Two thirds of the World is covered in water, whilst only one third is land mass, populated by 7.53 billion people. Only 2.5% of all the water on Earth is fresh and drinkable; the rest is saline and ocean-based. The fresh water on Earth today is roughly the same in volume as that which was present at the time of the dinosaurs, but our population has exploded. How do we get enough fresh water without polluting the planet?
Water is necessary to sustain life, and a lot of things we use every day from our clothes to our computers. Only 1% of all fresh water is easily accessible as much is trapped in glaciers etc. Whilst in the West we may not experience a lack of drinking water, around the Globe others are not this lucky. Water consumption in the US alone has grown at more than twice the rate of the population increase over the last century. Two thirds of the world live in a state of water-stress due to a number of factors. How can we manage our water?
Despite the Globe being covered in vast quantities of water, a very energy intensive process is required to turn salty water into fresh, drinkable water (i.e. desalination). This process removes salt from sea water in one of two ways: (1) sea water is boiled, and the fresh water vapour is collected, or (2) a sophisticated membrane (i.e. a type of filter) can be used to filter out salt and sea life. Desalination is carried out in some countries where water is scarce, such as Arab countries, but this also accounts for 15% of their energy consumption, using lots of fossil fuels in the process. Is there a way to purify water using clean energy?
This month (July), scientists have identified a way to purify water and produce electricity from one device. Their work created a solar panel which generates power from the sun and uses the heat energy captured to distil and purify sea water through a membrane. Usually electricity generation consumes huge volumes of water (up to 50% of water consumed in the US and UK is for energy production), creating a vicious cycle and thus, to conduct this with solar power is a great idea. However, traditional solar panels are actually quite ineffective, only converting 10-20% of the energy they could from the sun into useful electricity. By coupling a solar panel with desalination, the researchers could harness the wasted heat energy and use this to power the desalination process. The device generated a good amount of energy for general use, and used the excess heat energy to boil the sea water, which was then collected and passed across a membrane before being collected.
This research could make a huge difference to sunny places with a limited fresh water supply (in countries such as Mallorca), and a commercial scale device is expected to be ready in 5 years. Once scaled up, such a device could produce 10% of the total drinking water which was consumed in 2017. However, many steps are required before this can be commercialised, and large expanses of land would be required for such use. The idea is to be used in coastal areas but not for cities with over 1 million inhabitants; the land scale would be too large and thus, it is only sustainable for a small to medium scale. Despite this, the concept is amazing and shows that a combination of clean methods could lead to a solution for some water-poor areas. Clean water, clean air.