Carbon Capture and Storage (CCS). Is CSS the game changing energy technology of the early 21st century?

Introduction

You cannot solve a problem by using the same thought patterns that created the problem in the first place. (Albert Einstein)

In the present essay I argue that CCS can be seen as a game changing technology or as a game cheating technology, which allows us to further ignore the impacts of our behaviour on global climate until the carbon bubble bursts. As Albert Einstein has put it, we need to change our thought patterns if we really want to create a change. Using CCS technology to mitigate climate change only delays what we can already do now: Start thinking in a different way and stop our business-as-usual behaviour. On the other hand it can be seen as the only solution to the pressing problem global warming.

In the first part of the essay I explain how CCS works and what advantages and disadvantages different technologies have concerning safety and energy penalties. The following part will argue how CCS could be the game changing technology. I will discuss the positive effects that CCS can have on the overall constitution of our atmosphere.

In the last part of my essay I concentrate on the long-term outcomes of the implementation of CCS and how it can rather be seen as a game cheating than a game changing technology. I will come to the conclusion that CCS is a dead-end street in climate change mitigation even though it has certain advantages like a quick and immediate reduction of greenhouse gases (GHG) and that the money invested in CCS R&D and installation is better invested in a long-lasting change of industrialised production, transportation and energy consumption, but that it is also at the moment a viable option as bridging technology until renewable energy resources have found their market niche. Due to word limitation I will not discuss other aspects of CCS such as the reception of CCS in public or the liability of operators or states.

CCS – what is it / Technology / how does it work?

CCS currently is still in the demonstration phase but parts of the technology are already used in other processes such as the separation of CO2 from natural gas. This procedure is needed to allow the production of hydrogen and manufacturing of fertilizers (UCL CCLP). CO2 injection into oil fields has enhanced the oil recovery (Enhanced Oil Recovery - EOR) and facilitated the extraction of oil. The technology of CO2 injection into oil fields to make those fields economically more viable can be transferred to the CCS technology. Storage sites can be found offshore or onshore in porous rock formations covered by a so called ‘cap rock’ that hinders the CO2 from re-entering the atmosphere through leakage or sewage (UCL CCLP).

Capture

There are three main methods of capturing carbon: post-combustion, pre-combustion and oxyfuel. The advantage of physical post-combustion capture is that existing power plants can be retrofitted to capture CO2 as the process takes place only after the burning of fossil fuels. The concentration of CO2 in the flue gases resulting from the burning process, however, is very low (5% in gas burning resultants, 10-15% for coal). Additionally, the pressure of those flue gases is close to atmospheric pressure. To be able to capture resulting CO2 the flue gas has to be pressurised. This process adds high additional costs to the capital costs required by retrofitting power plants. An alternative to physical post-combustion capture is the chemical absorption of CO2, which is done by injecting amines into the flue air to capture CO2. The disadvantage is that amines degrade by use and require higher energy input in their reuse.

Both physical and chemical absorption is possible in the pre-combustion technology. It involves the production of synthesis gas, i.e. CO2 turns into H2 and CO2, and the resulting hydrogen can be burnt to run power turbines through integrated gasification combined cycles (IGCC). The remaining CO2 is liquefied and transported.

The third method, oxyfuel, requires the separation of oxygen from air. Oxyfuel combustion uses pure oxygen to burn fuels. It involves high costs for the separation of oxygen from air. The separation of CO2 takes place in the same way as in the pre-combustion method.

All three methods, however, need another step to make CO2 transportable. CO2 has to be dehydrated to enhance its transportability and to avoid corrosion of pipelines. (Smyth et al 2010: in Hydrocarbon Engineering)

Transport of CO2

CO2 can be transported either by pipelines or by ship. Both methods have large disadvantages.

CO2 is an asphyxiate that is colourless, without taste or smell and heavier than air. That means if there is a leakage it is very hard to detect. CO2 has been transported through pipelines for years but so far only far away from dense population centres. If this method is to be used in combination with CCS it will have to be installed close to populated areas. Furthermore, CO2 has distinctive phase behaviours. It has to be as pure as possible to make transportation feasible as contaminations of any kind change temperature as well as pressure of CO2, which either makes it less fluent or there is the possibility for the formation of dry ice which will block the pipelines.

Transport by ship is equally difficult and not yet fully researched. It is estimated that transportation of liquid CO2 will happen in a similar way as transportation of LNG. This involves the installation of ports capable of loading and unloading LNG/CO2 as well as the manufacturing of vessels that can transport high-pressure boilers. (Smyth et al 2010: in Hydrocarbon Engineering)

Onshore storage

CO2 is liquefied for transportation at the site of capturing and then transported to underground storage sites. The liquefied CO2 is stored deep underground in porous and spongy rock formations similar to the deposition sites of shale oil and gas, which are capped by impermeable rock layers. The CO2 is said to either dissolve into non-drinkable salt water or to chemically react with surrounding minerals and in this process to break down into its natural constituents. (Hydrocarbon Engineering) Depleted oil or gas fields are considered to be suitable storage sited for CO2 (UCL CCLP). CO2 can be stored by physical or chemical trapping i.e. either by a cap rock or chemical dissolution of CO2. A combination of both is considered to be the most effective technology (IPCC: 2005 208). Once CO2 is dissolved leakage is impossible as its components are trapped (IPCC: 2005 209)

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