Toyota is pushing hydrogen cars but will they ever be as cheap to run as EVs? - ABC News
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FF
Interesting article and emphasizes horses for courses. Up until now H2 has been seen as more suitable for a truck of other large vehicle application. What is does not discuss is the cost of hydrogen fuel. I was pleased to note that the Melbourne facility used solar for their electrolytic process.
Regards
Paul
Uh.Oh.... Not looking good....Quote:
Originally Posted by Bushmiller
Attachment 534836
Note that huge spot prices do not exclude negative prices at some point. However, the average is the crucial figure. My take is that these figures are significantly elevated for a weekendperiod.
Regards
Paul
PS: Note again that the averages are for QLD and not the NEM as a whole.
Sabine Hossenfelder has a video on Youtube about hydrogen. If I remember correctly she wasn't massively hopeful, though it was a while ago that I watched it.Quote:
Originally Posted by FenceFurniture
Warb
The video is about a year old so not too far out of date.
As I mentioned in a previous post, it will be horses for courses. I think trains could be the easiest application for H2 power. I have been "involved" with H2 for over forty years as power stations use hydrogen as the cooling medium in their generators because of the thermal properties and minimal windage compared to air. At Millmerran we buy the gas in from an outside supplier, but at Bayswater we made our own and also supplied Liddell, which was just across the road, literally.
The weight of Hydrogen, even when compressed is minimal compared to the weight of the tanks in which the gas is stored. One of our supplier's drivers told me the difference between his semi-trailer full and empty is only about five tons! The pressure, however, in the "torpedoes" is 16MPa! They are thick walled to combat initially the pressure and, down the track, hydrogen embrittlement.
Regards
Paul
Could you please expand on this, Paul. To a lay person like me it is the last place that I would expect hydrogen to be used. Simply the risk of a bang.Quote:
Originally Posted by Bushmiller
Could that be a solution to negative/low spot prices? Make some hydrogen?Quote:
At Millmerran we buy the gas (hydrogen) in from an outside supplier, but at Bayswater we made our own and also supplied Liddell
Deleted.
Greame, you are confusing He (the Nobel gas Helium) with H2 (Hydrogen).Quote:
Originally Posted by GraemeCook
The cost of Hydrogen is at least an order of magnitude less than that of Helium and possibly as much as two orders of magnitude (i.e. 100 times)
I am. Silly me. Very silly me! Thanks, Ian. I have deleted it.Quote:
Originally Posted by ian
Hi Greame, I'm not Paul but I think I can respond on this.Quote:
Originally Posted by GraemeCook
Hydrogen (H2) has a molecular weight of 2, compared to the molecular weight of air which as around 31. Air is a mixture of nitrogen (78%), oxygen (21%) and argon (about 1%).
It's the lower molecular weight of Hydrogen (2 vs 31) that contributes to the low windage within the generator itself.
I doubt it.Quote:
Originally Posted by GraemeCook
The negative spot price is what the generating company gets for supplying electricity to the grid. Even if you switch the electricity's usage to manufacturing hydrogen, you still have all the other costs of running a coal fired power station.
It would be much cheaper to diver the output of wind or solar farms to making hydrogen.
GraemeQuote:
Originally Posted by GraemeCook
To take your second question first, the production of hydrogen as part of the de-carbonisation process is only a sound proposition if it is made from renewables. There is no process that is 100% efficient and if you are using fossil fueled electricity to make the hydrogen you would be better off simply burning the coal directly for power.
On the first question, the generator in a power station is basically just an enlarged version of that you might find in an old car, but it creates a large amount of heat that has to be removed. The generator has two main components: The rotor and the stator. The rotor spins in a casing of hydrogen. Early generators and smaller units spin in air, but hydrogen has superior cooling properties and is, you may recall, only 1/16th the weight of air. All large generators since the 1970s have used H2. Attached to the rotor is a fan blade which circulates the H2 and this is where, coupled with the rotational speed (3000rpm in a 50Hz system) the windage issue comes into play.
It is of course important to prevent significant leakage of H2 through the generator shaft seals and there is a dedicated seal oil system, kept at a higher pressure than the H2, to ensure leakage is at a minimum. The hydrogen itself also undergoes cooling and this is achieved by separate water coolers. At Millmerran we use demineralised water direct and that water is cooled by large fans in cooling towers. At other stations I have seen a three stage cooling system that used initially demineralised water, which is then cooled by distilled water and finally the DW is cooled by straight dam or river water.
This leads me on to the stator, which also has to be cooled. It too is cooled by demineralised water and this is achieved by the stator having hollow conductors with water running through them. That probably sounds like another last thing you would expect. Water is in fact a very poor conductor of electricity. It is the impurities in water that are the good conductors. Once you remove the impurities, the water is a good insulator.
There is a little more information here if you scroll down to 9.1.3. Although it is for the American 60Hz system where the generators run at 3600rpm, it is exactly the same principle:
https://www.nrc.gov/docs/ML1125/ML11258A357.pdf
Hydrogen and demineralised water have to be managed well to prevent disasters occurring.
This is a diagrammatic video of the hydrogen system:
Bing Videos
I couldn't quickly find one of the stator system that was reasonable.
I hope that helps.
Regards
Paul
Thanks, Paul, that all makes a lot of sense.
Being mindful of the Hindenburg I just never thought of hydrogen being used that way.
In the text (para 9.1.3.1.1) it says that the hydrogen must be 90% pure. This implies that impurities up to 10% are tolerable. Am I right in guessing that the main contaminant would be air and that the resultant 2% oxygen is safely below the flash point given the 60 psi pressure and likely temperatures?
On the issue of hydrogen production I was trying to restrict my question to those periods when the price was negative. You cannot switch off a coal fired plant instantly, could you divert the power to a hydrogen generator?
I think most trains and eventually most trucks will eventually become electricQuote:
Originally Posted by Bushmiller
Rio Tinto hopes electric trains will help company halve emissions - ABC News
In case you haven't see this interesting development
https://www.tesla.com/semi
GraemeQuote:
Originally Posted by GraemeCook
The H2 purity is in fact maintained at a higher level. Greater than 97%. The introduction of air is the scenario we try to avoid. There is both an UEL (Upper Explosive Limit) and an LEL (lower Explosive limit). The former is around that 90% mark while the latter is about 4%. Any mixture in between is a potential bomb should an ignition source be introduced. When we need to empty the generator, for maintenance or an emergency de-gas, it is first purged with CO2 and only when down to that 4% mark is the CO2 purged with air and it gets tested all along the way.
Yes, we could divert the power making negative prices to H2, but the efficiency has just gone out the door, plus we have now made more CO2 than if we just ploughed the electricity straight into the grid. It's a pity, but that's the reality.
Regards
Paul
Edit: .....maintenance or an emergency de-gas...." ( "of" was a confusing typo)
I'm confused by this. The problem is that a coal fired plant can't be switched off, so in times of oversupply it remains running. During that time, it's releasing the same amount of CO2 whether its power goes to the grid, into a battery, or is used to make H2. On the surface it would seem that the only difference between those three scenarios is that the owners have to pay to send the power to the grid, whereas if they charge a battery they can sell the power later, or if they make H2 they can sell that (or convert it to electricity and sell that).Quote:
Originally Posted by Bushmiller
I don't see why efficiency of the power station is impacted*, or why extra CO2 is released. All that is happening is that the financial loss (paying to dispose of unwanted power) is removed, and a useful product is created (or stored). I can understand that the cost of installing a battery or an H2 manufacturing plant might outweigh any punitive cost for overproduction (negative pricing), although the "Warratah Big Battery" discussed earlier would suggest that the storage concept at least has some merit?
*Yes, it's less efficient than an optimised H2 generation system, but the driver here would be to save/recoup the -ve pricing, not to create H2 in the best possible way.