Tuesday, 8 July, 2025 / Edition 66

This edition of Enspired is all about membranes, baby! Splitting things into constituent parts with relative ease is underappreciated in our time, to be honest. It can help remove heat from processes and create the necessary ionic gradients to drive electron movement. Let’s dig in!

Sarah Compton

Editor, Enspired

Separating Hydrocarbons with Membranes

Roplant/Shutterstock.com

Most geos’ work in oil and gas ends when the hydrocarbons are removed from the subsurface, but that liquid still has a long way to go before it’s utilized. Engineering expertise and a thorough understanding of hydrocarbon chemistry, which can ostensibly fall under the purview of us geoscientists, are required after the initial handoff.

The typical process: Hydrocarbons go through a trial-by-fire, literally, to transform from the raw material that comes up the pipe to the products we’ve infused our lives with. The raw fluids are a mixture of different kinds of hydrocarbons that are fractionated into useful components using heat.

Why it matters: The separation process makes up about one percent of global energy use but about six percent of the world’s CO₂ emissions.

What’s new: Researchers have tried using more physical methods—membranes—to separate fluids, but the membranes kept absorbing too much organic material and swelling, lowering their effectiveness for a hydrocarbon application.

• Most of those filtration methods focused on polymers of intrinsic microporosity (PIMs), but a team at MIT took a page from another discipline and modified polymers used for reverse osmosis water desalination.

• These membranes have a good track record: Since 1970, they’ve lowered the energy required for desalination by about 90 percent. This has big impacts for reducing oil refining energy.

How it works:

• The membranes used for desalination are typically polyamide made from an interfacial polymerization process, but it swells too much and doesn’t have the right pore size for hydrocarbon filtering.

• To account for these shortcomings, the MIT team changed the bonds in the membrane from an amide bond to an imine bond and added a monomer called triptycene.

• Adding the monomer improved the pore formation process, resulting in spaces that are the right size for hydrocarbons.

• The change in bonds resulted in ones which are more rigid and hydrophobic.

• Those characteristics allow hydrocarbons to quickly move through the membrane without causing noticeable swelling of the film.

Is the juice worth the squeeze? The ingenuity here is impressive, but the effort required seems large compared to the one percent of global energy use and roughly six percent of the world’s CO₂ emissions at stake.

BUT, a look further down the commercialization pipeline says maybe the benefits are worthwhile:

• Improved efficiency: The final membrane improved the concentrations of some final hydrocarbon products like toluene by a factor of 20.
• Ready to scale: The membrane method is already widely used in an industrial setting, so scaling up shouldn’t be an issue.

Go deeper: If you thought that quick explanation was heavy on the chemistry, then I don’t recommend you go here to learn even more of the chemical details.

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Osmotic Power From Haline Gradients

Sweetch Energy/YouTube.com

As geoscientists, we have a rare appreciation for the haline gradient and what happens when two bodies of water with different haline gradients meet.

Something I missed, though, is the energy potential such a meeting holds.

Understandable oversight: I might have missed it because, generally, “on-demand energy” from water is associated with harnessing its movement, whether that’s through waves or dams.

But another option apparently exists: Osmotic power (not to be confused with the “phenomenal cosmic power” of the Genie from Disney’s Aladdin).

Catch up fast:

• Osmotic power has been around for decades but has flown under the radar because the materials required to harness it have been too expensive, until now.

• Osmotic power can take the form of harnessing pressure differentials between two bodies of water with different haline gradients.

What’s new: French company Sweetch Energy uses a special membrane to separate the ions so electrons will flow.

• The company’s INOD osmotic generators use advanced biomaterials to create their membranes and a stack design to maximize energy output.

• The tech was dispatched at the end of 2024 on the Rhone River at the edge of the Barcarin lock.

• As of February, Sweetch was planning to grow to 200 employees in 18 months.

What we don’t know: How Sweetch plugged the generated power into the grid was tough to find, as well as specific dispatch details: are the membrane stacks literally tossed in the river at a confluence? Was it somehow piped in from separate sources, run through the membranes, and then released again?

Great potential: The location has the potential to generate more than four million megawatt hours per year, which is one-third of the Rhone’s hydroelectric production of 13 terawatt hours.

Why it matters: Bodies of water with different haline gradients can now be thought of as a power source.

Here come the geos: Guess what discipline is best suited to know and understand these haline differences and how best to optimize them? Us! Geoscientists.

• Our understanding of river dynamics and haline gradients gives us a unique skill set to utilize in fluidics (leveraging fluid dynamics and fluid flow to perform tasks similar to those performed with electronics).

Go deeper: To learn more about Sweetch and its osmotic power solution, go here.

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