Biological Energy

Energy efficiency is the hottest trend these days.

Everyone wants to talk about it.  Do stuff about it.  Make changes to it.  Come up with alternatives to the sources we have.  Panic over the possibility that we might run out of it or not have enough of it.  Simply put, energy and the things we use to get it are loud, screaming issues for our society.

So it goes without saying (not really) that an alternative energy source of any sort might be of use to humanity.  Especially one that uses something we have a lot of, like say waste water or carbon dioxide.  Wouldn’t it be cool if we had a device that could take the muck we don’t want and convert it into energy that we need?  And wouldn’t it also be awesome if that device could potentially work forever without needing to be recharged?

I know you might be thinking, “But Jessica, you sly fox you, that’s just crazy science fiction talk that is”.  And while yes, I am a sly fox, this particular type of science is in no way fiction.  Not anymore.

Meet Dr. Lenny Tender.

Dr. Tender is a research chemist – and the branch head – at the center for bimolecular science and engineering at the Naval Research Laboratory in Washington D.C. where he has spent over a decade perfecting a science that uses benthic microbial fuel cells.  That’s a device that uses a method of extracting energy from the biological elements of sediment under water.

A device that uses the squishy sand at the beach to power stuff?  How does THAT work?

“Benthic microbial fuel cell is a device that extracts electricity from the sea floor,” Dr. Tender explains.  “That’s what benthic means; it’s the interface between the sediment on the bottom of a marine environment and the overlying water.  This technology being developed to persistently operate oceanographic sensors.  It’s able to generate electricity just like a windmill.”

Which means that the benthic microbial fuel cell is just that; an energy harvester.  Whoa.

But wait, this doesn’t mean we ought to take all of our alkaline batteries and just toss ‘em out.  Obviously there’s a process.

“At that at the bottom of the marine environment we have a sediment,” explains Dr. Tender, “and in the mud at the bottom of a harbor, river, lake or the ocean.  This sediment actually has quite a bit of fuel in it.”

Think of anything that has ever lived in the marine environment; phytoplankton, sea creatures, etc.  When they die they wind up settling down on the sea floor, just like leaves on the lawn.  So those creatures, as they start decomposing, represent a pretty potent fuel source.  Glucose for example.  That is the geological precursor for petroleum.

It’s also the sort of stuff that’s sitting there mixed into the sediment on the sea floor.

Well that’s a very useful fuel.  And by a fuel I mean that this is something that a microorganism can use to acquire energy from.  It’s also something that we can use to acquire energy from to operate marine devices.

“So what we do is come in and we put electrodes into this already made battery,” Dr. Tender says.  “We put an electrode into the mud, put an electrode just above in the overlying water and we connect them with a circuit and we can draw power pretty much indefinitely.”

Basically we’re utilizing the same type of process that biological organisms use to generate energy and we’re converting it to power.

It’s biological energy.

This type of science has a world of uses to the Department of Defense, not the least of which is assisting in maritime adventures.  Dr. Tender and his group have found ways of turning this kind of technology into a tool for the Navy.

“The Navy wants total awareness of what’s going on in the oceans,” Dr. Tender explains.  “One of the limitations to achieving that goal is power management.  If they’re all battery powered you can’t hope to keep thousands of sensors operating.  The logistics become huge, but if you can deploy them by extracting power off of the sea floor to operate the sensors then you remove the power management logistics problem.  If you utilize a sensor that is robust, something that can last for years in the ocean, it will run.  It won’t be limited by power.”

The benthic microbial fuel cells are the stepping stones to giving us sensor control over our waters.   And I don’t just mean the ones in the ocean.

“Waste water treatment and waste water conventionally requires a lot of energy,” Dr. Tender says.  “We’re right next door here to a massive waste water treatment facility.  It consumes 36 megawatts of electricity to treat that waste water.  But the inherent energy represented by the organic matter which is the fuel in the waste water can be used to generate electricity.”

There’s an opportunity to flip that equation upside down and to actually think of waste water treatment plants as power stations generating power.

“And that’s a concept that’s important for the nation because approximately 5% of our U.S. energy consumption goes to treating waste water,” says Dr. Tender.  “It’s a very important issue for the DOD because we have to treat waste water all around the world.”

But wait!  There’s more!  This technology doesn’t have to stay underwater.  Dr. Tender says there’s a possibility for using this kind of process to convert carbon dioxide to energy.

“One of the things that we’re pursuing now that I’m terribly excited about is the idea of using microorganisms as a catalyst on electrodes to take carbon dioxide to generate fuel,” Dr. Tender says.  “We actually have organisms that we’ve isolated from the benthic microbial fuel are very good at accepting the electrons from electrodes and reducing carbon dioxide.”

So what does that mean?

“You could actually have a large facility that would essentially suck the carbon dioxide out of the air, and at the end of it you might have a valve and out would come fuel that you could [use to] operate your car.  This is an opportunity to start drawing on the carbon dioxide that’s already in the atmosphere and then generating a fuel.”

Well, Los Angeles and Washington D.C. will not be for want of an energy source again.  Ever.

So how did the scientist who may effectively change the way we think about energy get started in this field?  “Totally accidental,” he says with a laugh.  “[For] most scientists – it’s like surfing the internet.  You don’t know where you’re going to wind up.”

I think I speak for humanity when I say it’s a good thing you ended up here, Dr. Tender.  Thanks for keeping us powered up.

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Jessica L. Tozer is a blogger for DoDLive and Armed With Science.  She is an Army veteran and an avid science fiction fan, both of which contribute to her enthusiasm for technology in the military.