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holowoodman | 1 month ago

> Most uses of fossil fuels are very inefficient. For instance, when you step on the accelerator in your car, only around 30% of the energy in the fuel you use actually is being used to propel you forward. The majority of the energy is wasted as heat. In a power plant that's more like 70% being captured and going towards the goal (electricity generation).

Yes, but there are also future inefficient uses of renewables. E.g. when making iron, you heat the ore (iron oxides) with coke (refined sulfurless coal). The coke will provide extra heat and act as a reduction agent, separating the oxygen atoms from the iron oxides. Now you can do the same thing with hydrogen as the reduction agent to avoid producing CO2 and to avoid using fossil fuels. However, creating renewable hydrogen is atm only 30% efficient, storing and transporting it has losses. Even with possible improvements, that hydrogen will be a very inefficient and costly use of electricity, and at least half of it will always be wasted.

So in terms of total energy usage, making those kinds of industrial processes use hydrogen, we will have to at least double our electricity output. And a lot of that doubling will be wasted because of the inefficiency of electrolysis, as opposed to directly using coal or natural gas.

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xorcist|1 month ago

The interesting bit about using H2 in industrial processes is that, while inefficient, it's also the school book example of variable loads. Solar and wind produces power extremely cheap but intermittent, so in a grid the push down prices when they produce the most. Variable loads can, at least in theory, be run when prices are the cheapest.

Borg3|1 month ago

Uh, can you provide any scientific papers that H2 can be used for Iron smelting? CO2 is very stable, even at high temperatures. Its hard to strip O2 from it (except photosintesis). Now, H2 itself is very violatile gas. When burn, it creates water. Water is not stable high temperatures. It become vapor and when temperature rise it can even break bond between H2 and O.

So, papers or are you hallucinating?