Hydrogen vs. Battery

[vfx]

...do we really want to create another system dependent on a single source of energy controlled by them? I know I don't.

Right. Electricity is used to make hydrogen from water or natural gas. So that electricity can be sourced from

Burning Oil
Burning Coal
Burning Natural Gas
Hydroelectric
Nukes
Wind
Tidal
Geothermal
Solar


A battery car is a multi sourced platform that can be filled and powered by any source from the above list (a few you can do at home).

A car that is fueled by hydrogen funnels that whole list into a single energy carrier made by middlemen who now control the pricing and distribution.

Been there, done that.

 

[dpeilow]

Also, in the UK at least, the whole car fleet could be refilled with electricity overnight with excess generating capacity. To do the same with hydrogen would require a doubling of our total number of power stations.

There was an interesting point in one of the EFCF papers that to make enough hydrogen to fill the 50 747s that take off from Frankfurt each day would require the entire city's water supply.

 

[JRP3]

Not to mention the potential mayhem from a plane filled with hydrogen. I doubt we'll ever see it for security reasons alone.

 

[richkae]

How is hydrogen more dangerous than jet fuel?

 

[Doug_G]

Jet fuel burns. Hydrogen explodes violently.

 

[Alfred]

There are two main differences that put those fuels into different classes:
1) To get jet fuel to explode (burn fast) its vapour has to be in a fairly narrow range of proportions to air, whereas Hydrogen can explode across a wide range of admixture to air.
2) The energy of the triggering spark has to be much higher for jet fuel than for hydrogen. Even gasoline (petrol, mogas) is a lot safer than hydrogen for the same reasons.

One advantage of hydrogen is that it is lighter than air. It cannot accumulate in trenches. Whether it is acceptable to have it in an underground parking, or other closed space, is a bit doubtful. To get an idea what hydrogen explosions do to a buildung, have a look at Fukushima Daiichi 3.

- Alfred

 

[doug]

That's not even considering the danger of damage to the storage vessel. As one who has regularly handled compressed gas cylinders, even when filled with inert gasses (like helium or nitrogen) I am very respectful of the energy contained within. At 700 bar, that's over 10 thousand pounds of force per square inch. That gas really doesn't want to be in there and given the chance it will come out explosively. This is even without combustion.

That said, I'm sure it can be handled safely (having done so myself). I would just prefer not to, given the choice.

 

[Doug_G]

That said, I'm sure it can be handled safely (having done so myself). I would just prefer not to, given the choice.

Sure, but if everyone is driving one, how many incidents do you think will happen?

There's a reason they stopped flying Zeppelins.

 

[vfx]

There's a reason they stopped flying Zeppelins.

I call shenanigans.

 

[stopcrazypp]

Sure, but if everyone is driving one, how many incidents do you think will happen?

There's a reason they stopped flying Zeppelins.

To be fair, we have plenty of gasoline fires every year. And from what I hear they have designed the tanks to withstand severe crashes. Supposedly if you are in a crash strong enough to puncture the tank, you wouldn't be doing too well anyways.

 

[JRP3]

True but not too long ago a Praxiar employee was hurt in a hydrogen explosion while filling a tank. This was a trained professional. Now imagine millions of average people doing the same thing millions of times a day.
http://www.13wham.com/mostpopular/s...Rochester-Airport/xu3d9NK_cE2sbQy8qByf3Q.cspx

 

[Doug_G]

To be fair, we have plenty of gasoline fires every year.

Indeed we do - fires not explosions. Gasoline isn't actually all that easy to start burning; if you drop a lighted match into a tank of gas it will simply go out. It's even harder to get gasoline vapors to explode, because you don't get a high enough concentration in the air under normal atmospheric conditions. Ethanol is actually much worse in that under warm conditions you can get a vapor concentration that will explode with a modest spark. That's one reason why we use gasohol instead of pure ethanol.

Car explosions are extremely rare and tend to only happen in Hollywood movies. Even the Mythbusters called that one busted.

Hydrogen on the other hand is incredibly explosive, needing only a very small spark to ignite it, and as has been pointed out a huge range of concentrations will ignite. It is far more dangerous than gasoline.

 

[TEG]

I was tempted to put up some Youtube videos of hydrogen explosions.
There is a refueling center at an airport in Michigan that exploded, and tons of science lab experiements making hyrdogren baloons and watching them explode.
But then I realized that there are even more videos of gasoline & propane explosions... Vehicles, filling stations, etc.
If you have a compact fuel that stores a lot of energy it can be dangerous if not stored and transferred properly.
Regardless which makes the more dramatic explosions, one downside with hydrogen is it is harder to keep it contained. Higher pressure and smaller molecules that like to leak out through any weak points in a seal.

 

[Doug_G]

Regardless which makes the more dramatic explosions, one downside with hydrogen is it is harder to keep it contained. Higher pressure and smaller molecules that like to leak out through any weak points in a seal.

Indeed. But hydrogen is more dangerous than most gasses for the following reasons:

• Hydrogen gas forms explosive mixtures with air if it is 4–74% concentrated; most vapors are only flammable in a relatively narrow range.
• A spark of only 0.017 mJ can ignite hydrogen; this is an order of magnitude less than most flammable gasses. A small electrostatic discharge can do it.
• Hydrogen flames are nearly invisible to the naked eye

About the only advantage is that it is buoyant, so it won't sit on the ground and burn like hydrocarbons do.

 

[Jaff]

Well, that's a relief! :biggrin:

Indeed. But hydrogen is more dangerous than most gasses for the following reasons:

• Hydrogen gas forms explosive mixtures with air if it is 4–74% concentrated; most vapors are only flammable in a relatively narrow range.
• A spark of only 0.017 mJ can ignite hydrogen; this is an order of magnitude less than most flammable gasses. A small electrostatic discharge can do it.
• Hydrogen flames are nearly invisible to the naked eye

About the only advantage is that it is buoyant, so it won't sit on the ground and burn like hydrocarbons do.

 

[TEG]

About the only advantage is that it is buoyant, so it won't sit on the ground and burn like hydrocarbons do.

I started to think that in some cases an explosion would be preferable to a slow burn.
I saw some videos of gasoline tankers that crashed into bridges and the fuel slowly burned, heating up the bridge above and slowly ended up melting the rebar and cement and ultimately destroying the bridge above.
With a sudden explosion the heat energy goes out in all directions and dissipates quickly.
Still the initial shock wave of a hydrogen explosion is probably worse than the slow burn if you are too close.
One thing I realized when watching the "amateur science lab" experiments with hydrogen is that it would be wise to wear ear protection even when dealing with small amounts of hydrogen.
There is one Youtube where someone bubbles hydrogen gas through soapy water creating a bunch of hydrogen bubbles. Igniting them one by one with a BBQ lighter they explode like firecrackers.

Another downside to hydrogen - you can't smell it. At least with gasoline and scented propane/NG you can smell when something is wrong and run away.

 

[doug]

To be fair, we have plenty of gasoline fires every year. And from what I hear they have designed the tanks to withstand severe crashes. Supposedly if you are in a crash strong enough to puncture the tank, you wouldn't be doing too well anyways.

Assuming a compressed gas tank didn't explode upon a puncture event, you'd instead have a rocket propelled unguided torpedo.

At any rate, though, if hydrogen were worth it, we'd deal with the safety issues. Stored energy in any form has its risks (e.g., even the gravitational potential energy of a coconut in a tree) and we're capable of engineering solutions to mitigate those risks (wear a hardhat, walk quickly or whatever =P ). It's just that hydrogen is such a poor solution, economically and environmentally, given the alternatives.

 

[vfx]

Indeed we do - fires not explosions. Gasoline isn't actually all that easy to start burning; if you drop a lighted match into a tank of gas it will simply go out..

 

[doug]

Green Car Congress: Pike Research forecasts sales of fuel cell vehicles to cross 1M mark in 2020

Pretty optimistic...

 

[doug]

Interestingly, it turns out that last year Pike Research predicted as many as 2.8 million HFCVs by 2020.

Pike Research: 2.8M fuel-cell vehicles will hit the road by 2020 | VentureBeat
Fuel Cell Vehicle Sales to Total 2.8 Million by 2020 - Pike Research

February 23, 2010

For a decade or more, Fuel Cell Vehicles (FCVs) have been touted as the “next big thing” in automobiles, featuring the promise of zero emissions, other than water and heat. Now, with fleets of FCVs in the hundreds and the increasing utilization of fuel cells in commercial vehicles, it appears that light duty FCVs will be commercialized by mid-decade. According to a new report from Pike Research, fuel cell vehicles will be commercially launched in most regions of the world by 2014, and cumulative sales of fuel cell cars and trucks will surpass 2.8 million vehicles globally by 2020.
...

Yet this year Pike's prediction is down to 1.2 million HFCVs by 2020.

Fuel Cell Vehicle Sales to Cross the 1 Million Mark in 2020 - Pike Research

April 19, 2011

Fuel cell vehicles (FCVs) are part of the continuum of electric drive technologies, which are projected to capture an increasingly large share of the global passenger car and transit bus markets. For the passenger car market, fuel cells offer the benefits of zero emissions operation without the range and charging limitations of pure battery electric vehicles (BEVs). The fuel cell car market is now in the ramp-up phase to commercialization, anticipated by automakers to happen around 2015. According to a new report from Pike Research, commercial sales of FCVs will reach the key milestone of 1 million vehicles by 2020, with a cumulative 1.2 million vehicles sold by the end of that year.
...

That's a 57% downgrade. I wonder what their prediction will be next year. They say three points make a trend...