mneary

I think my previous statements regarding safety were misunderstood.

I see no safety problem with using hydrogen, any more than natural gas. But if my neighbors start to build 5000 psi pressure vessels on a commercial scale I'll be really concerned. This thread is titled "Home Hydrogen Generator".

audioguru

I saw on TV a truck full of gasoline had an accident and the gasoline flowed down a street covered with snow and caught on fire. It was spectacular and nobody was hurt. Lots of black smoke.
A hydrogen accident won't burn, it will explode. BOOM.

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crashsite

But, what does any of that have to do with the generation and storage of relatively small and low pressure quantities of gaseous hydrogen?

The actual storage, transfer and transportation of the gas doesn't really concern me too much (for reasons I've given). And, I'm not sure how we got to liquid hydrogen here. Okay, I do know how but, it still doesn't resolve the question of....(here we go again)...

If, using an automated system and "free energy", can sufficient hydrogen be produced to make it economically viable (for the families generating, the accompanying hydrogen utility company and the nation at large).

Or, to put it into a more ABC level, with a modest solar array, can you perhaps generate sufficient hydrogen to (after all costs of collection, transportation, storage and distribution) at least cover the family's own hydrogen car needs with a little left over that the government can magnamoniously give it to the poor?

crashsite

A poorly designed hydrogen system, without proper pressure relief, venting and protection from nearby heat sources will indeed explode. As will ANY closed cylinder of any gas, flammable or inert.

Acetylene welding gas can only be stored at about 400 psi, in the tank, and must be regulated to under 15 psi when it escapes the acetone in the lines and torch head. but, you don't see Chicken Littles running around in circles yelling that the sky is falling every time somebody does a little oxy-acetylene welding. Because it's a known problem, they instead teach the safety procedures in welding classes.

Then it remains for the "terminally stupid" to create the problems. Like the woman who was returning an empty acetylene cylinder for her husband. The valve was leaking in the car and she (likely so "untechnically inclined" that she couldn't recognize the odor of acetone...or maybe because her years of smoking had ruined her sense of smell)....Long story short...her next ciggy was her last.

...Oh, yeah...and we can't forget that we need the Chicken Littles to breed the hysteria....would you agree, audioguru?

Nigel Goodwin

As you probably already realise?, NO! - with a MASSIVE solar array, you could probably generate enough to run your own car? - but solar panels aren't very efficient, and rely on lots of very bright sunlight to give decent output.

Then using the energy to split water into hydrogen and oxygen isn't a very efficient storage system either!.

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ericgibbs

Except if its the Hindenburg, perhaps a little before your time..

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Pommie

Solar panels are not cheap and certainly not free energy. Here in Australia solar costs about AU$10 per Watt. At this price it takes 26 years of 8 hours a day bright sunshine to get your money back (grid = 13c/kWh). If you buy in bulk and import direct from China you can half this price and get your money back in 13 years. If you convert this energy to Hydrogen via electrolysis then the efficiency will be significantly lower and the payback period will probably be back to 20 odd Years. Note, interest rates here are currently 7% and so you double your money every 14 years, it makes much more sense to leave your money in the bank for 14 years and then do it. Or when your money had doubled you could wait for 14 ..... etc. OTOH, when oil gets to $500 per barrel.

Mike.

ericgibbs

G'Day Mike,
Its a pity some goverment body cant make the decision to free issue solar panels to areas that get a decent amount of sunshine.

You may have heard that in the UK we are going to build a new coal fired power station,IIRC in Kent, first in about 25 years.
Also we considering going back to nuclear energy. The French seem to be running nuclear OK.

Plans are also on the table for the Severn river barrage.

From what we are told renewable energy sources are around the 1% to 2%
Quite a number of wind farms are running OK, perhaps this source could be used to crack sea water to H and 0.

I think the bottom line is, as a society we are in deep trouble..

Regards

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Pommie

Hi Eric,

I didn't know about the coal fire plant but I think the whole world is giving nuclear a second look. I don't think the new coal one will be much of a problem when China is commissioning a new one every 2 weeks. I also think that if wind is supplying less than 2% then it is not worth the eyesore that they are.

You may not know this but Australia is the biggest emitter of CO2 per capita than anywhere else on the planet. This is simply because all power stations are coal fired due to the abundance of coal here. It seems ironic to me that Aus is going to convert some power plants to oil and import the oil in order to reduce the per capita footprint. The really ironic thing is that Aus supplies most of the coal to fulfill China's needs.

As for solar, if panels can be bought for the equivalent of 1$ per Watt then it starts to make sense. I would certainly buy 10kW worth and it would work well for me as the biggest load would be the air con when it's hot. I could also store some for the pool as that takes an amazing 10kWh per day to run and it is most efficient to run it when it's dark. The equivalent of 1$/W solar panels is $500/barrel oil (or more likely $200 and some efficiency improvements) and that may not be too far away, oil seems to be doubling in price every 4 (edit was 2) years. I don't however imagine my power usage will be anywhere near as high if that were the case. Maybe it would be a good thing.

Mike.

crashsite

Well, I (obviously) like the idea of figuring out the puzzle of "returning the energy" to water. I also acknowledge its inefficiency and difficulty. But, I also believe those are mere technical problems and I am an eternal optimist when it comes to humans being confronted by the near impossible and making it a reality. In that vein, I was impressed by this little tutorial of what may be the most esoteric experiment ever done:

http://www.colorado.edu/UCB/Academic...bec/index.html

A problem with trying to "efficient-ize" the hydrogen cracking problem is one that we electronic experimenters know all too well. How can you justify designing and building something when you can buy it better and cheaper. Unfortunately, our global economy requires us to wait for crisis before it allows us to actually spend some real effort (and money) on a solution.

At the same time, I believe there's opportunity for those who will figure it out and either circumvent the crisis or, at least, be Johnny-on-the-spot when it occurs. Unfortunately, my name isn't, "Johnny".

jpanhalt

Small amounts of low-pressure hydrogen will only produce a small amount of energy. You would need to do a cost analysis to determine whether it is worth it. There will still be safety concerns.

We got onto liquid hydrogen because of a statement that hydrogen was liquid at something like 5000 psi, which it is not unless the temperature is low enough. One must be at or below the critical temperature to have a liquid state. Once at that temperature, LH2 can be handled like any other extremely cold liquid. The problem is that that temperature is very low and difficult to maintain. For example, it is below the condensation point for air, which will condense on its surface. That is not good, if you want to avoid mixing liquid hydrogen and oxygen in your home.

This all relates to the real life problem of using hydrogen as a commercially viable fuel. It is not that the problems can't be solved, but I don't believe the solutions are in the immediate future. So, current technology leaves us with choosing between dealing with low temperatures, high pressures, or adsorbing the hydrogen to a carrier from which it can be desorbed at the point of use. John

crashsite

That brings up another question:

I have seen this as a safer storage solution in cars but, don't really know how it relates to the big picture. Certainly hydrogen can be locked up in appreiable quantities in hydrocarbons (and carbohydrates). You can burn a chunk of wood or coal or petroleum and get substantial amounts of energy from it. Again, my chemistry ignornce comes to the forefront since I don't know the mechanism by which so much hydrogen can be so conveniently stored.

But, if that hydrogen can be absorbed and desorbed, in a man-made storage container, I'm not sure why a home generator could not perform that function as well as anyone else (unless it takes heroic measures to do it).

But, the general consensus seems to be that insufficient hydrogen could be produced this way to make it worth while. And, with that I will shunt this line of thought to a back burner and move onto my next "project".

Tnank you all for all your input, suggestions and ideas.

jpanhalt

It's basically cost per energy unit stored. The adsorbents are often rare metals, like platinum. General Motors, I believe, is still working on the storage units. Liquified hydrocarbon gases, primarily methane, propane, and butane, I believe have greater promise. Methane, for example, gives you 4 hydrogens per mole instead of just the 2 that you get with hydrogen, and a carbon thrown for free

More seriously, combustion of hydrogen produces 120 MJ/Kg; whereas, combustion of methane produces 50 MJ/Kg. So yes, hydrogen produces more energy per Kg than methane, and that is important if you are building rockets where weigt is such a limiting factor.

However, if the tank is sitting in my back yard, I don't care how much it weights; I care how long it will last between refills and the cost. So, lets look at the energy from the standpoint of volume. I will spare you the calculations of converting from mass to moles to volume at standard temp and pressure. If you do that, hydrogen produces 0.24 MJ/mole (0.0107 MJ/L) and methane produces 0.80 MJ/mole (0.036 MJ/L). Thus, per unit volume of gas, methane produces over 3 times as much energy. Moreover, methane (and the other gases mentioned) can be readily liquified to increase even more the amount of energy available per unit volume stored. John

3v0

Many of the best location for turbines have very low populations. Think square miles per person. The people who live in these areas often own the land and are more then happy to host a wind farm. Income from a wind farm is much greater then can be made by ranching or farming the land. And you still can farm or ranch as the space used by the towers is small.

Wind power is a sleeping giant. I have no idea what the practical limit on the numbers of generators that could be installed is world wide. It seems that there are vast areas in the US central plains states with enough wind to make it profitable there. As the generators improve (become cheaper) the number/size of profitable locations will increase. An increase in energy prices has an greater effect.

Wind power is not attractive to governments because it is not attractive to big energy. One can start a wind farm with far less money then it takes to build a traditional power plant. That might lead to completion and reduce the cost of energy. Is big energy willing to let that happen?

For that and possibly other reasons you do not see much official positive interest in wind power. But unless government and or BB takes aggressive active steps to stop it, it is going to happen.

The area where I live is quite windy. At one time we were told there was not enough wind to justify turbines. Last year a company came through and leased many square miles of land to do just that.

When I was growing up I seen the same pattern with oil leases in the Midwest.

Unlike an oil well a wind turbine does not go dry.

There are a few ifs here. But I am some what sure that it may in be in part true... It could be that we have only scratched the surface of wind power.

jpanhalt

What about the noise pollution from wind turbines? Some people are very sensitive to the low frequency sound produced. It is virtually impossible to insulate against it, because of its low frequency. Low population density doesn't mean none, and the sound travels for miles.

Second, assume we got more than a trivial amount of energy from wind. Would weather patterns be disrupted?
John