SINGAPORE – Efforts are underway around the world to reduce the amount of carbon dioxide (CO2) that warms the planet in order to reduce the adverse effects of climate change.
But researchers at the Singapore Earth Observatory (EOS) at Nanyang Technological University (NTU) are looking to go further and study how the CO2 already in the atmosphere after decades of economic activity can be reduced. .
Their answer could lie underground.
Studies are underway to see if Singapore’s rock formations will be suitable for CO2 storage. While natural habitats like forests have the natural capacity to absorb CO2 and store it in their soil and in tree roots and trunks, the Earth’s lithosphere – or rocks – is a much larger store of carbon. .
CO2 in the atmosphere naturally enters the lithosphere slowly over thousands of years through a series of chemical processes.
This means that it will not outgass in the atmosphere and trap heat, contributing to the planetary crisis.
EOS researchers are working on an underground map of rock formations in Singapore to determine whether the technology can be used to take atmospheric CO2 and pump it deep underground for storage.
With such technology, CO2 is compressed to such high pressures that it essentially turns into a liquid form.
The weight of the overlying rocks helps to maintain this pressure, which allows the carbon to stay underground for a long time.
This technology essentially speeds up the rate at which carbon can be locked in rocks, as the natural process takes time for humanity not to face catastrophic climate change.
But a previous study by five local agencies, including the National Climate Change Secretariat, found that Singapore must overcome various obstacles for carbon capture, use and storage technologies to be used here.
In terms of storage, the study found that Singapore does not have any suitable geological formation known to store CO2 permanently underground.
But the EOS researchers said the rock formations in western Singapore could potentially have potential for carbon storage, based on their analysis of rock samples there.
For geological formations to be suitable for carbon storage, they must have layers of porous rock at least 1 km underground, either on land or below the seabed.
The porous rock should also be curved downward – like an upside-down bowl, and capped with a layer of impermeable rock, which acts as a seal to prevent CO2 from escaping.
These structures are often found in depleted oil and gas fields, where reservoirs are known to be stable over time because they have contained fossil fuels for millions of years.
EOS seismologist Dr Karen Lythgoe involved in the study said rock formations in the western region of Singapore consist of sandstone, which is porous, and finer-grained mudstone which could form an impermeable layer. .
But more detailed studies are needed to make sure the rock is in the right shape, she added.
Assistant Professor Wei Shengji, who leads the research team, said, “The overall objective of this project is to estimate whether it is possible to sequester CO2 and to give a quantitative estimate of the sequestration capacity.
Rock samples collected in previous studies could give researchers some preliminary information about the rock’s effectiveness in retaining carbon dioxide and trapping it over time.
But more data is needed to find out if these rock layers have carbon storage capabilities.
Seismic imaging of structures and geological analysis can also help researchers assess the feasibility of carbon sequestration and estimate carbon storage capacity, he noted.
Assistant Professor Judith Hubbard, Senior Researcher at EOS, said: “If Singapore is to meet its carbon emissions targets, it is important to try a lot of different things at the same time, as it is quite difficult to find a solution that will be effective on a very large scale. “
This means that Singapore should not abandon its carbon mitigation efforts such as the deployment of renewable energies, even as it examines emerging low-carbon strategies such as carbon sequestration and storage, because carbon storage may not be suitable here, said Dr Hubbard.
There are currently 15 direct air capture plants around the world, capturing more than 9,000 tonnes of CO2 per year, the International Energy Agency said in September.
Global CO2 emissions totaled 31.5 billion tonnes.
Prof Wei said, “The team is open to collaboration with other scientists researching in areas examining Singapore’s carbon sequestration potential, or with those studying geothermal potential, as we believe that an underground Singapore model would be of great benefit in urban and underground planning, as well as resource and risk mapping.
They are looking to apply for available research grants.