We are currently heading towards irreversible climate change. Too much CO2 in our atmosphere is leading to global warming, which is causing climate change. The world’s leading scientists have warned that unless the rise in average global temperature is kept below 2°C, devastating and irreversible climate change will occur.
And yet, every day, we use energy and every day and we ask for more. And with the global population set to rise from 7 to 9 billion by 2050, world energy demand is expected to increase by 50 percent over the next 20 years alone.
Fossil fuels still supply 80 percent of our energy and we emit enormous quantities of CO2 when we burn them. Today, renewable energies provide only 13 percent of our energy and this could climb to 30 percent by 2020. But the fact remains fossil fuels will remain our principle source of energy for decades to come. This is particularly true of developing nations like China and India.
Fossil fuel power-plants, heavy industry (cement; steel; glass) and refineries are the largest emitters of CO2, accounting for slightly over half of global emissions worldwide, or around 15 billion tonnes of CO2 per year. It is these large fixed emitters that need to be most urgently addressed.
Energy consumption is going to continue to rise while CO2 emissions need to come down – fast. So, how can we meet this challenge? Through a combination of energy efficiency, renewable energy and CCS. It simply isn’t possible to achieve worldwide CO2 reduction targets without CCS – providing 20 percent of the global cuts required by 2050. And CCS is the only available technology that can capture at least 90 percent of emissions from the world’s largest emitters. In effect, implementing CCS on a global scale will give us the time we need to fully develop the sustainable energy systems of the future.
So, how do we capture, transport and safely store CO2 underground?
There are three main technologies that can be used to capture at least 90 percent of the CO2 emitted:
• Pre-combustion CO2 is captured before the fuel is burnt
• Post-combustion CO2 is captured after the fuel has been burnt
• Oxy-fuel CO2 is captured during fuel combustion
We already transport CO2 by pipeline and ships are used when a source of CO2 is too far from a suitable storage area. The widespread deployment of CCS will require the development of an equivalent and extensive CO2 pipeline network.
Compressed liquid-like CO2 is pumped deep underground into one of two types of CO2 storage reservoir:
• Deep saline aquifers, which are found between 700 and 3,000m underground
• Depleted oil and gas fields, found as deep as 5,000m below the earth’s surface
By storing CO2 underground, we are using a natural process that has trapped CO2, gas and oil for millions of years. Both oil and gas fields and deep saline aquifers have the same key geological features required for CO2 storage: a layer of porous rock to absorb the liquid CO2 and an impermeable layer of cap rock which seals the porous layer underneath, trapping the CO2.
Once injected into the porous rock layer, there are three natural trapping mechanisms that ensure that the safety of CO2 storage increases over time:
- Residual trapping: some of the injected CO2 becomes trapped in the tiny pores of the rocks and simply cannot move, even under pressure
- Dissolution trapping: a portion of the CO2 dissolves into the surrounding salt water
- Mineral trapping: after dissolution, some of the heavy CO2-rich water sinks to the bottom of the reservoir, where over time it may react to form minerals such as those found in limestone.
To ensure that a CO2 storage site functions as it should, a rigorous monitoring process begins at the reservoir selection stage and continues for as long as required.
The well, cap rock and adjacent rock formations are monitored for changes in pressure and CO2 concentration levels. The systems used ensure that response times are swift and decisive action can be taken when necessary. Monitoring continues even after a CO2 injection well is closed and, for instance, EU law requires that CO2 is safely and permanently kept underground.
The scale of the challenge is considerable, but doable. We need to move from the successful small-scale CCS projects in operation today to building 3,400 commercial scale projects worldwide by 2050, if CCS is to provide 20 percent of the CO2 reductions needed*. And in the midst of a recessionary climate, CCS offers considerable value for money: the IEA has calculated that meeting our 2050 CO2 reduction targets will be an astounding 70 percent higher should CCS not be a part of the low-carbon technology portfolio.
* IEA –Technology Roadmap, Carbon Capture and Storage
Written by Eric Drosin, Zero Emissions Platform
Founded in 2005, the Zero Emissions Platform, or ZEP, is a unique coalition of stakeholders united in their support for Carbon Capture and Storage, or CCS, as a key technology for combating climate change. ZEP serves as the European Union’s advisor on all aspects related to the demonstration and deployment of CCS. Click here to see an animation of the CCS process.
Tags: carbon capture and storage, CCS, climate change, co2, energy consumption, energy efficiency, Eric Drosin, fossil fuels, global emissions, global warming, oxy-fuel, post-combustion, pre-combustion, renewable energies, Zero Emissions Platform