The round trip is a net loss isn’t it? We use electricity to convert H2O into H and O.
Then in a hydrogen fuel cell car, we RE-convert the H and O back into H2O again.
So it is a round trip.
But since every mechanical device LOSES energy through friction and heat and waste, the round trip from H2O to H O and back to H2O LOSES energy.
Isn’t this right? So how will a hydrogen economy run the country or replace oil-burning cars?
Originally posted 2009-03-28 10:42:52.
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{ 11 comments… read them below or add one }
The processes involved are more efficient than gasoline engine.
But the real purpose is to limit CO2 to fight global warming, anyway. It’s a system which involves also building alternative electric power plants; nuclear, solar, and wind.
Yes the round trip is a energy loss. However most of the problem in energy is that it is generally available in places where and when it is not needed. Hydrogen will help bring the energy to where and when it is needed. For example if we can have giant wave energy stations in the oceans that convert seawater to hydrogen. Tankers can than ring the hydrogen to the cities where it can be used. Basically the world has more than enough incoming solar energy for all of humanities uses.. Bringing it to where it is needed in a form that can be used is the problem.
You’re right. It takes more energy to make hydrogen than you can get back from burning it. Otherwise you could make a perpetual motion machine. Don’t be too pessimistic, though, we may be able to use power from the (hydrogen-powered) sun to make electricity to make hydrogen fuel from water. Our current technology for doing that is pretty sorry, though.
One thing that gives me the creeps is biofuels. Making fuel from plants relies on photosynthesis, which is an almost unbelievably inefficient way of capturing the sun’s energy. Plants use photosynthesis because the ingredients for chlorophyll are so easily available. Plants don’t have a brain. I do, but it’s gonna wear out pretty soon. What’s your excuse. GET A MOVE ON!
You are right. Hydrogen isn’t an energy source – it’s a place to store energy.
Hydrogen will only adress carbon emissions if it’s produced with electricity generated from a low carbon or renewable source.
More efficient than gas? What a joke. Gas is the source for energy. Since hydrogen doesn’t exist naturally it requires energy to separate from oil, since oil has more hydrogen than water and oil is more plentiful.
It takes more energy to refine hydrogen than you get from combustion. The byproduct is water vapor, another green house gas worse than co2.
The hydrogen economy is simply a way to build a transportation system without reliance on fossil fuels. Like all energy systems, there is no free lunch. There are clean ways to get hydrogen that do not involve fossil fuels, such as electrolysis from wind, solar, or nuclear power. There is also the possibility of making hydrogen from a microbial fuel cell, which makes both hydrogen and electricity from common organic molecules like acetic acid, glucose, or cellulose.
Reasons why Hydrogen cars really aren’t such a good idea:
1. the most efficient place to get hydrogen is off natural gas reserves (still supporting oil companies, since none of the US oil wells produce natural gas, supporting foreign oil companies).
2. a Hydrogen car still produces water vapor… which isn’t as harmless as a lot of people think. It may not be toxic, but you are still introducing an artificial level of humidity into an area, which contributes to climate change (especially in more densely populated area).
3. the infrastructure currently doesn’t exist to get hydrogen into your car. you would have to build all new gas pumps (big expensive use of energy)
4. A hydrogen car still has an electric engine, so if hydrogen is so great, the better idea would be to put the whole electric grid on Hydrogen plug your regular electric car into your house.
If your in Washington state like me for example we have this wonderful recourse called hydro-electricity. Hydro as in water. After the water falls down from the top of the fall you turn a turbine and Voila create power. As for the fuel cell why don’t we just put the water in a big tank to dump it into your thingy that makes hydrogen and pure oxygen.
You are righat about the physics–but that’s about it.
Currently, we don’t get hydrogen from splitting water–its extracted from oil. The reson is the energy cost–which you pint to–reslts in to high an economic cost. In order for hydrogen to truely be a green energy source, we do need to develop a means of splitting water as you describe that is also cost-effective.
That-s doable–and there is a lot of research going on to that end. However, the fact that the entire cycle involves a net enrgy efficiency less than 100% isn’t in and of itself important. What is important is what are the by-products. If we use the cycle you describe, there are no byproducts to pollute the environment–you start with water and finish with water.
Any energy prodction system will be lessthan 100%–thats jsut physcs (its the second law of thermodynamics, if you want to get picky). Our cars–the internal-compustion engine–is only about 30% efficient. A hydrogen fuel car woudl do much better, even including the system losses you mention.
Also–soe people miss the point about energy conservation. The idea is not that we can’t use enrgy–and so will suffer a loss of our standard of living, etc. That idea comes from the propaganda of the special interests.
Energy efficiency is a good idea, even asid from environmental considerations, simply because the way we use energy now is incredibly wasteful. To take a good example–our cars now average 17 mpg. Raising that to 30+ mpg is entirely feasible–WITHOUT running up the price of automobiles. That would be good economics–it will cut consumer costs, leaving more money in people’s pockets t o spend on other things, driving economic growth–and, you will note, WITHOUT lowering our standard of living.
The same is true of many other things. Airlines are already moving to fuel efficient planes purely for economic motives. Those compact Flourescent lights make sense for no other reason that they save money.
The push for conservation in the environmetal context is based on two considerations: 1) if we use energy efficiently, we use less–and so burn less coal, oil, etc. And, such eficiency also makes it easier to switch to alternative enrgy sources, simply by cutting down on the scale of the changes needed.
But the key is: it doesn’t matter how much energy we use–its how we produce the energy that’s important. If hydrogen were to be produced by low-cost solar power genrating plants, for example, you end up with zero environmental impact–no thing burned to produce theenergy, and the water-to-water cycle also produces no pollution. That the cycle isn’t perfectly enrgy-efficient in the mechanical sense doesn’t matter–in fact, it really doesn’t matter HOW much energy you use–the environmental impact remains zero.
You cannot create hydrogen, you can only free it from the compounds it is tied up in (mostly water and hydrocarbons). This requires energy, and yes, in the end you use more energy than you get back from burining the hydrogen. As of right now, freeing hydrogen from methane is much less energy intensive than freeing it from water so this is the process used for commercial scale hydrogen generation.
Depends on where the hydrogen comes from for the fuel cell. Many fuel cells can get it out of methane- CH4. Some designs use heavy fuel oil as the source of hydrogen. For the hydrogen economy to work without using fossil fuels as the source of hydrogen, a cheap, clean way of producing more energy than we currently need will be needed. The excess can be used to split water and use it as a storage medium for the energy. Fuel cells are nearly twice as efficient as internal combustion engines at getting usable energy out of a given amount of hydroge.