New research by Berkeley University of California suggests that carbon capture and storage (CCS) could stress water resources in about 43% of the world’s power plants where water scarcity is already a problem.
According to the research, the technology deployed in these water-scarce region matters, and emerging CCS technologies could greatly mitigate the demand CCS places on water consumption.
Energy-producing facilities such as coal-fired power plants consume large amounts of cooling water. The type of cooling method used in a power plant affects water consumption.
Installing CCS at these facilities requires the production of additional energy to compensate for the energy used by the CCS process, with that comes additional cool water consumption.
Most CCS projects currently operations worldwide use adsorption technologies. Common absorbents are aqueous bases containing amine groups that bind CO2, separating it from other gases in the flue mixture.
The process of adsorption of CO2 into these solvents and subsequent regenerations of the solvents require energy withdrawal from the power plant. The circulation of large quantities of solvents results in water loss by evaporation.
Other state-of-the-art CCS technologies use far less water as they separate the CO2 from flue gas by adsorption onto solid materials or pass the exhaust gas through membranes.
These technologies potentially reduce both the energy load and water consumption.
In the research, the university examined how CCS can be implemented sustainably without compromising water resources. Specifically, how does the addition of CCS to power plant impact water consumption in any region of the world significantly enough to induce or exacerbate water scarcity.
The team modelled the hypothetical implementation of four different CCS technologies at every global coal-fired power plant of significant size globally and studied the impact on regional water withdrawals and consumptions.
Results showed that in cases where water scarcity does not already exist, the additional of CCS will not generally induce scarcity.
However, the researchers also found that 43% of the current installed global coal-fired power capacity is located within regions that now experience water scarcity for at least one month a year, and over 30% of global capacity faces scarcity for five or more months a year.
In these regions, implementation of CCS technologies worsens the water stress. Retrofitting power plants with less water-intensive capture technologies could mitigate competition for freshwater resources, and the choice of cooling methods becomes increasingly important.