# How do you power a cyborg?

In this answer about how to design the ideal cyborg, I said:

...

• Use electric tissue to power the machines. Cyborgs need some way to generate electricity when mechanical parts are involved. Rather than batteries, which can corrode and leak, generators, which are noisy, or charging, which isn't always an option, consider a polymer layer below the skin that turns chemical energy into electricity. Polymers solve everything.(™)

I reasoned that while installing such a layer would be invasive and somewhat painful, it would work in all locations, and would not need to be refueled in the traditional way.

## The cyborg in question needs minimal power - to aid locomotion a bit, to maintain an artificial heart, and to maintain a series of pumps throughout the body.

### Is this an efficient way to power a human cyborg?

What alternative technology could do the job better, assuming charging / refueling cannot happen frequently?

• A great first question would be to explore what the cyborg does that humans don't do, and how much energy and power the cyborg really needs. One thing organic bodies are really good at is being efficient in a remarkable variety of circumstances. A cyborg that needs 400W fits within our body's exercise budget. A cyborg arm that charges itself with 10W for a long time, and the unleashes it all at once is also very affordable. A cyborg that has to regularly dead-lift a thousand pounds is neither, and will require a very different power source. Dec 18, 2016 at 16:24
• @CortAmmon Edited Q a bit, I'm not looking for a ton of energy input but thanks for pointing that out Dec 18, 2016 at 16:39
• @CortAmmon Just for reference: 400W is about 100 cal/s or 0.1 kcal/s. For adult humans, energy requirements may vary from roughly about 2000 kcal/day to 5000 kcal/day depending on build and lifestyle. Additional 1000 kcal, could power 400W auxiliary devices for nearly 3 hours. Cort is completely right, prolonged but not constant 400W expenditure is perfectly plausible without major changes. Making it constant would most likely require changes to eating habits, but little more than that. Dec 18, 2016 at 17:16
• 400W is the maximum output a well trained cyclist can produce, steady state. Of course, that output is being produced at roughly 23% efficiency, so the actual calories consumed will be higher by a factor of five. It seemed like a good number to start from. If the cyborg has a more efficient way of consuming calories and translating them to useful work, then they could step beyond it. Dec 18, 2016 at 17:22
• I just felt like translating it to (in)famous kilocalories would be useful reference to most users. Dec 18, 2016 at 17:26

Diamond naturally generates electricity when exposed to radioactivity. So, radioactive diamond batteries are made by forming carbon-14 into diamond and encapsulating it in regular non-radioactive diamond.

These diamond batteries have a very specific purpose – low power and extremely long life. A standard twenty-gram non-rechargeable AA battery stores about 13,000 Joules and will run out of power in about 24 hours of continuous operation. One diamond with one gram of carbon-14 would produce 15 Joules per day, much less than an AA battery.

But the power output of the diamond battery is continuous and doesn’t stop. The radioactive diamond battery would still be putting out 50% power after 5,730 years, which is one half-life of carbon-14 or about as long as human civilization has existed. During this time, the diamond battery would have produced over 20 million Joules. And would produce another 10 million during the next 5,730 years.

These could be useful for pacemakers and other internal low power devices, since they do not have to be replaced via surgery.

## Thermoelectric Paint

Perhaps internal body parts could be coated with thermoelectric paint. That could absorb body heat and convert it to electricity.

## Piezoelectric Artificial Body Parts

While no one has made piezoelectric artificial muscle matrial yet to my knowedge, it seems like it could be an ideal innovation for cybernetics. Piezoelectric materials generate an electrical charge when deformed by mechanical stress. So, something like an artificial muscle that is always flexing and contracting could be a great possibility for piezoelectricity. In addition, bones, tendons and other natural body parts already are known to be naturally piezoelectric, so perhaps synthetic versions could be developed that produce even more electricity than normal.

• Not sure about your half life math, wouldn't it have produced more power in the first 5730 years, as the amount of radio active material is between 50% and 100%, and during the next 5730 is between 50% and 25%? (i.e. it's an exponential decay, not a linear decay) Dec 19, 2016 at 1:30
• @user2813274 I don't know, I didn't do the math, I just copied it from this article from Forbes. I'm not good with math at all. Sorry. Dec 19, 2016 at 1:33
• I upvoted because the diamond battery concept is really interesting, although it produces no way near enough power to be useful in this use case - i.e. it would take 570kg of them - more than half a ton - to generate 97W of power. However, from what I remember, artificial piezoelectric muscle can be constructed from fishing line. Dec 19, 2016 at 1:54
• @LukeBriggs That's interesting. Do you have a paper for that? Dec 19, 2016 at 2:54
• @bright-star it's slightly 'cheating' as the electricity is used to create heating which in turn expands/ contracts a very tightly coiled piece of nylon. Essentially, coil nylon around a wire. Searching 'fishing line artificial muscle' gives a wide variety of examples.- it's a semi-popular DIY project. Dec 19, 2016 at 3:27

Artifical photosynthesis has been making a lot of progress lately. Similar to your concept of a layer of skin which converts chemical energy to electricity, a possible better approach (depending, of course, on the lighting conditions of the host planet) would be to instead use a photosynthetic layer. That would make the cyborg very literally green as well as semi-transparent too. It has the bonus of running completely silent as well as requiring no daily dose of chemicals, aside from those found in your typical life-supporting atmosphere.

It's also worth mentioning that the most efficient kind of photosynthetic layer would appear deep black as it's absorbing all of the light that lands on it.

The structure of such a layer would likely be nanograss - a nanotechnology technique which helps maximise the available surface area, boosting the amount of sunlight it can capture.

One of my personal favourite real-world concept designs featuring this kind of layer is the Nokia Morph - a concept phone which explores the ways in which nanotechnologies might be beneficial in the future.

How much power could it generate?

At the equator, the average sunlight received by the top of Earth's atmosphere is about 1.3kW/m^2, according to NASA. On average, it's 340W/m^2. About 48% reaches the surface, giving us an average of about 163W per square meter, accounting for clouds etc.

Meanwhile, the average human male's body surface area is about 1.9 square meters - most of this is shaded, but that wouldn't necessarily be the case for a well designed cyborg which doesn't have any need for clothing. Humans also consume about 97W of power, on average. Keep in mind that a large portion of this is used for heating and digestion too, which the cyborg has little need for.

So, assuming our cyborg has a male build, is in Earth-like conditions and has human-like power requirements, as well as a nanograss power generation surface, it could easily have 4 square meters of power generating capacity; in the absolute best case scenario with 100% efficient panels, that means the best it can generate is 4 * 163 = 652W, which is well above the 97W it needs, giving a possibly large enough margin for efficiency losses due to shade and non-ideal solar conversion efficiency.

• Even impossibly 100% efficient photosynthesis in ideal conditions (i.e., no shade, middle of day in equatorial climate, all body surface used for that) would be implausible to power a cyborg. The cyborg would need to carry around a house-sized photosynthesis array to be sun-powered. There's a reason why animals don't use photosynthesis - the energy density is not sufficient for that. Dec 18, 2016 at 18:32
• (Moved my response to Peteris into the answer) Dec 19, 2016 at 12:25

The machine parts should be powered the same way as flesh, to take advantqge of the available distribution system.

It uses nano fuel cells to generate power from glucose and oxygen, extracted from blood.

See the details of the power supply for respirocytes for in-depth details on how that would work.

• by available distribution system that powers the flesh do you mean the mechanical one I describe or blood vessels / natural methods? Dec 18, 2016 at 17:04
• I mean the way energy is provided to the cells of the body. Continue to the middle paragraph of my answer. Dec 18, 2016 at 17:06
• Your question mentions no mechanical power: it rejects generators. The polymer you describe turns chemical energy into electrical power. But rather than a “layer” (where?) I point out that the real point is that energy is delivered via blood. Dec 18, 2016 at 17:09