Yes, hydrogen fuel cells as a power source are not as efficient as plug in electric cars as a system, but where many people fall down is by not considering energy density. We currently use petrol/diesel because liquid hydrocarbons are extremely energy dense, petrol has an energy density of 13,500 Wh/kg, Lithium ion batteries have an energy density of 350W/kg. This is why the Tesla car needs 500kg of batteries, compared to the C63 which might need 50 kg of fuel.

So for vehicles that require long range, plug in electrics are limited. Yes battery technology will improve, but so will hydrogen storage and fuel cell efficiency. As for hydrogen, its energy density is 39,000Wh/kg, the difficulty is that a litre of H2 at 150 bar (similar pressure to a scuba tank) stores 405 Wh/L, because hydrogen is so light. So thats why the Honda clarity stores H2 at 2000 bar.

So you can see that as technology improves we will be able to store significantly more hydrogen into smaller cylinders at higher pressure, probably faster than we can improve battery technology. Hydrogen fuel cells can be easily refueled (same system as LPG), and unlike battery technology fuel cell technology is still very early on in the development process, it will improve significantly with time.

Yes to generate hydrogen gas takes more energy than if you had just directly put that into a plug in car, but if the energy source is renewable, then where’s the loss? If you power the hydrolysis with solar or wind, then energy efficiency is not as important, as the world has more than enough energy, its just we currently use extremely limited resources for energy. With hydrogen fuel cells, you are trading in energy efficiency of the system with energy density, and in this case, energy density equals range and power. Thats why I think Honda is on the right track with using hybrids as an interim solution while we get the hydrogen infrastructure ready.

I like some of you also thought that hybrid cars would be an intermediate step between the future, which is hydrogen.

However, I think hydrogen as a potential automotive fuel will probably never match plug in electric cars.

www . efcf . com/reports/E04.pdf

To summarise that article, which is from the european fuel cell forums:

A car running on compressed gas hydrogen has a total efficiency of 22%

A car running on liquified hydrogen – 17%

Modern diesel cars – 25%

A hybrid diesel car – 33%

Plug in full electric car – 66%

I did notice that the article assumed the production of hydrogen would be from electrolysis (efficiency 0.7), and I think there are different industrial manufacturing processes that would be more efficient, but even if take away the energy loss from electrolysis you still only have hydrogen cars at 32% efficiency.

Hydrogen would obviously be more convenient though as you would presumably be able to fill your tank up much like you do with petrol/lpg, whereas a plug in electric car might take hours to recharge (at best).

So in summary, yes full electric cars are the answer, but the battery technology to make them viable is still some time off. This is where GM have it right. They have made a full electric car in the Volt, however as the battery technology isn’t available yet to give the Volt an acceptable range on the batteries alone, they have had to put in a small petrol motor to provide additional charge. When the battery technology becomes available to give the volt the desired range, while also being light and affordable, GM can quite easily remove the petrol engine. This differs from both the prius and the Honda which both rely on the petrol engine to operate, the volt on the other hand can operate without the petrol engine all together, it just has the petrol engine to extend the range. This is where I think GM’s technology is superior to both toyota’s and honda’s. People have a problem with GM and automatically assume that if there are three hybrids, one from GM, one from Toyota and one from Honda, then the GM one must be the least advanced, its people’s natural perception. But in this case, the Volt really is the most forward thinking hybrid of the lot and is only a short hop skip and a jump away from being a full electric vehicle, unlike Toyota and Honda’s which are still fully integrated with their petrol motors. If the Volt had Mitsubishi’s in wheel electric motors then it would be truly visionary!

I still think compressed hydrogen as the fuel in a fuel cell is not dense enough and there are other better fuels such as methanol.

NOW samR, & for anyone else who is interested. Im gona give u the links for 2 informative Clips of Hydrogen Cars. From probably the 2 best Motoring shows.

TOP GEAR
& Fifth Gear

Now for the top gear clip on the HiWire, if u wana get straight to the point. skip foward to 0:50 seconds play time

& here is the link

w w w (DOT) youtube (DOT) com /watch?v=hrp9N1soo0o

& for the Fifth Gear clip on the Honda
Here is the link

w w w (DOT) youtube (DOT)com /watch?v=pYgLukcssv4

FOR BOTH LINKs TO BOTH CLIPS copy them, then paste them in the address bar, get Rid of the spaces & REPLACE (DOT) with . & enjoy

I don’t think hydrogen fuel cell will be utilised in the short term, more likely to be a long term solution. I like the idea of battery based electric car, but the range limitation will always be a problem.

In the short run, hybrid and plug in hybrid will be the solution, but in the long run, hydrogen fuel cell will become the dominant form of transport. However, all these alternative fuel vehicles are still quite a long way into the future, and until they can bring the prices down enough to compete with petrol powered cars, they will remain a niche product.