What is CCS?
Carbon dioxide capture and storage (CCS) is a large-scale industrial process involving the capture of carbon dioxide (CO2) from large point source emitters, such as:
fossil fuel burning power plants;
biomass/biogas burning power plants;
- petrochemical facilities;
- and steel & cement plants.
The intention of this is process is to store the captured CO2 away from the atmosphere and ocean indefinitely.
Why do we use CCS?
It is a technology that mitigates the adverse impacts of these emissions such as:
- and sea level rise.
What are the Main Carbon Storage Options?
The main storage options are geological and are achieved by deep injection (>800m) into depleted oil and gas fields and large saline aquifers. At these depths the CO2 is in a dense phase where it behaves like a liquid and yet it is still a gas.
There are four main CCS storage options:
- Saline formations
- Injection into deep unmineable coal seams or coalbed methane
- Enhanced oil receovery (EOR)
- Depleted oil & gas reservoirs.
What Happens to the CO2 in Storage?
Over time it is immobilised in the geological environment by several processes such as:
dissolution into saline water;
mineral reactions with the rock minerals & brine waters;
- and pore trapping via capillary mechanisms.
Even in its dense phase CO2 is buoyant relative to brine, so escape to the surface must be prevented by ensuring that there are effective geological barriers, usually clay or shale layers, known as cap rocks. These seal the CO2 underground in the same way that oil and gas are trapped in natural systems for millions of years.
What is Carbon Capture, Storage & Utilisation (CCSU)?
The term carbon capture, storage and utilisation (CCSU) is applied to captured CO2 that is then used in an industrial process.
Industrial processes include, but are not limited to:
- enhanced oil recovery (EOR),
- fertiliser for fruit & veg growing,
- microchip manufacturing
- preserving atmosphere for chilled
- decaffinating tea and coffee,
- and in Japan, producing dry ice for the fishing and sushi industries.
Using Captured Carbon for Enhanced Oil Recovery (EOR)
By far the largest volume use is in enhanced oil recovery (EOR), where CO2 is injected into depleting oil fields to stimulate further oil production. There are 13 CO2 EOR operations in the world, spanning from North and South America to the Middle East, all of which are supplied with CO2 captured from industrial point sources. A further six CO2 EOR projects, including three in China, are expected to come on stream over the next four years.
In CO2 EOR the injected gas reacts with the trapped oil, reducing viscosity and selectively dissolving light oils and gases, which enables the hydrocarbons to flow toward the production wells. Oil and gas produced in this way reduces lifecycle emissions, as some CO2 is passively stored in the depleted field, as a result of the same physical and chemical subsurface processes as in a saline aquifer. For example, over 31 MT of CO2 have been stored through its use in EOR at the Weyburn oil field in Saskatchewan, Canada since 2000. Weyburn receives CO2 via pipeline from a coal gasification plant over the USA border in North Dakota and from a coal burning power plant at Boundary Dam in Saskatchewan.
Other Uses of Captured Carbon
There are smaller volume niche uses of CO2, such as fertilising fruit and vegetables in commercial greenhouses, as is done in the Netherlands. Microchip manufacture requires the gas as a cleaning solvent, while chilled food packaging often has CO2 as a preserving atmosphere and it is an important solvent for decaffeinating tea and coffee. In Japan the world’s first gas-fired power station to capture CO2 (Kansai Electric Company) provides dry ice (frozen CO2) to the fishing and sushi industries to keep fish fresh and chilled. Perhaps the most familiar use of CO2 is in the drinks industry where it is injected into drinks to make them fizzy (carbonated); and CO2 fire extinguishers are vital for dealing with electrical fires.
So, What Are the Main Problems with CCSU?
The main problem with CCSU is that in most uses, apart from EOR and emerging mineral capture technologies, the captured CO2 still passes into the atmosphere and thence to the ocean. Nevertheless, CCSU is an important revenue stream that can finance the building of capture and supply infrastructure, which could eventually be used to send the gas to dedicated geological situations for permanent storage.
The inability of such dedicated storage to cover its costs under present commercial conditions explains why there will be only five large saline aquifer storage sites in the world operating this year in:
- North America
- and Australia.
When Was the First CCS Project?
Statoil started the world’s first project for geological storage under the North Sea in a saline aquifer in 1996, by capturing and injecting approximately 0.8 MT/annum of CO2 from its offshore Sleipner gas production platform, just east of the Shetland Islands. This project makes commercial sense because the Norwegian government imposes a CO2 emission tax on oil and gas production.
What Are the Laws for Carbon Capture & Storage?
The legal situation for storing CO2 underground depends on the methods used and the jurisdiction hosting such sites. If the gas is used as a working fluid in oil and gas production, such as CO2 EOR, it is covered by long established petroleum production legislation. However, if the CO2 is injected for dedicated geological storage, on a world scale legislation is more patchy. The European Union has a directive which ensures that member states (and associated states, such as Norway) wishing to conduct dedicated geological storage comply with strict criteria for site selection to ensure effective permanent storage, safety and environmental protection. This criteria applies for all procedures:
- injection operation;
- monitoring & verification
- and final closure procedures.
CCS and CCSU so far in the UK
Geological mapping of the subsurface with a view to identifying and predicting the amount of storage space (geocapacity) available in the UK began in 1991, led by the British Geological Survey, with European co-funding. Over the following 20 years methodologies were developed, refined and standardised through several projects, in collaboration with industry, government and EU funding. This work also matched CO2 sources to potential storage sites.
In 2005 a Task Force was set up jointly by the UK and Norwegian governments to look at possibilities for collaborating on building a CCS infrastructure to receive CO2 from countries surrounding the North Sea. This culminated in a study, One North Sea, published in 2010, which summarised geocapacities under the North Sea and potential supply routes, via ship and/or pipeline. Meanwhile, the UK government initiated competitions for industry to bid for government support of up to £1bn to fund full scale demonstrations of CCS from up to three UK power plants.
As a result, by 2015 the UK was on track to deliver the world’s first full scale gas-fuelled power station fitted with CO2 capture, transport and geological storage of the gas under the North Sea. In 2015 the UK government then withdrew the £1bn capital grant set aside for funding such projects, leading to their cancellation, even though £168m of government money had already been spent in supporting the bids. The main excuse given by Government was that CCS was too expensive and costs needed to be reduced. This surprising decision has seriously delayed CCS deployment in the UK by at least 10 years.
The UK's Clean Growth Strategy
In October 2017 the UK government published its Clean Growth Strategy, which set out a road map of the research, innovation and deployment of low carbon technologies needed to enable the UK to meet its greenhouse gas reduction targets out to the period 2028–2032. These are legally binding targets, independently assessed and verified by the Committee on Climate Change, a body of experts to whom the UK government is accountable. In the strategy, gas becomes the most important fossil fuel as coal is phased out, leaving gas, renewables and nuclear as the main sources for heat and power.
Low Carbon Emission Technologies
The ambition is to have 85% of the UK’s electricity generation from low carbon emission sources in place by 2032 – a major challenge!
This requires CCS to be deployed in the 2030s, with emphasis on CCSU. Decarbonising the transport network, which accounts for 24% of UK emissions, will require more electric and/or hydrogen powered vehicles. Either way gas will be important as a source of hydrogen as well as electricity.
Natural gas is currently the main source of hydrogen, through a long-established process known as ‘steam reforming’, in which methane mixed with steam is converted over a catalyst into hydrogen and carbon monoxide. Hydrogen can then be converted to electricity and heat either by burning it in a gas turbine or by generating heat and power via a fuel cell. The carbon monoxide can be oxidised and captured as CO2.
Clearly there is a need to decarbonise gas use, otherwise the full benefits and deployment of low carbon electrification, hydrogen and heat will not be achieved. It is a ‘no regret’ part of the strategy which complements renewables and nuclear.
CCS Essential to Meet Greenhouse Gas Reduction Targets
The UK Clean Growth Strategy set out three possible pathways out to 2050, one of which does not involve CCS. However, the independent analysis of the strategy published by the Committee on Climate Change in January this year made it clear that it considered that CCS will be essential to meet the 2050 target, let alone the even more stringent Paris Agreement commitments that the UK has signed up to. The Committee points out that CCS may be needed as a greenhouse gas removal technology – for instance, by capturing CO2 from biomass to avoid it entering the atmosphere – long after fossil fuel dependency.
It advises that the ‘Development Pathway’ due to be published this year “must set out the Government’s proposals for the delivery model for CO2 transport and storage infrastructure, the funding mechanism for industrial CCS, and the allocation of risks between Government and developers, especially relating to long-term storage liabilities. Several promising projects exist in strategic cluster locations that could be in operation by 2025. If a decision on the future of the gas grid by 2025 is to be credible, then progress on demonstrating the business model for CCS will be needed before then.”
Funding CCS and CCSU
Furthermore, the Committee criticises the £100m allocation for early stage R&D support for CCS as inadequate, compared to the £1bn previously committed and withdrawn in 2015. It implores the Government to be more ambitious in the funding and timing of CCS deployment by setting out plans this year to ‘kickstart’ a UK CCS industry in the 2020s.
The UK, in partnership with countries that surround the North Sea, especially Norway, is exceptionally well placed to deploy CCS now whilst it has the offshore oil and gas skill sets and infrastructures in place. Procrastination is no longer an option, and yet more ‘studies’ will not help the rapid deployment of CCS.
How can oil & gas reduce greenhouse emissions?
The O&G industry too needs to be more ambitious: if oil and gas use is not decarbonised the rising public concern about the fossil fuel industry and diminishing investor support will accelerate.