In Britain alone, we use an average of 141 litres of water every day. With a population of 66 million, that means around 9,306,000,000 (9.3 Billion) litres disappear drain-ward every day. That’s enough to fill Wembley Stadium 8 times over, with enough spare to fill lake Windermere.
And that’s just water we use personally. A huge amount of water is also used for irrigation. In total, we collectively use 16,000,000,000 (16 Billion) litres of water – enough to fill The O2 6 times.
To feed this consumption, we tap into every fresh water source we can. Around a third comes from groundwater: water locked beneath the soil which we pump to the surface. The rest comes from ‘surface water’ like rivers, lakes, and reservoirs.
In the UK, we’re quite fortunate in that potable water is abundant enough in nature to meet our demands. Elsewhere however, other methods are necessary to sustain supply.
Desalination
71% of Earth’s surface is saline water – that is, salt water. Sea water. 1,386,000,000,000,000,000,000 (1.386 Sextillion!) litres of it. If we spread all of that water around the surface of the moon, it would be on average around 36km (22.4 miles) deep! However, just 0.014% of that water is accessible and fresh enough for consumption.
So the good news is that no one’s running out of water any time soon. The bad news is that this saline water fundamentally doesn’t agree with the human body, nor is it any use for crop irrigation. It’s like eating fresh vegetables everyday, laced with a tiny amount of poison. You can survive on it for a while, but the poison soon builds up.
Thankfully, it’s relatively simple to separate the salt – to ‘desalinate’ the water. The simplest way is to boil it (thermal distillation), collecting the steam as condensate in another vessel and leaving behind the salt deposit.
At scale, this simplicity becomes more complex. It’s a slow process that requires a large amount of energy for small returns, although more efficient and scalable methods have been developed.
Water Scarcity
We’re up a salty creek with an evermore expensive paddle. In essence, water scarcity is the lack of fresh water supply to meet demand. Over 40% of the population encounter this frequently.
To tackle this, 1% of the world’s population currently relies on desalinated water via over 18,000 desalination plants.
By the year 2030, at current trends, global demand will outbalance supply by 40% on average and desalination capacity will double.
Global water scarcity presents two major issues.
- Ecological Damage
Even in the relative water abundance of the UK, we’re not immune. As droughts become more frequent, the groundwater we rely on depletes faster and replenishes slower – in other words, we’re already drawing more from the Earth than the ecosystem returns back into it. By as soon as 2045, Britain could be facing severe water shortages.
- Energy Consumption
Desalination is a technology we understand well, and is an industry that processes the most abundant resource we own: water. So keeping up with water demand isn’t a challenge in more affluent countries. The challenge exists within the cost of this process. On average, extracting 1m3 of fresh water into the system costs around 0.2kWh compared to 3 kWh for the same amount of fresh water – that’s 15 times more expensive. Energy generation already stands as its own series of significant obstacles which future desalination solutions could contribute to.
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