Yeah I know some of you are gonna want to pick the following to s***, don't bother, it's just a hack - the numbers are pretty much ramdom(mostly from wikipedia
)
Whats the efficiency of a petrol engine 5%? (I honestly don't know!)
Ok so a BLDC (Brushless DC) motor for an electric vehicle can be had at around 95% efficiency, but we need a hydrogen fuel cell to generate the electricity, so whats the efficiency of a fuel cell? I saw somewhere it's around 40%
So our 95% is now down to 38% (0.95 x 0.4) not bad.
The power needed to split the water to hydrogen(and oxygen) had to come from somewhere though, lets say its from a dirty old coal fired power station with steam turbines and wotnot... I just read they're around 30% efficient, so we're now at about 11%, not looking so good now.
I also read that the best diesels are now around 20% efficient, seems kinda high but ok we'll use it.
Theres no silver bullet, the Hydrogen fuel cell system(TOTAL, including coal fired power) seems to be around(roughly!) twice as efficient as a petrol engine, and definitely less pollution(they scrub furnace exhausts.... apparently) but uses rare metals and there's the hydrogen storage issues, so gonna be pricey until a better system is invented. Lithium cells are looking good(A123 style, as used in the Tesla sportscar) and probably around 80% efficient, but their life cycle is kinda short(2000 cycles?) and they're still just a tad expensive.
Looks like Diesel is the immediate future, for a little while anyway, something better will come eventually. We're on the brink, gonna be an interesting couple of decades ahead.