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or you can maybe skip the hydrogen intermediary on one end and burn the iron in an iron-air battery. then you get much higher efficiency. electrowinning of iron in alkali is also feasible, eliminating the hydrogen on both ends
We have a cheap, stable, infrastructure-friendly, high-density storage formula for hydrogen. Or better, since the application here isn't hydrogen-specific but is simply looking to find a fuel-storage solution: energy storage. It's hydrocarbons. In this case, synfuel hydrocarbons as direct analogues of fossil-fuel based compounds of chain-lengths 1 (methane) to around a dozen or so (kerosene / aviation fuel, at a stre…
or you can maybe skip the hydrogen intermediary on one end and burn the iron in an iron-air battery. then you get much higher efficiency. electrowinning of iron in alkali is also feasible, eliminating the hydrogen on both ends
But then you have to keep on adding iron, which might be costlier than hydrogen. And you have to keep on removing iron oxide.
Earlier quoted context omitted.
How much incoming solar power ends up in the methane? And how do you get the energy back out?
The usual way—boiling water.
Boiling water, internal combustion (turbines or reciprocating engines), or external combustion (heating a boiler, and using the steam to drive turbines), would cover most of it. There might be some more exotic options of fuel cells, but those tend to be cost-prohibitive.
All combustion processes follow Carnot's laws, which limit fundamental efficiency.
Why would you use hydrogen to extract the energy of the iron? Wouldn't it be more efficient to burn the iron directly? Likewise, is there no better way to reduce iron oxide to iron than by creating hydrogen first?
production and conversion are inefficient compared to other sources of energy, as up to 60 percent of its energy is lost in the process.
Lost, as in turned into heat? Is it possible to capture that heat during production and conversion, and use it to run a turbine?
https://en.wikipedia.org/wiki/Combined_cycle_power_plant>
https://en.wikipedia.org/wiki/Cogeneration>
Seimans has a good video 'splainer: https://yewtu.be/watch?v=eeiu-wcyEbs>
GE also has numerous offerings in this space, and I've seen trade articles describing this in the past, though I'm not finding any presently.
There isn't some majyckal process by which all thermal energy can be converted to motion (or by extension, electrical generation), but it is possible, with additional complexity and capital equipment, to extract much of it.
This is a pretty elegant idea. It takes 826 kJ to split a mole of iron oxide (Fe2O3) and it takes 855 kJ to split 3 moles of water (H2O). So if you take H2 and blow over one mole of Fe2O3 you can strip the O3 for the cost of 826 kJ but then by burning the hydrogen in oxygen you get 855 kJ, for a net exothermic effect of 29 kJ, which is a rounding error. The opposite reaction requires 29 kJ, again negligible, there ar…
Earlier quoted context omitted.
How much incoming solar power ends up in the methane? And how do you get the energy back out?
>> How much incoming solar power ends up in the methane? As in how many power to gas plants are operating currently? I would guess not many due to the price vs fossil methane, but as the GP notes this is a major market failure due pricing the externalities of fossil methane. >> And how do you get the energy back out? Easy, burn it. For heat, or with a turbine, electricity. Zero carbon impact because it started out as…
> Zero carbon impact because it started out as atmospheric CO2.
This is a pretty elegant idea. It takes 826 kJ to split a mole of iron oxide (Fe2O3) and it takes 855 kJ to split 3 moles of water (H2O). So if you take H2 and blow over one mole of Fe2O3 you can strip the O3 for the cost of 826 kJ but then by burning the hydrogen in oxygen you get 855 kJ, for a net exothermic effect of 29 kJ, which is a rounding error. The opposite reaction requires 29 kJ, again negligible, there ar…
Earlier quoted context omitted.
>> How much incoming solar power ends up in the methane? As in how many power to gas plants are operating currently? I would guess not many due to the price vs fossil methane, but as the GP notes this is a major market failure due pricing the externalities of fossil methane. >> And how do you get the energy back out? Easy, burn it. For heat, or with a turbine, electricity. Zero carbon impact because it started out as…
> Zero carbon impact because it started out as atmospheric CO2. How about leaks? Isn't methane a far more potent greenhouse gas than CO2?
https://www.epa.gov/natural-gas-star-program/primary-sources...>
In situ / on-prem methane production, storage, and usage would tend to minimise much of that.
Further, I don't see methane synthesis as a likely option for synfuel storage applications as described here, as heavier fuels (~C-12 -- C-15 chain-length kerosene) is liquid (far easier to handle than a gas), nonvolatile (as contrasted with petroleum or lighter hydrocarbon distillates), and can be stored in simple, unpressurised, unrefrigerated tanks virtually indefinitely. You're creating a problem which needn't exist.