all the calculation, safety testing, fuel station safety and other precaution taken by big companies like honda and toyota. I am not going to declare one technology (considering I am not techno guy at all) better compare to others considering none have produce mass market car i.e. $20 or $25 car charge or refuel under 5 to 20 minutes for regular customers (who has no home base recharging or fueling capabilities)
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USA Today says fuel cell vehicles are "Electrics Done Right"
- Thread starter Atebit
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swaltner
Active Member
Yes, but it takes energy to move that container around. Currently, this would likely be in the form of diesel fuel for delivery trucks, so this could be a conversion of that into equivalent kWh of electricity.
To be fair, neither BEVs nor HFCVs are using completely renewable energy.
If we start with Natural Gas, it looks more like:
BEV:
100 kWh of natural gas ->
50 kWh of electricity ->
47 kWh of electricity at your house ->
40 kWh of energy in your battery ->
36 kWh of motive energy
HFCV:
100 kWh of natural gas ->
75 kWh of H2 ->
68 kWh of compressed H2 ->
62 kWh of compressed H2 at the station ->
31 kWh of electricity in the car ->
28 kWh of motive energy
Batteries are still more efficient at using natural gas, but only by 1.5X, not by 3X.
and BEVs can use renewable energy. HFCVs can only sensibly use natural gas; an HFCV using renewable energy to electrolyze water is environmentally somewhat worst case, because if that renewable energy were put on the grid instead, far fewer fossil fuels would be required for the grid.
Because it leaks out. Much is lost over time just sitting in it's sealed container. It's a very tiny molecule and so it can just slip right through (diffuse) the gaps in whatever material the container is made out of.
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The energy source powering BEVs can be completely renewable. A BEV owner can install rooftop solar sufficient to completely offset BEV charging needs. I estimate that one 250W solar PV panel per 1000 miles of annual driving is needed (I have 32 of these panels). Many BEV owners in California have installed solar, about 40% of them according to a state survey. Also, in some regions where BEVs are popular, nearly all grid electricity comes from renewable energy.
Point is a BEV owner has realistic options to charge with completely renewable power.
On the other hand, a H2 FCV owner cannot realistically install a system at home to generate and compress completely renewable H2 for his car. And he may have no other options to fuel up with completely renewable H2. FCV fueling stations in California are being required to have at least 1/3 renewable H2, but the rest is likely to be natural gas SMR H2.
Peter_M
Member
Agreed, and to add to that, in many areas, the electricity supply mix is much cleaner. In Ontario, where I live, natural gas is less than 30% of the mix and there's no coal or other fossil fuels in the mix. And at night, when most electric car charging happens, the gas portion of the mix is even less; close to zero some days.
So in some areas today, a HFCV is only a bit worse than a BEV, but in other areas, it's much worse, and it will only get worse over time as the supply mix gets cleaner. This cleaning of the supply is happening fast in Ontario - the gas portion of the mix is already much lower than the 30% number the IESO quotes on their web site. We will see this sort of thing at varying paces everywhere, unfortunately sometimes limited by political pressure and vested interests.
I have solar on my roof, and its generation easily covers the consumption of my car. However, I think it's ridiculous to claim that my car runs on renewable electricity. The solar panels on my roof decrease the amount of fossil fuels that PG&E burns while my car increases the amount that PG&E burns. That the former is greater than the latter is irrelevant: if I didn't drive, worldwide consumption of fossil fuels would decrease, therefore my car is powered partially by fossil fuels.
I believe this to be the case pretty much everywhere. You could construct an isolated system that isn't related to the grid, but then any excess capacity is wasted, so that's just silly.
I agree with you that BEVs can use renewable power that HFCVs can't, but
in today's world, if you drive a BEV, you increase the consumption of fossil fuels.
If you drive a HFCV, you increase that consumption noticeably more than if you drive a BEV.
In my case, I sized my solar PV system for both my home usage AND BEV usage.
More than two years ago when I initially submitted info about my solar PV system to PG&E, their initial response was that my PV system was substantially oversized since it would produce a lot more electricity than my home had consumed in the previous year. I explained my plans and they were cool with that. A year later when I got the Model S I added some additional PV panels to my system.
On a net basis most of my BEV charging is supplied by my solar PV system, not fossil fuels. I would not have installed a solar PV system as large as I have if I wasn't getting a BEV.
roblab
Active Member
To be fair, do any natural gas generators use other than combined cycle? I know that many nat gas gens are new, so I would expect they would. And combined cycle is up to 60% efficient.
which gives us 43 kWh motive energy from gas to 28 kWh from hydrogen. Well, it's better, anyway.
And, yes, where I live, the mix is nat gas, water, wind, geothermal, and my house tosses in solar. And I have a hard time thinking that I only get half efficiency using batteries.
I have heard gas engines (ICE) are only 18% efficient, as from power in tank to delivered to road. So it is obvious there are many ways to measure efficiency. You're giving me 79% battery to road, yet I hear 85% some places. Oh well.
I thought we were assuming 90% battery to road in the above?
I tried to look up natural gas plant efficiencies before writing the above post. It looked like 40% efficiency was a reasonable average for existing natural gas power plants. As you say, newer plants (e.g., GE FlexEfficiency 60) can get up to 60% efficient, but it's unclear to me if that 60% was for typical usage, or if the 60% was more best case. I figured 50% was more fair.
The fuel cell folks are touting more than 50% efficiency of their fuel cells, too, but again it's unclear to me how realistic the higher numbers are.
Gasoline engines at 18% total efficiency and a BEVs at 36% total efficiency seem reasonable to me.
Is that 18% for a 24-30 mpg car? I would think that a Prius would be higher.
AC1K
Member
i think we all forgot that natural gas doesnt magically appear, if you want to convert natural gas to hydrogen, you need to extract the natural gas first, does anyone have the energy figures required to do this?
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