Journal of the American Chemical Society
A group of researchers from the University of Deaing in Australia have discovered a way to harvest more blue energy from the oceans thanks to graphene.
A study from Deakin University in Australia has discovered a new graphene-based two-dimensional nanomaterial membrane technology that can improve blue energy harvesting processes from the oceans.
Blue energy harvesting is a type of renewable energy that generates electricity by osmosis, through the difference in salt content between fresh water and seawater.
As Weiwei Lei, associate professor and director of the project carried out by a group of researchers from the Institute for Frontier Materials (IFM) at Deakin University, explains, “Ocean energy is composed of five forms: tides, water waves, ocean currents, temperature gradients and salinity gradients, which offer an alternative and unlimited potential energy resource”.
Salinity gradient power, also known as osmotic power or blue power, has a power potential of 1 TW (8,500 TW h in one year), which exceeds the sum of hydro, nuclear, wind, and solar power in 2015.
The development of nanotechnology and 2D nanomaterials have enabled new 2D nanomaterial membranes with nanopores and nanochannels for blue energy harvesting.
However, the efficiency of energy harvesting from these membranes is still insufficient to meet the demands of practical applications.
A study reveals that graphene can harness the blue energy of the oceans
Journal of the American Chemical Society
According to Europa Press, the study published in the Journal of the American Chemical Society revealed a strategy to optimize nanochannels within 2D nanomaterial membranes to collect more energy, building nanochannels from graphene oxide nanosheets.
The sheets chemically exfoliate, shaking off loose reactive nanosheet fragments called oxidative fragments, which charge under alkaline conditions.
Negatively charged channels attract positive ions in seawater. The osmotic pressure can then push the ions through the channels to create a net current that can be collected.
In this way, the membrane can overcome the tradeoff between permeability (how easily ions can move through the channels) and selectivity (encouraging only positive ions to move through the channels).
This gives the membrane a boost in power generation compared to graphene oxide membranes that have not been treated to include negatively charged nanosheet fragments.
collect more energy
“This means that we can collect more energy through large volumes of water. This boosted energy generation is due to the enlarged nanochannels together with the enhanced local charge density of the separated oxidative fragments,” Lei says.
The new membrane design strategy that uses these oxidative fragments to decorate nanochannels provides an alternative and easy approach for many applications that can exploit ionic charges, such as ion exchange.
According to Lei, currently this research is still limited to lab-sized equipment, however, they are planning to purchase large facilities to manufacture large membranes and devices for large-scale application.
“In the real world, we think that membranes could be installed at river mouths or at outlet points for industrial wastewater,” he said.
“Wastewater from factories or industry has different surface charge ions with a higher concentration than normal water. If we can place our membrane at the end of their processes before the wastewater reaches natural watercourses, we can collect the energy and also treat that water,” he concluded.
