Can seawater cool a warming world?

A study published in the journal Energy Efficiency, led by the International Institute for Applied Systems Analysis (IIASA), has found that using seawater air conditioning might be a viable alternative to traditional air conditioners.

Seawater air conditioning (SWAC) works by pumping seawater from the ocean and exchanging heat with a district cooling system, and then returning warm water to the ocean.

According to the study, just 1m³ of seawater in a SWAC plant can provide the same cooling energy as that generated by 21 wind turbines or a solar power plant the size of 68 football fields.

A good example of how the system works can be found at Sydney Opera House. Designed by Danish architect Jørn Utzon and completed in 1973, Utzon and engineer Ove Arup implemented an innovative seawater cooling system to make use of the plentiful resource on the Opera House’s doorstep.

Chillers take in cool seawater from the surrounding harbour rather than fresh water, saving 15 million litres of drinking water per year. The heat recovered from the chillers is also used for warmth in cooler weather.

The IIASA researchers believe SWAC has strong potential for small islands in tropical areas, because energy costs are typically higher on islands. While SWAC has a high initial investment cost, the energy costs to operate the system are low compared to conventional AC units.

The research also explores how the cold water can be stored for future use. It is believed it could be stored in thermal energy storage tanks to meet any future cooling demands.

Other advantages of SWAC, according to the article, include “its reliability as a non-intermittent renewable source of cooling, reduction of greenhouse gas emissions from cooling processes, and the reduction of water consumption in cooling systems”.

However, researchers also caution that the technology faces challenges. For example, it could have a significant impact on the environment and local sea life.

For more information about the research, please click here.

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