When you're drilling deep under the seabed, the last thing you might expect is freshwater. Yet Danish scientists on a recent expedition in the Baltic Sea suddenly found freshwater gushing up from their drill. In fact, undersea freshwater reserves are hidden all over the world, and some claim this could quench our thirst for decades to come.
In the Baltic, the water was sealed in by a layer of sand deposited at least 100,000 years ago during the last ice age. The Danish team struck water in several place all over the Baltic Sea, though they don't yet know how big the reserves are. A report from last year, however, estimated there are 500,000 cubic kilometres of freshwater trapped underneath the world's oceans, 100 times the groundwater we've pumped from aquifers in the last century.
The research vessel Greatship Manisha, which found the water in the Baltic. ECORD
All of this water was trapped hundreds of thousands of years ago during a time of lower sea levels. At that time, these undersea aquifers were simply underground aquifers. Then glaciers melted and sea levels rose, but the water remained sealed by sand as much as 5km below the ocean's surface.
In an increasingly thirsty world, we're going to need all the freshwater we can get. Could we one day have offshore "water rigs" that drill for freshwater the way we drill for oil? That possibility has been floated by Vincent Post, the lead author on the undersea water mapping report. "There are two ways to access this water," he said in a statement, "build a platform out at sea and drill into the seabed, or drill from the mainland or islands close to the aquifers."
Well, let's consider the economics. Tap water in the US is absurdly cheap — something like 0.004 cents per gallon. Desalination, which is considered a very expensive means of getting freshwater, might cost 100 times that, or a whopping 0.3 cents per gallon. Now crude oil, which we do drill deep holes in the ocean for, costs just over $US100 a barrel, which comes out to 2.38 dollars per gallon. While oil companies may enjoy some hefty profits, this a 10,000 fold difference here.
Water prices will definitely go up in the future, and perhaps drilling costs will also go down, but that's still a lot of zeros to reconcile. Perhaps, instead seeing these undersea reserves as yet another resource to exploit, we can see them as want they are: Relics of an ancient Earth, buried and hidden long ago.