Scientists at Northwestern University have developed a unique potential solution to the problem of coastal erosion.
According to Interesting Engineering, a team led by Alessandro Rotta Loria has discovered a means of applying a gentle electric current to the sandy soil typically found along coastlines, which solidifies it into a cement-like substance. The team was inspired by the process mussels and clams use to build their shells.
The electricity solidifies dissolved minerals between grains of sand via a chemical reaction. With a moderate charge of two to three volts, the minerals become calcium carbonate, the material found in mollusk and mussel shells. A four-volt charge turns the minerals into magnesium hydroxide and hydromagnesite, which are both commonly found in a variety of types of stone.
"By applying a mild electric stimulation to marine soils, we systematically and mechanistically proved that it is possible to cement them by turning naturally dissolved minerals in seawater into solid mineral binders — a natural cement," Loria said in the press release on the discovery.
Coastal erosion is a massive problem. In the United States, beaches in Texas, Virginia, South Carolina, and Louisiana have lost more than two meters (about 6.5 feet) of coastline per year over the last 100 years, per the United States Geological Survey. As our planet warms and the sea level rises, those numbers are expected to increase significantly.
To make matters worse, we don't have good answers for how to solve the problem. Solutions like adding sand to beaches (as described by the Edgewater Environmental coalition), seawalls, or building reefs or oyster beds (as detailed by FEMA) can have a positive impact, but they can be cost prohibitive, take many years to reach full effectiveness, or have a temporary, limited impact.
According to the study's projections, it would cost between $3 and $6 per cubic meter of coastline to be electrically cemented, making it a much more affordable alternative to building a manmade wall or attempting to rebuild dunes as they erode, Interesting Engineering explained.
There is also minimal impact on sea life, as the level of charge required is low enough that marine animals aren't impacted. And if there are unforeseen consequences to solidifying large swathes of the coastline, the process can be undone.
According to Loria, the next steps for this technology is to scale up testing to see how it works at a larger scale while also "delving deeper into a number of fundamental scientific questions."
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