An Aston University academic has proposed a new process to decompose waste desalination brine using solar energy, neutralising ocean acidity and reducing damaging environmental impacts.
Although turning salty ocean water into fresh water is important to benefit poverty-stricken populations, desalination has a very damaging ecological footprint. Many environmental advocates see it as a last resort for retrieving fresh water, but fast growing populations mean it is becoming the only viable option. The amount of fresh water produced by desalination is predicted to double within the next decade to meet global demand.
Dr Philip Davies, of Aston’s School of Engineering and Applied Science, has devised a system using solar energy that could allow desalination plants to act as a sink, rather than a source of atmospheric carbon dioxide, and help to neutralise ocean acidity.
In Dr Davies’s model, magnesium chloride in waste brine is hydrolysed by energy generated by heliostat fields to magnesium oxide, which is discharged to the ocean. Due to its alkaline nature, this subsequently neutralises ocean acidity and gradually removes carbon dioxide through the conversion of magnesium oxide to bicarbonate, similar to ocean liming.
Although this approach increases the energy requirement of the plant by 50%, Dr Davies has calculated that this is offset by the carbon dioxide absorption capacity. His process would result in 0.4% of anthropogenic carbon dioxide emissions being absorbed given a doubling in the current desalination capacity.