Yeah fair enough Alan, you say Octopus, I say tree vis-vis potential products.
However IMHO we need some increased attention on our existing big three, membranes, super/ultra caps and lithium sulfur Batterys.
Alan I think we need to up the anti in promoting the membranes even with the potential JV with CLQ on the near horizon.
New desalination tech could help quench global thirst
Most modern desalination plants
use a technique that differs from these earlier efforts. Instead of evaporating water, pumps
force pressurized saltwater from the ocean or salty underground aquifers through special sheets. These membranes contain molecule-sized holes that act like club bouncers, allowing water to pass through while blocking salt and other contaminants.
The membranes are rolled like rugs and stuffed into meter-long tubes with additional layers that direct water flow and provide structural support. A large desalination plant uses tens of thousands of membranes that fill a warehouse. This process is known as reverse osmosis and the result is salt-free water plus a salty brine waste product that is typically pumped underground or diluted with seawater and released back into the ocean. It takes about 2.5 liters of seawater to make 1 liter of freshwater.
In 2015, more than 18,000 desalination plants worldwide
had the annual capacity to produce 31.6 trillion liters of freshwater across 150 countries. While still
less than 1 percent of worldwide freshwater usage, desalination production
is two-thirds higher than it was in 2008. Driving the boom is a decades-long drop in energy requirements thanks to innovations such as energy-efficient water pumps, improved membranes and plant configurations that use outbound water to help pressurize incoming water. Seawater desalination in the 1970s
consumed as much as 20 kilowatt-hours of energy per cubic meter of produced fresh-water; modern plants typically require just over
three kilowatt-hours.
There’s a limit, however, to the energy savings. Theoretically, separating a cubic meter of freshwater from two cubic meters of seawater requires a minimum of about 1.06 kilowatt-hours of energy. Desalination is typically only viable when it’s cheaper than the next alternative water source, says Brent Haddad, a water management expert at the University of California, Santa Cruz. Alternatives, such as reducing usage or piping freshwater in from afar, can help, but these methods don’t create more H
2O. While other hurdles remain for desalination, such as environmentally friendly wastewater disposal, cost is the main obstacle.
The upfront cost of each desalination membrane is minimal. For decades, most membranes have been made from polyamide, a synthetic polymer prized for its low manufacturing cost — around $1 per square foot. “That’s very, very cheap,” says MIT materials scientist Shreya Dave. “You can’t even buy decent flooring at Home Depot for a dollar a square foot.”
But polyamide comes with additional costs. It degrades quickly when exposed to chlorine, so when the source water contains chlorine, plant workers have to add two steps: remove chlorine before desalination, then add it back later, since drinking water requires chlorine as a disinfectant. To make matters worse, in the absence of chlorine, the membranes are susceptible to growing biological matter that can clog up the works.
With these problems in mind, researchers are turning to other membrane materials. One alternative, graphene oxide, may knock polyamide out of the water.
Membrane maze
Since its discovery in 2004, graphene has been
touted as a supermaterial, with proposed applications ranging from superconductors to
preventing blood clots (
SN: 10/3/15, p. 7;
SN Online: 2/11/14). Each graphene sheet is a single-atom-thick layer of carbon atoms arranged in a honeycomb grid. As a hypothetical desalination membrane, graphene would be sturdy and put up little resistance to passing water, reducing energy demands, says MIT materials scientist Jeff Grossman.
Passing through
Quique Kierszenbaum/MCT via Getty Images
Desalination plants (above) pump saltwater through membrane-filled tubes at high pressures. In each tube (below), water presses against rolled-up layers of porous material that allows water molecules to pass through and into a collecting tube while rejecting salt. Before disposal, the remaining salty wastewater is used to pressurize inbound saltwater.
M. Telfer
Source: h20distributors.com
Pure graphene is astronomically expensive and difficult to make in large sheets. So Grossman, Dave and colleagues turned to a cheaper alternative, graphene oxide. The carbon atoms in graphene oxide
are bordered by oxygen and hydrogen atoms.
Those extra atoms make graphene oxide “messy,” eliminating many of the material’s unique electromagnetic properties. “But for a membrane, we don’t care,” Grossman says. “We’re not trying to run an electric current through it, we’re not trying to use its optical properties — we’re just trying to make a thin piece of material we can poke holes into.”
The researchers start with graphene flakes peeled from hunks of graphite, the form of carbon found in pencil lead. Researchers suspend the graphene oxide flakes, which are easy and cheap to make, in liquid. As a vacuum sucks the liquid out of the container, the flakes form a sheet. The researchers bind the flakes together by adding chains of carbon and oxygen atoms. Those chains latch on to and connect the graphene oxide flakes, forming a maze of interconnected layers. The length of these chains is fine-tuned so that the gaps between flakes are just wide enough for water molecules, but not larger salt molecules, to pass through.
The team can fashion paperlike graphene oxide sheets a couple of centimeters across, though the technique should easily scale up to the roughly
40-square-meter size currently packed into each desalination tube, Dave says. Furthermore, the sheets hold up under pressure. “We are not the only research group using vacuum filtration to assemble membranes from graphene oxide,” she says, “but our membranes don’t fall apart when exposed to water, which is a pretty important thing for water filtration.”
The slimness of the graphene oxide membranes makes it much easier for water molecules to pass through compared with the bulkier poly-amide, reducing the energy needed to pump water through them. Grossman, Dave and colleagues
estimated the cost savings of such highly permeable membranes in 2014 in a paper in
Energy & Environmental Science. Desalination of ground-water would require 46 percent less energy; processing of saltier seawater would use 15 percent less, though the energy demands of the new proto-types haven’t yet been tested.
So far, the new membranes are especially durable, Grossman says. “Unlike polyamide, graphene oxide membranes are resilient to important cleaning chemicals like chlorine, and they hold up in harsh chemical environments and at high temperatures.” With lower energy requirements and no need to remove and replace chlorine from source water, the new membranes could be one solution to many desalination challenges.
Researchers manufactured sheets of graphene oxide (top) that function as water desalination membranes. Each sheet contains many graphene oxide flakes (bottom) linked together.
S. Dave/MIT
In large quantities, the graphene oxide membranes may be economically viable, Dave predicts. At scale, she estimates that manufacturing graphene oxide membranes will cost around $4 to $5 per square foot — not drastically more expensive than polyamide, considering its other benefits. Existing plants could swap in graphene oxide membranes when older polyamide membranes need replacing, spreading out the cost of the upgrade over about 10 years, Dave says. The team is currently patenting its membrane--making methodology, though the researchers think it will take a few more years before the technology is commercially viable.
“We are at a point where we need a quantum leap, and that can be achieved by new membrane structures,” says Nikolay Voutchkov, executive director of Water Globe Consulting, a company that advises industries and municipalities on desalination projects. The work on graphene oxide “is one way to do it.”
Other materials are also vying to be poly-amide’s successor. Researchers
are testing carbon nanotubes, tiny cylindrical carbon structures, as a desalination membrane. Which material wins “will come down to cost,” Voutchkov says. Even if graphene oxide or other membranes save money in the long run, high upfront costs would make them less appealing.
https://www.sciencenews.org/article/new-desalination-tech-could-help-quench-global-thirst
Call me biased but I think that savage and co should be looking to Perth and its environs for some early adoption of our Membrane technology.
Perth has two Desalination plants currently working.
It also has the Cragie recycling plant,and also the Mundaring water treatment plant.
http://trility.com.au/projects/mundaring-water-treatment-project/
https://www.engineersaustralia.org.au/portal/news/perth’s-groundwater-replenishment-scheme-takes-shape
https://www.watercorporation.com.au/water-supply-and-services/solutions-to-perths-water-supply/desalination?cid=sem0103&s_kwcid=perth desalination plant&gclid=CKfv7aXgq9ACFYOZvAodb4cNLQ
savage should have all this data because I sent it to mark muzzen, I just couldn't believe the tie up Ionic supposedly had with the SA water department, Perth is where Ionic should have a footprint IMHO.
Raider
