Hydrogen

[dakels]

I was just wondering why it's so cost ineffective to produce and use hydrogen. I understand that coal and fossil fuels are of course very plentiful and relatively easy to acquire, requiring little to no production/processing like hydrogen does but here are some facts:

Typically, a gasoline internal combustion engine (ICE) is 18-20% efficient (S&TR); hydrogen ICEs are about 25% efficient (Automotive Fleet); methanol fuel cells are about 38% efficient (AMI); and hydrogen fuel cell vehicles like Toyota?s FCHV-4 are 60% efficient?3 times better than today?s gasoline fueled engines. (Toyota)
#

The amount of energy produced by hydrogen per unit weight of fuel is about 3 times the amount of energy contained in an equal weight of gasoline, and almost 7 times that of coal.

-www.hydrogenus.com

Ok so what are the most common ways to produce hydrogen? Breaking down of natural gas and ethanol which is semi counterproductive in being a "clean" fuel. Electrolosis is a common way as well so I read.

How much coal are we talking about to produce the heat/electricity to make 1kg of hydrogen? If hydrogen can produce 7x the energy of coal then obviously it must take alot more 7kg of coal to make 1 kg of hydrogen through electrolosis.

Also on this note, related to hydrogen fuel cells and automobiles of course, I am really wondering how beneficial hydrogen fuel cell vehicles would be. I understand that the system is rather large still taking up alot of car room. Still, the by product/exhaust is water and it is much more energy efficient then anything else we use from gasoline to alcohols to natural gases. Also with the production of hydrogen you also get oxygen which of course is a good by product, if not for the atmosphere, liquid O2 is a high demand chemical for many industries.

I am not going to pretend to know alot about it or energy or fuel sources for that matter. It just seems this is an incredible technology which is in no way being recognized as amazing at it sounds. Maybe I am missing something. Maybe someday in the future we will lve in houses where hydrogen fuel cell systems in our basement power our houses and the hydrogen delivery guy comes once a month (like propane but gives us heat and electricity).

Any thoughts?

 

[Powermoloch]

Well...when we figured out to create better power plants (ex: coal, nuclear fission, or maybe fussion, thermal vents, ocean waves.., damns). Perhaps it is possible someday to extract the hydrogen molecules from plain water with better technologies without worrying about not having enough electrical power. But as of now, breaking the bonds of molecules, especially water into H2 and O requires alot of enegry and proved to be unefficient for the moment.

 

[Calin]

For some reasons, it seems that breaking down the oxygene and hydrogene links in the water molecule is a bit more expensive than the theoretical energy you could obtain otherwise. So, you use some energy to obtain hydrogen and oxygen. Now, you use them to create energy in a 60% efficient fuel cell - so you just lost half the energy you used to crack hydrogen from oxygen (and usually that energy comes from another lossy process, like - let's say - 50% efficient gas turbines, or huge 34% efficient internal combustion engines running on fossil gas)
Big diesel engines (like the ones on ships or train engines) could reach some 34% efficiency.

Let's talk about energy storage. I have a 70l fuel tank on my car, that contains 70l of fuel, or some 50 kg at atmospheric pressure. At the same pressure, hydrogen (gas) has some 2kg for every 22 cubic meters of volume. If you compress it at 1 000 atm, you have 2 kg of hydrogen in every 22 liters, so my car would have a 6kg hydrogen fuel tank of 70 liters. Just as much "fuel" as the gasoline
However, my fuel tank now has some 20 kg (or 50kg, it doesn't matter too much). An oxygen tank for 10 cubic meters (337 cu feet) of atmospheric pressure gas weights 60 kg (137 lbs) and occupy some 45 liters of volume.
So, my fuel tank would be easier when fully loaded (let's say 100 kg) and smaller in volume than two of these hydrogen tanks holding 2 kg of hydrogen (equivalent to 10 times or 20 kg of gasoline, or let's say 30 l of gasoline, or half the 70 liter fuel tank)

 

[Calin]

Now, if you use an internal combustion engine, instead having the hydrogen 10 times as efficient (3 times from fuel cell over ICE and 3 times from energy generated per kilogram), it is just three times as efficient, so you need bigger, heavier fuel cylinders.
No wonder the current hydrogen cars have just 200km (or 130 miles) worth of hydrogen fuel on board. My car has up to 1000km, or 5 times as much worth of fuel (or if these are 200km city traffic, some 3 times as much)

 

[Calin]

Maybe you want to talk about cryogenic storage... Here would be a link for liquid storage:
http://www.fuelcellstore.com/information/hydrogen_storage.html#3
I won't say anything else. There are better methods to store hydrogen for a slow and steady consumption. The requirements for space shuttles and space rockets are completely different

 

[Calin]

Liquid hydrogen is not so costly: look at the prices on this web page:
http://www.astronautix.com/props/loxlh2.htm

 

[Mark R]

I've seen a lot of variation in the efficiency figures quoted for different engine types - I really don't know what to believe.

E.g. Hydrogen ICE efficiency claims from Ford (52%) and BMW (50%) seem markedly different from the numbers given by the OP.

This isn't really the question though.

Currently, most hydrogen is produced from steam reformation of natural gas. Essentially, the gas is 'burned' together with high temperature steam to produce hydrogen and CO2. Efficiency is about 85%.

Alternatively, hydrogen can be produced by electrolysis of water. This is rarely done these days, because of cost.
A typical large scale electrolysis system has approx 80% efficiency. However, if fossil fuels are used to generate the electricity then things deteriorate greatly - If you use natural gas, power plant efficiency is about 55%. If you use coal it's about 40%. So, for coal the overall efficiency is about 32%.

This means that to generate hydrogen with the same amount of energy as 1 kg of coal - you would need just over 3 kg of coal to start with.

Hydrogen storage also requires that it be highly compressed or liquified at cryogenic temperatures. These require substantial energy inputs.

Based on current technologies - to compress 1kg of H2 to 500 atm would require energy equivalent to about 0.2 kg of H2. To liquify 1 kg of H2 would require energy equivalent to about 0.3 kg of H2. Approximate efficiencies (83% and 75% respectively).

So if you're using liquid H2 coming from coal - for every 4 kg of coal that goes in, you get 1kg of coal worth of energy into your car. Even though fuel cells or hydrogen ICE are more efficient than gasoline - the whole process start to finish is considerably less efficient and a lot more CO2 intensive (coal contains more carbon per unit energy, so produces more CO2 than burning gasoline or natural gas directly).

Coal powered electrlytic generation of hydrogen is technology, but it certainly isn't progress.

Future methods of hydrogen generation may be better:
Use of new renewable electricity for electrolysis (solar, wind, etc.) - disadvantages: likely to be enormously expensive. Generating H2 from fossil electricity is far too expensive to be useful; with renewables being up to 2-4x the price of fossil electricity, this may be difficult to afford.
Use of biological sources of hydrogen (e.g. algae farms) - still a very early concept - most lab studies have used a source of concentrated CO2 to enhance productivity (usually from a fossil fuel burning plant).
Advanced water cracking systems - e.g.
- steam electrolysis (the steam provides part of the energy as heat, meaning less electricity is required - where lots of waste steam is available (e.g. a fossil fuel power plant), this may be useful).
- solar assisted electrolysis (part of the energy comes from light, meaning less electricity is required) - still only table top scale
Nuclear methods
- electrolysis with nuclear electricity - Likely to be too expensive unless nuclear energy becomes considerably cheaper than fossil fuels.
- thermo-chemical cracking of steam - (Heat steam to 900 C with some clever catalysts and you can get hydrogen with 60% efficiency - no need first to generate electricity wastefully. Only been demonstrated on laboratory scale. Will require new generation of ultra-high temperature nuclear technology.

 

[bonkers325]

because of the costs of generating hydrogen versus the benefits of using the generated hydrogen

you need to generate the energy for electrolysis, which will probably come from fossil fuels. the amount of energy you put into making the hydrogen will always be greater than the amount of energy you can get from the hydrogen.

 

[supagold]

To me hydrogen just doesn't make sense for large scale energy distribution. As pointed out here, you have to use conventional energy generators to create your hydrogen, losing energy at every conversion step. Another thing to factor in is the cost is the new infrastructure to distribute/store these huge (if you're talking about switching over cars to hydrogen) amounts of hydrogen. This infrastucture costs not only in labor and materials, but also the energy used to put the infrastructure in place. The neat thing about a free marked economy is that all these issues are factored into the final cost. That's one reason this "peak oil" scare that's going on right now is sort of bunk. Oil's price will rise only until "alternative" energy become price competitive.

For tons of great hydrogen discussion, check out the sci.energy.hydrogen newsgroup.

 

[Calin]

Originally posted by: supagold
Oil's price will rise only until "alternative" energy become price competitive.

For tons of great hydrogen discussion, check out the sci.energy.hydrogen newsgroup.

No, oil prices will rise until "alternative" energy become almost price competitive. Then, alternative energy will start to take place of the gasoline/diesel fuel. However, some investitions in gasoline/diesel plants are made for the long run, and they won't be converted to alternative energy.
Now, the oil price will rise not until alternative energy become price competitive, but until alternative energy starts to replace a good part of the gasoline/diesel.
Take into account that once there is a lot of asking on the alternative fuels market, the price will rise also (as there will be more asking than offered, and some part of the alternative energy equipment/ alternative energy fuels are produced now using cheaper energy from fossil fuel.
It will be a waterfall of cost rises until a new balance will be reached (at much higher price than the current $3 per gallon of gasoline

 

[DrPizza]

But, Calin, you're not suggesting that hydrogen be considered an "alternate energy source", right? Hydrogen isn't a source of energy for us; it's merely a means of transporting energy. That is, until we find a hydrogen mine (joking) Otherwise one of the simplest physics laws - conservation of energy - applies. If we could get more energy from hydrogen than it takes to produce it, we could use the excess energy to produce more hydrogen. Not going to happen.

 

[Minotar]

What I find very interesting about this hydrogen-alternative fuel ongoin debate that everyone hears about is that all of these so-called "experts" ignore the facts! Here are the facts for you all to consider, and perhaps you will all not be so excited about hydrogen as a viable fuel sorce...

The primary ways of producing hydrogen are:
1). Decomposition of Methane
2). Coal-H2O gas shift reactions
3). Electrolysis of H2O

Now, this sounds great doesn't it? But, consider the details. 2 of the three ways listed here produce CO2 as a buy-product!!!!! Isn't the point to eliminate CO2 emissions? Electrolysis indirectly produces CO2 because the electricity used to drive the reaction is generated from coal burning (or nuclear power)!!!!!!!!!!!!!!!!!!! Decomposition of methane still produces CO, which will have to be converted into CO2.

So, the inefficiency is really irrelevant here! What is relevant is that we need to come up with a better way to produce Hydrogen because the current methods aren't much better than just burning gas like we already do.

 

[everman]

Originally posted by: Minotar
Isn't the point to eliminate CO2 emissions?

Well not exactly. There's also the issues of simply being dependent on oil at all. Things like dependence on foreign oil, and increasing demand on oil. China's consumption of oil is just starting to increase and it will continue to greatly. Supply is barely keeping ahead of demand.

We need to cut dependence on oil and hydrogen can do that. The problem is with the cost of making it efficiently. Efficiency ratings on gasoline is and other petroleum based fuels is pretty nice once you take into account the entire process starting from exploration and ending with burning the final fuel. Hydrogen is getting better and I think we should shift to more nuclear energy as well.

 

[DrPizza]

NO! Hydrogen cannot cut dependence on oil. Hydrogen only serves as a method to transfer and store energy. Yes, it's the fuel for the car, but to cut our dependence on oil, we need a sufficient alternative source of energy.

If we used more nuclear energy, then we could deliver that energy to cars via either batteries or hydrogen - then efficiency of one method vs. the other will matter, and we would have cut our dependence on foreign oil. Wind and solar are nice, but they can't deliver anywhere near the amount of energy the U.S. consumes. I read last summer that it would take ALL of NY state covered in solar cells just to power NYC. I didn't believe it. When I was done calculating it myself, wow.

Hey, this reminds me... time to start stocking up on coal for the upcoming winter season

 

[everman]

Well it can cut dependence on oil once our energy generation capabilities are more advanced. Whether that require nuclear fission, or advanced fusion plants, I don't know. I suppose to clarify, nuclear energy can cut our dependence on oil via distributing that energy by hydrogen.

 

[PowerEngineer]

Well...sure. We can cut our dependence on oil as an energy source when we find some other energy source to take its place (or learn to live a life style that requires a lot less energy consumption).

The only real advantage that hydrogen has over hydrocarbon fuels is that it burns cleaner at its point of use. So nothing but hydrogen cars in Los Angeles means the end of smog there.

This doesn't mean it's pollution free because hydrogen (like electricity) has to be produced by an energy consuming process (that inevitably takes more energy than it yields) and the pollution it produces has to be counted (even if it is dumped in some distance away).

Producing hydrogen using fossil fuels doesn't reduce overall pollution much at all. People in L.A. might breath easier, but people in the Four Corners area would be choking on the emissions from all the additional coal plants it would require.

 

[DrPizza]

It's too bad that there are a lot of environmentalists who don't realize that, powerengineer. "look, I'm not causing any pollution."

 

[0marTheZealot]

Originally posted by: Calin

Originally posted by: supagold
Oil's price will rise only until "alternative" energy become price competitive.

For tons of great hydrogen discussion, check out the sci.energy.hydrogen newsgroup.

No, oil prices will rise until "alternative" energy become almost price competitive. Then, alternative energy will start to take place of the gasoline/diesel fuel. However, some investitions in gasoline/diesel plants are made for the long run, and they won't be converted to alternative energy.
Now, the oil price will rise not until alternative energy become price competitive, but until alternative energy starts to replace a good part of the gasoline/diesel.
Take into account that once there is a lot of asking on the alternative fuels market, the price will rise also (as there will be more asking than offered, and some part of the alternative energy equipment/ alternative energy fuels are produced now using cheaper energy from fossil fuel.
It will be a waterfall of cost rises until a new balance will be reached (at much higher price than the current $3 per gallon of gasoline

Alternatives need trillions of dollars of investment, decades of growth, research, and prosperity before they are even ready to be competetive with fossil fuels.

If fossil fuels were the professional leagues (MLB, NFL, NHL), then alternative energy is less than the Little Leagues. Our energy "problem" is a matter of scale. It has taken fossil fuels nearly 100 years to achieve the growth that it has. To ask alternatives to replace fossil fuel dependance in a matter of months or years is extremely naive.

 

[Future Shock]

I really like the way DrPizza puts it - hydrogen is NOT an energy source, but merely a transmission media. Of course, the media don't present that, because they were all busy having a toke during high school physics class to even know the phrase "conservation of energy." (Not that there's too much wrong with that, just not during class time!)

Anyway, we will need a serious committment to nuclear energy before hydrogen becomes important. Be it pebble reactors, safer light water fission, or someday fusion, THAT is what we will need to power hydrogen conversion.

In the meantime, I really believe that the coming "peak oil" period is a huge relative economic advantage for the EU over the US. The EU has engineered it's society to be energy-saving, due to the high taxes placed on fuels. The US has engineered a society based upon cheap fuels, involving automobiles as a necessity in the suburbs, using airplanes not high-speed trains, etc. As the price of oil rises, the EU can make a judgement on easing fuel taxes to reduce the overall inflationary impact of the rise. But the US, with no real fuel taxes to cut, and an infrastructure that is WAY less energy efficient than the EU, will be hammered with highly inflationary price surges, and no easy way to migrate that infrastructure (it would take decades). Given the current slide of the dollar versus the euro, and given the huge level of US indebtedness to China and others, the EU will relatively appreciate vs. the US as this hits, unless the US can find the national will to address the problem.

Future Shock

 

[Wreckage]

The problem is not just generating the Hydrogen but distributing it and converting everything to use it. Conceivably Hydrogen could run your car, heat your house, power a generator, etc. It took decades to put in place all of the stations and pipelines that deliver natural gas and standard gasoline.

If Petroleum were to dry up tomorrow, Hydrogen could take its place. Instead of building oil rigs, you could build windmill and solar farms. You could convert oil and natural gas pipelines into hydrogen pipelines. I think Hydrogen could be the perfect fuel, however it will take a lot of time and money before we are all using it (just like Petroleum).

 

[PowerEngineer]

Originally posted by: Wreckage
The problem is not just generating the Hydrogen but distributing it and converting everything to use it. Conceivably Hydrogen could run your car, heat your house, power a generator, etc. It took decades to put in place all of the stations and pipelines that deliver natural gas and standard gasoline.

If Petroleum were to dry up tomorrow, Hydrogen could take its place. Instead of building oil rigs, you could build windmill and solar farms. You could convert oil and natural gas pipelines into hydrogen pipelines. I think Hydrogen could be the perfect fuel, however it will take a lot of time and money before we are all using it (just like Petroleum).

I have to disagree with you. The problem most definitely IS generating the hydrogen.

If cheap hydrogen suddenly became available, we would not have to change our distribution infrastructure overnight to take advantage of it. We could simply retrofit all the existing gas-fired electric generating plants to burn it (and build hydrogen-fired plants to displace those buring oil and coal). Infrastructure change would be relatively small. The energy from hydrogen could be delivered as electricity just as the energy from fossil fules is delivered today. The reduction in overall pollution would be huge (e.g. no more acid rain, etc.).

Conversion to any new energy source will start at the largest users first (e.g. power plants, large industrial plants, etc.) before spreading down to smaller users (e.g. commercial businesses and individuals).

But cheap hydrogen isn't available. There are no reservoirs of hydrogen gas we can drill into, or deposits of hydrogen we can dig up. Hydrogen (like electricity) must be produced using a process powered by some other source of energy. Hydrogen will not displace fossil fuels.

What could replace fossil fuels is a new energy source to power the hydrogen producing process that is so incredibly cheap that the end-use cost of hydrogen becomes less than the end-use cost of fossil fuels (or our society decides to consider the real costs of pollution!). Although wind and solar are becoming more competative, neither are cheaper than fossil fuels right now. That's why people are holding onto hope for new fission/fusion technologies.

I can agree that there would be challenges involved if we ever get to the point where it makes sense to try to distribute hydrogen for small end uses, particularly for transportation. But the far bigger challenge is coming up with that cheap energy source that would make hydrogen economically competative with the current fossil fuel alternatives.

Another two cents worth of my thoughts...

 

[silverpig]

The main reason is because we can just find oil laying around. A little processing and it goes into our cars. Same with coal. You dig it out of a hole in the ground and throw it on your furnace. You can't find hydrogen laying around anywhere like that. Getting hydrogen from water is basically the same as taking CO2 gas, turning it into coal and oxygen, and then re-burning it in an engine.

 

[Wreckage]

Originally posted by: PowerEngineer

Originally posted by: Wreckage
The problem is not just generating the Hydrogen but distributing it and converting everything to use it. Conceivably Hydrogen could run your car, heat your house, power a generator, etc. It took decades to put in place all of the stations and pipelines that deliver natural gas and standard gasoline.

If Petroleum were to dry up tomorrow, Hydrogen could take its place. Instead of building oil rigs, you could build windmill and solar farms. You could convert oil and natural gas pipelines into hydrogen pipelines. I think Hydrogen could be the perfect fuel, however it will take a lot of time and money before we are all using it (just like Petroleum).

I have to disagree with you. The problem most definitely IS generating the hydrogen.

If cheap hydrogen suddenly became available, we would not have to change our distribution infrastructure overnight to take advantage of it. We could simply retrofit all the existing gas-fired electric generating plants to burn it (and build hydrogen-fired plants to displace those buring oil and coal). Infrastructure change would be relatively small. The energy from hydrogen could be delivered as electricity just as the energy from fossil fules is delivered today. The reduction in overall pollution would be huge (e.g. no more acid rain, etc.).

Conversion to any new energy source will start at the largest users first (e.g. power plants, large industrial plants, etc.) before spreading down to smaller users (e.g. commercial businesses and individuals).

But cheap hydrogen isn't available. There are no reservoirs of hydrogen gas we can drill into, or deposits of hydrogen we can dig up. Hydrogen (like electricity) must be produced using a process powered by some other source of energy. Hydrogen will not displace fossil fuels.

What could replace fossil fuels is a new energy source to power the hydrogen producing process that is so incredibly cheap that the end-use cost of hydrogen becomes less than the end-use cost of fossil fuels (or our society decides to consider the real costs of pollution!). Although wind and solar are becoming more competative, neither are cheaper than fossil fuels right now. That's why people are holding onto hope for new fission/fusion technologies.

I can agree that there would be challenges involved if we ever get to the point where it makes sense to try to distribute hydrogen for small end uses, particularly for transportation. But the far bigger challenge is coming up with that cheap energy source that would make hydrogen economically competative with the current fossil fuel alternatives.

Another two cents worth of my thoughts...

Generating Hydrogen is a simple process of passing an electric current through water. Not to mention separating it from current hydrocarbon fuels or newly discovered bio-organic methods. It can be done at home. However electricity is not as cheap as fossil fuel (yet). The higher the price of Oil the closer using Hydrogen on a daily basis gets. There are already Hydrogen fueling stations. Cars can run on Hydrogen just like they run on gasoline.

Actually the only real barrier is the initial cost of converting our infrastructure from Petroleum to Hydrogen. No one wants to pay that bill. Not when coal and oil are still relatively cheap. Not to mention that 'Big Oil" has been protecting it's monopoly for decades.

If the dream of nuclear fusion ever became a reality it would only further the use of Hydrogen.

Hydrogen is the most abundant element in the Universe and it burns pure without pollution. It's the perfect fuel and eventually, it may be our only fuel.

 

[Calin]

Generating hydrogen might be a simple process (passing an electric current thru water). However, the efficiency of hydrogen generation is quite a bit lower than the theoretical 100% (using a perfect something to create electricity from hydrogen, you will end up with less electricity than what you used to separate hydrogen from water). And this is a significant problem, as the proportion is quite big.
Also, storing hydrogen is expensive: liquid hydrogen uses some kind of one third of its energy for the cooling process, and compressed (high-pressure) hydrogen uses a tenth of its energy to compress itself.
Transporting hydrogen in pipes might be even more lossy - as hydrogen will escape thru cracks to small for the air to escape (not to mention too small for gasoline to escape) - your losses can be much bigger if you pump hydrogen thru gas pipes.

 

[Calin]

However, one thing that can be hoped is that alternative energy production (whatever it might be) will be able to decrease the pressure on the oil production. If during the oil price surge of the '70s (I think) the price increased four folds when the production decreased just 5% (5% under the normal demand I reckon), then the investments in alternative energy could be just as big as to cover for those 5% of oil use in order to stabilize the price of oil