High velocity seawater air-conditioning with thermal energy storage and its operation with intermittent renewable energies

Julian David Hunt,Andreas Nascimento,Paulo Smith Schneider,Behnam Zakeri,Bruno Garnier,Márcio Giannini Pereira,Rodrigo Augusto Bellezoni,Pedro Paulo Bezerra Machado,Natália De Assis Brasil Weber,Dorel Soares Ramos

doi:10.1007/s12053-020-09905-0

Abstract

The rapid increase in cooling demand for air-conditioning worldwide brings the need for more efficient cooling solutions based on renewable energy. Seawater air-conditioning (SWAC) can provide base-load cooling services in coastal areas utilizing deep cold seawater. This technology is suggested for inter-tropical regions where demand for cooling is high throughout the year, and it has been implemented in islands with short distances from the coast and the deep sea. This paper proposes adjustments to the conventional design of SWAC plants to reduce implementation risks and costs. The approach is named high velocity SWAC and consists of increasing the excavation depth of the seawater pump station up to 20 m below the sea level, compared to 2 to 5 m in conventional SWAC projects. This allows a twofold increase in the speed of inlet pipeline seawater and cooling load of the plant. The cooling load can be expanded twofold with only 55% capital cost and 83% project costs, compared with the costs of a new system. In addition, this article shows that high velocity SWAC plants with thermal energy storage will have an important role supporting the dissemination of intermittent renewable sources of energy in regions where SWAC is a viable cooling alternative.

Highlights

World demand for air-conditioning is surging rapidly due to life quality improvement in developing countries and global warming
The other section focuses on presenting an example of operation of high velocity plant Seawater airconditioning (SWAC) with thermal storage in synergy with the generation of variable renewable energy (VRE)
The main aspects that influence the cost of SWAC systems are the distance from the coast to ocean depths were the seawater temperature is 5 °C or less, the depth required to reach this temperature, which varies from 700 to 2000 m, the demand for cooling, district cooling system costs, and electricity costs

Summary

Introduction

World demand for air-conditioning is surging rapidly due to life quality improvement in developing countries and global warming. Other estimates predict that demand for cooling is set to surpass heating around 2070, as shown in Fig. 1 (Isaac and van Vuuren 2009). Energy costs can be very high for airconditioning systems, especially in island locations, where electricity costs are usually high due to the reliance on liquid fossil fuels as the main generation resource. The deep ocean, located beneath the thermocline, is an almost unlimited heat sink (cooling source) that creates an opportunity to develop lower cost district cooling systems near the sea. The difference in temperature between surface and deep ocean have been extensively studied for electricity generation and desalination purposes (Khosravi et al 2019; Jung and Hwang 2014; Semmari et al 2012; Odum 2000)

Results

Discussion

Conclusion