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How does CCS work?
Nature has been storing carbon dioxide (CO2) underground for millions of years. Now Shell and others are developing technologies to capture CO2 from major industrial plants and store it safely underground. This approach, known as carbon capture and storage (CCS), could reduce global CO2 emissions by around 20% in 2050.
Major industrial plants such as power stations, cement factories, refineries and chemical plants produce a large share of man-made greenhouse gases.
Greater energy efficiency will help reduce emissions. So will replacing coal with natural gas, and more renewable energy. But the single most effective way to tackle emissions from energy-intensive plants is to capture CO2 and store it safely underground in depleted oil and gas reservoirs or saline formations.
What are the benefits of CCS?
Long-term demand for energy is rising, with the population set to reach around 9 billion in 2050 and as more people move out of poverty.
All sources of energy will be needed, with fossil fuels still expected to meet at least 65% of world energy demand by mid-century.
CCS is the only technology available to mitigate GHG emissions from large-scale fossil fuel use – particularly for power generation – according to the International Energy Agency (IEA).
Replacing a coal-fired plant with a gas-fired plant that has CCS can cut CO2 emissions by up to 90%.
By 2100, CCS could account for more than half of the CO2 reductions needed globally.
The IEA points out that the economic cost of stabilising these emissions through developing other technologies and energy sources would be 40% higher without the widespread deployment of CCS.
Is CCS safe?
CO2 occurs naturally in the atmosphere and is essential for life. For millions of years it has been stored underground in natural rock formations.
And for decades Shell and other companies have injected CO2 into reservoirs to push out more oil.
When stored in a reservoir after being captured from an industrial plant, for example, CO2 would be held in place by an impermeable “cap” rock.
This held natural gas securely in the reservoir for millions of years.
The pressure is kept within safe limits to ensure that the reservoir and its cap are not damaged.
Sensors inside the injection system and within the reservoir can detect minute changes in pressure or CO2 levels, alerting engineers early to any potential problem.