Not the bridging technology many claimed it to be. Photo: © Shutterstock – Everett Collection
CCS 2001–2018: Expectations and results
Carbon capture and storage is not a real mitigation option. There are faster, cleaner, surer, safer, more durable, more effective and cheaper ways to cut CO2: renewables, efficiency measures and the development of carbon-free industrial processes.
High hopes were pinned on CCS in the first decade of the 2000s. It gathered strong support from the US as part of the Bush administration agenda from 2001, and from the EU and the governments of the UK, Canada, Australia and Germany, especially after the IPCC special report in 2005. In 2008, the EU energy and climate package aimed to have 12 large demonstration plants in operation by 2015. The UN general secretary (and Angela Merkel) appointed the CEO of Vattenfall, Lars G. Josefsson, a leading coal apologist and CCS champion, as climate advisor. The Norwegian prime minister, Jens Stoltenberg, declared in 2007 that CCS was “our moon landing”.
The IPCC special report in 2005 claimed that “in most scenarios ... and in a least-cost portfolio of mitigation options, the economic potential of CCS would amount to 220–2,200 Gt CO2 cumulatively, which would mean that CCS contributes 15–55% to the cumulative mitigation effort worldwide until 2100”.
Almost every major power company believed coal was the future, and the only way to reconcile this with the belief that global warming was a serious threat was CCS. The European Commission summed up the mood in May 2008:
“Introducing CCS may delay the need to reduce levels of fossil fuel use by at least half a century.”
The conventional wisdom was that
- renewables were too expensive to grow fast. “CCS would be a bridge technology while alternatives to fossil fuels are further developed and deployed”
- there was a strong link between economic growth and energy growth, and especially electricity consumption, so the efficiency option was limited
- there was no realistic option to stop coal growth, so the fuel shift option (from coal to gas) was limited
- 550 ppm CO2 and higher were considered as mitigations.
Some of these assumptions were reasonable at the time. Solar power was indeed very expensive, as was offshore wind. Energy and electricity demand grew with GDP. The coal lobby was a strong political force. The US had abandoned Kyoto, and an international climate policy which did not include the US did not seem realistic or relevant.
Since then, everything has changed. Global CO2 emissions only rose 0.5% per year in 2013–2017, compared to 2.5% in the previous 10 years. Electricity consumption fell in the US, the EU and Japan. Coal use for power fell in the OECD from >4,000 TWh to <3,000 TWh in 2007–2017. New coal power became a no-no in an increasing number of countries, and a lot of capacity has been phased out. Globally, wind power grew from 104 TWh in 2005, when the IPCC CCS report was published, to 1,123 TWh in 2017, and solar from 4 TWh to 443 TWh.
None of the 12 European CCS demo plants were even started. Several CCS projects were abandoned in the UK, the Netherlands, Germany, Denmark, Algeria and Norway.
CCS was supposed to bridge the gap between a fossil-based world, especially for power, and a renewable world. But renewables have stormed ahead while CCS got nowhere.
The Australian CCS Institute has listed all large-scale CO2 storage projects around the world.
There are only four storage projects that do not use enhanced oil recovery as of July 2018, two in Norway and one each in Canada and the US, started between 1996 and 2017, and one under construction in Australia. Their combined capacity is stated as 7.4 million tons per year.
None of the five projects take CO2 from the big streams: fossil power, steel or cement production. Three of the five projects are for gas processing. Since CO2 is not wanted in natural gas, it has to be removed, and this happens to take place within reasonable distance from a good storage site. This for-free CO2 is untypical. Gas processing is a minor diversion of carbon from the extraction of fossil gas, as most of the carbon goes with the product, natural gas.
Natural gas production started in 2016 for the Australian project, but CCS has been delayed. The total investment is $88 bn, of which CCS accounts for 2.5 bn. CCS was a political necessity for a project that will emit more than a gigaton of CO2 when the gas is burned.
One of the five projects is for hydrogen production, which is used in tar sand oil production.
Globally, wind power produced 1,123 TWh in 2017. Assuming 0.5 kg of CO2 emissions per kWh, wind power avoided 561 million tons of CO2. All non-hydro renewables avoided, by the same account, more than 1,000 Mtons of CO2 in 2017.
Efficiency measures, such as LED lighting and heat pumps, avoid similar amounts of CO2.
CCS avoided, at most, 3.7 million tons of CO2 in 2017.
CCS technologies are briefly analysed here, see attached boxes. To summarise all those analyses, carbon capture and storage is not a real mitigation option. There are faster, cleaner, surer, safer, more durable, more effective and cheaper ways to cut CO2: renewables, efficiency measures and the development of carbon-free industrial processes.
Keeping the CCS option open will only divert attention and resources from the rest.
CCS is not fast. It would take decades for it to make a significant contribution to mitigation.
It is not reliable. Even with a huge effort, there is no way to know that it will deliver.
It is not safe. CO2 may escape over various timescales, carrying immediate risks to health, for inducing earthquakes and for renewed warming.
It is not clean. CCS uses about 25 per cent more fuel, which means more fossil extraction with several associated problems. A BECCS plant means more use of biofuel, which is a limited resource.
It is not durable. Fossil fuels are finite, and it is unsustainable to keep extracting them in enormous amounts in one place and burying the CO2, which has three times as much mass, somewhere else.
It is not effective. The process captures much of the CO2 but still emits 10 per cent or more directly into the atmosphere. The life cycle emissions from a CCS power plant are much higher than from a renewable plant.
It is not economic. A dollar spent on CCS mitigates less than a dollar spent on renewables etc. for the next year, the next decade or the next century.
If CCS is to play a significant role as a mitigation option, it must store several billion tons (Gtons) of CO2 per year. To store several Gtons, an enormous infrastructure will be needed, in the form of pipelines and/or CO2 tankers. Even if there were political unanimity, and unlimited finance, such an infrastructure has a long lead time. It must also be coordinated with the capture of CO2. That is hardly going to take place.
Carbon storage in geological formations has been tested since 1996 on the scale of up to a few million tons per year. On that scale, it does not matter very much if the storage sites leak. But it is not worthwhile to develop the whole scientific, engineering, political and legal machinery for just a few megatons.
Storage on a meaningful scale must be very resistant to leaks.
Perhaps it is possible to store CO2 for billions of years, but we cannot know for sure.
“The fraction retained in appropriately selected and managed geological reservoirs is very likely to exceed 99% over 100 years and is likely to exceed 99% over 1,000 years,” according to the IPCC CCS report.
“Very likely” means a probability of 90–99%, which would mean a 1–10 percent probability of faster or bigger leaks. “Likely” is a probability between 66 and 90%, meaning approximately “perhaps”. Both assessments are qualified, and apply to appropriately selected and managed sites.
If this assessment stands, it means there is a probability of 10–34 percent that more than 1 percent will leak.
If, as a theoretical example, the leak rate is 0.1 percent per year, after 1,000 years 73 percent will have returned to the atmosphere, to which should be added some 10 percent losses at capture. After 10,000 years 99.995 percent would have leaked.
Small leak rates matter, as the one stable natural sink for CO2 is silicate weathering, which operates on very long timescales.
The question of what happens at badly managed sites is very relevant in a perspective of several thousand years. We have no experience of international institutions that have such longevity.
Anything from bankruptcy and associated failure of monitoring equipment to war, earthquakes or tsunamis could increase the risk, as could careless mining or drilling.
CO2 under pressure is an extremely efficient lubricant and may trigger earthquakes. “Large-scale CCS may have the potential for causing significant induced seismicity,” according to the US National Academy of Sciences.
Irrespective of the actual risk, carbon storage has to take public opinion into consideration. Storage projects have been scrapped in Germany, the Netherlands and Denmark, as fossil companies have not been able persuade people that the benefits outweigh the risks.
Carbon capture from fossil fuel combustion is technically proven on an industrial scale, but it is very expensive.
Capture adds cost and complexity to unabated fossil fuel combustion. The capture plant is the same size or bigger than the power plant itself, so both capital and operational costs are greatly increased.
Carbon capture also consumes energy, so to produce power or some other useful service, around 25 percent more fuel is needed than if emissions were not captured.
Because CCS only captures around 90 percent of CO2, the carbon footprint of fossil power CCS is greater than that of renewables and efficiency measures.
There are three ways to dispose of the captured carbon: geological storage (above), enhanced oil recovery (EOR) and CCU.
EOR is clearly not a way to cut CO2 emissions. 17 of the 21 operating CCS projects in the world 2018 are EOR .
CCU (carbon capture and utilisation) in which carbon is used as a feedstock, is not a serious climate mitigation option. If CO2 is used to fertilise algae or greenhouses, the harvested plants will have to be stored forever. If they are combusted, all the CO2 will be emitted.
The same problem occurs if the CO2 is combined with hydrogen to produce methanol, for example.
Direct air carbon capture takes CO2 from the air, of which it makes up 0.04%. This is technically possible, but economically absurd, estimated by the American Physical Society at $600/tCO2. This does not include transport and storage of CO2.
Carbon Capture and Storage (CCS)
The most obvious candidate for CCS would be coal power. That is where there are very large amounts of CO2, and in high concentration. Some power stations emit 10 Mt of CO2, or more, per year, creating an economy of scale for capture, transport and storage. What works well in one coal power station can largely be replicated at another coal power station.
The second biggest stream of CO2 is natural gas power. It is still worse than coal power, as gas power plants produce less CO2 per kWh, tend to be smaller, and operate for fewer hours per year.
The economic reality is that fossil power CCS costs much more than renewable power. No such plant exists. No power producer would consider building a new coal or gas power plant with CCS, or retrofit an existing power plant for CCS, unless somebody else pays.
The economic case for power CCS used was originally based on a higher carbon price. But even a much higher carbon price will not necessarily help. Coal and gas are cheap to extract, but wind, solar and efficiency measures have no fuel costs at all. Fossil fuel costs are unpredictable and may increase. It is expensive and time-consuming to open a new coal mine, so the investor faces a lot of economic and political uncertainty.
Fossil power CCS is almost dead before it was born. Most of the opportunities for CCS have now gone, leaving only niche applications, which will then have to carry the full cost of research, development and infrastructure.
CCS for industrial processes is still under discussion. The iron and steel industry uses coal and coke to reduce iron ore (oxide) to metal. Similar processes are used for other metals, such as aluminium and copper. The cement industry uses fossil fuels to heat limestone, which then emits CO2. District heating and some other industries (e.g. paper and pulp) emit CO2 from fossil fuels or biofuels or a mix (e.g. household waste incineration). Other potential big point sources are oil or biofuel refineries.
The rationale for industrial CCS is that there is no alternative. There are however good arguments to the contrary, at least in a 2030–2040 perspective.
Iron ore mining should be reduced, through better recycling. Ore can be reduced by using hydrogen from the electrolysis of water, as renewable electricity can deliver vast amounts of cheap electricity. This is the strategic choice of Europe’s biggest iron miner, LKAB and the Swedish steel company SSAB.
Aluminium can be produced either with hydrogen, or with inert electrodes instead of graphite electrodes.
CO2-emitting Portland cement is one way of bonding rocks and sand together to make concrete. There are other binders: geopolymers (clays), pozzolans (volcanic ash, ash from coal combustion), slag, and magnesium-based cements.
Incineration of household and other waste with a large fraction of plastics is unsustainable. Waste prevention should first reduce, then reuse, then recycle the plastic in society.
District heating or industrial heat are far from ideal sources of CO2 for CCS, because they are typically much smaller than power plants, as they are typically not operated anyway near base-load, so CCS will add greatly to the cost. If district heating costs are excessive, customers will defect and use other heating sources.
If it is recognised that fossil power CCS is too expensive, then more decentralised collection of CO2 from district heating plants, steel mills, paper mills etc. must be much more expensive. A typical industrial or district CHP/heating plant is 1–100 megawatts. Each plant needs its own tailored engineering design, environmental impact assessment and associated political process. If a single 2 GW coal power plant, capturing 10 Mt CO2/year does not make sense, 100 smaller plants, 10–100 kilometres apart, make even less sense.
Bio-Energy Carbon Capture and Storage (BECCS)
If biomass is combusted in a power plant and then the CO2 is captured and stored, we would have a plant with negative emissions.
Biomass is a limited, though large, resource. Bio-CCS requires that it is used in large combustion plants, which may not be the optimal use. They will suffer the same parasitic loss as fossil CCS, so 20 or 25 per cent of the biomass feedstock will be needed for energy for CCS – unless the energy requirements for capture and compression are supplied by other renewable energy. That renewable energy would be better used directly to replace coal power for many years to come.
Market forces and climate considerations will arrive at the same conclusion every time: wind, solar and efficiency measures will always be the preferred alternative to bio-CCS.
The rationale for bio-CCS or other negative emissions comes when the whole power sector, and some other minor large point sources, are decarbonised. Then, bio-CCS could draw down CO2 from the atmosphere.
It is however very difficult to conceive that such a time will come, when mankind sees that all options to cut emissions are exhausted and that we must switch to draw-down mode. The decarbonisation process is not synchronised between countries and sectors. Some can and probably will achieve near-zero carbon in 10 or 20 years’ time, while big emitters will still be operating elsewhere. It is not clear who should shoulder the responsibility of building extremely expensive BECCS plants, and when.
The strategy of overshoot – first use a lot of fossils, then draw down the CO2 later – suits the fossil industry. It shifts the focus away from what we know can and must be done.