Cracking Hydrocarbons

Yeah, but when we burn it in cars and heaters and power plants, it gets released again. There is no denying of the negative influence on the atmosphere (unless you're George Bush, that is )

 

Yes, it gets released back to atmosphere but no new CO2 gets added in the process, it stays on the same level. With fossil fuel burning you constantly add new CO2.

 

This is true, but very silly.
Ethanol isn't a fuel by that standard, petroleum isn't a fuel by that standard, coal isn't a fuel by that standard.

All of those are from biomass that the sun provided the energy to grow. It is just that we did not go to the work to create petroleum and coal the earth did over millions of years so we imagine they are somehow free. They are not, it took a lot of work we just didn't do it.

 

But if you recycle stuff like plastic etc. with the process mentioned in the topic, you also add new CO2 although it's not from fossil fuels, that's what I meant.

 

Well, there my definition of "fuel" is that it takes less additional energy* to create it than is released when used. If we go back far enough pretty much everything has got its energy from the Sun and is renewable.
*) I'm not counting in solar energy, only what humans produce using other energy sources and use, e.g heat and electricity.

Talking specifically about H2, it takes more than twice as much energy to produce it than it gives out when used in a car. Regular gas used to give 50x amount the energy it took to pump and refine it. Today it is probably a bit more expensive as pumping has become more difficult but it is still a lot more energy efficient than producing hydrogen.

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Technically, it is still from fossil fuels as plastic is made from it. Had it not been recycled it wouldn't have ended up as CO2 in atmosphere, at least not as quickly. Then again dumping it won't be that much better either.

 

SMR can be over 85% efficient. Fuel cells >50%

42.5% efficiency. What is the efficiency of burning gasoline in an internal combustion engine do you know? It isn't 42% I can tell you that. It is more like 20%. So while technically true saying it takes more than twice the energy to make it than it produces it is not a valid comparison to say gasoline is 50x better. Gasoline is actually worse from an efficiency perspective.

Someone is misleading here. I am not a proponent of the H2 model. I think batteries are better, but I also think we should try to get accurate information if possible. The real problem with H2 is the infrastructure and cost of fuel cells etc...

 

Actually modern combustion engines have about 33% efficience. Still bad anyway.

 

Does that include the energy it takes to produce the hydrogen or only efficiency of the engine?

Yes, gasoline engines are awfully inefficient. Diesels are a bit better. Both are worse than hydrogen and all three are lagging way behind electric motors.

Though I wasn't talking about engine efficiency but energy efficiency of the whole fuel manufacturing cycle. That means from pumping to burning in an engine for gas or from natural gas to hydrogen to car engine. Put together all the energy it takes to go through the process and compare it to the amount of energy you get when finally burning it in the engine. Again here I don't count the energy Sun gave to the plants that turned into fossil fuel.

To simplify my point (with random numbers), for one liter of gasoline you can pump, refine and transport to gas station around 10L of gasoline. For one liter of H2 you can produce less than one liter of H2.

I may be able to find real numbers for those things but it surely won't be exactly simple. I do remember seeing some grap some time ago comparing energy efficiency of a fuel cell to a regular battery car, I might be able to find that one but don't hold your breath.

Yes, they waste a lot of energy through heat, no doubt about that. Then again the whole cycle of producing H2 will waste even more energy than producing and burning gas in inefficient engines.

Yes, batteries would be much better if they weren't so expensive. Also it gets a bit tricky if ten million cars in a city needs to recharge their batteries during the night. It will cost a lot to rebuild the infrastructure to allow using electric cars on a large scale. Anyone remembers the blackouts in US?


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Here is an interesting table.

 

Look hoho, a normal household produces about 50x as much CO2 as any car. But fact is, we're pumping way too much CO2 into the atmosphere way too fast. The climatic effects are very obvious on every corner, so I really don't get what you're trying to say here.

H2 is not an option due to the current processing technology, so what's left at the moment is electricity. But we surely need some better tech rather soon or the climatic changes will become irreversible.

 

SMR means steam methane reforming. So you take Natural Gas-->H2 that is 85% efficient some say it can approach 90%, but 85% is reasonable.

The other is a fuel cell in a car, you use a fuel cell not an engine. You create electricity to drive electric motors. Hydrogen in an ICE is just a poor idea.

That doesn't include the cost to get natural gas, but natural gas is actually fairly inexpensive still. Obviously this is not sustainable, but it is not anywhere near as bad from an efficiency standpoint as those that are anti-H2 try to make it out to be. It is expensive though. (Not SMR, the fuel cells are the expensive part SMR is cheap.)

I don't have a whole lot of faith in that chart you posted. I would prefer something from a scientific journal myself. Looking at the airpline one is what got me b/c it is not accurate. It is taken from an industry website though so it isn't surprising.

 

Yes, I know. Most of that comes from coal powerplants. Electricity production is somewhat solvable as it is much more efficient to create energy in a big plant than in thousands of inefficient car engines.

I'm trying to say we do not have a real alternative energy source to fossil fuels.

I'd add infrastructure rebuilding to both electricity and H2.

Yes, we do. Nuclear fusion is coming in a few decades but problem is that oil will very likely get way too costy to pour into car a lot sooner and with too expensive oil it might be difficult to develop fusion powerplants.

 

You can capture and control waste as well. (I mean I agree with you that plants are much better)

IGCC coal plants can capture almost all their waste. http://en.wikipedia.org/wiki/Combined_cycle

They call it nuclear power and it is an alternative. Fission is a realistic alternative now not in some rosy future where fusion suddenly works out and hydrogen bubbles out of magic lakes under the antarctic ice sheet.

 

Yes, but it was enough to con a gullible (and allegedly corrupt) senior politician in Australia some time ago.

 

Yes, in relatively short term it could be an alternative. Though currently only ~6% of energy is produced with fission. It will be difficult (and expensive) to build enough nuclear powerplants to provide enough enery. Not to mention it would still need major infrastructure modifications to even think about using lots of electricity powered cars.

 

It won't take the amount most people think though. It will take far less infrastructure than biofuels or hydrogen.

 

I somehow doubt that replacing pretty entire powergrid and building a whole lot of new powerplants is exactly cheap. At least with hydrogen you could get by just by building a few stations in cities.

 

Well then you have proven my point that people overestimate the cost. Thank-you. I was afraid you might be someone who was well aware that the cost would not be excessive and would prove the exception to my generalization.

 

BTW this isn't some entirely new thing. Anerobic production of hydrogen is basically how it has always been done. The problem was that the bacteria would produce a lot of H2 then quit until you let them go aerobic and then put them back in anaerobic mode. The newer developments seemed aimed at consistency more than anything.