[NightWoundsTime]

I did hear something about the energy balance of oil vs. ethanol. Supposedly with extraction, refining, transportation and all the rest, oil still has a very high rate of return as far as the pure energy is concerned. The same is supposedly not true with ethanol, which takes a huge amount of energy to produce while barely breaking even on return.

Where's the Hydrogen though? Wasn't that the hot thing a few years ago with speculations of a 2010 crossover?

 

[Wodgy]

Hydrogen is not an energy source, just an energy carrier. It takes some other form of energy to generate hydrogen and fill a fuel cell -- that is, hydrogen is always a net energy loss -- so hydrogen only solves half of the energy problem. If we could rearrange things so that most hydrogen was produced via some sustainable form of energy, like nuclear or wind, we could come out ahead of the game with hydrogen. But surprisingly, the majority of hydrogen produced these days is made via oil, natural gas, and coal, not electrolysis.

 

[HiGHFLYiN9]

FWIW I know that the stations carrying e85 has been increasing fairly rapidly in states that have a large amount of corn like Minnesota. Whether it ever shows up in other states remains to be seen.

 

[aerius]

Quote:

Originally Posted by NightWoundsTime Where's the Hydrogen though? Wasn't that the hot thing a few years ago with speculations of a 2010 crossover?

Wodgy pretty much nailed it, but in addition to that, making & transporting hydrogen is very energy intensive, and storing it is a pain in the butt to say the least.

There was an article in a recent issue of Car And Driver which outlined the energy costs of converting our transportation system to hydrogen. As of now, the US uses roughly quads (quadrillion BTUs) of energy every year to run the cars & trucks. Converting to hydrogen would roughly double the energy expenditure to 32 quads. That energy has to come from somewhere, and that somewhere is mostly coal-fired power plants, the most polluting & ecologically damaging form of power generation in existence. The only way to make a hydrogen based transport system work is to build massive numbers of nuke plants, breeder reactors, and spent fuel reprocessing plants, in other words a closed loop nuclear fuel cycle on an unprecedented scale.

To put some numbers to this, a gallon of gasoline has about 125,000 BTUs, and a modern car engine is about 20-25% efficient, so you get about 25,000-30,000 BTU's of useful energy out of each gallon of gas.

Fuel cells are about 80% efficient, let's for now assume 100% efficiency in converting electrical energy to make hydrogen. 1 kWh of electricity is equal to ~3400 BTU, so you need 10 kWh of juice to make enough hydrogen such that when it's used in the fuel cell it'll give the same energy as a gallon of gas that's burned in an Otto cycle engine.

So assuming a 15 gallon tank equivalent, you'll need to suck about 150 kWh of electrical power to fill up a tank in a fuel cell car given perfect efficiencies. Realistically you're looking at about 250-300 kWh with the efficiency of current technologies. If electricity costs 10 cents/kWh, it ain't gonna be much cheaper than filling up the tank with gasoline. For reference, the average home in the US uses about 850 kWh per month.

 

[SiBurning]

Apologies. I went to find the article to give the source for what I read about how we mistreated china, and only then realized it was in that piece. For a moment I thought about not posting it, but I decided to reference the little bit that was there, rather than trying to find another source. That's why I specifically pointed out the section to reference. The other point to note is the source isn't necessarily reliable, which kind of makes it even more important to give sources. I certainly didn't intend to introduce the rest of that article into this thread. Obviously some people think it was a bad call. Since I wasn't sure myself at the time, all I can do now is apologize for the mistake. I've also removed the link.

 

[Sladeophile]

Quote:

Originally Posted by SiBurning Apologies. I went to find the article to give the source for what I read about how we mistreated china, and only then realized it was in that piece. For a moment I thought about not posting it, but I decided to reference the little bit that was there, rather than trying to find another source. That's why I specifically pointed out the section to reference. The other point to note is the source isn't necessarily reliable, which kind of makes it even more important to give sources. I certainly didn't intend to introduce the rest of that article into this thread. Obviously some people think it was a bad call. Since I wasn't sure myself at the time, all I can do now is apologize for the mistake. I've also removed the link.

Accepted.