[bad_alloc]

This article assumed carbon capture from the air to form methane will risk depleting CO2 from the atmosphere. This methane is supposed to be used as an energy storage medium.

...wat? The proposed process is extremely wasteful and almost any other carbon source is much more available, nevermind other forms of energy storage. This might be reasonable on Mars, but why would we ever want to convert solar power to Methane on a scale that changes the atmosphere? Am I missing something?

[stickyricky]

> almost any other carbon source is much more available

Two things: the author addresses this by saying these other sources will become more scarce in the future (undeniably true as they're non-renewable however who knows how the economics of this will actually shape up).

The second thing I'll say is that despite the availability of alternatives there are externalities to burning it (i.e. climate change). Air extraction may be less efficient but that inefficiency may be worth it to A) prevent continued CO2 pollution and B) reverse existing CO2 pollution.

[dgroshev]

There is effectively unlimited amount of carbon in the form of limestone, at the very least.

[marcosdumay]

The air is the most limited source of carbon we have. There is probably more of it in coal, and certainly more in fossil fuels.

But anyway, a huge part of the Earth's crust is composed of carbon-rich rocks. If we ever take the carbon from the air, it will be to regulate its amount. Taking it from rocks is much easier and requires a comparably tiny amount of infrastructure.

[Zandikar]

> Am I missing something

Considering reading your comment gave me whiplash after reading the article, one of us is.

> extremely wasteful

What's the waste?

> almost any other carbon source is much more available

More available than the air?

> on a scale that changes the atmosphere

Because we're filling the air ground and water with carbon and nitrous oxide poisons from burning more and more fossil fuels extracted out of the ground when instead we could use solar to recycle carbon emissions back into fossil fuels without (allegedly) a net increase in atmospheric CO2.

Ignoring the carbon cycle, this still has benefit though, as this solves a HUGE logistical problem with a lot of renewables, and that's storage and transport of energy. Being able to store your electrical potential at standard temperatures and pressures in a fluid form that is cost effective to transport or store is massive in it's own right.

Now, I'm not saying what they claim is as easy, viable, clean, efficient, scalable, and or otherwise possible. It may or may not be, I'm not qualified to make that distinction, it's not my area of expertise. The devil is in the details of course and I've become quite jaded and cynical of such high minded claims by nascent technologoies, but if we assume the process works more or less as they say, the WHY of this seems pretty clear to me.

[bad_alloc]

> What's the waste?

Any conversion from electrical to chemical energy is inherently lossy, and Methane would need to be burned later to release the energy. In general the less conversions needed, the better.

> More available than the air?

The air is 0.04% CO2, which in turn is mostly oxygen by weight. The biosphere is a much larger source and is self-recycling.

> WHY of this seems pretty clear to me.

I also got quite jaded and often see this at some attempt to save fossil-burning infrastructure, instead of truly adapting out energy use. For example maximizing use during the day and relying on a much smaller store in batteries, hydropower or heated salts at night. The premise of "energy anytime" might hurt us a lot.