Hydrogen fuelled cars: good idea in theory

[Harajuku]

Hydrogen may be the miracle fuel, but the problem is there aren't any hydrogen filling stations! Apparently, there's one in Essex, but this is used to supply buses that are used in demos to show how great hydrogen is. How are we supposed to go green without the practical means to do so..?

 

http://www.thefirstpost.co.uk/index.php?menuID=3&subID=998

[insane_alien]

the technology still needs to have a few bugs ironed out(primarily the mass storage of pure H2) and then there is the road block of corporations...

 

"we won't build pumps until people have hydrogen cars"

customers

"we won't get hydrogen cars until there are pumps"

manufacturers

"we won't build hydrogen cars till there is demand"

customers

"we won't(can't) buy hydrogen cars until they are availabe"

 

and so on ad nauseum

[iglak]

http://www.switch2hydrogen.com/

basically, this group has created a system that converts your combustion engine (and computer systems) to burn hydrogen.

4 long-range tanks, which are comparatively small, and fit well in most trunks, supply about 450 extra miles worth of gas.

the system also seamlessly transitions from hydrogen fuel to gasoline fuel (automatically when the hydrogen runs out).

the kit also comes with a hydrogen generator and 5 2'x4' solar panels (the minimum Wattage required to run the generator).

 

the only problem is, it takes a week or two to fill the tanks using the solar panels.

[ecoli]

to add what alien said... until they start getting produced in larger quantities, hydrogen vehicles aren't going to be cost effective for the average person.

 

Obviously, we can wait till the oil runs out, and we have no choice but to switch over, or the government can step in, and provide tax incentives for consumers and companies to make the switch. Neither of these things has truly happened yet.

[chilehed]

http://www.switch2hydrogen.com/

basically, this group has created a system that converts your combustion engine (and computer systems) to burn hydrogen...

I'm not sure that those guys know what they're talking about. Like here:

Due to the fact that Hydrogen gas burns so much faster than Gasoline, engines with compression ratios greater than 9.5 to 1 are very susceptible to damaging predetonation (engine knock).

Hydrogen has an octane rating of about 130, which means it can handle compression ratios a lot higher than 9.5/1. Its high combustion rate is precisely one of the things that contributes to its octane rating. A high combustion rate results is less tendency to detonate or preignite, not more.

 

One big issue with H2 is its low ignition energy, which makes it critical to manage hot spots in the combustion chamber. You can't do that merely by recalibrating the software unless you're willing to give up much of the potential efficiency improvement. The combustion characteristics of H2 are so different from hydrocarbons that you need engineer the engine differently from the start.

 

IMO it's a dumb idea, if you want dual-fuel you'd be a lot smarter to go with natural gas.

[insane_alien]

piston engines kinda suck in general never mind the hydrogen. the most viable concept so far is a hydrogen fuelcell to produce oodles of current and voltage to drive an electric motor. more torque(especially at 0RPM) more power per kg and per volume. don't need so many gears as an electric engine can handle about 20000RPM without too much sag on the wire if its done right.

[swansont]

Obviously, we can wait till the oil runs out, and we have no choice but to switch over, or the government can step in, and provide tax incentives for consumers and companies to make the switch. Neither of these things has truly happened yet.

 

 

How do you make the hydrogen? We can't wait until the oil runs out; the means to produce the hydrogen have to be in place before that.

 

Hydrogen is not a fuel source, it is a storage medium. Focusing on hydrogen vehicles is to look at only half of the problem.

[lucaspa]

How do you make the hydrogen? We can't wait until the oil runs out; the means to produce the hydrogen have to be in place before that.

 

That's part of the problem. Electrolysis is the most common method of making hydrogen. But where do you get the electricity? The cheapest way is coal-fired generating plants. But the pollution and greenhouse gasses released by this are going to be greater than that saved by having hydrogen fuel (second law of thermodynamics).

 

Then there is transportation. How do you transport hydrogen from where it is being generated to the filling stations? Pipelines don't work too well.

 

Hydrogen is not a fuel source, it is a storage medium.

Explain please.

 

Focusing on hydrogen vehicles is to look at only half of the problem.

Or less. We may have traded less pollution and greenhouse gasses in the city for more pollution and greenhouse gasses overall.

[MattC]

I like the idea of a car that runs on both hydrogen fuel (fuel cell or otherwise) AND gas, as a stepping stone toward a different fuel economy. The car could be sold along with a kit to generate fuel from solar energy - yes, it would take a long time, but it may very well be enough to satisfy the energy needs of many drivers who do not commute long distances. Certainly it would be enough for people like me, who walk or bike any short distances, and drive only when necessary. Ultimately, that's the best solution for the short term - not only to energy problem, but also to the obesity problem.

 

I really would feel bad, though, for people biking around in cities that aren't bike friendly. Even in the best of places, cars will chug past you leaving a foul-smelling smoke while you ride along, and in the worst places you may be regularly run off the road, honked at (even though you may obey the law and act curteously), and in general treated horribly.

[ecoli]

How do you make the hydrogen? We can't wait until the oil runs out; the means to produce the hydrogen have to be in place before that.

 

Absolutely right. Hydrogen fuel is not the entire answer. We also have to look at solar or wind powered electrolysis plants and things of that nature.

[swansont]

Explain please.

 

You already stated the physics/chemistry of it: hydrogen is not something that can be mined; you typically get it via electrolysis. As such, the first and second laws of thermodynamics tell you that it has a negative energy return — you must add more energy to it then you get back. So hydrogen is not a replacement for oil, which does have a net energy return to it (a source). It's a way of turning some other form of energy (electricity) into a more convenient fuel and storing it, like a battery (storage medium).

 

So when you think hydrogen, don't think "oil," think "battery." Hydrogen cars are as much a solution, in general, as electric cars are. The battle is over convenience and efficiency. But you still have to come up with "green" electricity.

[chilehed]

You already stated the physics/chemistry of it: hydrogen is not something that can be mined; you typically get it via electrolysis...

On-board reformers is another way. You can fuel up with hydrocarbons, strip the hydrogen out of the molecules (burning the carbon as the heat source for the reaction) and use it to run a fuel cell. You waste all of the heat from the combustion of the carbon because it's not moving you down the road, but the H2 fuel cell reaction is so efficient that you end up with a net improvement in miles per gallon.

[lucaspa]

On-board reformers is another way. You can fuel up with hydrocarbons, strip the hydrogen out of the molecules (burning the carbon as the heat source for the reaction) and use it to run a fuel cell. You waste all of the heat from the combustion of the carbon because it's not moving you down the road, but the H2 fuel cell reaction is so efficient that you end up with a net improvement in miles per gallon.

 

Again, the Second Law of Thermodynamics states that the energy needed to strip the hydrogen atoms and then using them to move the car must be less efficient than burning the hydrocarbons as fuel for moving the car down the road.

 

Also note that one of the advantages of hydrogen is that combustion doesn't release greenhouse gasses -- all you get is water. BUT, in your system, we still get as much CO2 emissions as we would with gasoline. If your hydrocarbon source is coal, then we also have the problem of sulfuric acid and nitrous oxide emission. We can take care of a lot of that in coal plants by scrubbers, but in individual cars? Nope.

[lucaspa]

ou already stated the physics/chemistry of it: hydrogen is not something that can be mined; you typically get it via electrolysis. As such, the first and second laws of thermodynamics tell you that it has a negative energy return — you must add more energy to it then you get back.

 

But that's true of fossil fuels, too. However, the addition of energy was by the sun and geology several million years ago.

 

As we get oil to use in cars, it is fuel -- for the cars. Hydrogen would be the same thing -- fuel for the cars.

 

So hydrogen is not a replacement for oil, which does have a net energy return to it (a source). It's a way of turning some other form of energy (electricity) into a more convenient fuel and storing it, like a battery (storage medium).

 

Again, that is also true of oil. Oil is a way of turning solar energy into a more convenient fuel and storing it. It's just that we, today, do not have to do the energy input; that was done by the sun via photosynthetic plants tens or hundreds of millions of years ago. Then geology compressed the plants and converted them to coal and oil -- again using energy.

 

Also don't forget that refining the oil takes energy.

 

But you still have to come up with "green" electricity.

 

There we agree. And wind and solar simply are not available in large enough quantities to make the amount of hydrogen we would need if we switched all our vehicles to hydrogen.

[lucaspa]

I like the idea of a car that runs on both hydrogen fuel (fuel cell or otherwise) AND gas, as a stepping stone toward a different fuel economy. The car could be sold along with a kit to generate fuel from solar energy - yes, it would take a long time, but it may very well be enough to satisfy the energy needs of many drivers who do not commute long distances.

 

That makes no sense. Hybrid cars are simpler and cut emissions and increase mileage to levels comparable for hydrogen vehicles. Remember, hydrogen vehicles don't necessarily get better mileage, they simply don't use oil (at least not at the car end). Unless you live in Arizona or the Namibian desert, solar is too unreliable and inefficient to power a car.

 

So, for you, get either an electric car that you plug in at night, or a hybrid.

 

Even in the best of places, cars will chug past you leaving a foul-smelling smoke while you ride along, and in the worst places you may be regularly run off the road, honked at (even though you may obey the law and act curteously), and in general treated horribly.

 

My Toyota Prius does not leave a foul-smelling smoke. It's "super low emissions". The biggest danger would be when it's running on batteries and the biker would never hear it coming and might make an ill-advised left turn.

[swansont]

But that's true of fossil fuels, too. However, the addition of energy was by the sun and geology several million years ago.

 

As we get oil to use in cars, it is fuel -- for the cars. Hydrogen would be the same thing -- fuel for the cars.

 

I agree that oil and coal are essentially solar energy stored in the ground. I don't believe I stated anything to the contrary. (All of our sources are ultimately solar power, in some fashion) The big difference is that they are in a form such that we can extract that solar energy from them, at a net gain, and that is not true of the electrolysis of water to get hydrogen.

 

edit: The issue is that Hydrogen is being sold as a replacement for oil, and it isn't. There is a fundamental difference in the energy budget.

 

 

Again, that is also true of oil. Oil is a way of turning solar energy into a more convenient fuel and storing it. It's just that we, today, do not have to do the energy input; that was done by the sun via photosynthetic plants tens or hundreds of millions of years ago. Then geology compressed the plants and converted them to coal and oil -- again using energy.

 

Also don't forget that refining the oil takes energy.

 

Still, you can drill, pump and refine oil using oil-based machines, so there is energy left over. It's not clear if, e.g. ethanol can claim an analogous truth.

 

(and chilehed's mention of reformers doesn't get us away from oil, it just uses it in a possibly more efficient way)

[Severian]

There was an interesting experiment on Fifth Gear (a motoring TV show) where one of the presenters put vegitable oil in his diesel car with absolutely no modifications. He then drove 200 miles with no problems!

[swansont]

There was an interesting experiment on Fifth Gear (a motoring TV show) where one of the presenters put vegitable oil in his diesel car with absolutely no modifications. He then drove 200 miles with no problems!

 

I've also heard of diesel cars using filtered cooking oil. The problem was that it all smelled of french fries (chips), or Chinese food, or popcorn, depending on where the oil was obtained.

[chilehed]

Again, the Second Law of Thermodynamics states that the energy needed to strip the hydrogen atoms and then using them to move the car must be less efficient than burning the hydrocarbons as fuel for moving the car down the road.

It says nothing of the sort.

 

The part you're missing is that the hydrogen fuel cell reaction is vastly more efficient than an IC engine, such that even when throwing away the heat value of the carbon you can still end up with more efficiency overall.

 

...BUT, in your system, we still get as much CO2 emissions as we would with gasoline...

Not if you're using fewer gallons per mile. Plus there are no NOx emissions and virtually no CO, unlike an IC engine.

[swansont]

Again, the Second Law of Thermodynamics states that the energy needed to strip the hydrogen atoms and then using them to move the car must be less efficient than burning the hydrocarbons as fuel for moving the car down the road.

 

I have to agree with chilehed here. An IC engine is not the most efficient engine.

[lucaspa]

I agree that oil and coal are essentially solar energy stored in the ground. I don't believe I stated anything to the contrary.

 

Yes, you did. Otherwise I woudn't have objected.

 

The big difference is that they are in a form such that we can extract that solar energy from them, at a net gain, and that is not true of the electrolysis of water to get hydrogen.

 

OK, now your point is becoming clearer. You are using "fuel" as getting more engery out of as substance than we have to expend in getting the substance. That's not the standard definition of fuel -- thus the confusion -- but I see your point.

 

Yes, we have to expend more energy making hydrogen than we are going to get out of it. In the case of oil and coal, the energy expenditure to make them was by geological processes, not us.

 

edit: The issue is that Hydrogen is being sold as a replacement for oil, and it isn't. There is a fundamental difference in the energy budget.

 

OK, I understand your complaint now and it is a valid complaint. The energy to make the hydrogen by hydrolysis has to come from somewhere. That energy expenditure -- and the environmental consquences -- are not discussed. That is essentially my complaint about hydrogen not being a solution to pollution. If we use coal to generate the electricity for hydrolysis (the most abundant and cheapest means for electrical generation), then we simply shift pollution from the middle of the cities to the whole planet with a net increase in the level of pollution.

 

It's not clear if, e.g. ethanol can claim an analogous truth.

 

I think ethanol can make the same claim. After all, again the sun is doing the work of generating the energy. So if you use ethanol vehicles for planting, cultivating, and conversion of the organics to ethanol, then you get a positive energy balance.

[john5746]

http://www.msnbc.msn.com/id/11322873/

 

I think the hybrid will lead to electric cars, once battery technology catches up. Once you have a battery, then you can concentrate on eco-friendly ways of charging the battery. I would imagine solar panels on houses would increase if people could charge their cars overnight, etc.

[insane_alien]

another option being considered is "super" capacitors that are getting damn close to storing the same energy as batteries. eitherway a switch to hybrids is a step in the right direction. after all, once we have a decent electrical system behind the engine all we need to do is switch the power source from an IC to a fuel cell.

[if_u_say_so]

To build an electric car you need a lot of very heavy batteries to give the car reasonable performance. Wouldnt it be better to use a fuel cell as the power source because hydrogen is so much lighter than a lithium battery?

 

I have seen fuel cell motorbikes that use hydrogen from a tank and oxygen from the air to react in a fuel cell to power the bike for a reasonable length of time, and the bikes only weigh about 80kg. Other battery powered motorbikes have the same performance but they are much heavier because of the batteries needed.

 

Can you store just as much energy or more in a tank of hydrogen (under pressure) as you can in a battery of the same size and weight?

[insane_alien]

actually hydrogen under pressure is lousy. at least if you compare it to hydrogen stored in the form of metal hydrides. thiis is currently what would be used if we mass produced fuel cells. metal hydrices can contain about 3times more hydrogen than if you have a block of hydrogen ice as the hydrogen source for equal volume apparently. a battery/supercap back up system would also still be there just for back up and fuel efficiency.