I found a source on the weight of the hydrogen tanks. 8 kg of hydrogen can be stored in a 140 kg tank at 10000 psi. My new estimate is that the Sequel fuel cell will turn these 8 kg into 120 kWh. If the fuel cell weight 160 kg (estimated from looking at the picture, I know not accurate but better than nothing) we have a 300 kg system that delivers 120 kWh. That is 400 Wh/kg for the hydrogen fuel cell system which is better than the 110 Wh/kg for the A123 battery.

Alternatively you could use a direct ethanol fuel cell. Ethanol contains 8 kWh/kg and the efficiency of the ethanol fuel cell is about 25%. Accordingly for such a system to deliver 120 kWh we need (120/8)*4= 60kg of ethanol or about 15 gallons. If the direct ethanol cell is 160 kg and the ethanol tank with ethanol is 70 kg we get 230 kg for 120 kWh system or 521 Wh/kg. If it is possible to do the ethanol fuel cell at 50 kg the system would be 120 kg for 120kWh or 1000Wh/kg. Lithium is probably not capable ever to get close to that level of energy density.

Note that if the price of hydrogen is $6 kg it costs $48 to fill the tank whereas it will only cost 16*2,1 = $31,5 to fill the comparable ethanol tank.

The third alternative is to use an ICE ethanol genset. An optimized ICE ethanol engine has 40% thermal efficiency and the alternator has about 60% efficiency. Correct me if I am wrong but that should imply a system efficiency of 0,4*0,6 =25% or the same efficiency as the direct ethanol fuel cell. Again correct me if I am wrong but it should be possible to build a 73 kW (the Sequels power) ethanol genset with a weight of 160 kg. If true then this ICE genset would also do 521 Wh/kg.

I would not be surprised to see a PHEV on the market before ultimo 2011 with lithium batteries and a flex fuel ICE range extender. All the technology is ready and they should be able to make a nice SUV doing at least 100 mpg on average for less than 40k (15k of battery, 5k genset and 20k for the rest).

This is the source for the hydrogen tanks http://www.lincolncomposites.com/products.html

Well remember again they already obsoleted the sequal big time with the volt...

Twice the fuel econ a fuelcell better and as powerful but half the mass...

And they are well into gen 5 er or 6? of the fuel cell and who knows what happens this time or the next 2-3 gens before market...

Its entirely possible a car as small as a prious running on the 2012 system could go 480 miles on just 2 tanks.. 4 k of h2.

Hell right noe the are pushing a nearly 2 ton blob of a car 300 miles on that much fuel.

Heck we could see a small car with a chopped fc and 1 tank getting 300 plus mile ranges.

Even at current tech thats just a fc HALF the size of a 4 cylinder engine and 1 88 lb tank... That would fit into anything.

And thats TODAYS tech.. imagine what a 2012 2018 system will manage.

Sequel emits 600 grams of CO2/mile? How absurd!

First of all, as a pure EV, the Sequel takes ~.33 kwh to travel a mile, considering smaller EV's taking ~.25kwh/mi. Assuming FC stack at 60% efficiency as reported for the latest Honda FCX, you divide 0.33 by 0.60 to get 0.55 kwh/mi, not 1kwh, and that ought to knock it down to 330grms/mile.
Secondly, it is not economical nor efficient to make H2 from electricity generated from coal-burning plants at ~35% efficiency! If you multiply this 35% efficiency with the 75% efficiency of electrolysis, overall coal to H2 via electrolysis will be only 26%-efficient. Not very smart!
Make H2 directly from coal gasification, whereby an efficiency of 75% can be obtained, or higher if the heat of this operation can be recycled into further electricity generation. Thus, you can get almost 3x the efficiency of H2 production by direct coal gasification. So, instead of 330 grams of CO2/mile, the actual CO2 emitted per mile traveled will be ~115 gms/mile, or on par with the Prius, even though the Sequel may be 30% larger and heavier!

Cost of H2 at $5.40 /kg using electrolysis at current commercial rate? Not very smart. Using direct coal gasification, H2 can be obtained at ~$2 USD perhaps with including profit. Waste biomass can be substituted for coal to avoid net CO2 emission, or CO2 sequestration may be contemplated.

Take-home message: H2-FCV's using H2 made from coal gasification can be more efficient than BEV's using coal-fired power plants' electricity to recharge.
H2-energy storage is far more compact and lighter than battery electricity, and can be filled up in a few minutes. Until more H2-filling stations will be available, FC-PHEV's would be the best compromise.

Wintermane my point is that hydrogen fuel cells cars will be more expensive compared to the alternatives both with regard to the fuel and the cost of the system. Hydrogen evaporates and you will need a large lithium pack anyway to 1) be sure that you can run the vehicle even after a vacation and in order to 2) prolong the life of the hydrogen cells. I am rather sure that a 73 kW ICE gensets (the Sequels power) can be mass produced for perhaps as little as 3k. You will never see a complete hydrogen fuel cell system with tanks for 3k. However, maybe the direct ethanol full cell system will make it to 3k. These cells are expected to come out for cell phones and notebooks next year.

I forgot to mention the possible use of turbines as range extenders. They can achieve 25-35% efficiency and they will be very lightweight. Anybody knows the weight and likely cost of a 73 kW turbine? A website reference to this would be much appreciated.

It should also be noted that in a PHEV configuration the cost of the fuel for range extension (hydrogen or ethanol) will not be that important since the vehicle will use electricity from the lithium pack for 80% to 90% of the annual miles driven. The cost of the range extender system will be much more important for people’s willingness to buy the car. The availability of the range extender fuel will also be extremely important and that is probably the issue that finally kills’ the hydrogen concept for commercial transportation. There will be other uses for hydrogen full cells so the R&D made now will not be completely wasted.

Well see I look at the trends and the limits.

Lithium has a limiy and isnt oo far from it... its alwats gona be bulky and heavy.

Fuel cells... well just look at what they have done so far... then look at the goals.
H2... goal of 3.5 bucks a kilo... sound nuts? What was it in 2002?

What ARE the limits of fuek cells? How small how efficient how cheap can they become? How cheap could h2 get?

At what point does h2 become cheaper then gas? That day eill come.

At what point is a fc car an ok car? A good one? A great one? Can it ever become the best?

Do we ever manage a battery beyond lithium? How good will that one be and WHEN?

Gona be fun finding out.

"Sequel emits 600 grams of CO2/mile? How absurd!"

You're right it is absurd. It is actually 600 grammes CO2 per kilometre, which is 960 grammes CO2 per mile.

The facts are in the article. They claim a 300 mile (480 kilometre) range from 8 kg of H2, which requires 480 kWh of electricity to produce by electrolysis - hence 1km per kWh of primary electricity. As the current US grid generation mix emits 600 grammes of CO2 per kWh of electricity produced (coal alone is around 900-1,000 g/kWh), that means the sequel emits 600 g CO2 per km if it is refueled with H2 from grid electrolysis.

As for coal gasification - the National Academy of Engineering review (http://books.nap.edu/openbook.php?record_id=10922&page=84) cites an average figure of 5.1 kg C emissions per kg H2 produced, which is 18.7 kg CO2 emitted per kg of H2 produced. As sequel goes 60 km per kg H2, it would therefore emit 312 grammes CO2 per km if the H2 came from coal gasification.

That's the same carbon emissions as a gasoline vehicle that gets 17 mpg (US).

Um you do know its grams per km not mile dont you?

As for the sequak ignoring the fact irs a huge bonking suv and the prius aint and ignorubg the fact they arnt going ro use the sequak fc in any production car and ignoring he fact the sequal has about half a ton of test equipent onboard and forgetting the fact its just one car running only on solar powered h2 and forgetting its 2 years out of datein a fast moving tech andignoring you screwed up miles and kilometers and ignoring the fact its just a prototype and ignorung the fact that anyone willing to buy this kind of car within 10 years likely has green power and ignoring everything else... you didnt make any point at all.

Except that the Sequel currently emits more carbon dioxide emissions than a gasoline vehicle that gets 17 mpg (US). A Hummer emits less CO2 and uses less energy than the Sequel.