How exactly would carbon capture work offshore? An engineer breaks it down

Removing carbon from the atmosphere is a growing global concern, with Newfoundland and Labrador throwing its hat in the ring. 

Earlier this week, Premier Andrew Furey announced something called the Carbon Capture Utilization and Storage Innovation Challenge. 

What does CCUS mean … and what is the government attempting to do? 

The $6-million plan aims to help develop technologies required to help decarbonize offshore oil industries in the province and open to the door to potentially service carbon markets elsewhere. 

"There will be a global demand for carbon storage solutions. Solutions innovated, invented, created right here in Newfoundland and Labrador, will have a global reach," said Furey, adding that there is potential for a gigaton of carbon storage in the offshore. 

"That's equivalent to a billion metric tonnes and represents a significant impact to the global environment, and a huge impact to the economy here in Newfoundland and Labrador," Furey said. 

To learn more about how offshore carbon storage would work, St. John's Morning Show's host Krissy Holmes spoke with engineering professor Lesley James. 

This interview has been edited for length and clarity.

Q: What exactly is carbon capture and and how do you do it?

A: So carbon capture has been around for decades now. We've used it to purify gas streams that we want to then bottle.

When we have an exhaust coming out of a plant, it will have a mixture of different gases in it, carbon dioxide being one. There'll be some nitrogen that maybe hasn't been combusted, and there could be some sulfur dioxides and other things.… There's a whole bunch of constituents in the gas.

Now if we try to put that down, and take the whole gas stream and put it underground, well, it's kind of inefficient because why do we need to put nitrogen down if nitrogen is already 78 per cent or 79 per cent of our atmosphere? So let's just get the CO2, or the bad stuff, remove that from all the other gases, including some oxygen that's going through, and worry about [storing] the bad stuff down underground.

We can do it in a number of different ways, and the way that's been around for decades is essentially absorption, where those CO2 molecules would prefer to be in certain liquids as opposed to in the gas phase. So they preferentially like to go, 'Oh, I want to be in that liquid,' and kind of move across to that phase and are quite happy there.

So that's how carbon capture works. That's one way — the absorption. There's other ways as well, but that's the long-standing way.

How many options are you exploring at this point?

There are many options being explored. 

It's the absorption now, it's how do we make absorption more efficient and how do we scale it so that it's not only economic at these big industrial scales, but that we could potentially put on a small diesel generator that is providing power to one of our small communities on the on the northern coast or in Labrador.

So we want to work on the efficiency and the scale and we can do that by increasing surface area and putting some of those organics, those liquids, inside the surface area of certain molecules. Dr. Michael Katz, in chemistry, is working on that. It's called metal organic frameworks. 

Once you've actually got that carbon isolated, what then? Does it need to travel somewhere for processing? 

So the other way, by the way, is absorption.  So we can actually absorb the carbon onto solid surfaces.

We can think of charcoal, right? So when we use often charcoal as a filter to get rid of noxious smells, that same type of trapping mechanism that happens there, happens with CO2 as well. And Dr. Kelly Hawboldt, who you've spoken to before, works on that — using bio-absorbance that that she generates from waste.

But once we get it, then OK, we either want to keep it stored in the liquid or in the solid, preferably not the liquid because we want to reuse [that].

So then we're going to release it from the liquid, usually using a little bit of temperature, and that will cause the gas to come out of the CO2 and then we need to compress it. So now we want to go from gaseous CO2 to supercritical, or dense phase, CO2 so that we can store much more of it in the same volume.

So then the storage part — how does that work?

Once we get it compressed, we've essentially got CO2 liquid — almost.

Then we want to actually use the same type of wells we use to to produce oil and gas, and we actually want to inject it underground into the pores of the rock.

You know when you're at the beach and you've got water running through sand? Think of that sand, you know, cement it together a little bit, but it still has all the space in it, like a sponge.

So let's store the CO2 inside the pores of that rock or sponge, and that's what we want to do.

How safe is it? How do you prevent it from emitting further? What do we know about that part?

That's where the research comes in because I'm not doing anything nearly as cool as coming up with new capture techniques. I'm actually looking at working with a bunch of the earth science folks and chemistry and physics folks to actually make sure that we're comfortable with the risk of injecting CO2. So how do we know that?

Well, one, we want to sample some of the rock that's down there — both the rock that we're going to store it in, and the rock that's going to keep it there, the container, the seal or caprock, we call it.

We want to check that for mineral interactions, and that we're not going to have a bad reaction or anything happening to dissolve certain parts of the rock and create an escape route.

Then we want to make sure that the layers of the geology that we've got — maybe extra layers, or they're thick enough and that we've examined them through seismic and different techniques — to make sure that we don't see any big leakage pathways.

It's really understanding how that CO2 is going to interact with the water in which we're injecting it, because those pores of the rock are already filled with something. And in this case, we're talking about a really saline brine. It's not a fresh water system, it's saltier than sea water.

And the rock — we don't want to have anything happen. We want to make sure it's there, and we do that through lab, and modelling and seismic. A whole bunch of ways.

How significant is this innovation challenge on the world stage at this time?

It's absolutely critical. We need every possible storage site that we can get.

Already from the seismic and the data we know we've got great, great potential here, and now we just need to prove it.

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