[DavidPBL]

There are a couple of things at play here.

So first, if you need to do 'work', then definitely just use electricity directly to do the job, which is much more efficient.

I agree it wouldnt make sense to split natural gas (into CO2 + H2) and then recombine it back into ethanol, although oil companies would love to do this as they have billions in stranded assets in the form of natural gas.

Ideally you couple some process that generates CO2 (not from burning fossil fuels) with renewable electricity to recycle that carbon back into useful chemicals to displace petroleum derived chemicals. Two examples of this would be cement manufacture and industrial brewing. But yes you need an external energy input, like with most things.

As a side note, the impact of this depends on where you get your energy (renewable of course) and your carbon. Some companies have caught onto this. For example Unilever created a carbon 'rainbow' to separate the types of carbon. Recycling renewable carbon is the goal here.

[semi-extrinsic]

How do you see the scaling up to multiple gigatonnes per year?

For me that has alwayd been the hard part to understand about CCU, where is there a market large enough to absorb that volume? And where the product does not get burnt or emitted anyway in the end?

[DavidPBL]

The short answer is with great difficulty!

If you do some back of napkin math on petrochemicals, which accounts for roughly 20% of oil usage there is a huge opportunity to displace petroleum using recycled carbon.

Global oil consumption is roughly 100 million barrels / day (today). 1 barrel is 160 kg, so annual petrochemical volumes are roughly 1.1 billion tons of product (20 million * 160 kg / 1000 (to get tons) * 365 days). That is at todays consumption. Chemical usage is expected to grow over the next several decades. Of course this is ignoring recycling carbon into e-fuels. There will be a need for those too.

In terms of actually scaling the technology, heavy industry is widespread and is a source of large scale point source emissions, ranging from as little as 10,000 tons of CO2 emissions / year all the way up to 10 million tons of CO2 / year. It is all about retrofitting these industrial sites with this type of technology to supply local markets the chemicals they need. This ignores the other sources of carbon that will become available via carbon capture (stationary or mobile) as well as direct air capture. It's tough to imagine exponential growth, but things can be very different by 2040.

[PaulHoule]

There is a huge amount of talk about things like this or CarbFix which all seem secondary to the "capture CO2 at some generic capture point and pump it into a saline aquifer" approach which seems to be pretty scalable.

Even though the technology is on the shelf it's not being deployed largely because there is no financial incentive to do so... Yet the widespread use of this technology really needs to be happening now if we want any of these carbon capture things to happen.

[DavidPBL]

I find it ironic that carbon capture and storage technology was originally (might be wrong here) developed for enhanced oil recovery (EOR).

But yes we really need better systems to incentivize the capture and storage or utilisation of CO2. Carbon taxes a great place to start.

[PaulHoule]

You can drill in Texas and find CO2 underground and people used this for advanced oil recovery before it was captured at power plants. It is a use of CO2 that people will pay for.

[DavidPBL]

Didn't know that! I assumed it was always captured elsewhere.

As we find new profitable uses for CO2 the demand for it will increase, which should help create new carbon value chains.

[IgorPartola]

> So first, if you need to do 'work', then definitely just use electricity directly to do the job, which is much more efficient.

Pardon me but this doesn’t sound right. If you want to generate heat, burning natural gas is going to be a lot more efficient overall than first burning natural gas at a power plant then transmitting electricity to your facility to convert it to heat. Similarly with rotational energy, etc. Your second point stands: if you power your process by solar, wind, or hydro you could get ahead of CO2.

[DavidPBL]

I may have misused the term 'work' here. I was trying to describe the displacement of an object through the actions of something like a motor. You can achieve that by burning fuels (combustion engine), or steam, or an electric motor. I was trying to allude to the latter being the most efficient.

[IgorPartola]

No I know what you mean by “work”, my degree is in physics. What I think is not clear is what you mean by “efficient”.

[DavidPBL]

Gotcha, I reread what you wrote andit makes more sense to me now.

What are your thoughts on using renewable electricity for heating applications as a way to displace burning of fossil fuels?

[IgorPartola]

I mean obviously if you use something like solar or wind it will not produce CO2 so any CO2 your process extracts will be a net gain. If you use it to make ethanol that then gets burned you’ll just be putting CO2 back into the air. If you make construction bricks with it, you won’t.

Solar can also be used to heat things more directly than first converting to electricity (and taking a big loss on that), but then you really are subject to when the sun shines. But if you put your facility in a desert in Arizona you’ll probably do quite a bit with a set of mirrors used to heat specific objects.

[DavidPBL]

I should have been more specific. I was trying to ask about generating renewable energy and then using that at some other site for heating purposes. What kind of efficiency does electricity to heat get you compared to just burning fossil fuels on site? I am not sure if that is the best way of asking this question.