you suggest.

There are a lot of possibilities. An interesting one is to generate both power and synthetic natural gas, via the Sabatier reaction with the CO2 stream from an oxy-fueled power plant. Microchannel Sabatier reactors were researched under a NASA contract for fuel production on Mars. They appear practical even at the scale appropriate for a handful of solar-thermal hydrogen units of the type described.

While I don't like the whole hydrogen economy thing the processes used here could get much cheaper with time. There are some exotic materials but most of it is engineering and just knowing how to do it. It also does look scalable to smaller sizes even home size. At that point a hydrogen ICE powered car does not bother me.

If used for biomass processing the mistiming between rainy and sunny weather becomes less important as feedstocks are built up. Onsite gas storage need not be high pressure which is one of the bugbears of portable applications like FCVs.

Max: Is that tower actually being constructed? or are they stalled for funding.

Store the large and low pressure H2 tank outdoor for local electricity generation and heating. If there is a HealthyBreeze blowing around, any H2 leakage will dissipate quickly heavenward like a homesick angel!

You can also built your H2 furnace outdoor and conduct the hot air inside the house, but it would be more energy efficient to use H2 for electrical generation to sell to the grid while use the waste heat of electrical generation to warm your house, or the same waste heat to cool your house using vapor-absorptive cooler.

For automotive use, it may cost less in term of hardware investment to fill up your future H2-vehicle at a "gas station", due to the high pressures involved.

cool technology but only useful if there is a need for H2 near the powerplant. A much more universal solution would be concentrator solar power (csp)plus high voltage DC transmission lines. Such as setup solves the distribution problem. Taking the energy to where it's needed. If H2 is used as an energy carrier for phev's then it could be generated where it needed by electrolysis. For more info see http://www.trecers.net/concept.html

Their web site shows some clear fossil-fuel killer cost and efficiency claims. About $1 (US) per kg hydrogen ($1/gallon gasoline equivalent). 44% Solar Energy-to-Hydrogen conversion. A very simple device. Off-the-shelf tracking solar concentrator, plus $600 in volume ($4500 initially) for their separator device.

Direct thermolysis is a very efficient way to make hydrogen, and is perhaps the best argument for hydrogen as an energy carrier. It certainly is a good replacement for the fossil fuel of hydrogen's existing supplies, which would improve the situation with fossil fuel and all of its problems. Especially the market inelasticity-spawned problems; a new strong competitor will do that. And the hydrogen will be good for aircraft.

I can imagine using this to make ammonia for fertilizer in the corn belt in the winter, when crops won't grow, for instance. Or making hydrogen from solar power to be stored in old natural gas wells, to produce energy indirectly when the sun isn't shining on your PV arrays and you need it. I'm still confident PV is going to come out on top for efficiency and will be primary.

My biggest concern is whether this company will be able to achieve long thermocycle life; their operating temperature of 2200 C is much higher than what SOFC people are operating, who are already finding this difficult. If you have to resort to stuffing the device in a thermos to keep it hot at night to prevent thermocycles, that will add quite a bit to your cost.

I hope they succeed. Just don't take your eye off the battery-drive (PHEV etc.) ball; that's the next major meaningful step for cars, the subject of this site.

Roger,

Your numbers look favourable, though I'd question how much energy might need to be stored given global HVDC supergrid combined with massive solar grid output in each of the world deserts.

I agree though that this has pretty aswesome potential.

Would be nice to see a few studies comparing solar CHP with H2 energy backup vs CSP (PV or thermal) with a global HVDC grid plus other energy storage such as molten salt thermal storage.

It looks like both could could provide an expanding world with all its energy needs, but which:

Has the lowest installed and lifetime costs?

Has the highest energy output per area of land?

Is least vulnerable to storms and weather extremes.

Is better for conversion to other energy carriers: methanol, syngas etc

At first glass I think you might be right that a mix would be best, but there's quite a lot of metrics to compute ; )

I am skeptical of any system that expects components with temperatures in excess of 1000 C, let alone 2200 C, to operate for sufficiently long to make economic sense. Examples of even the lower temperature are few and far between, typically with the component being low complexity and robust (like liners of furnaces).

That said, the very high temperatures achievable with high-concentration solar are one of the interesting pluses for that energy source. I am attracted to solar water splitting cycles in which (in one step) metal oxide particles are brought to very high temperature and partially decomposed to lower oxides and free oxygen. This would not require any system components except the particles be exposed to the high temperature, as they could be dropped through the focus of a power-tower-like concentrator.

very important

Love solar hydrogen! Let's not think of cars running on it though. I mean, why would we need to go to all the trouble of installing gas stations for hydrogen fuel cell cars? Solar hydrogen gives us the electricity for our homes etc and if we are driving the fast electric cars General Motors killed off, we just plug in don't we?

thanks