Carbon-capture technologies

E. Rubin, H. Mantripragada, A. Marks, P. Versteeg, J. Kitchin The outlook for improved carbon capture technology. Progress in Energy and Combustion Science, 38(5). 2012. 

Another integrated carbon capture technology is called the fuel-flexible process developed by General Electric (GE). This process takes different feedstocks such as coal and biomass and produces hydrogen and electricity in adjustable ratios (Rizeq et al., 2002). The reaction scheme for this process involves two chemical loops operated using three fluidized-bed reactors as shown in Figure 17.5. 

It is estimated that the installed cost of a 1 gW thermal solar power plant is about 3 billion. The mass production of solar collectors is just beginning, and it is probable that with it will come a substantial drop in collector prices. The cost of a new nuclear power plant, if one includes the waste disposal and decommissioning costs, is about 5 to 6 billion. On average, nuclear plants generate 1 gW of electricity, which is about twice the electricity production of typical fossil power plants. The cost of a 1 gW fossil fuel power plant (two 0.5 gW plants), if carbon-capturing technology is included and if carbon emission charges are also considered, is the same as nuclear plants. 

Carbon capture and storage technology is the most promising technology to significantly decrease C02 emissions. Nevertheless, it may be possible to use C02 as a raw material for other industrial uses. In this chapter, authors explain both ways to decrease C02 emissions. 

In this chapter, authors review the carbon capture, storage technology (including the C02 transport through pipeline), and C02 utilisation technologies. 

The most promising emerging technologies applied to carbon capture are discussed in this section to complete the overview of the C02 capture technologies currently under research. 

This technology shows benefits for carbon capture. Limestone is cheap and widely available, and there is a potential for process integration, which can lead to low energy penalties, i.e., heat released from carbonisation can be utilised in a steam cycle or the heat used in the calciner reactor can be recovered in the carbonation process. 

Goel Carbon capture and storage technology for sustainable energy. 2009 Jawahar-lal Nehru University, New Delhi, India. 

For each ton of hydrogen produced from hydrocarbons, approximately 2.5 t of carbon is vented to the atmosphere [44-47], However, for each ton of hydrogen produced from current coal technology, approximately 5 t of carbon is emitted to the atmosphere. Principally, C02 capture and sequestration is a precondition for use of these fossil fuels. However, the sequestration necessity varies, because the relative atomic hydrogen-to-carbon ratios are 1 2 4 for coal oil natural gas. There are two basic approaches to C02 sequestration either at the point of emission (in situ capture) or from the air (direct capture). In either case, C02 must be disposed off safely and permanently. With the capture and sequestration of C02, hydrogen is one path for coal, oil, and natural gas to remain viable energy resources [46]. Carbon sequestration technologies are discussed in detail in Chapter 17. 

The absorption technique using hot potassium carbonate has also been developed to capture C02 (Probstein and Hicks, 1990). The chilled ammonia process is another solvent-based C02 capture technology where ammonia carbonate slurries are used to capture 90% of the C02 in the gas stream mixture gas forming ammonia bicarbonate in the process. A pilot-scale chilled ammonia unit for 5 MW equivalent flue gas capture is under construction by ALSTOM and EPRI. Although this process is developed for a combustion system, the results will provide valuable information for the future development of such a process for hydrogen production. According to ALSTOM, commercial products on chilled ammonia process will be available by 2010 (Alstom, 2007). 

Ruether, J. et al., Prospects for Early Deployment of Power Plants Employing Carbon Capture, National Energy Technology Laboratory, Pittsburgh, PA, 2002. 

When investigating the processes and policies that could raise the potential acceptance of carbon capture and storage, Shackley et al. (2004) found that more certainty about risks would be helpful. The main concerns about risks connected with carbon capture and storage were possible leakage, ecosystems and environmental impacts, the untested nature of the technology and human health impacts. 

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