For many years, Gaz de France's Research & Development Division has conducted experimental research programmes on the techniques of capture and geological storage of CO2. The goal is to develop new technologies and acquire knowledge and expertise that will give the Group a strong position on an emerging market.
In recent years there has been a great deal of debate on the risks of climate change, but there is now a scientific consensus that those risks are real and directly linked with greenhouse gas emissions. Following the ratification of the Kyoto Protocol, a European CO2 emission quota trading system was set up in 2004. This measure gave CO2 a market value, which is currently some €1 to €2 per metric ton, but soared as high as €30 eighteen months ago! This system suffers from a long-term visibility problem because of the variability of CO2 prices. At the same time, Europe set up its ZEP (Zero Emission fossil fuel power plants) platform, which aims to establish a European strategy to move towards zero CO2 emissions from fossil fuels, and includes CO2 capture and storage. A wide-ranging regulatory framework is currently being set up. As part of this same process, the European authorities may make CO2 capture and storage compulsory by 2015-2020.“For this to happen, CO2 capture and storage will need to be included in CO2 quota observes Samuel Saysset, project manager in the R&D Division's CO2 Capture and Storage section.
A dozen programmes in Europe
CO2 capture and geological storage is a promising solution which would hugely reduce atmospheric emissions of greenhouse gases, along with other measures such as controls on energy consumption and the use of renewable energies. The technologies have existed for more than 20 years, but they need to be developed if they are to be applied on a large scale and become economically acceptable. So the task now is to improve those methods by reducing capture costs by 20 to 30%, and possibly to combine them with other technologies. Everyone involved in the field is already working on this, exploring the different options. As part of this process, a number of pilot operations have been launched. Up to a dozen programmes should be beginning on large-scale industrial pilot sites, covering all the likely industrial conditions. In all the different areas – CO2 capture, transportation or storage – Gaz de France has for several years been actively involved in different international research programmes.
Transporting CO2 to the storage sites
There are currently few research projects on the intermediate stage in the chain, the transport of CO2 from the capture point to the storage point. However, there are still a few technological barriers to be removed. The most common method of transporting CO2 is by pipeline. This is essentially used in the USA, where more than 3,000 km of CO2 pipelines have been laid in more than thirty years. CO2 can also be carried by sea, but currently this is essentially a small-scale operation. R&D Division is taking part in the National Research Agency's Trans CO2 project. Under this programme, a number of feasibility studies on the technical and economic aspects of CO2 transport are underway, in particular transporting CO2 by ship.
A pilot CO2 capture project
As regards capture, one of the benchmark projects Gaz de France is involved in is the CASTOR (CO2 from Capture to storage) programme. Part of the 6th European Framework Research and Development Programme (FRDP), the aim of CASTOR is to help cut the costs of capturing CO2 in flue gases and to look at the feasibility of geological storage. The main target is to halve the cost of CO2 capture, which is currently €40 to €60 per tonne of CO2 emissions prevented. CASTOR began in February 2004 for a four-year period, with a total budget of €15.8 million. One of its flagship research projects is the installation of a pilot CO2 capture project on a coal-fired thermal power station at Esbjerg (Denmark, operated by Dong Energy), which is one of the world's biggest installations of this type. Up and running since the beginning of 2006, the operation entails capturing 1 tonne of CO2 per hour by means of an amine washing process, currently the most advanced method in use. The process involves dissolving the CO2 in a solvent, and then recovering the liquid solvent with the CO2 and flue gases locked into it (see computer graphics below). The CO2 is extracted by heating. However, this method of CO2 capture is still costly and requires significant quantities of energy.
The social challenges of the new technologies
The sociological aspect, in particular public perception, is crucial to the success or failure of a new technology. That is why public acceptability surveys are being conducted on CO2 capture and storage projects. “At present, there is resistance to storage technology. It is unfamiliar orperceived as not yet proven. In addition, CO2 is associated with global warming and is perceived as a poisonous gas”, comments Maud Minoustchin, research engineer in the Economics-Sociology Section. Another factor is that some people see the absence of a legal framework for CO2 as meaning that governments are not interested in the subject, which also makes people suspicious.
“One approach would be to establish forums for information and discussion between all the stakeholders (industrial companies, researchers, public authorities, residents' associations, etc.)”, suggests Maud Minoustchin. “Which is why Gaz de France is involved in the National Research Agency's SOC-ECO2 project.”
Options for geological storage
At the other end of the chain comes the CO2 storage phase. Of the different alternatives envisaged a few years back, the only option now under consideration is geological storage. There are three possibilities: storage in non-viable coal seams, in depleted hydrocarbon wells or in saline cavities. Storing CO2 in the deep oceans is no longer being considered because of the complexity of the natural phenomena involved and the potential impact on marine fauna. There is still a lot of work to do on these methods of geological storage. “Coal seams could represent a niche market for certain countries, although the storage capacity is small. This technology is still in the pilot stage, whilst the other methods are already being demonstrated on an industrial scale“, observes Samuel Saysset. In this type of geological structure, the main obstacle is permeability, which is sometimes insufficient to guarantee the optimum conditions for injecting CO2.
Storage: Saint-Martin-de-Bossenay experiment (Marne)
Report by Christophe Rigollet, geology project manager at Exploration-Production Division
“As part of the GéoCarbone-Picoref programme, we are conducting a study at the Saint-Martin-de-Bossenay site on the feasibility of injecting and storing CO2 in two types of geological formation: a saline aquifer and a depleted deposit, the latter split into two layers. The method entails injecting CO2 to increase the pressure and push the remaining hydrocarbons into extraction wells. We are not carrying out in situ experiments. The aim of the studies we have conducted since 2004 has been to describe the geometry and volume of the site reservoirs, and to understand these geological formations better. The geological analysis phase is now over. The engineers are now simulating different CO2 injection scenarios.”
Storage experiment
Using depleted hydrocarbon wells is an easier alternative. The potential global volume is some 1,000 billion tonnes, of which more than 40 billion are in Europe, mainly in the North Sea. Gaz de France is currently running a pilot operation on the K12B natural gas field, which is now virtually depleted. The block lies 3,800m below sea level, north-west of Amsterdam. Since 2004, the CO2 produced by the processing of natural gas on the production platform has been reinjected into the well it was extracted from. This injection operation is one of the case studies that the CASTOR project is based on. Three other types of underground storage are being considered as part of CASTOR: a deep offshore saline aquifere at Snøhvit (Norway) in which Gaz de France is a partner, a nearly depleted offshore petroleum deposit in the Mediterranean Sea and an onshore deposit in Austria. At Snøhvit, CO2 is being injected into an aquifer situated below a natural gas pool. Another potential large-scale storage operation is Altmark. This virtually depleted gas deposit in Lower Saxony represents one of Europe's largest potential depleted field CO2 storage sites. “This site represents an ideal location for a short-term demonstration operation. A partnership agreement has also been signed with the Vattenfall Group, which will supply CO2 produced by a pilot power station“, explains Samuel Saysset.
Saline aquifers: the most potential
Deep saline aquifers represent the most promising long-term solution. Located at great depths, these underground layers of saline aquifers are of no use as potential sources of water for drinking or irrigation. They have a dual advantage: they offer larger storage capacity than hydrocarbon deposits and are relatively better distributed around the world. Worldwide CO2 storage capacity in these deep aquifers is estimated at between 400 and 10,000 billion tonnes. At present, our knowledge of these geological structures is poor (hence the wide range of estimates) and a great deal of exploration will be required before we can understand their context. Different sites are being studied: Sleipner since 1996, In Salah (Algeria) since 2004, Snøhvit (Norway) and finally Satoryl, where work will start at the end of 2007. Reflecting the widespread interest in this topic, a Franco-German symposium on the subject was held near Postdam on June 21-22 this year, at the Ketzin site, where CO2 is currently being injected into an aquifer. And within the framework of the 6th FRDP, a programme called CO2 Sink is looking at the storage of CO2 in depleted oil and gas wells.
As we can see, the capture and geological storage of CO2 is a major topic of international research, especially in the USA, Japan, Europe, and particularly in France. Gaz de France is part of this big international drive towards CO2 capture and storage. Promising as they are, these questions still require more research and investment before industrial applications become possible. At a time when researchers are working on the development of hydrogen fuel, a mastery of capture and storage techniques would make it possible to produce hydrogen without generating CO2. That could be the start of a new era in energy.
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Gaz de France