Science Questions

Eels: a source of electricity?

Tue, 17th Mar 2015

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Bonga asked:

Can we harvest the power from eels as a source of electricity?


Bonga tweeted us asking if we could ever use eels as a source as electricity? Would it be efficient? And how would it compare to other energy sources? Khalil Thirlaway caught up with Dr David LaVan from the National Institute of Standards and Technology to find out...

Khalil - All organisms give off a weak electric field. But electric eels are one of a small number of fish species that can generate strong pulses of electricity with their body and they use them to great effect. But how do they do this? I spoke to Dr. David LaVan from the National Institute of Standards and Technology.

David - Electric eels produce electricity in brief spikes, in much the same way that humans do. When a human decides to move a muscle, an electric impulse called an action potential, fires in your brain, travels through neurons causing a muscle to contract. These individual signals carry very little power.

Khalil - The eels use a weak electric pulse to scan for the natural electric fields of smaller fish in the murky Amazonian waters, where they live. Once they find something tasty, they send out a stronger pulse that can paralyse or even kill their victim, making for an easy meal.

David - The cells that produce electricity in the eel, called electrocyte,s also create action potentials. But the electrocytes are stacked together to increase the total voltage in current. Large eels can produce up to 600 volts.

Khalil - Ouch! 600 volts is nearly three times the voltage of mains electricity in the UK and 5 times what you get in America. So can we harness this stunning power?

David - It is technically feasible to power human devices from eels or electrocyte cells but practically speaking, the electricity from eels is not very useful for us. First, it’s important to recognise that eels convert energy from the food they eat to electricity. There's no free energy.

Secondly, electric eels are just not very efficient in producing electricity. It turns out, they can convert about 15% of the energy in their food to electricity under ideal conditions in their natural environment. However, that value doesn’t consider the energy needed to maintain them in an artificial habitat. Energy needed to heat and purify their water as well as the energy needed to grow and transport their food, all would reduce the efficiency even further if you were trying to domesticate them.

Khalil - This seems like a lot of effort. How does this compare to other renewable forms of energy?

David - Commercially available solar panels like you find on many roofs these days are about 15% efficient in converting sunlight into electricity. The newest solar materials coming out of research labs are about double that efficiency. So, for the most part, it would be better off using sunlight to make electricity using solar panels, rather than growing food, to feed to an eel, to make electricity.

Khalil - So, in answer to your question, yes, it is possible to harness the electricity of eels, but no, it isn’t practical for our everyday electrical needs. There are some situations however, where eel electrocytes might conceivably be a useful power source. For example, to power disposable biodegradable electronics. Scientists like Dr LaVan are also suing what they’ve learned from electrocytes to inspire research into designing new, artificial power sources. Thanks to David LaVan for that electrifying answer. Next week, we’ll be answering this cheesy question from Chris…

Chris - Is it true that cheese gives you nightmares?


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Apparently electric eels can generate a 2mS pulse of 500v and 1amp, not a very useful source of power syhprum, Mon, 16th Mar 2015

Does the buck have to stop there? Obviously, capturing eels and raising them for their energy would be inefficient, but what about just taking the mechanism they use and building on it. Could genetic engineering be used to increase the efficiency and/or amount of energy they release? What about using eel cells to build a biomechanical device? I'm not sure if there's an efficient way to nourish individual cells outside of a body, but grouping the cells to build a biological power source would allow you to skip the process of raising and domesticating. I'm not sure how much of what I'm saying is venturing outside of science in sci-fi, but I would love to hear a more in-depth follow up. Craig, Fri, 24th Jul 2015

This idea just needs the right application. Eels are not a plausible source of general purpose electrical energy as there are much more efficient and scalable methods of converting biofuel (food) into electricity. However, if certain bio-compatibility issues can be resolved, cultivated eel tissue could perhaps be used as a local power source for bio-implants. Other attempts at ATP based power sources for CMOS applications have proven quite difficult, e.g. ~Ken Seehart Ken Seehart, Thu, 17th Mar 2016

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