Background to the Study

Energy and water consumption are closely connected. The Energy-Water nexus defines the relationship between energy and water to ensure the availability of both resources. Energy production consumes significant amounts of water; and equally, providing water demands energy. Power generation can impact water resources and increased electricity demand is projected in the coming years. In this scenario, the installation of carbon capture technologies in locations where the availability of water is limited must be studied, particularly in regions already suffering from water stress.

Introduction

IEAGHG identified the need of a comprehensive techno-economic assessment of the Energy-Water-CCS nexus. This study was conducted in two phases. Phase 1 developed a hypothetical base case scenario of power plants with and without a PCC system in The Netherlands, assuming both on and offshore storage, and with and without treatment of the water extracted from the storage site for its reuse in the power plant.  Phase 2 was based on four hypothetical PCC systems in South Africa, Australia, China and India.

Key messages

•    If more restrictive regulations are imposed on power plants that currently use evaporative freshwater cooling, the use of extracted and treated formation water in an integrated CCS-water loop could be a cost competitive alternative to retrofitting a power plant with an air cooling system.
•    The outcomes from this study confirm that the selection of the cooling system has a strong impact on the water consumption.  
•    The results from this study confirm that adding a CO2 capture system to the power plant may increase the water consumption of the whole facility. However, this increase can be mitigated through the implementation of different fitted strategies.
•    In the first phase, 16 Water-Energy-CCS nexus cases were modelled for a hypothetical location in the Netherlands. Results show that, if water extraction is necessary for storage purposes, its treatment and beneficial reuse may present the most economic option, compared to the direct disposal in the onshore storage scenario. 
•    In the second phase of this study, power plants in South Africa, Australia, China, and India were modelled.  The results of this work show that the location of the power plant (with and without CO2 capture system) influences the water availability, consumption and costs, due to the regulations, feedstock, ambient conditions, and cooling system. 
•    The lowest water withdrawal and consumption rates are evident from the case in China due to the ambient conditions.  In this scenario, building an air-cooled USCPC (Ultra Super-Critical Power Coal plant) is 30% cheaper, while this option is 20% more expensive in Australia and South Africa, compared to the USCPC base case in The Netherlands.
•    Water extraction and treatment add a comparatively small capital cost to the examined CCS cases (5% increase), while the LCOE can increase by 11 – 12%.
•    The treatment of extracted water may provide a value in water-stressed regions, especially when considering the associated cost of water shortages. In this study, the cost of product water, accounting for brine treatment and disposal costs, was found to be comparable to local water tariffs in the four countries.  When water extraction and transport costs are also included, product water cost exceed local water supply charges.