CO 2 capture and storage

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CO 2 capture and storage (technical terms: CO 2 sequestration and CCS ( english c arbon dioxide c Apture and s torage )) is a method for reducing CO 2 - emissions into the atmosphere by the technical spin-off at the power plant ( End of pipe ) and "permanent" storage in underground storage facilities . There are large-scale projects of this type, all of which are pursued without any attempt to demonstrate economic viability.

CO 2 acts as a greenhouse gas in the atmosphere and is the main cause of human-made global warming . The area of ​​application of CO 2 capture and storage is to be large point sources of CO 2 , primarily in power plants with fossil fuels , but also in industrial processes and in mining. The process steps are the separation, the transport (if necessary) and the geological storage of the CO 2 . Possible CO 2 - deposits special geological formations such as deep saline water-bearing apply aquifer (aquifers) or depleted oil - and natural gas deposits , possibly also deep coal seams are possible, but where the safe enclosure is questionable.

With CCS, the CO 2 emissions of fossil-fuel power plants can be reduced significantly - but there are still notable greenhouse gas emissions. While z. For example, in a life cycle analysis , conventional hard coal power plants show CO 2 emissions of 790-1020 g / kWh, whereas the emissions of a CCS power plant of 255-440 g / kWh are lower but still significantly higher than with renewable energies or nuclear power plants . In addition, CCS technology worsens the efficiency of power plants. In modern coal-fired power plants, it is assumed that there is an increase in fuel consumption of approx. 24 to 40% compared to power plants without CCS technology, mainly for the separation and compression of carbon dioxide.

CO 2 capture and storage in power plants is still in the development and pilot stage. As of 2016, the technical and economic feasibility of CCS power plants is still pending, despite two decades of research and the construction of prototypes. The profitability of the technology is questionable, as it is assumed that some renewable energies will have the same or lower production costs as early as 2020.

In 2005, the IPCC issued a special report on the capture and storage of CO 2 . According to the calculations of the Intergovernmental Panel on Climate Change ( IPCC), " negative emissions " - i.e. the removal of CO 2 from the atmosphere - are necessary in order to keep the average warming at a maximum of 1.5 ° C in accordance with the 2015 Paris Climate Agreement . The majority of the scenarios that aim to limit global warming to 2 ° C are based on the availability of processes to achieve negative emissions, whereby bioenergy with CO 2 capture and storage (BECCS) in particular is accorded an important role. However, since the BECCS technology has some disadvantages and, above all, would require very large areas for biomass cultivation, it is questionable whether it will ever be available on a large scale.

Final storage to protect the climate requires suitable space for similar amounts of carbon as is extracted from the earth, in any modification or chemical compound. Since geological storage sites only exist to a limited extent and are only sufficient for a few decades, there is also competition for use between the different carbon sources, for example between carbon from fossil fuels and from biomass .


The separation of CO 2 in power plants can be done with different methods, for. B. after combustion in a CO 2 scrubbing from the exhaust gas ( post- combustion), separation after coal gasification ( CO 2 -reduced IGCC power plant , pre- combustion ), or combustion in an oxygen atmosphere ( oxyfuel ) . All three processes are being developed in parallel with each other and implemented in pilot plants. Each of the techniques has specific advantages and disadvantages over the other. It is still completely open which technology (and whether one at all) will prevail in large-scale use. Critical variables include efficiency losses, the separation rate (which proportion of the CO 2 is recorded), the purity of the separated CO 2 , other environmental effects on the air, water or waste path, the costs and the inertia of the process in load-following operation .

Downstream separation in the exhaust gas

Sequence of CO 2 separation in the post-combustion process (including CO 2 transport and storage)

A CO 2 scrubber can be installed as the last step in cleaning the exhaust gas after desulfurization . This process is also called post- combustion capture (eng. Combustion = 'combustion'; capture = 'capture'). In a coal-fired power plant with an assumed efficiency of 38% without separation, 0.32 kg of hard coal are required to produce 1 kWh of electricity, from which approx. 0.88 kg of CO 2 is generated. The main component of the exhaust gas is the nitrogen contained in the atmosphere, which does not take part in the combustion. The CO 2 - partial pressure is about 15%. This makes washing processes relatively complex, as the nitrogen has to be dragged through the entire process as “ballast”.

Various washing methods are currently being tested. Here, too, it is unclear which method could prevail for large-scale use. Amine scrubbing is known on an industrial scale in natural gas processing (but not in the power plant sector) . During the amine wash, the CO 2 is attached to the carrier, finely divided amine droplets, at 27 ° C. In a second step, the amines enter a separator (stripper), where they release the CO 2 in concentrated form at 150 ° C and are then fed back into the process. Amines are considered to be the third leading cause of workplace cancer; this separation technology would be associated with considerable risks for workers and the population. Such emissions are when using non-volatile amines such. B. the amino acids proline or sarcosine not to be expected. Such a process based on an amino acid salt solution was tested at the Staudinger power plant from 2009 . The efficiency of the power plant alone fell by six percentage points (6%), the CO 2 separation efficiency was over 90%.

A carbonate wash with hydrogen carbonate works in the same way . In the case of carbonate washing, the accumulation takes place at approx. 40 ° C and the splitting off at 105 ° C. The carbon dioxide can also be removed from the flue gas with organic solvents, e.g. B. with methanol (Rectisol wash), N-methyl-2-pyrrolidone (Purisol wash) or polyethylene glycol dimethyl ether (Selexol wash). The separation rate with this method is up to approx. 95%, the energy consumption is comparable to other methods and reduces the efficiency of the power plant alone by more than 5%.

Other separation methods are membrane filters, chilled ammonia or the carbonate looping method (or L IME L OOP C O 2 - R eduction process). In this process, lime is used as a cycle medium for the process. Accordingly, the two calcium compounds CaCO 3 and CaO are found in the process . The process takes place in a temperature range of 650–900 ° C. This results in a comparatively low loss of efficiency. The actually lower efficiency has only been argued in qualitative terms so far.

What all washing processes have in common is the high energy requirement that is necessary, for example, to regenerate the detergent. In the case of a coal-fired power plant, the overall efficiency drops by an estimated eight to twelve percentage points (6–12%); the fuel consumption increases accordingly. A modern hard coal power plant has an efficiency of approx. 45%, due to the CO 2 separation the efficiency then drops to approx. 33–37%, which means an up to approx. 35% higher coal consumption for the same electricity production. So far, none of these separation processes has shown a CO 2 separation rate of over 90% on an industrial scale. Previous systems either separate significantly lower amounts of CO 2 or are still in the testing and development phase.

Several test facilities are currently in operation, in Germany at the TU Darmstadt .

For chemical syntheses , it appears energetically sensible to convert the CO 2 with coal to carbon monoxide ( Boudouard equilibrium ). Hydrogen would also be required to produce methanol.

Separation in IGCC combined cycle power plants

In combined cycle power plants with integrated coal gasification ( Integrated Gasification Combined Cycle , IGCC) and CO 2 separation ( Carbon Dioxide Capture and Storage , CCS), the coal reacts in a first step ( gasification , partial oxidation ) in a stoichiometric manner with water to form hydrogen and carbon monoxide .

With the help of suitable catalysts , carbon monoxide and water vapor can react to form carbon dioxide and hydrogen (homogeneous water gas reaction ). This enables a gas mixture to be obtained which mainly consists of hydrogen and carbon dioxide. Due to the gasification at pressures up to 60 bar, a high CO can 2 concentration and thus a high CO 2 - partial pressure be adjusted in the gas mixture. Under these conditions, CO 2 can be absorbed from the gas mixture using tried and tested methods ( physical absorption ). This process is known as pre- combustion capture , since the CO 2 is removed before combustion. The desulphurisation is carried out according to the same principle (separation of hydrogen sulphide ). The fuel gas processed in this way then consists mainly of hydrogen (up to 90 percent by volume possible) and can be used in a combined cycle process . For this, however, a completely new development of a hydrogen turbine is necessary. Since IGCC power plants already have to struggle with technical problems without CO 2 separation, it will take decades for this technology to be ready for the technical and economic market. According to calculations, this variant of CO 2 separation has a low loss of efficiency (less than 10%). A pilot plant has existed since 2011 in the Dutch Buggenum power plant.

Deposition in the oxyfuel process

In the oxyfuel process , the coal is burned in an atmosphere of pure oxygen and CO 2 (recirculating flue gas). The resulting flue gas is not diluted with air-nitrogen and consists essentially of CO 2 and water vapor. The water vapor can be condensed with little effort, so that a highly concentrated CO 2 stream (concentration in the ideal case close to 100 percent) remains. The CO 2 can then be compressed and transported to the warehouse. After a successful test in a pilot plant, a pilot plant for CO 2 sequestration with a thermal output of 30 MW was put into operation in September 2008 in the Schwarze Pump industrial park in the immediate vicinity of the Schwarze Pump power plant .

With the oxyfuel process, too, the overall electrical efficiency drops by around 10 percentage points compared to a system without CO 2 separation , which corresponds to a 30-50% higher coal requirement depending on the efficiency of the underlying process. That means a decrease of the thermodynamic efficiency by approx. 15%. In this case, the additional main energy consumer is the air separation plant for the production of pure oxygen.

Deposition in industrial processes

The easiest way to capture CO 2 is in systems that separate CO 2 from natural gas , because there it occurs in a very pure form. Initial attempts at CO 2 sequestration are therefore aimed at this area and not at coal-fired power plants. B. In Salah ( Algeria ).

Geological risks

In the Sleipner gas field in the Norwegian part of the North Sea , approx. 1 million tons of CO 2 have been separated and injected annually since 1996 , in the Snøhvit gas field in the Norwegian Barents Sea, a good 700,000 tons annually since 2008. In Sleipner the pressure does not rise and 24% of the injected CO 2 can no longer be found. For this purpose, a fracture 3 km long, up to 200 m deep and 10 m wide, which could not be found with previous examination methods, appeared only 24 km away. In the Snøhvit had compression of CO 2 in the lineup Tubåen be set because the pressure rise so much that the overburden threatened to tear. The Stø formation has been grouted in Snøhvit since 2013.

The increasing demand for petroleum is making coal liquefaction more profitable to produce hydrocarbons for fuel. This results in large amounts of CO 2 because the amount of energy bound per carbon atom in the product (hydrocarbon) is much greater than in the raw material (coal). Primary energy must therefore be transferred in the process. Part of the carbon is energetically upgraded (reduced), while another is oxidized to release energy.


In connection with the construction of new coal-fired power plants , the terms “CCS-Ready” or “Capture-Ready” are increasingly used, which are intended to denote that the new power plant is prepared for subsequent installations for separation. These terms are currently not precisely defined or protected by law. The TÜV Nord has defined its own standard and awards based on that certificate. There are no legal requirements.

Since areas that correspond to more than half of the original power plant area are required for the construction of the separation, these areas should be available and released for use when a new power plant is built or renovated. A new power plant without these prerequisites cannot normally claim to be “CCS-ready”.

For a solid approach to ecology, an overall balance must be drawn up. This includes providing evidence of access to a warehouse either directly at the power plant site or via long-distance transport and providing evidence of actually available storage capacities.

Direct air extraction

Other programs are exploring ways of filtering carbon dioxide directly from the air using chemical absorbers . This technology is mostly referred to as DAC ( direct air capture ). The first prototypes exist which are testing the process experimentally, but the disadvantage is the high cost. As of early 2018, this was around USD 600 per tonne of carbon dioxide. Developers of this technology hope to be able to reduce the cost of carbon dioxide capture from the air in the long term to around $ 100 / ton, not including storage.

Storage (sequestration, storage)

Most researchers in the field of CO 2 sequestration favor (as of the 2000s) storage in deep sediment layers , the pores of which are filled with salt water. From a depth of approx. 800 m , pressures occur at which the introduced CO 2 is so compressed that it remains in the supercritical state. In order that a renewed exposure of the carbon dioxide is practically excluded, these layers must be covered by an impermeable cover layer. Despite the pressure prevailing there, the density of CO 2 is less than 700 kg per m³ , which is why it will swim on it. In the upper area of ​​the deposit, the salt water is therefore displaced from the pores, creating space for the injected CO 2 . Where the displaced salt water stays is one of the critical questions of CCS technology. It is mainly displaced to the side (laterally) and can then rise in geological fault zones, even at a great distance from the injection site, and reach the groundwater (drinking water) or the seabed. The lateral extent of the pressure anomaly can be many times greater than the spread of CO 2 in an aquifer . If pressures are used to inject CO 2 and displace salt water that are well above the formation pressure and the tensile stress of the rock, induced earthquakes can occur, which in individual cases can also lead to vibrations that are above the perceptible limit.

When using deep aquifers, sequestration is in competition with other uses, for example the use of these aquifers for sustainable electricity generation from geothermal energy . Questions of the environmental damage caused by the disposal of large amounts of CO 2 in aquifers have not yet been investigated. The storage capacity of aquifers is also limited. The estimated 20 billion tons of storage capacity on German territory roughly correspond to the CO 2 emissions of the German power plant park over 30 to 60 years. Experience with these rock strata in Sleipner and Snøhvit shows that the actually available storage capacity would have to be set significantly lower. Since the EU prescribes a non-discriminatory right of access for all EU states to these final storage sites, CO 2 from other member states should also be allowed to be disposed of in Germany. Since the landfilling of waste is generally not permitted in Germany , legal questions still need to be clarified.

While only a few years ago it was assumed that the CO 2 in saline aquifers would either dissolve in salt water or mineralize, current studies show that a substantial proportion will probably persist as supercritical fluid over the long term.

Carbon dioxide can be stored in the form of carbonates , which could also be dumped openly and without safety concerns. The main starting materials for this are silicates of the alkaline earth metals . These can be converted exothermically to carbonates and silicic acids with dissolved carbon dioxide . Particularly promising are non-polymerized or low-polymerized silicates such as olivines , pyroxenes and pyroxenoids , e.g. B. forsterite , monticellite , wollastonite , diopside or enstatite , less layered silicates like the serpentine . The slow response speed is still a problem. Products to be dumped would be magnesium or calcium carbonate and silicon dioxide precipitated from the silica. In 2008, researchers at New York's Columbia University under Professor Klaus Lackner were able to show that peridotite , a rock made of olivine and pyroxene, can carbonate significantly faster than previously assumed , even in situ . This also makes technical use in situ possible, which would save dismantling and landfilling. With the drilling of a larger number of boreholes, hydraulic fracturing of the rock and initial warming, the researchers consider reactive CO 2 sequestration at greater depths, where higher pressures and temperatures already exist, to be possible on an industrial scale. An international team of scientists reported in 2016 in Science that mineralization in basalt rock is very efficient. In the CarbFix pilot project on Iceland, they injected 220 tons of heavy carbon labeled carbon dioxide along with water at depths of 200 to 400 meters. The measurements showed that after 1.5 years, about 95% of the injected carbon was a component of calcite and other minerals.

Carbon dioxide can also be injected into deep, non-degradable coal seams . The advantage of this method is that the CO 2 is sorbed (fixed by weak physical interactions) on the carbon. The so-called seam gas methane normally contained in coal is thereby displaced and can be extracted and used as a relatively clean energy source.

Since 2008 the exchange of methane hydrates in sediment layers on the sea floor for CO 2 has been researched. The commercial mining of gas hydrate deposits for the purpose of extracting fossil fuels has so far only been carried out in a western Siberian permafrost deposit. In Japan, the USA, Canada, South Korea, China, India and other countries, however, extensive funding programs are being set up, which aim to begin the large-scale mining of submarine hydrate deposits in about ten years. The aim of the SUGAR research project is to exchange the methane extracted from the sea floor for CO 2 .

Model calculations on the basis of demonstration systems showed that with the so-called CarbFix method, depending on the respective local conditions, storage costs of approx. 25 to 50 dollars / tonne of CO 2 can be possible. These values ​​are lower than with conventional CCS methods.


The CO 2 can outgas and create cold water geysers with the existing groundwater . This happens continuously in Germany, for example in Andernach and Wallenborn in the Eifel . These can release considerable amounts of toxic heavy metals from the rocks locally in the subsurface and thus carry them into the regional groundwater. In addition to the displacement of salt water from the injection horizons in aquifers, heavy metal pollution in drinking water would also have to be expected.

According to one at the Stanford University study, consists in the compression of carbon dioxide into the ground a high probability of weak earthquakes in the storage area. These would be too weak to cause major damage to the surface, but the resulting cracks could leak and the stored carbon dioxide could escape back into the atmosphere. Because of this fact, the large-scale storage of carbon dioxide is viewed in the study as a risky and probably unsuccessful strategy for greenhouse gas reduction. Since the separation, transport and compression of CO 2 would result in considerable amounts of additional CO 2 emissions, the CO 2 content of the air could even increase significantly within 100 years due to CCS with leak rates of only 1% per year .

Legal framework

The technique chain of CO 2 sequestration touches a plurality of jurisdictions of immission - via the civil protection - up to the mountain - and water law . However, none of these laws adequately describes the new activity of CO 2 sequestration. Legal systems that do not know that there is no mountain freedom of mineral resources must also clarify the legal relationship between the CO 2 storage facility and the land above it.

Mining law, in Germany the mining law , is generally only applicable if CO 2 sequestration is used in the context of traditional mining activities, for example for the extraction of oil or gas.

International law of the sea

The ban on shipments of waste at sea ( dumping ) and the export ban on waste for shipment to the sea, which are laid down in the London Convention (1972) and the OSPAR Agreement, also apply to CO 2 storage in the sea or below the seabed . Since the world's first CO 2 storage project was carried out offshore on the Norwegian oil rig Sleipner, there was a need for regulation. The contracting states decided to adapt the OSPAR agreement in 2007 and the London Convention in 2008. According to this, the transfer of CO 2 into geological formations below the sea floor is permitted. The transfer of CO 2 into the open water column, which was discussed up to then (and in some countries to this day) , has since been prohibited by the respective contracting states .

EU law

At EU level, Directive 2009/31 / EC on the geological storage of carbon dioxide regulates the selection, approval process and operation of CO 2 storage facilities. This guideline has been in force since June 25, 2009 and regulates, among other things, the procedure for the approval process for the exploration, operation and closure of CO 2 storage facilities and specifies material standards for the nature of geological formations.

Further requirements such as the compulsory use of CCS in new power plants and the retrofitting of existing ones were discussed, but are not included in the guideline.

The EU directive does not apply directly in the member states. They have to translate the directive into national law. The member states had a period of two years for this, i.e. H. by June 25, 2011. According to the EU Commission, 25 of the 27 member states missed this deadline. Only Spain and Romania reported completion on time. The EU Commission examined sanctions against the defaulting states in accordance with the European Treaties .

The European Union's funding of CCS has not been successful under the NER300 program. Despite almost 4 billion euros in subsidies, none of the projects was successful, as the European Court of Auditors criticized.

CCS law in Germany

In Germany, the use of CCS has been regulated by law since August 24, 2012 by the Act to Demonstrate the Permanent Storage of Carbon Dioxide (Carbon Dioxide Storage Act - KSpG) . Germany has thus also implemented the EU Directive 2009/31 / EC into national law. The law contains a maximum storage amount for Germany of four million tonnes of CO 2 per year in total and 1.3 million tonnes per year per storage unit, as well as a state clause that is intended to give individual federal states the option of a general ban on CO 2 storage on their territory.

This was preceded by two attempts by the federal government to pass a carbon dioxide storage law. A first attempt by the grand coalition to pass a CO 2 storage law failed in June 2009 before the end of the 16th legislative period. Substantial protests among the population also contributed to this. In Schleswig-Holstein, the discussion about the draft law came at a time of massive protests against a CO 2 storage project and the election campaign for the state elections in September 2009 .

Since both the 2009 Bundestag election and the Schleswig-Holstein state election resulted in black and yellow majorities, but these took opposing positions on CO 2 storage in Berlin and Kiel , the renewed submission of a CO 2 storage law lasted until April 2011. The new draft law had taken up criticism of the old draft and emphasized the character of the demonstration more strongly through time and quantity restrictions. Furthermore, at the instigation of Schleswig-Holstein and Lower Saxony, it contained a state clause which was intended to give the federal states the option of a general ban on CO 2 storage on their territory. This draft law failed in September 2011 in the Federal Council. The federal government then called the mediation committee . After months of negotiations, an agreement was reached, on the basis of which the Bundestag and Bundesrat passed the law at the end of June 2012. It came into force one day after its publication in the Federal Law Gazette 2012 Part I No. 38.

The Ketzin CO 2 test storage facility is approved under mining law. Further permits for exploration of CO 2 storage facilities were also applied for before the KSpG came into force (in the absence of a suitable legal framework) under mining law (“exploration of brine ”) and could be converted into exploration permits under the KSpG. However, when the KSpG came into force, there were no open application procedures.

In a position paper published in 2012, the energy supplier EnBW criticized the CCS technology. There is currently no acceptance among the population for the underground storage of CO 2 and, moreover, "CCS technology is associated with considerable costs which, in the long term, significantly exceed the costs of promoting renewables, including photovoltaics". In addition, EnBW committed to the energy transition and saw the systematic and economic advantages of renewables, which should now be expanded.

Other countries

In the EU, other countries, e.g. B. the Netherlands and Great Britain , implement the EU directive promptly and discuss appropriate legislation. In Austria , CO 2 disposal was banned. Only research projects up to 100,000 t CO 2 were permitted.

In Australia, a new law regulates offshore CO 2 storage in territorial waters. Some states have regulations governing storage on land. Similarly, in the United States and Canada, CO 2 storage is regulated in individual states. A national legal regulation is in the US in the public hearing.


Advantages and opportunities

A rapidly increasing use of renewable energies and an increase in energy efficiency on the generation and consumption side can only replace fossil energy generation in the medium or long term. It remains to be seen how long it will take large growth countries (e.g. the People's Republic of China and India ) and emerging countries to make this transition. The permanent storage ( final storage ) of the carbon dioxide is a possibility to reduce the otherwise expected increasing pollution of the atmosphere with greenhouse gases.

Carbon dioxide stored in sediment layers can (locally limited and in the amount of no importance) increase the production pressure in almost exhausted oil deposits. Corresponding programs are running in Great Britain (North Sea) and the USA . This technique is called EOR (enhanced oil recovery). The same risks exist here as with CCS.

If biomass is used as fuel, CO 2 in conjunction with CCS could be withdrawn from the atmospheric cycle and thus theoretically removed from the atmosphere CO 2 emissions caused by human activity .

Usability of technology

With the current state of the art, the loss of efficiency at the power plant leads to a loss of efficiency in power plants of around 10 percentage points . This corresponds to an approximately 30% increase in the use of resources. In addition to high costs, this results in faster consumption of partly scarce resources and additional environmental pollution from landscape destruction (e.g. in the case of lignite mining), transport, the increase in waste heat and the emission of other pollutants (fine dust, heavy metals). Further environmental impacts arise from the increased accumulation of sewage and waste as a result of the separation process. These cannot yet be quantified with the current state of knowledge.

In any case, the technology would make electricity from coal-fired power plants much more expensive.

With pipeline lengths of more than 500 km, the losses are likely to be higher. A CO 2 pipeline network of 22,000–37,000 km in length is planned for Europe . Based on experience from the USA, a 25,000 km pipeline network would have six leaks every year. Long-term use of energy is not included, as the deposits should be monitored for thousands of years. In this respect, the question arises whether the energy balance of CCS power plants is positive at all.

The technology does not enable CO 2 -free, but only CO 2 "poor" electricity production. Only around 70% of CO 2 emissions are actually avoided.

Storage of carbon dioxide

The storage of carbon dioxide in deep saline aquifers (saltwater- bearing underground layers) and disused oil and gas deposits is currently being discussed (as of around 2009) . According to the Federal Institute for Geosciences and Raw Materials , the capacities of these are around 20 billion tons (saline aquifers, added up) or 2.75 billion tons (disused oil and natural gas deposits, added up). These capacities would be sufficient to store emissions from all German power plants for around 30–60 years. So it is not a long-term solution, after about a generation of power plants, the storability of German underground storage facilities would be exhausted. This could be in line with the short to medium term goals for which the technology is designed.

With some types of storage, especially when discharging into the sea, the stored CO 2 could get back into the atmosphere over the course of a few 100 to 1000 years, so that only a delay in the emission occurs or even an increase in the CO 2 - Emission would come (due to the increased fuel consumption, more CO 2 is produced than without separation). Even with some underground repositories, which are in principle much more reliable, the tightness of the repository is difficult to assess. The observation of CO 2 stores is therefore an important subject of development. The risk of gradual outgassing, which would possibly undo the climate policy effect of CO 2 sequestration unnoticed, also makes the search for suitable storage sites more difficult, because the final fate of the gas must of course be ensured (depending on the opinion for at least 200 or 10,000 years). In 2007, the German federal government named a maximum leakage rate of 0.01% per year acceptable from a climate policy perspective, at which about 90% of the CO 2 remains in the repository after 1000 years .

When storing very large amounts of CO 2 , the salt water is displaced from the aquifers. Since this cannot move “downwards”, it will flow to the side and ultimately rise to weak areas in the mountains (fault zones), so that it can then mix with the groundwater . Safe storage locations have to be sufficiently far away from fault zones that have such a high degree of permeability to the surface of the earth. Since, according to the BGR, there are more than 16,000 deep bores, cracks and fractures up to the planned storage horizon in Lower Saxony alone, the number of possible CO 2 repositories is once again reduced significantly.

A sudden occurrence would be far more dangerous than the gradual outgassing of the stored carbon dioxide. This would result in high CO 2 concentrations that have a suffocating effect (see Nyos accident ). Based on observations during natural gas production, the occurrence of earthquakes in the area of ​​the deposit and thus possible exposure through cracks or defective boreholes cannot be fundamentally excluded.

The introduction of large amounts of CO 2 into the sea can have massive ecological consequences, for example by lowering the pH value or the formation of "CO 2 lakes" on the sea floor, which kill the life there (see also the carbon cycle , here especially problems technical solutions ).

The processes for CO 2 sequestration cause additional costs for electricity generation. The economic feasibility therefore depends to a large extent on the prices of emission rights set in CO 2 trading. The aim of the European emissions trading scheme is to promote CO 2 -reducing technologies. These include CO 2 sequestration.

In the meantime - 2014 - the production costs for electricity from wind and sun (photovoltaics) have fallen sharply; Numerous fossil power plants in Germany cannot even generate the costs for fuel and CO 2 rights in operation. The CCS technology - it implies a significant increase in the cost of electricity production from fossil fuels - thus appears obsolete.


Critics of CO 2 sequestration argue that alternative power generation and an exit from coal- fired power generation are less problematic, more developed and cheaper (already or at least for the time being). In particular, the following are mentioned here:

Biological sequestration

Previous research or projects have generally only dealt with the storage of liquid or gaseous CO 2 or in the form of dry ice . In addition, there is also the possibility of binding the CO 2 as biomass and storing it as the carbon obtained from it, e.g. B. as pyrogenic carbon in the form of biochar or black earth (see also Terra preta : black soil in the Amazon, or: Hydrothermal carbonization ). Most of the above-mentioned points of criticism no longer apply to this aggregate form. However, this detour shows that it would be most effective to leave the fossil carbon deposits untouched instead of restoring them afterwards.

Another possible sequestration is reforestation , which, according to the Gesellschaft Deutscher Chemiker (May 2004), can be realized more sensibly and significantly more cheaply than the separation of CO 2 from exhaust gases. However, CO 2 is only permanently bound if the wood produced is not burned or rots, but is built into houses or furniture. Wood is a storable, bound form of carbon, from which a compact form that is protected from rotting could also be produced. The rewetting of moors would also be effective , as the growth of peat moss can bind carbon in the additional peat that is created. The rewetting leads to the exclusion of air, which prevents the decomposition of the organic substance and thus the renewed release of CO 2 . Often such measures also benefit other environmental protection goals.

Private individuals can sequester CO 2 through afforestation.

The fertilization of marine areas with iron is also currently being researched. This is intended to promote the growth of algae. Like plants on land, these bind CO 2 , then ideally sink to the sea floor and remain there. However, the effects on the ecosystems that are strongly influenced by this are largely unknown and it is unclear how much CO 2 is actually permanently removed from the atmosphere by this method. In 2009 the Alfred Wegener Institute carried out the LOHAFEX experiment (see also EisenEx ) in order to gain knowledge on these questions.


The costs of CO 2 sequestration are made up of:

  • Capital costs for the separation systems
  • Operating costs of the separation systems
  • Costs for the additional fuel input due to the reduced efficiency of the power plants
  • Transport costs to the camps
  • Storage costs including monitoring.
  • Costs for disaster control and defense against damage.

The amount is currently not known. The Global CCS Institute estimates that the cost is currently between US $ 23 and US $ 92 per tonne of CO 2 avoided and that future research and development work may further reduce this cost  . Since the prices of CO 2 certificates in the EU are seen to be over 20 euros in the long term, CCS technology can thus achieve profitability. A prerequisite here, however, is that other alternatives (e.g. renewable energy sources) are not available in sufficient quantities or only at higher costs.

Criticism of the Environment Council

In May 2009, the CCS bill met with clear criticism from the German Advisory Council on the Environment . Instead, a research law for a limited number of demonstration projects is recommended. The paper warns of risks and hidden costs and lists the following points:

  • Risks are still unexplored. However, the law would make CCS possible on a large scale. The storage is irreversible .
  • To date, there is no acid-proof concrete to be able to close the drill holes. Another, uncontrollable repository problem threatens.
  • Perpetual costs over several thousand years from taxpayers' money, as the energy companies are handing over the storage facilities to the federal government 40 years after they have been closed. This then bears the liability risk and the monitoring costs.
  • Conflicts of use with geothermal energy and compressed air storage for wind power. CCS would de facto take precedence under the law.
  • The draft law is hasty, as no significant contribution is expected from CCS by 2020.
  • Indirect support for coal power through free access to limited storage capacity resources
  • High direct subsidies for CCS for energy companies at the expense of renewable energies
  • lack of spatial planning / influence on site
  • important details not regulated
  • Acceptance problems underestimated

In addition, the Environment Council expresses criticism of CCS in connection with coal power:

  • Separation, transport and storage decrease the efficiency of the power plants
  • Technology would only be available after huge investments

Ratio of coal and wind power

Coal-fired power plants are considered unsuitable for flexibly supplementing the growing amounts of wind and solar energy. With changing wind conditions, such base load power plants are z. B. unable to ramp up or down quickly. Gas or hydropower plants, on the other hand, can react more quickly and are therefore better suited to supplement.

The discussion leads to the question of whether new coal-fired power plants can be dispensed with with complete security of supply. The Environment Council is clearly positioning itself here: "The system decision should be made in favor of renewable energies."

Use of the deposits

The Environment Council does not reject CCS in principle. Instead of using up the deposits for coal-fired power plants, CO 2 should be actively withdrawn from the atmosphere by biomass at a later point in time . This could be necessary in the second half of the 21st century in order to keep climate change within limits.

Preferential CCS

After an investigation, the law gives companies the right to use the underground resource permanently. Private property rights or planning sovereignty of municipalities, districts and federal states then no longer play a role. The authorities would be forced to approve: The one who “first submits an application” comes into play. Thus, in the opinion of the Environment Council, CCS is clearly given an advantage over future alternative energies such as geothermal energy and compressed air storage, as these would then no longer be an option.


  • The statement puts the research funding of the current programs in the EU at 745 million euros.
  • In the EU's economic stimulus plan of March 2009, a further 1.05 billion euros are planned.
  • In addition, there would be an estimated 9 billion euros in emissions certificates, which were reserved specifically for CCS until 2015.
  • State aid for environmental protection could also flow into CCS projects.
  • The European Investment Bank is to receive 1 billion euros in loans and a. provide for CCS funding.

Conclusion from the statement: "The additional costs incurred by the companies (...) could - depending on the price of the emission certificates - be largely or completely covered by the planned funding at EU level". It must be examined "how the subsidization of CCS affects the competitiveness of other climate protection technologies".

Criticism from environmentalists

In addition to the Advisory Council on Environmental Issues, CCS has also been repeatedly criticized by environmental protection organizations. For example, in a statement published in 2009, WWF Germany expressed doubts as to whether such technologies would be available worldwide quickly enough to make a significant contribution to reducing CO 2 emissions. Greenpeace even called CCS a “sham package”.


At the end of 2015, according to the IEA, 13 large-scale CCS projects were in operation worldwide, which captured a total of 26 million tons of CO 2 per year. That was less than a thousandth of global emissions. Between April 2016 and February 2020, over 300,000 tons of carbon dioxide were captured and stored in the seabed in the Tomakomai industrial park . That corresponds to the annual output of 75,000 cars.

Research programs

Laboratory-scale CO 2 separator (at the Institute for Energy and Environmental Technology), Duisburg

Research is being conducted into CO 2 sequestration in many industrialized countries around the world. The European Union has increased its previous research budget for this area from 30 to 200 million euros. As part of the European Energy Program for Recovery in 2009, funding commitments of over 1 billion euros were made for CCS projects. Such a research program has also existed in the USA since 1997.

In the Federal Republic of Germany , research projects within the framework of the Geotechnologies and Cooretec programs are investigating how the necessary new power plant construction in Germany of 40  GW (about 1/3 of the bottleneck capacity of all German power plants) should be designed in such a way that the necessary reduction in CO 2 emissions can be achieved. In particular, the efficiency of the power plants must be maximized because this minimizes the amount of CO 2 at the source. Furthermore, the implementation of power plant technologies with CO 2 separation is being tested (forecast: first use by 2030) as well as possibilities to separate the gas from the flue gases of conventional power plants. Finally, options are being sought to store the separated CO 2 permanently and safely.

In September 2009 the Federal Ministry of Education and Research (BMBF) stopped financing a project to investigate storage locations.

The technology platform for CO 2 -free power plants (TP ZEFFPP) was set up at EU level, which examines the state of research in international cooperation with experts from non-governmental organizations , science and industry and determines the need for action in order to implement the vision of CO 2 -free power plants . This body also develops proposals for the orientation of the 7th research framework program of the EU. It should be noted, however, that the term CO 2 -free power plants is misleading; at best, it is about a reduction in CO 2 emissions into the atmosphere. This is especially true if not only the power plant but also electricity generation from coal is considered as a whole.

In Switzerland, a repository is currently being tested in the Mont Terri rock laboratory (as of January 2019) .

Pilot plants for deposition

The CO 2 separation in power plants is currently being tested on a pilot scale in various plants :

The CCS technology was tested by Alstom and Vattenfall Europe at the Schwarze Pump power plant, and on April 9, 2014, it became known that Vattenfall is completely shut down and dismantled the plant due to the political framework.

Storage sites, projects and public protest

The possible storage capacities for CO 2 for the Federal Republic of Germany are assumed to be around 12 billion tons (= gigatons) of CO 2 plus / minus 3 billion tons. These numbers are largely based on estimates and have changed significantly in the past, mostly downwards. Extensive studies can be found at the Federal Institute for Geosciences and Natural Resources (BGR).


The electricity supplier RWE had plans between 2006 and 2010 to install CO 2 capture at a new lignite-fired power plant on the site of the Golden mine in Hürth and to pump this CO 2 into northern Schleswig-Holstein via a 530 km pipeline and inject it there . The plant was originally scheduled to go into operation in 2015.

Schleswig-Holstein's Environment Minister Christian von Boetticher , Economics Minister Dietrich Austermann (both CDU ) and RWE Dea had initially announced the “joint project” with a “starting shot” . Initially, there was roughly talk of North Frisia and East Holstein as storage regions. In May 2009 the State Ministry of Economics approved soil surveys in both regions. RWE Dea initially started in Südtondern / Schafflund in a 20 x 15 km region in the offices of Südtondern , Central North Friesland and Schafflund .

At the end of May and beginning of June 2009, RWE Dea then presented the project in detail to the mayors of the affected communities for the first time. Several 1000 underground blasts were planned for seismic tests to determine the suitability of the geological formations. The plans encountered strong opposition on site. According to its own statements, the citizens' initiative against the CO 2 -Dendlager eV in Schleswig-Holstein collected more than 80,000 signatures for a petition between May and November 2009 , created regular demonstrations, stickers and posters and organized human chains. In the summer of 2009, authorities and municipalities organized numerous well-attended information events at which RWE-DEA presented the project and various speakers from research, authorities and environmental associations discussed controversially.

State SPD , SSW , Greens and Die Linke spoke out against the project early on in Schleswig-Holstein. In June and July 2009, numerous unanimously adopted resolutions by district assemblies, municipalities and associations followed. The cross-party protest on site meant that the Schleswig-Holstein CDU also turned around and did not want to advance the project. The FDP also gave in . Thus, the Schleswig-Holstein State Parliament decided unanimously on June 17, 2009 to reject the storage project and to reject the CCS law in the Federal Council. After the state elections in 2009, the state government reaffirmed its negative stance. RWE then stepped back from its plans and put the entire CCS project on hold.


Citizen protest

In Brandenburg , the energy company Vattenfall wanted to split CO 2 off a new block of the lignite power station in Jänschwalde , transport it via pipelines and inject it underground at Beeskow ( Oder-Spree district ) or Neutrebbin ( Märkisch-Oderland district ). EU funding of 180 million euros was earmarked for this project. The response to the project was divided in the country. While the state government , the Chamber of Commerce and Crafts as well as parts of the trade unions such as the IGBCE endorsed the project, there was rejection, especially in the targeted storage regions. The citizens' initiatives CO 2 ntraEndlager and CO 2 -Endlager-Stopp eV had collected more than 10,000 signatures against the project . The Brandenburg citizens' initiatives receive political support from the CDU member of the Bundestag, Hans-Georg von der Marwitz from Märkisch-Oderland , who sees CCS as an economic and environmental wrong track. The Evangelical Church Berlin-Brandenburg-Silesian Upper Lusatia (EKBO) also spoke out against the testing of CCS in Brandenburg in a resolution passed by the Synod on October 30, 2010 due to unexplained risks. The left is divided on the CCS question: While individual votes reject CCS, the Brandenburg state party and in particular Economics Minister Christoffers stand by the coalition agreement with the SPD, in which they support CCS, even though Die Linke previously campaigned with the slogan "Consistently against CO 2 - Endlager "had advertised.

After the State Office for Mining, Geology and Raw Materials Brandenburg (LBGR) had issued the exploration permit for the exploration region Birkholz-Beeskow and Neutrebbin in 2009, Vattenfall was asked to draw up operational plans for the exploration ( seismics , drilling ) and to have them approved. This did not happen again. In December 2011, Vattenfall discontinued the project with reference to the delayed legislative procedure for the Carbon Dioxide Storage Act (KSpG).

Lower Saxony

According to press reports, E.ON Gas Storage GmbH (EGS) had submitted applications for the exploration of brine in the Wesermarsch and Cuxhaven districts and other districts in connection with power plant planning in Wilhelmshaven in June 2009 . E.ON did not pursue the project after 2010.

In 2009, the Danish company Dong Energy considered using CCS for a new coal-fired power plant in Emden. A deposit has not yet been named.


In the Maxdorf area , Altmarkkreis Salzwedel , the company GDF Suez, together with Vattenfall , planned to test the storage of carbon dioxide in connection with the extraction of the remaining natural gas in the amount of around 2 billion m³ in the almost empty natural gas subfield Altensalzwedel. Operation of the plant was ended in 2012.

International Energy Agency timetable

“The CCS technology has had enormous setbacks lately. The timetable of the International Energy Agency (IEA) from 2009 has long been obsolete. This called for around one hundred CCS projects to be set up between 2010 and 2020 and to store 300 million tons of CO 2 in the process. But politicians thought the costs were too high and many projects were stopped. ... The updated IEA timetable from 2013 only mentions a good 30 CCS power plants. "

See also


Overview literature

Legal texts


  • Robert H. Socolow: Can We Bury the Climate Problem? In: Spectrum of Science . Heidelberg, 03/2006, p. 72 ff., ISSN  0170-2971 , available free of charge from Wissenschaft-online (PDF; 348 kB)
  • Oliver Mayer-Spohn, Markus Blesl, Ulrich Fahl, Alfred Voß: Logistics of CO 2 sequestration - options for CO 2 transport . In: Chemical Engineer Technology . 78.2006,4, pp. 435-444, ISSN  1522-2640
  • L. Dietrich: CO 2 capture and storage (CAA) in German and European energy environmental law . Baden-Baden 2007, Forum Energierecht Vol. 12, plus dissertation Universität Osnabrück, 264 pages, ISBN 978-3-8329-2864-3
  • Lutz Wicke : "With CCS or not at all" . Article on the technical feasibility and economic viability of sequestration, which leads a "silent cartel of senior engineers" analogous to the discussion about the separation of sulfur dioxide in the 1970s.
  • Rainer Wolf: CCS, Plant Permit Law and Emissions Trading . In: Journal for Environmental Law (ZUR) . Edition 12/2009, pp. 571-579. (PDF file; 149 kB)
  • Ernst Riensche, Sebastian Schiebahn, Li Zhao, Detlef Stolten: Carbon dioxide separation from coal-fired power plants - from the earth into the earth . In: Physics in our time 43 (4), pp. 190–197 (2012), ISSN  0031-9252
  • Dirk Asendorpf: "We could absorb all emissions". Norway is making a tempting offer to Europe: Empty natural gas fields off the North Sea coast are to become CO 2 final storage facilities, in: Die Zeit No. 33, August 9, 2018, p. 31.

Web links

Individual evidence

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  4. ↑ German Advisory Council on Environmental Issues : Separation, Transport and Storage of Carbon Dioxide. ( Memento of the original from October 17, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . In: . April 2009, accessed October 17, 2016. @1@ 2Template: Webachiv / IABot /
  5. Jacco van Holst, Patricia. P. Politiek, John PM Niederer, Geert F. Versteeg: CO 2 capture from flue gas using amino acid salt solutions . In: . University of Twente . September 17th, 2009 (PDF)
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  9. recommendations of COORETEC Advisory Council to promote research and development of CO 2 -emissionsarmer power plant technologies and CO 2 capture and store carbon technologies (PDF file)
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  12. The Sleipner project of the Norwegian company Statoil (storage of CO 2 in the Norwegian North Sea seabed) ( Memento of the original from October 14, 2012 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (English) @1@ 2Template: Webachiv / IABot /
  13. Johannes Peter Gerling: Carbon Dioxide Storage - Status in Germany and Europe , in: Spectrum of Science , Dossier 4/2009, Die fiebernd Erde , p. 70
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  23. CO2SINUS ( Memento of the original from March 5, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. CO 2 storage in locally converted coal seams - research project at RWTH Aachen @1@ 2Template: Webachiv / IABot /
  24. IFM-GEOMAR: SUGAR project ( Memento of the original from July 15, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Research into CO 2 sequestration in submarine gas hydrate deposits @1@ 2Template: Webachiv / IABot /
  25. ^ Ingvi Gunnarsson et al .: The rapid and cost-effective capture and subsurface mineral storage of carbon and sulfur at the CarbFix2 site . In: International Journal of Greenhouse Gas Control . tape 79 , 2018, p. 117-126 , doi : 10.1016 / j.ijggc.2018.08.014 .
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  31. CCS in Europe (information pages of the EU Commission on the regulation of CCS )
  32. "EU Climate Protection Package 2020: CO2 capture and storage" , website of the European Parliament, May 14, 2008
  33. Presentation to the EU Commission October 2011 ( memento of the original from August 10, 2012 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . In: . (PDF) @1@ 2Template: Webachiv / IABot /
  34. Special report No. 24/2018: Large-scale commercial demonstration of carbon capture and storage and innovative technologies for renewable energies in the EU: The progress planned for the last ten years has not been achieved . EUROPEAN COURT OF AUDITORS. Retrieved July 12, 2019.
  35. Act to demonstrate the permanent storage of carbon dioxide (Carbon Dioxide Storage Act - KSpG) . In: .
  36. Spiegel Online report on the failed CCS law from June 2009
  37. Press release of the Federal Environment Ministry on the CCS bill April 2011
  38. wbr / Reuters / dpa: Federal Council prevents law on CO2 disposal . In: Spiegel Online . September 23, 2011.
  39. Announcement from the Bundestag to call the Mediation Committee November 2011  ( page no longer available , search in web archivesInfo: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.@1@ 2Template: Toter Link /  
  40. EnBW position paper ( Memento of the original dated January 3, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot /
  41. ↑ The race for white coal , Die Zeit, 2009
  42. Hans-Werner Sinn : The green paradox: Why one must not forget the offer in climate policy. (Ifo Working Paper No.54; PDF; 687 kB) Ifo Institute for Economic Research at the Ludwig Maximilians University in Munich and Chair of Public Finance, January 2008, p. 45 , accessed on June 21, 2009 : “[…] unfortunately is Such a solution [...] expensive because you need a lot of energy for the pressing (about a third of the energy generated). "
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  44. GeoCapacity projectDescription
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  46. see e.g. B. RWE press release of August 14, 2014
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  48. ^ Opinion of the Advisory Council for Environmental Issues ( Memento of the original from September 3, 2014 in the Internet Archive ) Info: The archive link was automatically inserted and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF file; 429 kB) @1@ 2Template: Webachiv / IABot /
  49. ^ Setting the course for the power supply (Prof. Hohmeyer) ( Memento of the original from March 4, 2011 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF file; 174 kB) @1@ 2Template: Webachiv / IABot /
  50. ^ Opinion on the law regulating the capture, transport and permanent storage of carbon dioxide (CCS). (PDF) WWF Germany , March 5, 2009, accessed June 30, 2016 .
  51. Sham package CCS. Greenpeace , accessed June 30, 2016 .
  52. How coal doesn't get clean , Handelsblatt, December 7, 2015
  53. Red disk in the sea floor; in: TAZ of February 10, 2020
  54. Archive link ( Memento of the original from April 13, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot /
  55. Geotechnologies research program
  56. ^ Cooretec research program
  57. Friederike Balzereit: CCS research project stopped . In: Christian-Albrechts-Universität zu Kiel . Press release 92/2009. September 16, 2009.
  58. Markus Gross: CO 2 storage in the fissured rock. In: ETH Zurich , January 17, 2019, accessed on January 29, 2019 .
  59. Press release Siemens and E.ON Kraftwerke set up a pilot system for CO 2 capture from coal-fired power plants on
  60. Press release Federal Ministry of Economics funds pilot project for a CO 2 wash by RWE Power, BASF and Linde on
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  62. Alstom receives order for CO 2 -free power plant in Schwarze Pump
  63. Knopf et al .: Recalculation of possible capacities for CO 2 storage in deep aquifer structures ( Memento of the original from September 19, 2015 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. , in: Energy industry issues of the day , 2010 @1@ 2Template: Webachiv / IABot /
  64. Federal Institute for Geosciences and Raw Materials ( Memento of the original from December 27, 2011 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot /
  65. a b Chronology of the CCS project Schleswig-Holstein
  66. RWE project CCS power plant and storage
  67. Press release of the EU Commission on the promotion of CCS from the economic stimulus package
  68.  ( page no longer available , search in web archivesInfo: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.@1@ 2Template: Toter Link /  
  69. ^ Position paper by Hans-Georg von der Marwitz MdB (CDU) on CCS
  70. ( Memento of the original from February 22, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot /
  72. Archived copy ( Memento of the original dated February 22, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot /
  73. Archive link ( Memento of the original dated February 23, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot /
  74. europaticker 11/02 Exploratory Advisory Board to clarify whether CO 2 can be stored underground in East Brandenburg
  75. [1] Press release from Vattenfall on the discontinuation of the Jänschwalde CCS project
  76. Nordsee-Zeitung about CCS plans in the Weser area
  77. ^ Ostfriesen-Zeitung about CCS plans in Emden
  78. Out for the planned CO 2 injection near Maxdorf. Volksstimme of November 21, 2012, accessed on September 6, 2015
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