Tiny New “Artificial Jellyfish” Taps Wave Energy For Carbon Capture

April 19th, 2020 by Tina Casey

Fossil fuel stakeholders still have this dream that carbon capture can breath new life into coal and gas power plants. However, new technology is throwing cold water on the idea. After all, why burn fossil fuels to pump additional carbon out from underground, when there is already plenty of extra CO2 swimming around up top, ripe for the picking? Good question! That leads to another challenge: how to pick your carbon fruit and sell it, too.

Carbon Capture & Renewable Energy

The “how” gets to the nut of the carbon capture challenge. Aside from the infrastructure that needs to be built, carbon capture systems also require energy to run.

That can create a problem in terms of lifecycle carbon emissions from gas and coal production. A Stanford University scientist took a look at the issue last year and found evidence that the carbon capture systems at both natural gas and coal power plants produce just a fraction of their promised CO2 benefit when the electricity is generated by natural gas.

Running a carbon capture system on renewable energy offers more promise from a lifecycle emissions perspective, but it still has a couple of big-picture problems. Two, in fact. First, as applied to power plants it doesn’t address the root of today’s climate crisis, which is the habit of digging up sequestered carbon from the ground and pumping it into the atmosphere.

Second, there’s the matter of accelerating the energy transition. If you’re going to construct new wind turbines and solar arrays, it may be more efficient from a climate-saving perspective to apply that clean power directly to consumers rather than feeding it through a fossil power plant.

The Rise Of Ambient Carbon Capture

The ambient carbon capture approach can skirt around both of those issues, since it tackles an existing problem without directly incentivizing more fossil extraction.

Though our friends over at Carbon Brief warn that ambient capture is not a standalone solution for the climate crisis, interest in the field is growing.

Somewhat ironically, the oil industry appears to be among the first to figure out the financials, by capturing carbon at oil fields through a chemical scrubbing process and using it for enhanced oil recovery.

On the other hand, the enhanced oil avenue may be a moot point now that the global oil market has tanked.

One Wave Energy Device To Rule Them All

With all this in mind, let’s take a look at newly published research on a new wave energy device developed by a team of scientists from the Department of Materials Science and Engineering at the City University of Hong Kong, lead by Professor He Jr-hau.

Here’s the rundown from the University of Hong Kong:

“The system features three components: a spherical spring-assisted triboelectric nanogenerator (TENG) that can convert the mechanical energy of the wave into electricity; a power management circuit with a supercapacitor to temporarily store the harvested energy; and an electrochemical setup that can reduce carbon dioxide to formic acid.”

If you caught that thing about TENG, that’s the key point. This new wave energy device is not like conventional ones.

Typically, wave energy converters use the up-and-down motion of waves to spin an electromagnetic generator to produce electricity. Triboelectric generators start with the same up-and-down mechanical energy, but they are based on the same principle that creates static electricity.

Here, let’s have our friends over at tribonet.org explain:

“It is generally believed that after two different materials coming into contact, a chemical bond is formed between some parts of the two surfaces, called adhesion, and charges move from one material to the other to equalize their electrochemical potential.”

Adding Value to Carbon Capture

The other unusual aspect of the new device is its spherical, jellyfish-like design, and that’s where the real magic happens.

Instead of transferring electricity directly to land via cable, the new wave energy device leverages electrochemical technology to capture carbon dioxide on site, and reduce it to liquid formic acid.

Formic acid (CH2O2) is the same stuff that ants and other insects use to mark their territory. In past years the global market for human-made formic acid was somewhat limited and confined mainly to leather processing.

More recently, the market has expanded to include preservatives for livestock feed. Formic acid is also emerging as an energy storage option for renewable hydrogen.

Rising demand for formic acid could spell good news for the petrochemcial industry, since formic acid is made from methanol. However, the new wave energy device could cut off that avenue by achieving the green trifecta of sequestering carbon and producing renewable formic acid with renewable energy.

For more details on the City University of Hong Kong study, check out “Blue energy fuels: converting ocean wave energy to carbon-based liquid fuels via CO2 reduction,” in the journal Energy and Environmental Science.

What’s That Thing About Renewable Hydrogen Again?

Separately, Professor He has worked with another research team on photoelectrochemical systems for solar-to-hydrogen conversion.

If photoelectrochemical rings a bell, that’s the “artificial leaf” approach to solar conversion. It differs from solar cells because it relies on a chemical reaction to convert sunlight directly into electricity.

Photoelectrochemical devices can “split” renewable hydrogen from water, which circles back around to that emerging market for formic acid.

You can find all the details on that work in “An efficient and stable photoelectrochemical system with 9% solar-to-hydrogen conversion efficiency via InGaP/GaAs double junction,” in the journal Nature.

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Photo (cropped): Wave energy converters via City University of Hong Kong.









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