(CN) — Researchers at Northwestern University believe they have found a shocking new way to combat coastal erosion using electricity.
Researchers found that a mild electrical current would harden marine sand into a solid rock, and they are hopeful that this method could be used to strengthen eroding coastlines.
The researchers detail this novel method in a study published on Thursday in the journal Communications Earth and the Environment.
“My aim was to develop an approach capable of changing the status quo in coastal protection — one that didn’t require the construction of protection structures and could cement marine substrates without using actual cement,” said Northwestern professor Alessandro Rotta Loria, who led the study. “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.”
Using a mild electrical current of only two to three volts, researchers were able to harden the dissolved minerals found in sea water, and when sand was present, they acted like an adhesive.
“After being treated, the sand looks like a rock,” Rotta Loria said. “It is still and solid, instead of granular and incohesive. The minerals themselves are much stronger than concrete, so the resulting sand could become as strong and solid as a sea wall.”
Rising sea levels caused by climate change have worsened coastal erosion, and a 2020 study by the European Commission’s Joint Research Center says that the current conditions, “could result in the near extinction of almost half of the world’s sandy beaches by the end of the century.”
Traditional erosion mitigation techniques involve building structures like seawalls, which will eventually succumb to erosion themselves and collapse, and are costly to design, build and maintain.
Rotta Loria and his team think their method is economical, costing between $3 to $6 per cubic meter of electified “marine cement,” whereas current methods cost as much as $70 per cubic meter.
The injection of cement into the ground has also been used to combat this type of erosion, but Rotta Loria thinks his team’s solution is less harmful to the environment.
“Injecting cement and other binders into the ground has a number of irreversible environmental drawbacks. It also typically requires high pressures and significant interconnected amounts of energy,” said Rotta Loria.
The team’s method has little environmental impact, as the voltages used on the sand are very mild. Similar methods have been used by other researchers to strengthen underwater structures and coral reefs.
The researchers also claim that their method is reversible and can be easily undone.
“The minerals form because we are locally raising the pH of the seawater around cathodic interfaces,” Rotta Loria said. “If you switch the anode with the cathode, then localized reductions in pH are involved, which dissolve the previously precipitated minerals.”
Joining Rotta Loria on the team were Andony Macias, a former doctoral candidate in Rotta Loria’s lab, and Northwestern University professor Steven Jacobsen, who all hope to next test their method on a beach.
“The applications of this approach are countless,” Rotta Loria said. “We can use it to strengthen the seabed beneath sea walls or stabilize sand dunes and retain unstable soil slopes. We could also use it to strengthen protection structures, marine foundations and so many other things. There are many ways to apply this to protect coastal areas.”