| Capture and geological storage of CO2 (ccs) as a way to solve the global climate crisis |
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LESIKHINA NINA The environmental group Bellona was founded in 1986 as a non-governmental initiative organized to conduct environmental research aimed at combating pollution and destruction of the environment, as well as preventing the harm that environmental violations cause the well-being of the human population and the negative consequences that come as a result of certain strategies of the global economic development. Bellona’s goal is to facilitate deployment of practical solutions that would minimise the harmful consequences of mankind’s activities on the planet.Bellona seeks to inform the public and mass media – and just as importantly, politicians and policy-makers – on pressing environmental risks, as well as participate in the development of strategic projects needed in order to find solutions to these problems. A better part of the energy consumed by the world is derived from fossil fuel sources such as oil, coal, and gas. Burning these fuels provides the energy necessary for human activities, but also produces carbon dioxide (CO2), a compound that causes global warming. CO2 is a major factor behind the warming effect taking place in the Earth’s atmosphere, which, in its turn, causes the elevation in the world’s sea level as glaciers melt, ocean water’s acidity level rises, and permafrost gradually disappears. The task of stabilizing the world’s climate requires that global CO2 emissions be reduced by 50-85% by 2050. This objective can only be achieved through new policies favouring more efficient energy consumption and a universal decrease in energy use, as well as development and introduction of renewable energy sources and of technologies enabling the capture and geological storage of carbon dioxide. These technologies will be a sizable contribution to the cause of finding an exit out of the climate change predicament. In March 2007, leaders of several European Union (EU) member states pledged to build by 2015 between ten and twelve fully functional demonstration plants for energy production that would employ CCS technologies. The financing mechanism approved in October 2008 implies extending 500 million credits to cope with CO2 emissions. These credits – approximately 3% of all credits that EU will allocate between 2013 and 2020 – will serve to fund the construction of the plants as part of the European Union’s CO2 emissions trade system. By ratifying the Kyoto protocol to the United Nations (UN) Framework Convention on Climate Change in 2004, Russia, too, committed itself to cutting its CO2 emissions. As Russia’s economy started to grow, its CO2 emissions increased as well, rising yearly by 4% to 5%. At the same time, however, projects aimed at reducing greenhouse gas emissions are not being implemented in Russia, while consequences of climate change are becoming more pronounced and harmful with each year. CCS technologies are a tangible solution to the global climate crisis. It is imperative, thus, that the Government of the Russian Federation commit itself to developing and providing a legislative foundation for the mechanisms of introducing such technologies into the country’s energy cycle as soon as possible. CO2 capture means creating a concentrated high-pressurised flow of CO2 which will then be easy to transport by pipelines or ship to a storage location. There is a number of various CO2 capture systems, which generally fall into three groups: post-combustion, pre-combustion, and so-called oxy-fuel systems, where fossil fuel is burnt using pure oxygen rather than air. Post-combustion CO2 capture systems separate CO2 from flue gas that is generated as a result of burning primary fossil fuel. In these systems, liquid absorbents are used to capture the small amounts of CO2 present in the flue gas out of the exhaust gas stream, in which nitrogen is the main component, as it comes from air. Pre-combustion systems process primary fuel in a reactor using an air- or oxygen-saturated flow to create a mix that consists predominantly of carbon monoxide and hydrogen gas. This synthesis gas can then be reformed into CO2 and hydrogen before separated into a pure CO2 gas stream and hydrogen stream. As for the oxy-fuel systems, oxygen, rather than air, is used when burning primary fuel to generate exhaust gas that would be made of, predominantly, water steam and CO2. This technology provides for higher concentrations of CO2 in flue gas (over 80% of the total amount of flue gas). Water steam is then removed through cooling and gas flow compression. Thanks to these technologies, between 85% and 95% of all CO2 that is processed in the capture system can be successfully captured.
CO2 transport.Pipelines are a preferred means of transporting significant amounts of CO2 over distances of up to 1,000 kilometres. Other transport means, such as shipping by sea, may be more attractive economically – if such an option is acceptable in principle – when transporting volumes of less than several million tonnes of CO2 per year or transporting over larger distances involving oceanic routes. Transporting CO2 through pipelines is a technology characteristic of a developed market, such as that of the United States, where over 40 mln. tonnes of CO2 is pumped yearly through pipelines stretching over a distance of as many as 2,500 kilometres. Provided certain circumstances are in place, transporting CO2 in ships – done in much the same way as shipping liquefied petroleum gas – becomes a viable economic option. However, at present it is only available to a limited extent due to an underdeveloped demand for such services. Carbon dioxide can also be transported by rail or in tank lorries. However, these are less attractive when large-scale CO2 transport is the desired objective. Natural oil and gas reservoirs have, on the whole, been well researched and are considered safe for storage of CO2 as they have held oil, gas, and quite often CO2, for millions of years. When CO2 is pumped into suitable oil and gas reservoirs to depths of over 800 metres, various physical and geochemical capture mechanisms can be relied on to keep carbon dioxide in place and ensure against leakage. Usually, the presence of overlying rock serves as the main confining physical mechanism. Injecting CO2 in some of these oil and gas fields will help further develop the depleted sites and resume excavation of the oil or gas that may still be left in them. Profit turned from the extraction of the remaining oil and gas can then be used to compensate for the expenses incurred by CO2 storage. This process has now been successfully used for a number of years in the United States exactly for the purposes of enhanced oil recovery, rather than CO2 capture. In Canada, the sequestration of acid gas – a residual product of reprocessing natural gas, which consists predominantly of CO2 and H2S – in oil and gas fields and deep saline aquifers has also been practiced for many years now. Deep saline aquifers are underground formations, usually deep sands, which contain saline water. As sites with an enormous potential for the geological storage of CO2, these formations are available in most countries, are often found close to industrial sources of CO2 production, are usually quite considerable in size, and have, therefore, sufficient capacity to hold enormous amounts of CO2. Technologically, sequestering CO2 in these formations is similar to injecting carbon dioxide into oil and gas fields. The Norwegian project Sleipner, an offshore gas field in the middle of the North Sea, is the world’s first commercial CO2 storage project. At this site, around one million tonnes of CO2 is pumped yearly into a saline aquifer under the sea, which clearly demonstrates that large amounts of CO2 can be efficiently sequestered without leakages using deep saline aquifer storage technology. Underground coal seams sometimes make coal recovery difficult or impossible if they are too thin or are located at depths that are too great. Additionally, they contain certain amounts of methane gas. It has been shown that when injecting CO2 into unminable coal seams, CO2 “binds” more easily with coal than methane does, and as such, it releases methane contained in the seams. This means that these coal seams can be used as sources of natural gas production, which can successfully cover the costs of CO2 capture. Coal beds have held methane for millions of years and it is quite possible to use them to hold CO2 for at least thousands of years more. Global experience with CCS technologies. Three major industrial-scale CO2 sequestration projects are currently under way: the Sleipner project at a sea-based saline aquifer in Norway, the Weyburn project in Canada, and the In Salah project in Algeria. Furthermore, several projects are being planned all around the world. The Sleipner project, operated by the Norwegian oil and gas giant StatoilHydro, is now running on over twelve years of experience of commercial application of carbon dioxide storage technologies. StatoilHydro was forced to introduce CCS technologies at the Sleipner field in the North Sea to minimise production costs: The gas it extracts from the field is approximately 9% CO2-associated impurities. According to requirements set forth by Norwegian law, levels of such impurities in the gas supplied from onshore terminals to local consumers or sold to the European market can not exceed 2.5%. Consequently, StatoilHydro used one of its platforms at the site to build a special purification system, where a chemical process is used to separate natural gas from concentrated CO2. Carbon dioxide is then injected for storage into a sub-sea reservoir located above the field’s gas deposit. This reservoir – an aquifer bearing saline water – is called the Utsira formation. StatoilHydro decided to store the CO2 instead of emitting it to the atmosphere due to the Norwegian CO2 tax which put a considerable cost on CO2 emissions from the offshore petroleum industry. Carbon dioxide underground storage technologies are also used today in Algeria, at the site of the In Salah gas drilling project in the Algerian part of the Sahara desert. Natural gas extracted here by British Petroleum, Statoil, and Sonatrach contains too much CO2 to make it suitable for immediate commercial use, which is why excess carbon dioxide is removed from the gas recovered from the field using chemical absorbents, then compressed and injected under pressure into an underground saline-bearing formation at a depth of two kilometres. The world today is dependent on fossil fuels. Changing the energy cycle we live by will require decades. CCS technologies can ensure a gradual transition from hydrocarbon energy sources to a diversified energy system that will minimise humankind’s impact on the global environment and will run on a renewable basis in the long term. During this transition, the current system of energy supply will, for the most part, remain what it is today, however, new infrastructure – such as power plants and large industrial enterprises – can be equipped with efficient capture mechanisms and transport pipelines to deliver carbon dioxide to storage sites. Bellona is thus urging the Government of the Russian Federation to develop a state programme that would introduce carbon dioxide capture and storage technologies at fossil fuel based energy sites, provide for a financing mechanism to support first fully functional power plants running on CO2-emission-free technologies, and launch pilot projects to start making use of what these technologies have to offer. Sources: |