Policy can include limiting fuel inefficient vehicles either by regulation and/or taxation policy to encourage vehicle owners to select low fuel consumption vehicles. The benefits of such policy include extending the life of current reserves, reducing emissions and setting the scene for hydrogen fuelled vehicles which are likely to be low power (kW) rating in an effort to reduce the hydrogen quantity to be stored on board and extend the distance travelled prior to refuelling.

Such policy initiatives may also assist the adoption of alternative energy storage such as batteries if consumers expectations with regard to vehicle power and vehicle bulk can be modified.

Scratching deep beneath the surface of the hype, one can find that oil companies have a very pressing problem that can be solved by increased production of hydrogen. Oil refineries that produce useful transportation fuels from low quality hydrocarbons use a process known as hydrocracking to upgrade the high carbon, heavy residue oil to something closely resembling gasoline or diesel fuel.

This process is becoming even more important as regulations demanding lower sulfur content and other improvements in the quality of motor fuels get phased in.

The quantity of hydrogen consumed by hydrocracking is growing quite rapidly and is projected by some US government sponsored studies to range into the billions of standard cubic feet per day.

A massive hydrogen production capacity is going to be needed to supply this material to the oil refineries. Improvements to the production processes that may come from tax payer subsidized research will directly benefit some of the richest and most powerful companies in the world.

It seems to me that companies reporting quarterly PROFITS in the billions of dollars should fund their own research without asking the public to do it for them.

However, like any self respecting big business, oil companies will gladly accept corporate welfare if it is offered. Their political contributions often provide some of their highest return on capital. They get plenty back from the taxpayers in return for supporting political leaders on both sides of the aisle.

My prediction is that after a decade or so of taxpayer subsidized research into improved methods of hydrogen production we will be told that the best way to store and transport the material is to combine it with carbon to make it an energy dense liquid that can be distributed using the existing infrastructure. IOW the hydrogen will be used to upgrade heavy oils and oil from tar sands just like it has been for several decades.

The Sulfur-Iodine Cycle uses thermochemical processes to obtain hydrogen and oxygen from water. The figure right depicts the cycle. In the initial stage, water reacts with iodine and sulfur dioxide to form intermediate products. The intermediate products break down to constituents upon heating, releasing hydrogen and oxygen. The iodine and sulfur are recycled in the system.

This cycle, powered by a HTGR (High Temperature Gas Reactor), may one day supply hydrogen efficiently, without any dependence on fossil fuels. As shown, the cycle uses only energy (as heat) and water as inputs. The only products are hydrogen and oxygen and some reject heat. With a predicted efficiency of ~50 percent, the cycle is more attractive than electrolysis according to research by the Japan Atomic Energy Research Institute (JAERI). JAERI has successfully conducted continuous production experiments using S-I technology. Scale up will require significant additional research and development in the following areas.

* Large scale components will have to be constructed of materials able to resist the highly corrosive and high temperature environments encountered with the S-I process. * Solution concentrations are critical to the success of the cycle, and these parameters currently are difficult to control in large scale. * Process improvements using membrane technology for the HI decomposition step need to be refined.

This process or something similar is likely to become the primary fuel source for all uses. And with rational regulations could likely compete evenly with hydrocarbon fuel production right now.

"In the USA, this hydrogen industry produces 11 million tonnes of hydrogen a year with a thermal energy equivalent of 48 GWt. In so doing, it consumes 5% of the US natural gas usage and releases 74 million tonnes of CO2."

Your logic falls apart when you consider that it takes more than one unit of energy (from some other source) to produce one unit of energy in hydrogen. Hydrogen is not an energy source, but merely an energy carrier, and it requires a substantial sacrafice (in efficiency) even to convert the other energy source into hydrogen energy.

You say that finding and separating out the hydrogen at a local site is "easy and cheap" whereas delivering traditional energy sources (e.g. fossil fuels) to that site is "difficult and expensive". This is clearly not true given that you'd have to deliver 2 or 3 units of fossil energy to produce one unit of hydrogen energy at your location. And the (above) fossil fuel approach is the LEAST expensive way to make H2. At present, other (renewable) energy sources are far more expensive than are fossil fuels (whether used directly, or to make hydrogen). Creating H2 locally from biomass would be much more expensive, and the land use requirements would be enormous.

You may have a point about using local electrolysis. It could very well be true that it is cheaper and more efficient to ship the energy in the form of electricity, over power lines, than it is to ship the energy in the form of hydrogen, through a pipeline system. This is especially true given that the power grid already exists, whereas the hydrogen distribution infrastructure would have to be built, at great expense. Also, if hydrogen is mainly produced via natural gas reformation (likely to be the case in the short-to-mid term), it may be more efficient to use the existing natural gas distribution infrastructure, and perform the gas reformation near the point of demand, instead of reforming all the H2 at centralized facilities, and shipping the H2 over some new distribution system. For example, if we were to use H2 fuel cell powered cars, I would envision the first adopted approach being reforming natural gas into H2 at the service stations.

Indeed, decentralization (and the hatred of large centralized utilities and other institutions) has an almost religious appeal for a fraction of the population. These are precisely the influences that should NOT be allowed to influence public policy, however, especially given that people who feel strongly about such issues already have the right to go with a personal system (whatever the cost may be). Decentralization has its merits, but it needs to be evaluated rationally, based upon those merits (and possible drawbacks).

Using grid power to locally produce (via electrolysis) hydrogen wouldn't even really count as a distributed energy source, since the power is still being generated at a large centralized plant, and the power grid is being used to distribute the power. And why would anyone use grid power to generate hydrogen, and then use the hydrogen to generate electricity again (winding up with only ~35% of the power they started with)? Electrolysis of hydrogen only makes sense as a source of H2 for vehicles. We will NEVER use hydrogen as a way to store electricity, as it is far more expensive than several other storage approaches. The best approach, of course, would be to save our limited gas supplies for use in inexpensive peaking plants (as opposed to using it for baseload generation...).

Using natural gas locally to create hydrogen, to power a car or stationary fuel cell, better qualifies as "distributed generation" as many of the normal benefits of distributed power apply. These include reduction in reliance on the grid (and the associated power losses) and the potential to make use of most of the waste heat given off by the reforming process. Any other system that uses natural gas locally (such as a stationary fuel cell directly powered by gas, or a microturbine, etc..) would be equally eligible for the "distributed generation" label.

After the gas runs out, the only real distributed energy source would be solar PV, but that power would be used directly, and not to make H2, since it is generally produced at the time of peak demand. Wind may be used to generate H2, especially given that this largely alleviates its intermittantcy problem. Wind, however, is not really "distributed", as it is usually generated in large, centralized farms that are owned by utilities, etc... Thus, after gas is gone, I do not see H2 being generated in a distributed fashion. The only exception to this prediction is that, if we find H2 distribution from centralized sites to be a nightmare, we may use local electrolysis to generate H2 for use in vehicles (but for vehicles ONLY). Even this, however, is less likely than us just compromising and going with synthetically created natural gas or methanol to power our cars (where a carbon source is combined with water, using an external source of heat, to create hydrocarbons).

If the wall tension counteracting the gas pressure were borne by steel, the mass fraction of hydrogen would not be "several percent of the total weight of the tank", it would be substantially less than one percent. Researchers have made such tanks out of carbon filament composite, and in that case the H2 mass fraction can indeed be several percent, but costs so far have stayed in the tens of thousands of dollars per tank. Researchers are crying out for public funding with which to attempt to reduce this. If I have any opinion as to the merits of that request, it is not included in this posting.

Liquid hydrogen tankage is less than half as bulky as 10-kpsi gaseous, and need contain only a few tens of psi. If the current hydrogen enthusiasm were not ... of a certain nature, I don't think high-pressure ambient-temperature containment would be being pursued.

--- Graham Cowan http://tinyurl.com/ymps -- how motoring gains nuclear cachet

Y'know, we don't need anyone to point out (repeatedly, at every turn, ad ...) the issues which need to be resolved to get off fossil. We all know that eventually, be it 30 years or 300 years, autos WILL stop burning fossil fuels. Why not do the planning in advance?

20" by 32" by 5.5" is 57.7 litres. Packing 10 STP m^3 of hydrogen in there is a 170-fold volume reduction. Liquid hydrogen tanks, *including* their thick walls, reduce volume 700-fold. Metal hydride is safer, maybe safe enough that you plan to spend time on the factory floor next to hydride-powered forklifts, but much heavier and, as your data show, less compact.

It seems to me I'm doing some of the advance planning you mention, and we do in fact need people to point out the various places where, when genuine interest in hydrogen power goes one way, the recent and soon-to-be-forgotten hydrogen enthusiasm goes the other-- as in this instance, liquid hydrogen versus various bulkier, heavier, more complex methods. I don't believe liquid hydrogen is the answer, but if it isn't, how much less must they be.

--- Graham Cowan http://tinyurl.com/2cmge -- how motoring gains nuclear cachet