Why not use electricity directly instead of hydrogen

[HyperTechno]

As far as I know, that's basically it. You lose in efficiency by using hydrogen as an intermediary, but the idea would be that it would be as easy to use as gasoline. The main problem is that is way more dangerous than gasoline.

But, the battery technologies develop so fast and we'll see batteries that can be charged faster than the li-ion batteries and more denser in energy than the li-ion batteries in near future. And by then there would be no reason to even worry of hydrogen.

 

[mheslep]

Theoretical faster charging batteries need i) a connection that can provide a faster charge, and ii) a system to reject the heat of the charge. Tesla's chargers are already 120 KW, so perhaps a 1 MW grid connection at all those stations, which is expensive.

A 10 gal/min gasoline pump delivers chemical energy at 20 MW. I don't see people connecting 1MW charge cables to their cars, which dissipate 50 KW of heat while charging.

 

[litup]

Please do, I know nothing about hydrogen and I love to learn.
See, I never thought about that and turns you are right. Will go to bed a little bit more knowledgeable tonight.
After a simple search, apparently they can go well below the 1500 lb mark rather easily. From 45 kg (@145 L) to 215 kg (@55 L) for 3 kg of H₂ (130 mi range) and from 90 kg (@320 L) to 222 kg (@200 L) for 7 kg of H₂ (435 mi range). The source is from 2002 and there seems to be room for improvement.
Yeah, they don't say how much they cost ...

Nobody is considering using H2 as a compressed gas. The way it would work in the real world is storage of H2 in a metal/organic framework, where the pressures and temperatures involved are a lot less than brute force gas compression. Anyway, if compressing was found ultimately to be the only viable alternative, the tanks would not have to be 2 inches thick. I worked with a company that made small cannisters of Xenon gas at 12,000 PSI and they were not very thick, nothing like 2 inches thick. Still, I think solid state capture of H2 is how it will be done, a lot safer than simple compression.

 

[gmax137]

Anyway, if compressing was found ultimately to be the only viable alternative, the tanks would not have to be 2 inches thick.

Yes, already clarified that I was stuck in the steel pressure vessel paradigm... The real question we were trying to work out is, what is the weight of the hydrogen storage system that is equivalent to the current sheet-steel tank and its 25 gallons of gasoline? Do you have a kg/joule value for the metal/organic hydrogen storage? Thanks!

 

[mheslep]

...the tanks would not have to be 2 inches thick. I worked with a company that made small cannisters of Xenon gas at 12,000 PSI and they were not very thick, nothing like 2 inches thick.

The differences between Hydrogen and Xenon are relevant. H2 is a tiny molecule that works it's way into the solid matrix of the structural containment, so plastic liners are commonly used. Also, if the tank is to used outdoors, not in a temp/humidity controlled lab, and where it's frequently charged and discharged, thermal insulation might be required.

 

[HyperTechno]

Theoretical faster charging batteries need i) a connection that can provide a faster charge, and ii) a system to reject the heat of the charge. Tesla's chargers are already 120 KW, so perhaps a 1 MW grid connection at all those stations, which is expensive.

A 10 gal/min gasoline pump delivers chemical energy at 20 MW. I don't see people connecting 1MW charge cables to their cars, which dissipate 50 KW of heat while charging.

Well I have this question . Speaking of globally , wouldn't a large amount of energy be wasted in the transportation if hydrogen powered vehicles are used due to the energy loss that happens when separating hydrogen by water , (speaking of the purest form of extracting hydrogen- using renewable energy to separate hydrogen from water )

 

[HyperTechno]

And then another runner in the race is road transmission: Store small amounts of power in the car, and once you get on the highway, draw electricity from wires in the road.

Well it needs an expensive totally new infrastructure which can make that very unpractical.

 

[HyperTechno]

True but storage is a solvable problem. H2 distribution still has no feasible solution, nothing remotely close.

Extraction of hydrogen from water using renewable energy locally would solve the problems related to the purity and transportation. Only a water supply is needed.

 

[mheslep]

Well I have this question . Speaking of globally , wouldn't a large amount of energy be wasted in the transportation if hydrogen powered vehicles are used due to the energy loss that happens when separating hydrogen by water , (speaking of the purest form of extracting hydrogen- using renewable energy to separate hydrogen from water )

H2 efficiency from well to wheels is much lower than that of pure electric vehicles. Regardless, EVs remain slower to charge and have less range than h2 or liquid fuel vehicles.

 

[mheslep]

Extraction of hydrogen from water using renewable energy locally would solve the problems related to the purity and transportation. Only a water supply is needed.

Not only. A multi MW utility connection and a multi MW electrolyzer and a multi MW compressor are needed. To appreciate the scale involved, start with the fact that *one* gasoline pump delivers 20 MW of chemical energy, a ten pump highway station perhaps 200 MW. Alternative transportation systems may be a little more efficient, but must operate on the same order of magnitude of energy consumption.

 

[Algr]

Well it needs an expensive totally new infrastructure which can make that very unpractical.

Many cost estemites dishonestly assume that you'll start by tearing up a brand new road to put wires in. But highways have to be rebuilt and replaced on a regular basis. If you add wires when the road is scheduled to be redone anyway, the cost is magnitudes lower. You pay for the electricity the same way you pay for the asphalt. Or include some kind of meter in the car.

 

[rootone]

Electrified road transport would not make any sense done on the basis of a bit here and a bit there whenever the roadway needs maintenance.
There would need to be complete routes between cities (or within cities), otherwise it's a pointless exercise.

 

[Algr]

You don't need complete routes. You just need the gaps to be less then the battery range of the car.

 

[mheslep]

Many cost estemites dishonestly assume that you'll start by tearing up a brand new road to put wires in. But highways have to be rebuilt and replaced on a regular basis. If you add wires when the road is scheduled to be redone anyway, the cost is magnitudes lower. You pay for the electricity the same way you pay for the asphalt. Or include some kind of meter in the car.

Shifting the transportation system (US ~250 million vehicles) to an alternative is much more difficult than, say, switching from land-lines to mobile phones in communications back in the 1990s. The problem with transportation is that a vehicle owner rightly expects the vehicle to be operable anywhere on the continent, so that a notional electrified road system has to be available everywhere, nearly simultaneously. When mobile phones and networks were under early development, one always had the fall back of using the land lines when roving out of the area. And an investment of a few hundred dollars in a phone versus several tens of thousand dollars in a vehicle made the lack of availability more tolerable. That is, electrified roads in east coast city A may accommodate an e-vehicle owner there. The same owner who moves to west coast city B can't tolerate a useless vehicular there, with road updates a decade or two away.

 

[mheslep]

You don't need complete routes. You just need the gaps to be less then the battery range of the car.

Same all-at-one problem as rootone mentioned, just a bit smaller scale.

 

[Algr]

. The same owner who moves to west coast city B can't tolerate a useless vehicular there, with road updates a decade or two away.

But none of those vehicles are ever useless. Right now the lowest cost (Total cost of ownership) car in the US is one of Toyota's Priuses. Adding a road pickup to that car would add maybe $500 to the cost of the car, and then you'd save money with reduced fuel costs. All electric cars with 80 mile ranges are also selling today. Even a single electrified highway would make such cars more appealing to people who drive on that highway every day. And you can actually sell your car if you move. These problems aren't as insolvable as you make them out to be.

 

[HyperTechno]

Many cost estemites dishonestly assume that you'll start by tearing up a brand new road to put wires in. But highways have to be rebuilt and replaced on a regular basis. If you add wires when the road is scheduled to be redone anyway, the cost is magnitudes lower. You pay for the electricity the same way you pay for the asphalt. Or include some kind of meter in the car.

So, how the cars receive electricity?

 

[HyperTechno]

Not only. A multi MW utility connection and a multi MW electrolyzer and a multi MW compressor are needed. To appreciate the scale involved, start with the fact that *one* gasoline pump delivers 20 MW of chemical energy, a ten pump highway station perhaps 200 MW. Alternative transportation systems may be a little more efficient, but must operate on the same order of magnitude of energy consumption.

Still, won't the local Extraction be more efficient and convenient than a centralized Extraction facility that needs transportation? The initial costs may be higher but considering the difficulties in transportation, wouldn't that be more convenient?

 

[mheslep]

Still, won't the local Extraction be more efficient and convenient than a centralized Extraction facility that needs transportation? The initial costs may be higher but considering the difficulties in transportation, wouldn't that be more convenient?

Maybe so. Either way, installing an national h2 fueling system is going to be very expensive.

 

[mheslep]

But none of those vehicles are ever useless. Right now the lowest cost (Total cost of ownership) car in the US is one of Toyota's Priuses..

The hybrid Prius available in the US does not have a full power electric motor. An electrified highway doesn't add much value to such a car.

For that matter, any plug in hybrid that does have a full power e motor (e.g. Volt) pretty much solves the clean transportation problem, or 90% of it anyway, and I expect much more cheaply than electrifying all the highways, even incrementally.

 

[rbelli1]

start with the fact that *one* gasoline pump delivers 20 MW of chemical energy

Also consider that the pump is not running 24/7. It will only be at 20MW for a small percentage of the time. You still end up with a rather large number for the average daily usage of even a single pump. The wire to wheel efficiency is going to be embarrassing for hydrogen in any case.

BoB

 

[HyperTechno]

Maybe so. Either way, installing an national h2 fueling system is going to be very expensive.

Yeah. Of course it's expensive. About 2 million $ per filling station. One reason for HFCV to progress much slower than the pure Evs.

 

[mheslep]

Yeah. Of course it's expensive. About 2 million $ per filling station. One reason for HFCV to progress much slower than the pure Evs.

Much more than that for a station with local h2 production, equivalent to the energy flow of an existing gasoline station.

 

[HyperTechno]

Much more than that for a station with local h2 production, equivalent to the energy flow of an existing gasoline station.

Yeah. And I don't think the existing hydrogen filling stations have the energy flow of a gas station.

 

[Algr]

The hybrid Prius available in the US does not have a full power electric motor. An electrified highway doesn't add much value to such a car.

Yes it does:
https://en.wikipedia.org/wiki/Hybrid_vehicle_drivetrain#Full_hybrids

Plug in hybrids and pure electrics benefit because range is extended on the highway, where it matters most.

So, how the cars receive electricity?

http://money.cnn.com/2015/08/18/technology/uk-electric-cars-roads/

 

[HyperTechno]

http://money.cnn.com/2015/08/18/technology/uk-electric-cars-roads/

Very impressive technology. But still the cost would be insanely high, which could limit that to R&D. How ever who knows, could be successful too. But the initial higher costs could keep this from happening for a long time. I think so. By the way the article doesn't give any information related to the rate of charging... What do you presume about those?

 

[NTL2009]

Yes it does:
https://en.wikipedia.org/wiki/Hybrid_vehicle_drivetrain#Full_hybrids

Plug in hybrids and pure electrics benefit because range is extended on the highway, where it matters most.
http://money.cnn.com/2015/08/18/technology/uk-electric-cars-roads/

Regarding charging an EV from the road while driving:

But fast charging batteries reduces their life-span. Nissan says fast DC charging will reduce battery life.

So in round numbers, a Nissan Leaf has a range of ~ 80 miles, and takes 4 hours to charge with a 220/240-volt 40 amp supply (7.7 kW allowable draw - 6.6 KW charger). So at 55 mph, it takes ~ 1.5 hours to discharge the batteries. So even being in contact with that high rate of charging current 100% of the time wouldn't keep the battery charged up. You are using energy at 2.6 x the rate you are getting it at. And transferring larger currents is hitting practical limits.

An occasional lane along the route won't have much impact on range at all. Let's see, 80 miles range in 4 hours charging provides a re-charge rate of about 20 miles / per charge hour. I'm still on my first cup of coffee, there might be some interaction or secondary effect I'm ignoring, but I think that means that if you had access to a charging lane for 1/4 of the time (one hour out of your 4 hour trip), you'd get an extra 20 miles of range?

That's 20 miles out of 80 miles of charge lane length that you would need. That's a lot of infrastructure for marginal gain it seems.

 

[NTL2009]

Catching up with some older posts:

But the objective of having an electric car is not cheaper transportation, it is lower emissions. ...

I think people should take some personal responsibility for the state of the environment, ...
It's reasonable to care about the environment enough to spend more than I would normally. ...

I don't know how much difference there is between driving an electric car and a gasoline car In terms of the environment and pollution. After all the majority of electrical production in the US comes from burning natural gas and coal. The energy used to power an electric car still comes from a source that pollutes. I'd just be trading one for another. Now if clean ways of generating electricity become the majority, going with electric could make more of a difference.

This is key, and I didn't see it addressed much in this thread. The batteries in EVs just store energy that was produced, so from a pollution view, it is the production of that electrical energy that matters.

And EVs create extra demand on the grid. And the average mix of renewable energy on your grid matters little. Since we are already using all the nuke energy and renewable energy available to us, that extra energy demand will be produced by fossil fuel (nat gas turbines if intermittent, and likely by using more coal if the demand is predictable).

If we occasionally have an excess of wind energy at night, that helps - but it is unlikely that the excess will occur regularly enough to power a very significant amount of a large EV fleet. And even a small amount of back-fill by coal makes a huge difference in overall pollution (coal is far dirtier than nat gas - particulates, Nox, Sox, acid rain effects).

Same with hydrogen. It takes energy to get it in a form that a car can use.

... Though sticking it to the evil oil companies would be some compensation. ...

But the hydrogen for fuel cells is currently produced from hydrocarbons, the hydrocarbons produced by those 'evil oil companies'. Same thing if you generate hydrogen from electrolysis - that takes electricity, so the same demand issue I outlined above. Going hydrogen for energy storage won't change that, it will still use oil or nat gas from oil production.

 

[Algr]

Regarding charging an EV from the road while driving:

But fast charging batteries reduces their life-span. Nissan says fast DC charging will reduce battery life.

If you are on the road, you are not using the power to charge the batteries, but to power the motor. So the range extension can easily be longer than the amount you actually drove on powered roads. Neither of us have numbers about how much this costs, but the fact that the brits are trying this out suggests that it isn't much more expensive than a regular road.

 

[NTL2009]

If you are on the road, you are not using the power to charge the batteries, but to power the motor. So the range extension can easily be longer than the amount you actually drove on powered roads. Neither of us have numbers about how much this costs, but the fact that the brits are trying this out suggests that it isn't much more expensive than a regular road.

Yes, but I think it is still a lot of power. Check my math, but a Nissan Leaf uses ~ 280 watt-hours per mile ( 30kWh battery gets 107 mile range).
At 55 mph, you get: (55 miles / hour) x (280 watt-hours / mile) = 16.5 kW ( the miles and the hours cancel, leaving watts)

So if I did that right (seems roughly right, as 16.5kW ~ 22 HP, and that's roughly what it takes steady state to propel a vehicle at 55 mph), that means you need 75 amps at 220 volts just to propel the vehicle, not charge the battery. That seems like a lot of power to transfer wirelessly. So if you had 25% of the highway with this high power installed, you would only increase your range by 25%.

Is that worth the expense? Sounds very questionable to me.

I could maybe see this approach for intercity buses/taxis? Wireless charging embedded at most stop lights and bus stops? Would it make sense to charge while you are waiting? A bus can pull into the bus stop space for most red lights, but sometimes traffic would block them.ooops, are we too far away from the original topic (hydrogen)?