Electronics > Power/Renewable Energy/EV's
EV Physics question
redkitedesign:
--- Quote from: CatalinaWOW on October 05, 2022, 10:32:59 pm ---
--- Quote from: themadhippy on October 05, 2022, 09:02:27 pm ---
--- Quote ---Generating it by using electricity to crack water is inefficient and then once you generate it, you have to expend further energy compressing it into a form that can be reasonably stored
--- End quote ---
If you've access to unlimited free green electricity who cares about efficiency.Iceland could become the next saudi if they play there cards right
--- End quote ---
Hydrogen has a a few fundamental problems that make it tough for use in the energy chain. Foremost it is difficult to store. It permeates through almost anything, requiring expensive materials to contain it. It is the tiniest molecule and slips through the tiniest of cracks so sealing joints and connections is difficult.
--- End quote ---
Hydrogen has a very easy, exothermic reaction with CO2. The result is CH4 (and some water), also known as methane, or natural gas
We know very well how to store, transport and use natural gas. The biggest disadvantage of this reaction for the American market is probably that it was discovered by a Frenchman (Sabatier).
And if you use CO2 from the air to produce methane, you inherently compensate for the CO2 released by the use of that methane.
nctnico:
--- Quote from: coppice on October 05, 2022, 10:17:43 pm ---
--- Quote from: nctnico on October 05, 2022, 10:04:45 pm ---
--- Quote from: coppice on October 05, 2022, 10:01:15 pm ---
--- Quote from: nctnico on October 05, 2022, 09:53:14 pm ---You may believe that but Toyota is still releasing model updates for the Mirai. They would not do that for an obsolete model. Additionally, in 2023 Toyota is planning to launch a hydrogen powered version of their very succesfull Prius and Corolla models.
--- End quote ---
Toyota recently released a completely new Mirai, based on the high end Lexus LS platform. Its a lot cheaper than a Lexus, though, so its pricing doesn't seem to make any sense. It looks like another compliance stunt.
--- End quote ---
Compliance for what? Toyota doesn't need to sell Mirais (or BEVs) to stay withing their CO2 emission qouta. Their hybrids do that just fine by themselves.
--- End quote ---
Specific laws and government run pilots schemes in specific places. California is the main one. Where it doesn't benefit them to sell the Mirai them they don't sell them. They only recently offered them in the UK, but you can't really use one here, unless its for local use around one of a handful of fuel stations. Looking at the Toyota UK web site, they seem to have removed the Mirai. It was shown there for a while, with prices. Hyundai still has their Nexo on their UK web site, and that site shows where the UK's hydrogen stations are. They seem to have removed the pricing, though. They are basically supplying a government run scheme.
--- End quote ---
That doesn't make sense. The number of Mirais sold at any place does not make a significant impact anywhere in the world (IIRC Toyota sells about 40k units per year). So there has to be a long term strategy behind their hydrogen cars. Otherwise Toyota would have been selling BEVs like anyone else if they needed to make compliance sales. The only country where Toyota is selling BEVs in large numbers is China.
richard.cs:
--- Quote from: tszaboo on October 04, 2022, 07:46:11 am ---Your numbers are off. P2G2P has a round trip efficiency of 60-70% today, expected to become even more energy efficient in the future. And it's a seasonal storage, unlike any energy storage method, battery or even hydro. Plus, you don't even need to think about the G2P part, because it is well understood and has been working for decades now.
--- End quote ---
So what technology are you proposing for the G2P part of P2G2P to achieve this 60-70% round trip efficiency? It certainly is not the "well understood and and working for decades now" combined cycle gas turbine. Taking the best current numbers for electricity to hydrogen as 80% and the best current numbers for CCGT fuel gas to electricity as 64%, I get a round trip efficiency of 51% ignoring any further energy losses due to compressing for storage, etc.
--- Quote ---You can even just feed in the methane to the gas network, and turn ordinary houses heating system renewable, without any investment of the owner.
--- End quote ---
You can, although it burning it to convert to heat with an efficiency of perhaps 95% works out worse (by around a factor of two) than converting to electricity at say 60% efficiency and feeding a heat pump with a coefficient of performance of three or more.
--- Quote ---Considering that it literally reverses global warming with carbon capture.
--- End quote ---
It's only global warming reversing carbon capture if you stick the synthetic methane in the ground and never burn it.
CatalinaWOW:
--- Quote from: redkitedesign on October 06, 2022, 05:33:36 am ---
--- Quote from: CatalinaWOW on October 05, 2022, 10:32:59 pm ---
--- Quote from: themadhippy on October 05, 2022, 09:02:27 pm ---
--- Quote ---Generating it by using electricity to crack water is inefficient and then once you generate it, you have to expend further energy compressing it into a form that can be reasonably stored
--- End quote ---
If you've access to unlimited free green electricity who cares about efficiency.Iceland could become the next saudi if they play there cards right
--- End quote ---
Hydrogen has a a few fundamental problems that make it tough for use in the energy chain. Foremost it is difficult to store. It permeates through almost anything, requiring expensive materials to contain it. It is the tiniest molecule and slips through the tiniest of cracks so sealing joints and connections is difficult.
--- End quote ---
Hydrogen has a very easy, exothermic reaction with CO2. The result is CH4 (and some water), also known as methane, or natural gas
We know very well how to store, transport and use natural gas. The biggest disadvantage of this reaction for the American market is probably that it was discovered by a Frenchman (Sabatier).
And if you use CO2 from the air to produce methane, you inherently compensate for the CO2 released by the use of that methane.
--- End quote ---
I am not an industrial chemist so I can't comment on converting hydrogen to methane. But I do know that those pushing a hydrogen fuel cycle generally aren't pushing methane as the storage and distribution method. I agree, natural gas is a well understood technology.
bdunham7:
--- Quote from: nctnico on October 06, 2022, 06:41:31 am ---That doesn't make sense. The number of Mirais sold at any place does not make a significant impact anywhere in the world (IIRC Toyota sells about 40k units per year). So there has to be a long term strategy behind their hydrogen cars. Otherwise Toyota would have been selling BEVs like anyone else if they needed to make compliance sales. The only country where Toyota is selling BEVs in large numbers is China.
--- End quote ---
Toyota hasn't sold 40K Mirais in all of history, it's more like 9-10K in the US (mostly CA), 7K in Japan and 3K in the rest of the world. The new model from 2021 forward is less odd and more luxurious and they are making/selling a few more than before. The FCV vs BEV makes sense if you understand the details--they get 7 ZEV credits for every FCV. And in any case Toyota is a huge company that can afford to have projects that don't make money.
Mirai sales are very heavily subsidized here, both by Toyota and various government entities. The new model is a luxury car that costs $70-80K in gasoline hybrid form but is priced at $50K. Then discounts, rebates and tax credits will drive that price down well under $20K and they throw in three years of free maintenance and fuel. If I lived near one of the dozen or so available H2 stations I might get one myself--just pick out a new one every 3 years and throw the old one away.
An ultra-cheap subsidized luxury commuter car in CA and they still only sell miniscule numbers. That's tough to pitch as a market success.
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