this post was submitted on 04 Feb 2024
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Northwestern University researchers have introduced a soil-microbe-powered fuel cell, significantly outperforming similar technologies and providing a sustainable solution for powering low-energy devices.

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[–] [email protected] 55 points 7 months ago (5 children)

How much power does it produce? It must be pretty bad since they don't mention it anywhere in the article.

[–] Tar_alcaran 38 points 7 months ago* (last edited 7 months ago) (3 children)

They claim "68 times more than required to operate the sensors", then mention a sensor to measure soil moisture.

A basic soil moisture sensor, like say, the ones I have stacked on a shelf here, will work on 2 AA batteries. It runs on 2V at 10mA. So that's 20 milliWatts, and in willing to be a fair bit of that goes into the electronics that make a red, green or orange led light up at certain moisture levels, and the bit that beeps when below a certain level.

Still, this sets something of an upper limit at 1.3W, or maybe 680 mA? Those seem rather high, so I'm betting their moisture sensor is a bit more delicate than my model. It depends on the size and number of cells though.

[–] [email protected] 14 points 7 months ago

Im pretty sure most soil moisture measurment devices just measure the capacitance to measure dielectric permittivity. U can design such a setup to use any arbitrary amount of power depending how close the electrodes are rogether etc etc.

[–] [email protected] 5 points 7 months ago* (last edited 7 months ago)

Yeah, I am imagining the soil moisture things from the garden store, with the little needle gauge thing, that takes so little power that there's no battery slot. I feel like the amount of power this thing makes is extremely low.

[–] [email protected] 1 points 7 months ago

Probably generates nanowatts

[–] [email protected] 12 points 7 months ago

The linked article has a table that gives 1.74 uW/cm^2. However glancing over the rest of the paper there's a ton of variability of output.

[–] [email protected] 11 points 7 months ago (1 children)
[–] [email protected] 2 points 7 months ago

Damn I hoped it would go to eleven, I need that little bit extra.

[–] [email protected] 9 points 7 months ago (1 children)

For low power applications. You won't be charging your phone off this.

[–] [email protected] 5 points 7 months ago

Depends on how many fuel cells you get and are able to shovel dirt into

[–] [email protected] -2 points 7 months ago

1.21 gigawatts

[–] [email protected] 33 points 7 months ago (1 children)

Love these pie in the sky articles that get debunked immediately in the comments

[–] [email protected] 4 points 7 months ago (1 children)

Who debunked this? I don't any comments debunking it.

Also if you read the article it has limited applications so it's not some pie in the sky you think it.

[–] [email protected] 10 points 7 months ago

I kind of get op's point. It's not straight up debunked, but it's so few microwatts that they can power the sensor but they can't store log data.

It requires a close proximity powered base station nearby to fire a signal out to get reflected back somehow.

I'm having a hard time picturing any viable setup outside of a laboratory experiment. If you've got a powered base station within a few inches of it why not just power it with that?

[–] [email protected] 24 points 7 months ago (1 children)

" As long as there is organic carbon in the soil for the microbes to break down, the fuel cell can potentially last forever.”

It's also a stationary battery

"Although the entire device is buried, the vertical design ensures that the top end is flush with the ground’s surface."

[–] [email protected] 16 points 7 months ago
[–] [email protected] 14 points 7 months ago
[–] [email protected] 5 points 7 months ago (2 children)

So if the tip is sticking out for airflow, how does it handle a flash flood?

[–] [email protected] 3 points 7 months ago* (last edited 7 months ago) (1 children)

"Furthermore, the researchers used waterproofing material on the cathode's surface, allowing it to work during flooding and assuring progressive drying after submersion."

https://interestingengineering.com/innovation/new-fuel-cell-taps-energy-from-dirt-dwelling-microbes-to-power-sensors

[–] [email protected] 2 points 7 months ago

I missed that part in the article, I should have just searched for the word flood, woops

[–] [email protected] 1 points 7 months ago

Sensuously?