Carbon storage gets thorough scrutiny in the Otways

In a field 40km down the road from Warrnambool in Western Victoria, scientists are beginning the next stage of a long-term carbon storage project.

The Otway International Test Centre, run by the CO2CRC, has been injecting carbon dioxide into the ground for 20 years. This month, it’s starting Stage 4 of the research, pumping 15,000  tonnes of CO₂ 1,500m below the surface at the rate of about 140t a day.

“CO₂ is a waste – so through carbon capture and storage, we are trying to get rid of this waste,” project lead Dr Hadi Nourollah tells Cosmos.

“We intend to inject it into a safe zone thousands of metres under the ground, [and] monitor this waste – how it behaves, how it changes the environment, and how it stays for many years.”

But the carbon dioxide being stored underground at the Otway centre isn’t a waste. In fact, it’s come directly from underground. A nearby well provides access to a reservoir of naturally occurring CO₂, which is piped across to the injection site.

“Access to CO₂ is the $100 million question, because capturing the CO₂ at these volumes from industrial facilities still comes at a very high cost,” says CO2CRC CEO, Dr Matthias Raab.

Capturing carbon dioxide from industrial polluters, or directly from the air, is still an expensive and difficult process. The reservoir makes testing its storage much easier.

“It is essentially coming for free by having access to the well,” says Raab.

So – if the bottleneck is in capturing the carbon, why test its storage?

“By storing it underground, we want to make sure that we actually have net benefits for the climate, and that we have no adverse impact to the environment,” says Raab.

Once it’s removed from the atmosphere, geological formations are considered the most reliable place to store carbon – theoretically, locking it away for thousands of years.

But this is likely to be no small undertaking. The UK government has recently committed nearly £22 billion (A$43 billion) to carbon capture and storage technologies. With a price tag that high, the storage needs to be very thoroughly assured.

In this stage, the team are aiming to test a few new ideas. One is rock quality: previous projects at the Otway centre have all been on ideal, super-porous rock.

“Stage 4 is looking at the poor quality rocks that are more widespread around the world,” says Nourollah.

They’re also road-testing fibre-optic cables to monitor the storage, in conjunction with Japanese organisation RITE. These cables will be able to track minute changes in temperature, acoustics, and any other signal coming from the rock as it absorbs CO₂.

“It’s trying to replace the conventional geophones,” says Nourollah.

Geophones, which use sound to record seismic information, are the traditional way of monitoring stored CO₂.

“The downside of the geophones is that you have to roll them out in high numbers,” says Nourollah.

“There will be a lot of cables, it will have a lot of what we call a surface footprint, and then you have to maintain it. So it’s a relatively expensive product to deal with, to collect the information.”

Fibre-optic cables, conversely, should be able to provide the same information for lower effort.

“You can lay out the fibre cable for tens of kilometres, and you can charge and collect data over this length with minimal energy,” says Nourollah.

“It’s low cost, and the longevity is very high. When you roll out the fibre cable, it can stay there for 20, 25, 30 years.”

These cables work in basically the same way as internet broadband.

“The NBN workers came and installed fibre to premise to my house, and they were so surprised that I know so much about the fibre that they almost have contracted me to install my own internet,” jokes Nourollah.

The researchers at Otway already have 20 years of data to confirm the efficacy of their storage.

How much storage will be required globally, however, is still up for debate.

The Intergovernmental Panel on Climate Change considers carbon capture and storage a feasible way to reduce emissions, particularly in hard-to-abate industries. But the amount of carbon dioxide that needs to be stored will vary hugely depending on emissions.

A study published today in Nature warns against “overconfidence” in overshooting emissions targets and chalking up the deficit to CCS.

“We cannot be confident that temperature decline after overshoot is achievable within the timescales expected today,” write the researchers.

“Only rapid near-term emission reductions are effective in reducing climate risks.”