Carbon capture and Storage Technology and its Application Potential in Sri Lanka

By Eng. (Dr). M. C. M. Nasvi

1. Introduction to Carbon capture and Storage Technology

Increasing demand for energy with the urbanization has resulted in an increase in the use of fuels, especially conventional fossil fuels (coal, oil and natural gas). Fossil fuels, which currently provide more than 85% of the world’s energy requirements, have been the major energy source throughout the 20th and 21st centuries due to their availability, competitive cost, and ease of transport and storage (Nasvi et al., 2016). However, the combustion of fossil fuels emits greenhouse gases (carbon dioxide, etc.) to the atmosphere, and this is a serious environmental problem to be addressed. Greenhouse gas emission can be reduced by some options such as improving the energy conversion efficiency of fossil fuels, shifting energy production to low carbon sources, enhancing uptake by terrestrial and marine biomass, and capturing and storing CO2 deep underground (Bruant et al., 2002). Of all the available solutions, carbon capture and storage (CCS) is found out to be one of the viable methods for long term reduction of greenhouse gases (Siggins, 2006; Li et al., 2020).

The CCS is a process consisting of the separation of CO2 from industrial and energy-related sources such as fossil fuel power plants and Portland cement factories, transport to a storage location and long-term isolation from the atmosphere (Metz et al., 2005). Table 1 shows industrial activities leading to large point sources of CO2. The captured CO2 is injected into deep underground formations through the wellbore. Geological formations such as depleted oil and gas reservoirs, water bearing reservoir rocks (saline aquifers) and un-minable coal seams store the CO2 for the long term (Figure 1). In terms of the capacity, deep saline aquifers offer significantly higher potential for storage compared to other reservoirs (Rubin and De Coninck, 2005). The concept of CCS was first introduced in 1977 when it was suggested that CO2 from coal power plants can be injected into geological formations (Marchetti, 1977). international energy agency has claimed that CCS technology can reduce global CO2 emissions by 17% in 2015 and it recommended that CCS technology is practised in each and every country in the world as policy to reduce greenhouse gas emissions (Mets et al., 2005).

There are many CCS projects initiated in the past few years such as CO2SINK in Germany, InSalah in Algeria, RECOPOL in Poland, Sleipner in Norway, and Otway in Australia in different countries (Raza et al., 2019). Of these projects, Sleipner and In-Salah are the pioneer CCS projects. In the Sleipner project in Norway, injection was started in 1996 and injected CO2 in a saline aquifer with the capacity of 0.9 million tons per year (Mt/yr). The In-Salah project in central Algeria was started to test the feasibility of CCS for re-injection of CO2 into an aquifer with the capacity of 1.2 Mt/year (Herzog, 2016). At present, there are 22 large scale on-going CCS projects worldwide (Raza et al., 2019).

Economic feasibility of CCS is a critical concern that must be considered based on the technological cost of planning and operation (Raza et al., 2019). These costs can be further divided into a number of different categories including CO2 separation, transportation (typically with compressors and pipelines) and injection. Application of CCS technology to electricity production through coal power plants increase the electricity generation cost by about 0.01 – 0.06 US dollars per kilowatt hour (US$/kWh) (Metz et al., 2005). For an instance, cost of electricity production in a reference coal power plant without CCS will be about 0.04- 0.05 US$/kWh, whereas the production cost in a power plant with the CCS will be 0.06-0.10 US$/kWh. The cost of a full CCS system for electricity generation from a newly built, largescale fossil fuel-based power plant depends on a number of factors, including the characteristics of both the power plant and the capture system, the specifics of the storage site, the amount of CO2 and the required transport distance. In the U.K., CCS may cost each household an extra 10% per year for electricity and it may seem expensive. However, if CCS is developed now as part of a portfolio of global climate protection, the costs of CO2 abatement required in 2050 are predicted to reduce from $500 to $50 per ton (Haszeldine, 2009).

2. Application Potential of CCS in Sri Lanka

In Sri Lanka, with the introduction of Lakwijaya coal power plant in 2011, CO2 emission levels have gone drastically up. The total CO2 emissions in the country is 20.9 Million tonnes, and of this total, the emissions from electricity sector is 8.7 million tonnes (IEA CO2 Emissions from Fuel Combustion, 2018 Edition). In addition, the Ceylon Electricity Board (CEB) has made a long term generation expansion (LTGE) Plan 2013-2032 to build 1,700 MWs of coal power plants by 2022 (The Island, December 2018). In addition, current total cement consumption in Sri Lanka is 8.0 million tonnes per annum (Economic and Social Statistics of Sri Lanka, Central Bank Annual Report 2019) emitting approximately 8.0 million tonnes of CO2, as 1 tonne of 4 ordinary Portland cement (OPC) production emits approximately 1 tonne of CO2 (Gunasekara et al., 2015). Further, it has been found that there are some saline aquifers for CO2 storage capacity in Sri Lanka at the Cauvery basin located offshore to the northern island (Figure 2) (Holloway et al. 2009). The Lakwijaya coal power plant in Puttalam is well located with respect to the inferred CO2 storage potential in the Cauvery basin. Considering the CO2 emission levels, geological settings for CO2 storage, recent developments in the power sector and the proposed electrictiy geenration expansion plans, it is evident that Sri Lanka is well placed to introduce the CCS technology in the country. However, being a developing country, whether the additional cost of electricity to be incurred by combining the CCS technology with the coal power plant is affordable is a question that needs to be answered.

References

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Eng. (Dr). M. C. M. Nasvi has earned his first degree in Civil Engineering (First Class Honours with three awards) from University of Peradeniya, Sri Lanka in 2009 and PhD degree in Geotechnical Engineering from Monash University in 2014. He is currently working as Senior Lecturer at Department of Civil Engineering, University of Peradeniya. His research interests include well cementing, flow and mechanical behaviour of geopolymers and Ground improvement (Chemical stabilization and mechanical methods).