Oh yeah, great idea: turn your backs on nuclear and build floating bombs instead. *facepalm

It's more dangerous in that when/if the hydrogen is allowed to enter into a gaseous state (note that "boil-off" gas is being used to cool the electrical motor) it's much harder to prevent leaks as hydrogen can tunnel through any material.

I do however question the idea that this hydrogen will be "CO2 free." Just how effective is the CCS?

Furthermore, liquefying H2 will rob about 30-40% of its energy, not to mention significant cost investment in cryogenic machinery and storage vessels. Simply making H2 locally and store it in underground caverns would be best. However, in earth quake prone Japan, that, too, might be dangerous in certain area.

Roger:

Like many of these 'cunning plans' for very high percentages of renewables, it all looks great until you start considering the cost of equipment and capacity utilisation factors.

How are you going to amortise the electrolysers if you are only running them in the limited amount of time you have surpluses in wind and solar?

For solar the times are pretty clear, it would be in the middle of the summer, in the middle of the day.

It sounds as though your electrolysers will be idle much of the time.

For wind, supply is very lumpy.
For instance Spain, which on average gets around 10% of its total electricity from wind, can have a lull of a week or more.
Conversely in very windy conditions the percentage of grid supply can reach over 100%.
Clearly those gales do not generally last a high percentage of the time, although they comprise a high percentage of total energy.

Again, you would have a lot of equipment idle a lot of the time.

Solar panels dedicated solely to H2 production?
That still would not run the electrolysers all the time, or would need extensive battery back up, with annular variation still making the electrolysers under used in winter.

I don't know where you are getting your costings from, to say that electrolysers will get so cheap that you don't have to worry about not using them much of the time, as you don't detail your costings, and AFAIK that is not remotely in prospect, so perhaps you would specify your sources.

Your assumptions on the costs of wind and solar seem equally optimistic.
Panel costs have dropped a lot, but the same doesn't hold for the rest of the system, and since many of the most favourable sites for wind are already taken and offshore wind is much more expensive, I can see little support for your notion that all the costs will be so low that normal methods of working out how efficient a total system is, and ensuring high capacity utilisation of assets, do not apply would not seem to me to have foundation.

Even liquid hydrogen is not very heavy. It seems a hydrofoil would work well (high speed, low energy use) for a ship like this.

So does Kawasaki Heavy Industries own brown coal mines in Australia or what? This is a loopy idea in so many ways.

@Roger:
'When both solar PV and wind turbines outputs are dedicated toward the same set of electrolyzers, you can see that they will complement each other nicely!'

With no personal disrespect, it is loose armwaving like this that makes me tear what little remains of my hair out.

So you are assuming that a fairly close contiguous area has both good solar AND good wind resources?
Or alternatively you are conjuring up a grid capable of transferring sudden massive loads to the central site of the electrolysers, and incidentally negating one of their great advantages, that they can generate the power pretty well where needed.

With a wave of the other arm, still more geographically limited pumped storage is created, when the suitable locations are pretty fully occupied providing peaking power.

I've been arguing against those seeking to dismiss hydrogen as an energy source here and on other sites for years, but it seems to me to be way, way to optimistic to simply assume that costs will fall so far in the supply chain that normal criteria for capacity utilisation do not apply, or that alternatively a whole bunch of other capital intensive and geographically constrained equipment can be deployed and amortised.

The easy way of doing things is to use HT reactors such as China's PBR and produce hydrogen utilising the remaining waste heat in combined heat and power, so that the electrolysers etc can run 24/7, but what we are actually going to be stuck with is a very messy set of compromises.

My guess is that renewables will be used to some extent, but what will actually provide the grunt for the hydrogen economy is reformed gas obtained by fracking, and within 10 years or so a large input from methane hydrates and maybe coal bed gassification, and global warming will be largely disregarded.

That would still be a lot more efficient and release a lot less CO2 than present systems.

For instance fuel cell transport after reforming losses is around twice as efficient as petrol.

The Californian alternative fuels mandate specifies 30% should be from renewable resources, which if you are using NG to keep the electrolysers running when wind and sun are not available is do-able.

So emissions would be around a third of present levels, which is pretty good going.

Well Roger, for a start you have used the DOE's projected costs for PEM fuel cells at a production rate of around 500,000 car fuel stacks a year.
PEMs don't hit anything like 73% efficiency, and is even pushing it for SOFC's, whose costs have precious little to do with that for PEMs.

You then hypothesised that the total system costs would be double that of the stack, but forgot about that when you decreased the stack life to only (!) 45,000 hours.

I can't be bothered to dig out the actual figures, but stack life is currently more like 12,000 hours than 45,000.

AFAIK there is not a wind facility in the world which hits anything like 50%, and 30-35% is going some.

The wind for the electrolyser will not be available anything like as much as that though, as the 'cunning plan' is to just use the surplus, and most of the time when there is power from the wind it will just be fed to the grid, not used for electrolysis to hydrogen.

So it seems to me that you have just put a set of extraordinarily bad figures to the notion that if all the costs get really cheap, it will end up really cheap.

One thing even on these premises it won't do is get as cheap as running the electrolysers 24/7 from nuclear, or as reforming NG all the time.

The notion that it is in some weird way economic to use solar and wind to produce hydrogen is dependent on their already having a heavy level of subsidy and mandates, so there is a massive sunk cost, and so surplus's are at the margins free as they would otherwise be thrown away.

True enough, in a rather Alice in Wonderland sense, but that does not make it other than ruinously expensive to build out wind and solar further to generate bigger excesses to make hydrogen.

So IOW generating enough hydrogen by this means to really make a substantial difference to energy consumption would cost enormous amounts of money, as a quick check on the energy losses would show.

None of this means that no hydrogen at all could be generated in this way, but I don't see your notion that it would be in any way cheap, and it would take a lot better figures than you have shown to persuade me otherwise.

Of course, if they can up artificial photosynthesis to an efficiency of around 10% from the present 5%, the ball game changes, but that is a different subject to electrolyis from renewables, or at least a totally different technology.

A tank full of liquid ammonia at 70°F contains roughly 30% more hydrogen than LH2 at its atmospheric boiling point.  Shipping LH2 trans-oceanically is ridiculous from a great many points of view.

Of course it is, but after Fukushima the public will never allow it.

I have had some communications with a Japanese who showed all the signs of hysteria over the issue, including illness due to induced stress.  The actual casualty toll of the Fukushima radiation releases is 3 injuries from beta burns, all workers at the plant, all recovered.  Proper public education would fix all of that.  If the Japanese people won't accept the truth, I'm afraid they deserve the results.

@Davemart,
The way to maximize revenue from a RE farm is to sell peak-pricing electricity to the grid at significantly higher rates than base rate, and then use off peak RE output for electrolysis to make H2. When the H2 is priced on competitive level as petroleum, then a lot of money can be made.

Please be reminded that the cost of transmission and distribution of electricity through the grid is ~3 cents/kWh. If you are using grid electricity to make H2, then you already are at a 3 cents disadvantaged per kWh of power consumed. For example, coal-fired electricity at 4-6 cents/kWh must be added to 3 more cents of transmission cost thru the grid. Instead, you use electricity from PV panels or wind turbines nearby and bypassing this 3 cents cost penalty, in order to get ahead on energy cost reduction for the production of H2. Using solar PV panels with raw output of electricity cost of 2 cents/kWh by bypassing transmission cost thru the grid and avoiding the use of grid-tied DC to AC inverter will reap you far more profit in H2 production. Ditto for the use of raw wind turbine output at 4 cents/kWh when bypassing the cost of grid transmission.

However, if your solar PV farm is producing a lot of output during peak electricity pricing, then you may use a limited amount of grid-tie inverter and to-the- grid transmission line to sell some of this extra output if the revenue of this peak pricing can outmatch what you will earn from H2 production. The advantage of having limited grid connection is to take advantage of low-cost night-time electricity in the grid for H2 production during times of simultaneously low solar AND wind availability. It's all in the economic calculations to determine what will bring back the most revenues.

FCV's demand for H2 will bring out an entire new economic model for RE that will be far more profitable than the previous model of just supplying energy to the grid. Remember that steam reformation of NG to H2 must be done in very large installation to realize cost-effectiveness. Then, you will have to include the considerable cost of transportation of the H2. With on the spot H2 production from solar PV and wind turbine farms nearby, disperse H2 filling stations can be economically built and will be 100% CO2-emission-free, and can spring up anywhere there are enough solar, wind, geothermal and hydroelectric potential.

In short: It will be years before they know what the actual casualty toll of the Fukushima radiation releases is. Years of waiting, years of stress & years of fighting any effort to build new nuclear plants. The Japanese need energy NOW, not after they've been re-educated by some lengthy, proper public education, campaign.