Wouldn't it be better to use the hydrogen to run a fuel cell on board the Prius to run the electric motor, instead of burning it in an inefficient ICE? You would still use gasoline but the range would be greatly extended. This way the ICE is helping bridge the gap to an eventual all electric fuel cell powered vehicle. Just a thought.

Now we are talking: a Diesel, Lithium, plug in Hybrid.
If you could get the diesel to start nice and smoothly, you would have a winner.
The objections to diesel fumes would be reduced as the engine would be used very little.
"All" we need are a many cycle large Lithium battery and a smooth start diesel engine.
Might add some ultracaps for better braking regeneration.
Might cost quite a bit until production picked up.
But these ideas are not pie in the sky: they are pie on the next table.

They are ahead of schedual on getting hydrogen cheaper then gasoline by thier deadline.

They are also ahead of schedual on getting the storage method good enough by deadline.

They are also ahead of schedual on making the fuel cell itseld durable and cheap.

Nuff said.

It's a good step, hydrogen will just be an intermediary step until battery technology can displace it anyway (after all, hydrogen fuel cells are just a refillable chemical battery).

But the lower power ratings of ICE hyrogen are horrible, I don't think this car could work well in mountains or hilly areas. The ICE barely makes up for the kWs drained by the 2 electric motors.

If hydrogen can be made from carbohydrates at $3/kg, then the 50 miles/kg economy of this vehicle works out to a fuel cost of 6 cents/mile.  This is roughly competitive with gasoline.

They still need better range (and what does the weight of the gas cylinders do to vehicle capacity?), but that's not too bad.

H2 is a very inefficient energy carrier. If made from electricity (possible renewable sources) via electrolysis, around 50% is lost. Then it must be compressed (~15% loss?) and transported, usually inefficiently as a gas. Finally, if burned in a fuel cell, 40-50% of what's left is lost; 70+% in an ICE. All this gives an overall efficiency of less than 21% (<13% with an ICE), compared to around 60% for a battery electric (BEV). And the H2 Prius' 80-120 mile range is equivalent to that of a pre-Li-ion BEV. Other sources of H2 are natural gas, oil, and coal. All release greenhouse gases (coal especially), natural gas is beginning to get imported as well as oil, and natural gas would be much more efficient to use in an ICE directly instead of first converting it to H2.

Carbon output of a BEV (or PHEV, see below) running worst-case on coal-produced electricity matches that of an efficient gasoline hybrid and is 50% better than an ordinary ICE; on the US 50% coal mix, it is 40% better than the hybrid; and in California, it is at least 80% better. Natural gas (24-39% BEV well-to-wheels efficiency and clean but beginning to be imported), coal (dirty but plentiful), and hydro (renewable but harm to rivers) are the major fuel sources for U.S. electricity. Some states like CA have laws mandating an increasing percentage of renewables in electricity generation every year, and individuals can put solar panels on their homes and businesses to remove all pollutants from the EV fuel source. BEVs and PHEVs would charge mostly at night, using unused grid capacity (making the grid more efficient and matching most windpower output) vs. the need to create an H2 infrastructure from scratch.

A pluggable hybrid (PHEV) could get the efficiency advantage of BEVs for much of the vehicle's mileage, then use e.g. cellulosic ethanol (or H2 if necessary) for its range extender fuel. We don't have nearly enough farm wastes, forest brush, and room to grow e.g. switchgrass to make enough carbon-neutral cellulosic ethanol to fuel all our vehicles, but we would if they were PHEVs!

I just found an article claiming 66% efficiency for electrolysis, the highest I've ever seen. On the other hand, most fuel cells run at closer to 30% efficiency; the 50% I used is more of an ideal projection. And even at 66% and 50% my relative efficiencies argument still holds.

Renewables have no feedstock cost, but do have a capital cost that must be amortized. We need to use renewables as efficiently as possible, and the battery electric portion of a PHEV's range is 2 to 4 TIMES as efficient as via the H2 cycle, even using fuel cells (vs. H2 ICE) -- meaning that kWh of renewable energy goes TWICE to FOUR TIMES as far via batteries than via H2!

(I may not continue to monitor and respond further to this blog)

Your appraisal of PHEV vs. ethanol is spot-on according to my own calculations.  Bravo.

mike, any updates on the PHEV priuses being studied by the aqmd?

I will park that car, let me have it. Safety, etc. systems can always be developed, as can fail safes and secondary or tertiary, or quaternary seals if need be.