Submitted by Sorin61 t3_z90dii in technology
defcon_penguin t1_iyee1ce wrote
Reply to comment by BallardRex in The days of the hydrogen car are already over by Sorin61
Hydrogen must be produced by electrolysis, which is only 75% efficient. It must be compressed and refrigerated for transport, which takes energy. It needs to be converted back to electricity in fuel cells, which are at most 60% efficient. There are losses everywhere, much more that in long distance HVDC lines.
BallardRex t1_iyeeere wrote
There’s so much wrong there, Jesus Christ.
First of all 75% efficiency from solar -> hydrogen is absolutely incredible, yet you say that likes it’s a bad thing.
Second compression and refrigeration on site using solar power, and once it’s in a pipeline that’s that.
Third What are you talking about? I’m not suggesting that hydrogen be used for fuel cells, I’ve already stated “power plant” more than once, specifically combined cycle plants.
defcon_penguin t1_iyeh941 wrote
The energy that would be used to compress and refrigerate is also a loss, even if you use solar, because it could otherwise be transmitted and sold.
BallardRex t1_iyehfp7 wrote
https://www.americanscientist.org/article/combined-cycle-turbines
You’re not the first to raise that concern, here it is answered by a researcher in the specific field in question.
> Dr. Langston responds: You are correct that taking useful electrical power to electrolyze water in order to produce hydrogen—which in turn would produce more electrical power—would result in a fairly great loss of available energy. However, the key words in my explanation (on page 82) are “created from a surplus of renewable energy.“ One problem with wind- and solar-generated electricity is what to do with those electrons when there is no market for them, because there is no economical means of storing them.
> For instance, Denmark has on occasion resorted to paying neighboring countries to take surpluses of its extensive wind power electricity rather than shut down whole arrays of wind turbines. Germany has had a similar problem with surplus solar power generated in its southern states.
> Wheeling electrical power from one electrical grid to another certainly leads to electrical losses. And some grids don’t talk to one another. That problem was made evident last year in Texas when millions of people lost power following an ice storm, and neighboring states could not supply energy to Texas’s isolated grids.
defcon_penguin t1_iyeieac wrote
Sure, using surplus energy to produce hydrogen is better than simply discarding it. But I am arguing that long distance interconnections are even better.
defcon_penguin t1_iyeimxn wrote
The fact that the Texas grid is not connected to the other American grids is more a testament to the stupidity of the local politicians than a demonstration of why long distance connections don't work
badDuckThrowPillow t1_iyejahp wrote
75% efficiency is incredible... if compared to gas combustion. Its horrible if you compare it to solar->battery directly. As solar panels get more common in homes/businesses, the infrastructure model will change completely.
defcon_penguin t1_iyeh2gw wrote
HVDC lines have less than 5% losses every 1000 km. 75% efficiency, which is the theoretical maximum of electrolysis, means 25% loss, the same of a 5000km line. Combined cycle plants also have around 60% efficiency
BallardRex t1_iyeh7gf wrote
Those lines still have to be maintained, built, constantly inspected, and you’d need a staggering volume of them to achieve what Dr. Langston was describing.
defcon_penguin t1_iyeheua wrote
Why? Pipelines don't need to be built and maintained? Or hydrogen transport ships?
BallardRex t1_iyehogv wrote
The pipelines already largely exist. Again, you would save us both a lot of time and trouble if you’d read the damned link.
DonQuixBalls t1_iyetl7e wrote
Existing pipelines can not move hydrogen. They're still exploring how much it would take to convert them and if it's even possible.
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