RENEWABLE ENERGY
by REDStack on a large scale with a prototype plant in the Netherlands. Despite encouraging results, none of
the current attempts have yet reached a sufficient power density to be considered as economically profitable. Both strategies rely on separation of
water from ions or ions from water. Yet, the main source of difficulties of these systems is the membrane. To be completely impermeable to the solute molecules, the membrane may only be slightly permeable to the solvent molecules, or vice versa. Indeed, for the salt not to pass through
we need a membrane that has nanometric to sub-nanometric pores. With such small pores, the permeability of the membrane is extremely low and therefore, the water flow is not very intense. So, even if the pressure difference is gigantic, the power that can be recovered from these systems is measured in a few W/m2
above the threshold of economic viability that is estimated to be 5W/m2
MEMBRANES WITH NEW NANOMATERIALS For blue energy to become a large-scale exploitable and competitive energy
source in the future, it is necessary to make progress not only in the design of membranes, but also in our understanding of the mechanisms at work. Major efforts have been made in recent
years through multidisciplinary research combining chemistry, materials science and nanoscale fluid dynamics. In 2013, membranes made of boron nitride (BN) nanotubes were investigated. Tese are materials structurally similar to carbon nanotubes, except that carbon atoms are substituted by nitrogen and boron atoms. Nanotubes with a radius of tens of
, below or sometimes slightly .
layer with nanopores of few nanometres in diameter led to an outstanding power density of 106 W.m2
. Tese remarkable performances are
in part attributed to the extremely narrow widths of the membranes. Indeed, the flow through the membrane is expected to be inversely proportional to its width.
renewableos.com
RENEWABLE OIL SERVICES ONSHORE
Stéphane Pleutin is a materials scientist consultant.
www.matmatch.com
nanometres showed an osmotic energy conversion density of several kilowatts per square metre, three orders of magnitude larger than the energy conversion density obtained with PRO or RED processes. In 2016, membranes made of an atomically thin molybdenum disulphide (MoS2
)
One year later, atomically thin membranes based on hexagonal BN and graphene were investigated showing power densities in the range of 700W.m2
. All these recent
results of extremely high osmotic power densities for devices using new materials as membrane supports have undoubtedly revived the field. With our recent discoveries we have
certainly made great progress on the road to ideal artificial membranes and, in the meantime, have advanced our knowledge, but there is still a long way to go. Perhaps we should listen more carefully to what nature has to tell us about how to effectively harness blue energy. Matmatch offers a material consultancy
service to connect engineers and product developers with materials suppliers and consultants, as well as providing reliable, up-to-date technical information of commercially available materials for energy generation projects on its website.
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