The science on climate change is now widely accepted: the more humans produce carbon dioxide, the greater the imperative to mitigate global greenhouse gas emissions. We need to reduce these emissions to zero by 2050 to stabilise the atmosphere.
Lowering our atmospheric carbon dioxide (CO2) is the only way to start tempering some climate change impacts. However, net zero or negative emissions are the ultimate goal.
Arresting the current acceleration of climate change requires a range of tools. Australia’s incoming chief scientist Dr Cathy Foley says Australia should not only cut its emissions, and quickly, but lead the world in renewable energy.
Yet, even if all emissions stopped today, billions of tonnes of CO2 still need to be removed from the atmosphere every year to meet the Paris Agreement.
Allison Hortle is a Senior Researcher with CSIRO Energy. She says while CCS is not the silver bullet for removing all atmospheric CO2, it is one of many tools that can help high carbon output industries—including steel, aluminium, cement, explosives and fertiliser—decarbonise.
What is carbon capture and storage?
In a nutshell, CCS is the process of directly capturing and then storing the CO2 emissions that are a by-product of industrial processes. The aim is to stop the CO2 from reaching the atmosphere.
The captured CO2 is typically compressed, transported to a well and injected into a deep underground reservoir. This is a porous rock such as a sandstone—much like a kitchen sponge—which is capped with an impermeable layer of rock that stops the gas from moving buoyantly upwards. Here, the CO2 is stored for many thousands of years.
“The technology has been around for decades. In many ways, it’s simply the reverse process of producing fluids, such as hydrocarbons, from reservoirs,” Ms Hortle said.
“In the US and other places, CO2 is injected into the ground so more oil can come out the other end. Now, we can benefit from that knowledge, we understand a lot about the process of injecting and monitoring CO2 underground. We also have the expertise and engineering know-how to store large volumes of CO2 underground safely and efficiently.”
Why should we use it?
CCS can reduce the CO2 emissions from a modern conventional power plant by about 80–90 per cent.
“If we want to significantly reduce greenhouse gases and minimise climate change, we need to take CO2 out of the system,” Ms Hortle said. “There is no other method with the same potential for volumetric change.”
She says CSIRO has invested in CCS research for a couple of decades now, because of its potential for large-scale decarbonisation.
“Starting in the early 2000s we asked: What are the technologies? What are the economic opportunities? And do we have the geology for it?” she said.
CSIRO invested in a Victorian-based demonstration project, the Otway Project, now the Otway International Test Centre, for research into technologies for injecting and monitoring CO2 underground.
“We observe how it behaves, ask if it’s safe, if it’s predictable and we track it,” Ms Hortle said.
Is this a silver bullet for the fossil fuel industry?
A huge barrier to tackling climate change lies in transitioning the world towards net zero emissions. CCS is not intended to replace the need to transition. And the change is not one that can happen overnight, though current efforts are considerable.
Ms Hortle says when CSIRO first started looking into CCS, the idea did seem like a simple solution to the climate problem.
“It could capture CO2 from coal fired power stations, we’d inject it deep underground where it would stay for thousands of years. It seemed so straightforward,” she said.
“But today, even though we’re seeing a rapid transition away from coal, we still have a lot of CO2 in the atmosphere.”
Ms Hortle says while Australia’s seems unlikely to build new coal-fired power stations, other countries are still using coal, and they need methods to decarbonise. She also says even if fossil fuels were phased out tomorrow, there are still other industries emitting CO2. Not to mention all the excess CO2 already in the atmosphere.
“CCS is not about coal or fossil fuels, CCS is about CO2,” she said. “What do you do with all this excess CO2 we’ve already produced and will continue to? CCS is the only large-scale option for permanent removal of CO2 from the environment.”
Waste as an opportunity, not a problem
Rather than seeing CO2 emissions as a problem, Ms Hortle sees an opportunity. More and more countries and industries are under pressure to decarbonise. Here in Australia, we have enormous capacity in our underground reservoirs to take that CO2 and put it away permanently, deep underground.
Alternatively, we can use some of it to enrich our soil or turn some of it into new, low carbon products.
Each of these activities will require people and skills to capture and transport the CO2, to convert it to other products (for example building materials), to measure, regulate and account for the volume of CO2 prevented from reaching the atmosphere. In this way, each tool in the decarbonisation toolbox, including CCS, has the potential to create new industries in areas such as synthetic fuels, chemicals, carbon fibre and building materials.
The misconceptions of CCS
Many countries committed to the Paris Agreement with plans and targets for mitigating their CO2 emissions. CCS was one of the tools touted to help this process, yet it has struggled to get off the ground at a commercial scale under the weight of misconceptions.
Is CCS safe?
Ms Hortle says an important part of her work is engaging with local communities and answering questions about the safety of CCS.
She says CO2 is not directly toxic. “It exists in natural hot springs, we have it in beer and in soft drinks. I was once asked if I would have a CCS project in my back yard and I was able to honestly and emphatically say ‘Yes, I would.’”
The biggest risk to humans from CO2 is our own emissions to the atmosphere—and, once there, the impact it has on the climate.
“Permissions for this type of work aren’t just given,” Ms Hortle said. “A lot of effort goes into deciding whether a site is suitable in the first place. It takes time to understand, map and test the geology. We need to understand if it can store the CO2, then use a range of industry standard tools to track it and predict where it will go over the long term.”
She says the rules, regulations, permissions, approvals, monitoring and accounting all add up to an intensive regime with strong drivers to ensure the CO2 is in the best place possible.
“If there are risks, whether from fault lines or potential damage to well integrity, then the site would be downgraded and alternative locations sought; there would be no purpose to permit an unsuitable site.”
“The objective is to stop the CO2 re-entering the atmosphere. If the CO2 escapes, the whole point is lost,” Ms Hortle said.
What about the cost of adopting CCS?
Ms Hortle says—as with any technology—the more it’s implemented, the cheaper it becomes.
“What is too expensive anyway?” she said. “We are talking about an industrial by-product we have to manage—but again, this is potentially an opportunity for new industries, revenue and jobs.”
She says continued investment in CCS can generate new partnerships that bring engineering, technology, economics, sciences and communities together.
There are now more than 65 commercial CCS facilities identified by the Global CCS Institute Status report for 2020—and the largest CCS project sits within the Gorgon LNG project on Western Australia’s Barrow Island. In September 2020, the currently largest CCS project had sequestered three million tonnes of carbon dioxide.
Ms Hortle says while the opportunities of CCS are yet to be translated into its own industry, it has the potential to be a game-changer.
“CCS is just one of the portfolio of solutions to reduce emissions while meeting increasing energy demands,” she said. “It’s not the only answer, but it is one of many.”
“We all want to move rapidly towards a sustainable energy future, but we need a good toolbox to do that. CCS is one of those tools.”