Hydrogen Power

kenmabmcc · Posted: Tue Aug 05, 2008 10:24 pm Post subject: Hydrogen Power

The fuel of the future could be hydrogen

Quote:

Chemist Daniel Nocera, head of the M.I.T.'s Solar Revolution Project, focused on one side of the equation: splitting water into its constituent hydrogen and oxygen molecules. This can be done well, but it remains difficult to actually separate the molecules. But Nocera and postdoctoral fellow Matthew Kanan discovered it could be accomplished by simply adding the metals cobalt and phosphate to water and running a current through it. In contrast to platinum, cobalt and phosphate cost roughly $2.25 an ounce and $.05 an ounce, respectively.

That is the Hydrogen

Quote:

Chemist Bjorn Winther-Jensen of Monash University in Australia and his colleagues addressed that problem by developing new electrodes for fuel cells made from a special conducting polymer, that costs around $57 per counce.

During experiments, the polymer proved just as effective as platinum at harvesting electricityâ€”and the work could prove immediately relevant in mini fuel cells, such as the kind that are being designed for computers.

And this would give the electricity.

Or else the hydrogen could be used fuelling a turbine powered electricity plant.

This could be part of the Obama "clean energy" project.
Wink

bern · Joined: Mar 12, 2007 Posts: 887 Location: ann arbor

kenmabmcc wrote:

Or else the hydrogen could be used fuelling a turbine powered electricity plant.

This could be part of the Obama "clean energy" project.
Wink

It is certainly pleasant to contemplate Hydrogen as an energy transfer/storage medium.

However, just a bit of physics: You can't mine hydrogen. You have to get it either from hydrocarbons, or from water. And the energy you get from burning hydrogen (either in a fuel cell, or in an internal combustion engine) is equal to the energy you have to put in to split the water into hydrogen and oxygen in the first place. So the ultimate source of the energy is either the sun (wind, solar, coal) or Creation (the sun or Uranium). This means that the Hydrogen is not an energy source, but is merely a storage/transport medium for the energy.

So, how good is hydrogen as a storage/transport medium? Gasoline has a much higher index of energy per cubic foot than Hydrogen gas does. The problem is that Hydrogen is a gas, and is not easily liquifiable. As a liquid its boiling point is so low, that it is impossible to store it in closed containers. They will explode like an old fashioned pressure cooker. So, it is always boiling off. Leave your car in the garage for a week with a full tank, and when you get in it is out of H2. And storing it as a gas under high compression doesn't get you anywhere close to a good energy per cubic foot ratio.

Now, it is possible these storage problems will be solved. But as far as I know, there is no solution in sight as yet. The implications of all this is that either the vehicle will have poor range, or that an inordinate amount of interior space will be used for explosive fuel storage. Or that you will have to fill up weekly regardless of how far you drive.

And, of course, if the water is electrolyzed by a coal burning plant, you have not gained one iota in reducing your carbon footprint.

kenmabmcc

As the cost of making hydrogen from water lowers from the use of new technologies,
it would make a good energy storage medium.

Solar and wind power, being intermittent, need a back up.
If large numbers of these plants are operating, making more electricity than what is required at that time,
the hydrogen making plants, can be utilised to store energy until it is needed.
Turbine powered, hydrogen fuelled, electric plants would have a rapid response time
to cover any short fall in electricity generation.

Storage of hydrogen as a gas, can be very low tech on sites that have the generation plants
that are close to population centres but not in population centres.

Hydrogen used in this way is a lot safer than liquefied petroleum gases
as any gas escape goes up into the atmosphere as hydrogen is the lightest gas.

I would think hydrogen is not a solution for transport, as most solutions for that seem high tech.
Electrical transport systems are viable, especially as the cost of petrol increases post peak oil,
and is a low tech solution.

Most nations have solar and wind resources that are many times their energy requirements,
it is only storage of that energy that is the problem.

The energy transport medium is electricity which is well understood,
hydrogen gas generation/electrical generation combined plants can be close to population centres
where the main electrical demand is,
and will either store energy or release it as electrical demand changes.

Making hydrogen from coal burning plants is a waste of energy,
also polluting the environment.
Wink

bern · Joined: Mar 12, 2007 Posts: 887 Location: ann arbor

kenmabmcc

Read the link in the first post.

Water

Wink

bern · Joined: Mar 12, 2007 Posts: 887 Location: ann arbor

Well..

It is a shame you never studied chemistry or physics. You would have the same issues with that article that I have.

To begin: In physics You can't get something for nothing. You can't magically split water into hydrogen and oxygen, get energy out of recombining them and then magically split them again.

You missed the critical words "pass a current through it" at the end of the second paragraph. The writer clearly doesn't understand the issues either. (this has been happening commonly in SA in the past few years. That's why I don't subscribe any more). The platinum, cobalt, etc. do nothing without the current. In fact, you can make hydrogen and oxygen in a high school chemistry lab without any of the expensive elements with just a few batteries and a couple carbon electrodes (from an old battery) We all did that in high school and had great fun with the ensuing hydrogen explosion we produced.

But here is the crux: the vital thing to know is that the energy level of the chemical bonds of hydrogen combined with oxygen is much lower than the energy level of the bonds of hydrogen and oxygen alone. When we allow them to combine (by burning the hydrogen) we get this extra energy in the form of heat. And (this is important) in order to split them again, we need to put this energy back into the system. That is what the electric current mentioned above is for. So, to get enough hydrogen to generate a Joule of energy, you have to put (at least) a Joule of energy into the process of splitting water. This is true no matter if the process also involves Platinum, Cobalt, or any other enhancer. There are problems and inefficiencies involved with the production of large quantities of Hydrogen not related to the basic need for large amounts of energy that these new ideas may solve. But the fundamental "you can't get something from nothing" better known as "the law of conservation of mass and energy" still holds.

So, in order to make your large quantities of hydrogen, we need a power plant on site. This can be wind, solar, or nuclear. We can then ship the hydrogen anywhere we wish. But to run another power plant with it clearly makes no sense. As you said, wires do a better job of transporting energy than trucks.

So the hydrogen will mainly be used in transportation, and in small fixed sites that need an energy source. The energy density problem of hydrogen is a hindrance in the transportation field, but the process of adsorption on the surfaces of special materials may solve that issue eventually. As you know (I hope) a fuel cell is simply a way to burn hydrogen (allowing hydrogen and oxygen to combine) and getting the energy out in the form of electricity rather than as heat. This is probably how it will be used in transportation.

It is right to be excited about hydrogen as a power source. But please be excited for the right reasons. Very Happy

kenmabmcc

bern · Joined: Mar 12, 2007 Posts: 887 Location: ann arbor

[quote="kenmabmcc"]