Carbon capture has been in the news a lot recently, but what exactly is it? Never fear, we're here to help explain this technical topic (using chocolate!).

Chocolate: the tastiest way to explain a complex process

We’re researching a broad portfolio of energy technologies to ensure we can keep the lights on, remain economically competitive and importantly, lower emissions. Carbon capture and storage (CCS) is one key solution, and our researchers are on the case.

But what exactly is CCS? How does it work? What can it achieve? How can I sound super-smart when I’m with my friends and the topic comes up?  Never fear, we gentle science folk are here to help give you the scoop on this technical topic (including the best kind of analogy: a chocolate-based one).

How does it work?

CCS is a process used to capture carbon dioxide (CO2) gas emitted while producing power or making materials such as steel, cement or fertiliser. Broadly speaking, the gas is captured, transported, and then safely stored underground – permanently. By doing this, we can typically capture 90 per cent of the CO2 that would otherwise be emitted from power stations and industrial facilities.


Energy from fossil fuels such as coal, oil and natural gas is released in the combustion (burning) and conversion process, which also results in the emission of CO2 as a by-product. It’s possible to capture the gas before it is emitted, and we’re working at Victoria’s AGL Loy Yang Power Station to make the capture process more efficient.


CO2 is transported by pipeline, truck, rail or ship. In fact, there are already many pipelines around the world that safely transport large amounts of CO2 every day.


The gas also has many uses in the food and beverage industry (like creating the bubbles in your soft drink!) and it can assist with industrial processes such as the recovery of oil from underground. Of course, there’s only so much soft drink we can consume, so we also need to think about what to do with the remaining CO2.

Storing CO2 

Once CO2 has been captured and transported, it is injected deep underground, usually at depths of over 1 km. This process is sometimes called ‘geosequestration’. Generally, the rock needs three features to be suitable:

  1. Sufficient pore spaces in which CO2can be contained (porosity)
  2. Pathways connecting the pore spaces for the CO2to move through (permeability)
  3. A solid, sealing layer of rock on top of the porous, permeable layer, to stop the CO2moving outside the target area (seal or ‘cap rock’).

Here’s a delicious example of why these geological features are important.

A Tim Tam and an aerobar

The humble Tim Tam is a lot like a reservoir rock, while the Aero Bar, although seriously delicious, has no chance of holding your milk. Images: and

Let’s consider a Tim Tam and an Aero Bar as two possible types of reservoir rock and milk as our CO2. Both chocolate bars have plenty of porous space in them, yet if you bite an end off each and try to use them as a straw through which to draw milk, the permeability of the Tim Tam will allow the milk to be pulled through the porous spaces into your mouth, but the Aero bar won’t.

This is because the Aero Bar, although porous, does not have any channels connecting the spaces and therefore the milk cannot move through the chocolate. The principle is the same for the reservoir rock needed to store CO2. The CO2 needs to be able to move through the rock and fill all the porous spaces.

Storage of CO2 has safely happened around the world for many years, and we’re finessing the finer points at our National Geosequestration Laboratory.

Serious potential

In addition to limiting the emissions expended to power our homes, CCS can play a vital role in decarbonising energy-intensive industries (such as steel production) which involve the continued use of fossil fuels. If fossil fuel is replaced by biomass, applying CCS will actually start to directly reduce the CO2 levels in the atmosphere, demonstrating its large potential for climate change mitigation.

While we’re working on making these technologies more efficient and cost effective, a number of major CCS projects are already operating or being built, capturing and storing many million tonnes of CO2 per year.

Achieving a low-emission economy for Australia


  1. Mother nature has already done a terrific job of burying all that carbon in a solid form that will stay down there. It’s already geosequestered – leave it there. Put the research effort into accelerating the cost and efficiency gains in renewables to power the grid.

  2. No Coal needed.
    Iron, cement and other processes that generate CO2 in the manufacturing process can be changed to generate water vapor by using hydrogen instead.
    This is not new technology and money spent on capture would be better spent to implement the change.
    Hydrogen can be generated using solar panels and water.
    Digging up carbon to put it back where it came from is stupid.

    1. Alan.
      Generating hydrogen is a very inefficient energy process. One needs to work out the energy costs, amongst other things, before proposing such schemes.

  3. I posed the following question (03Feb17) on the CSIRO blog
    “” …. so far unanswered by anyone,

    “OK, so you can reduce carbon dioxide emissions, but can you – or anyone you know of – show that changing carbon dioxide levels have ANY effect on climate changes??
    [CO2 is a greenhouse gas, but so are all gases in the atmosphere as all gases absorb heat one way or another, eg IR, conduction, convection, winds, etc. Do you imagine that gases do NOT absorb heat, eg would cold oxygen or nitrogen or argon, etc in a sealed container remain cold when placed in a warm environment? That’s never been noted, but that’s what AGW proponents state – implicitly only, because it sounds/is stupid as an open statement.]
    As the so-called “greenhouse gases” constitute only a tiny proportion of the atmosphere, then so are their contributions to the atmosphere’s heat content, and therefore tiny effect on climate changes.”

    The answer needs to be answered before one even considers doing anything about “carbon emissions”.
    Anyway, carbon capture, even if successful, will lose about 30% of the energy produced, ie one needs to burn about 30% more coal!

    1. Hi Peter,
      the difference between CO2 and and O2 is the amount of energy the can absorb, hence CO2 is defined as a greenhouse gas, O2 is not. Here is a pretty good overview on how and why this is:

  4. Just who is this, really? Big-Fossil LNP CSIRO? Nobody at the real CSIRO is this stupid. … A bit of checking reveals a government-funded fraud

  5. Is this a joke? It looks like a joke. So we’re going to take 500 million tonnes of coal and turn it into 2 billion tonnes of CO2 and shove it down a hole each year. That sounds like a plan!

    Just don’t burn the bloody stuff

    1. Peter Carson is correct – as a trace gas in our atmosphere, CO2 is not and never will be the key driver of our climate. Burning hydrocarbon fuels and feeding the exhaust gasses through a series of greenhouses would demonstrate what a boon CO2 is to plant growth and therefore food production. CO2 is the ‘gas of life’ and all plants die without it – and if all plants die – all other living things go soon after. Nature has been sequestering carbon ever since life on Earth began in what could ultimately be a process of global suicide – helping to re-cycle some of that carbon can do nothing else but increase food production by stimulating plant growth and making plans more drought resistant – thereby helping to protect both ourselves and our environment!!

      Fossil fuels and nuclear are the most efficient methods of energy storage. You can’t operate 24/7 heavy industries on battery power and anybody suggesting ‘pumped hydro’ just doesn’t have a clue about overall energy efficiency let alone the geographic limitations of that concept. Carbon capture and storage (CCS) rates strongly alongside pumped hydro as a ridiculously energy inefficient process with zero real benefit.

      If our past governments had any sense we would have majored on nuclear power years ago and the Greens would have no hope of wrecking our industrial capability through their blind belief in the global warming scam.

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