Pioneering Marine Cloud Brightening Atomizer System for Enhanced Reef Resilience – From Concept to Regional Deployment
Cheng Chen¹, Daniel P Harrison^1,2, Luke Harrison³, Chris Medcraft², Ceylena Holloway², Stuart MacLennan⁴, Sophie Allum<sup>4

1</sup> Sydney Institute of Marine Science, Sydney, NSW, Australia
² National Marine Science Centre, Southern Cross University, Coffs Harbour, NSW, Australia
³ School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, Sydney, NSW, Australia
⁴ Ron Allum Deepsea Services, Sydney, NSW, Australia

Abstract

Marine Cloud Brightening (MCB) involves intentionally spraying microscopic particles into low-lying marine clouds to enhance their solar radiation reflection, thereby reducing energy absorption by the climate system. Despite theoretical modelling and lab-scale investigations, validating MCB concept through field observations at scale remains elusive. To bridge this knowledge gap, we proposed an innovative MCB system with 640 effervescent nozzles deployed within the Great Barrier Reef Marine Park, as part of the Reef Restoration and Adaptation (RRAP) Cooling and Shading Subprogram. This nozzle system achieved a unparallel droplet production rate of approximately 8.28 × 10¹⁴ per second, which marked a significant engineering advancement in cloud manipulation.

This study outlines the engineering efforts in system development and vessel deployment, presenting field observations of critical parameters such as mass flow rates, pressures, gas-to-liquid mass ratio, droplet production rate, and particle size distribution for the first time. The attained particle size distribution, with a geometric mean of 49.53 nm and a GSD of 2.17, aligns with the literature's recommended effective particle size for MCB, affirming the practical viability of the effervescent atomizer in generating sea salt aerosols from seawater for MCB applications. Energy consumption analysis revealed the value of power draw at about 345 kW at full capacity, and its fluctuations primarily linked with compressor operation. This study also introduced the Particle Production Efficiency Index (PPEI) serving as a useful metric for assessing particle production efficiency per unit of power. Beyond advancing MCB engineering at scale, this work lays a solid foundation for future large-scale MCB systems, impacting climate intervention strategies. Furthermore, future research should aim to increase droplet production rates, enhance energy efficiency, and adopt renewable energy sources, thus bolstering the technological readiness of MCB for real world applications.

 

marine cloud brightening, nozzles, production rate, particle size;marine cloud brightening, nozzles, production rate, particle size