I'd just like to clarify something, because I felt that the following, from another thread, was an unnecessarily dismissive POV on the viability of domestic hydrogen fuelling:
That's only as long as a piece of string. What rate of compressed flow do you think a home-fueler needs?
Yes, there are existing home systems that can deliver the equivalent of a tank's worth of compressed CNG from a domestic feed over a couple of hours. And, yes, the slower ones deliver no faster than a gallon equivalent in an hour.
But a good fuel cell can achieve 55% thermal efficiency, so that's around 20kWh per hour in terms of ultimate traction energy to the road. If you have a 7kW home charger, that'll be 6kWh or so ultimately delivered to making your car go.
So if home charging EVs is considered viable, what's wrong with CNH and hydrogen home fuelers?
But there are two further points, a) you could buy a bigger CNG/H2 fueler, it is easily expandable. That may not be so for a domestic electricity supply, and b) you could have a storage tank system which is recharged over 24 hrs and you fill you car in a minute because if it is already compressed you only need to transfer it from one vessel to the other in its compressed form.
Next point is that if you were using solar-electrolysis to generate the H2 then this would be a slow process anyway. Even a small compressor system would likely keep up with your H2 generation from a domestic solar array. So you'd want a storage tank anyhow. And why not! Storing your excess solar energy in the form of hydrogen could enable several new ways of managing your domestic energy.
The next point is that electrolysis is not the only way to generate H2. You could reform CNG, there are even currently domestic heating systems on trial that perform steam-reformation on domestic CNG suppy. This is exothermic so can double up to heat your house in winter, or could run a Sterling engine generator.
Also to mention, it makes no sense not to have a good sized battery pack on a hydrogen car. This is because it is a huge complication and expense to have a fuel cell fully sized to your maximum power requirement. You'd simply never do this. Instead you'd have, say, a 10kWh battery pack with a 10kW fuel cell.
There will be NO commercially viable hydrogen cars without a substantially sized battery pack, so ultimately there will be no difference between a 'hydrogen PHEV' and a 'BEV hydrogen REx'. And anyone who builds a hydrogen car without adding a charging socket on it to access that battery pack is a dim-wit - though Toyota could still surprise me as they seem to really hate 'plug-in'. But that's Toyota's issue, not the technology's!
I can see a bright future for home fuelling of hydrogen PHEVs if the safety regulations are proportionate and can get it right. There is no need to think 'either-or'. Hydrogen and electron power go hand-in-glove. Be open-minded. There is a world of possibilities opening up for both domestic and EV energy, don't miss it!!
I will mention that in no way am I 'pro-hydrogen'. I have my doubts too, but not over these issues. We will see better battery technology, but not for a long while yet. And even then, range extending 'fuelled' options will still figure, no matter how big a range BEVs get, because it will always be a 'fall-back' to throw some sort of fuel into a car when the journey is too far or to cover for electrical infrastructure failures or over-subscription. However, it is clear that there is still a strong argument for hydrogen, and integrating it with domestic energy management is, IMHO, one of those strong arguments.
Flashman said:
That's only as long as a piece of string. What rate of compressed flow do you think a home-fueler needs?
Yes, there are existing home systems that can deliver the equivalent of a tank's worth of compressed CNG from a domestic feed over a couple of hours. And, yes, the slower ones deliver no faster than a gallon equivalent in an hour.
But a good fuel cell can achieve 55% thermal efficiency, so that's around 20kWh per hour in terms of ultimate traction energy to the road. If you have a 7kW home charger, that'll be 6kWh or so ultimately delivered to making your car go.
So if home charging EVs is considered viable, what's wrong with CNH and hydrogen home fuelers?
But there are two further points, a) you could buy a bigger CNG/H2 fueler, it is easily expandable. That may not be so for a domestic electricity supply, and b) you could have a storage tank system which is recharged over 24 hrs and you fill you car in a minute because if it is already compressed you only need to transfer it from one vessel to the other in its compressed form.
Next point is that if you were using solar-electrolysis to generate the H2 then this would be a slow process anyway. Even a small compressor system would likely keep up with your H2 generation from a domestic solar array. So you'd want a storage tank anyhow. And why not! Storing your excess solar energy in the form of hydrogen could enable several new ways of managing your domestic energy.
The next point is that electrolysis is not the only way to generate H2. You could reform CNG, there are even currently domestic heating systems on trial that perform steam-reformation on domestic CNG suppy. This is exothermic so can double up to heat your house in winter, or could run a Sterling engine generator.
Also to mention, it makes no sense not to have a good sized battery pack on a hydrogen car. This is because it is a huge complication and expense to have a fuel cell fully sized to your maximum power requirement. You'd simply never do this. Instead you'd have, say, a 10kWh battery pack with a 10kW fuel cell.
There will be NO commercially viable hydrogen cars without a substantially sized battery pack, so ultimately there will be no difference between a 'hydrogen PHEV' and a 'BEV hydrogen REx'. And anyone who builds a hydrogen car without adding a charging socket on it to access that battery pack is a dim-wit - though Toyota could still surprise me as they seem to really hate 'plug-in'. But that's Toyota's issue, not the technology's!
I can see a bright future for home fuelling of hydrogen PHEVs if the safety regulations are proportionate and can get it right. There is no need to think 'either-or'. Hydrogen and electron power go hand-in-glove. Be open-minded. There is a world of possibilities opening up for both domestic and EV energy, don't miss it!!
I will mention that in no way am I 'pro-hydrogen'. I have my doubts too, but not over these issues. We will see better battery technology, but not for a long while yet. And even then, range extending 'fuelled' options will still figure, no matter how big a range BEVs get, because it will always be a 'fall-back' to throw some sort of fuel into a car when the journey is too far or to cover for electrical infrastructure failures or over-subscription. However, it is clear that there is still a strong argument for hydrogen, and integrating it with domestic energy management is, IMHO, one of those strong arguments.
