This series of articles was written by:

SYED MUGHEES ALI - PHD

Trinity College Dublin

linkedin.com/in/syed-mughees-ali-phd-980562206

https://www.webofscience.com/wos/author/record/ABD-9375-2021

Series Introduction
Why Carbon Capture Needs Engineering, Not Just Ambition

Every second…

Humanity releases more than 1,000 tonnes of CO₂ into the atmosphere.

Most of it becomes invisible almost immediately.

It disperses. Mixes into the air. And disappears into the background of the planet.

But here’s the real question:

Because this is the real challenge of carbon capture:

⚛️ We are trying to reverse mixing at an industrial scale
And physics does not make that easy.

Most people imagine carbon capture as: A filter, a machine, and a box attached to a smokestack

But in reality…

👉 Carbon capture is an entire engineering system.
It involves:
Thermodynamics
Heat transfer
Mass transfer
Fluid mechanics
Chemical kinetics
Materials science
Reservoir engineering
Infrastructure design

🎯 Insight:
👉 Carbon capture is NOT one technology

👉 It is a chain of interconnected engineering problems

So why does carbon capture exist at all?
Because some emissions are extremely difficult to eliminate.

Especially in: Cement, Steel, Refining, Chemicals, Hydrogen production, High-temperature industrial heating

And here’s the important part:

In many industries…

CO₂ is NOT only produced by combustion.

👉 It is produced by the chemistry of the process itself.

Take cement production 👇

Even if the kiln were powered entirely by renewable electricity…

The conversion of limestone into lime would STILL release large amounts of CO₂.

🎯 Insight:

👉 Some industrial CO₂ emissions are embedded directly into the chemistry of modern materials production

Carbon capture is fundamentally a separation problem
At its core, CCS asks one deceptively simple question:

👉 How do we separate CO₂ from everything else?
That “everything else” may include:

Nitrogen, Oxygen, Water vapour, Hydrogen, Methane, Sulfur compounds, Industrial exhaust gases

And this is where thermodynamics becomes unavoidable.

Because nature has already mixed those gases.

To capture CO₂…

👉 Engineers must partially reverse that mixing.

And reversing mixing requires energy.

🎯 Signature Insight:

👉 Carbon capture is the engineering challenge of fighting entropy at an industrial scale
Now here’s where things become even more interesting 👇

The difficulty changes dramatically depending on the source.

1️⃣ Concentrated Industrial Streams
Examples:

Natural gas processing, Ammonia production, and hydrogen plants

These streams often contain:

Higher CO₂ concentration,
Higher pressure,
Easier separation conditions.

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🎯 Insight:

👉 High CO₂ concentration usually means lower separation difficulty

2️⃣ Flue Gas Capture
Typical sources:

Power plants, Cement kilns, and Industrial furnaces

Here, CO₂ is much more dilute, often only ~4–14%. The rest is mostly nitrogen.

👉 That means: Larger equipment, higher energy penalty, and more difficult separation

🎯 Insight:

👉 Dilute CO₂ streams make carbon capture dramatically harder

3️⃣ Direct Air Capture (DAC)
This is where physics becomes brutal. Atmospheric CO₂ concentration: ~420 ppm. That means CO₂ is extremely diluted in air.

So engineers must process enormous volumes of atmosphere to recover relatively small amounts of CO₂.

🎯 Insight:

👉 The lower the CO₂ concentration, the harder the thermodynamic challenge becomes

CCS is much bigger than “capture”
Most discussions stop at the word “capture.”

But the real system is far larger.

One such example of a complete CCS chain is: