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Comment by hn_throwaway_99 | Hacker News Reader

I think once you do the math, and realize how incredibly little power a human can generate compared to modern electricity, you realize it's not really worth it. Literally forgetting to turn the light off in your bathroom twice a month would probably waste more power than a super-committed, hour-every-day stationary-bike-using person would generate.

I don't mind these kinds of "solutions", but I do object when they go in the "make me feel guiltless about everything else I do because I hooked my bike up to a generator" bucket.

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You’re correct on the side of power generation, it’s a tiny amount. On the other side, we have come a long long way when it comes to efficiently using power. The combined power usage of my bathrooms lights is probably less than 60W. The largest MacBook uses less than a moderately trained human can produce. On average, fridges need paltry amounts, compared to what they needed a decade ago.

Certainly, running a vacuum or boiling water won’t work with human power generation, but if you want that as a backup, you probably can fall back to a broom and use a gas/multifuel cooker in the meantime.

> I think once you do the math

> Literally forgetting to turn the light off in your bathroom twice a month

8h * 5W * 2 = 80Wh per month

(Unless you're talking about using incandescent light bulbs, which would be like using a 4mpg vehicle in a discussion about average vehicle efficiency. Personally I think a 3W LED is better than a 5W, but I know most people disagree.)

Our main bathroom light draws, I'd guess, 0.1W. It shows up as 0.0 with a kill-a-watt so I don't really know. And it's only used for about half an hour a day at most.

> a super-committed, hour-every-day stationary-bike-using person

60W * 1 * 30 = 1800Wh per month

So no, forgetting to turn a light bulb off for an entire night, twice a month, does not waste more electricity than that gained by a cyclist who is capturing their electricity.

I think it's a great hack to turn this machine into an electrical generator.

Come on, this is "missing the forest for the trees" pedantics. I think you will find that the average bathroom in the US uses way above 5W.

Regardless, it's just an example. The DoE says the average US residential customer uses 909 kilowatt hours per month. Using your math of a committed cyclist that generates 1.8 kwh per month, you're still looking at under .2% of energy replacement. Which, again, even the smallest efficiency improvements in a house would completely dwarf what a human could produce.

I can only respond to your words. If you don't like my choice of bulb, then do your own math and show it like I did. See what watt bulb (not bulbs plural, or moving the goalposts even further, an entire bathroom) it takes for your assertion to be true. Actually I'll just do that myself because it's easy.

Now, we already discussed generating 1800Wh per month using this bike. So:

1800 / (8 * 2) = 112.5

Or in other words:

112.5W * 8h * 2 = 1800Wh

So you'd need to run a 112.5W light bulb for 8 hours per night, twice per month, just to equal the amount of electricity produced by the article author. Although you said that leaving the light on wasted more, so, let's just go with a 113W bulb. I'm old enough to remember 100W incandescent light bulbs, but even then, they were rarely bought and used because that's an insane amount of electricity for indoor lighting.

Now where I live I can't even buy incandescent bulbs because they're not for sale. For 112.5W to be average, there would need to be millions of Americans using stadium lighting just to take a shit.

I think you should take a step back and reflect on why you're so quick to attack someone for doing a cool hack (this is Hacker News) that reduces their electrical usage (in the time of climate change).

Here's a neat video of an olympic cycle sprinter powering a toaster: https://www.youtube.com/watch?v=S4O5voOCqAQ

1800 watt-hours, or 1.8 kilowatt-hours, is 20 cents worth of electricity. Using a cycle to power things makes for a neat demo, and might be good for educating people about electricity and suchlike, but anyone who expects to notice it on their energy bill or carbon footprint, or even for the installation to pay for itself, is off by a few orders of magnitude.

Yeah, the thing is, the by far best use for "bike power" is actual transportation. 0.15kWh of pedaling power can get you surprisingly far (one hour of moderate effort cycling), but would be rather unimpressive for the usual electrical applications. Apparently, almost two centuries of doing that have lead us to some very clever and pragmatic efficiency tweaks, probably because the effort-motion feedback loop is so extremely compelling to the human mind (evolution has made us brains on an endurance locomotion machine, everything else is rather unimpressive compared to peer mammals).

Not to mention bicycles are designed for converting rotary motion into, well still rotary motion, but forwards travel; not electrical potential.

I haven't done any research or taken measurements, but particularly the low-end style tyre-on-roller that I have must be awfully inefficient.

It's been briefly popular (to some extent) a couple of times to power a light while cycling. These things don't typically have large capacitors or batteries to store surplus charge, because powering the light is about all you can do! (Ok not totally fair since you're also cycling, but still.)

Many (most?) bathrooms in the US have more than a single, lonely bulb.

The author of the article is using the bike as a back up to his solar panels when the power is out. He isn't going to be running AC and arc welders off the power generated from his bike. More likely some lights and phone/laptop charging.

The power from the bike is likely to be more than sufficient for those use cases.

I really think room lights are approaching 5W/bulb. I have a 3x5w bulb setup and keep 2 unscrewed just because it’s too bright when I have to go in at night.

Incandescents are a hard sell when LED bulbs are $1-$2 and pretty reliable.

8h * 5W * 2 = 80Wh per month

Question - where did you get 5W from? a LED nightlight?

More realistic, a washroom is using 60W MINIMUM.. most have those light bars above the mirror and they are closer to 300W.

I recently replaced my Halogen lights with LED and cut the kithen lights from 600W to ~60W. Substantial savings, but how many people replaced everything with LEDs?

I literally just went into my bathroom and checked the main light.

5W.

Above the mirror we have three huge bright bulbs we only use when brushing teeth.

5W each, or 15W total.

I literally don't think I've been in a house in the past 3-4 years that isn't 90-100% LED bulbs.

Color reproduction sucks in LED though. So if they do more than brushing teeth with bathroom mirrors they could be still rocking good old incandescent.

What have you got to do in the bathroo that requires color? Calibrate monitors for high quality print?

People that apply cosmetics need proper color representation. There’s even dedicated mirrors with built-in lights for that.

However, on average, that will not be a primary driver of energy usage in the average since most people don’t spend a substantial chunk of their time painting their face.

I am very sensitive to color temperature at night, and it really affects my sleep. E.g. Night Shift on OSX isn't enough for me so I still have the reddest possible setting for f.lux set on my computer.

I hate the light that LED bulbs give when I'm getting ready for bed. Thus, I have LEDs in most places in my house except for my bathroom and bedroom where I have incandescents.

Just as a quick example: Bringing a pot with 1 litre of regular room temperature water to boiling temperature takes about 0.1 kWh. A regular person produces about 100W during strenuous but still aerobic exercise so you'd need about an hour of cycling to generate enough energy. This doesn't include heating the pot itself btw.

Not disagreeing, but just wanted to point out that if the goal was to generate heat then humans could potentially be more efficient because of internal efficiency. The ballpark number I often see is 25% efficiency, so if you were able to somehow capture the waste heat they'd be able to heat up the water 3x as fast.

This would probably work better when heating up rooms rather than water. The benefit of using electricity as an intermediate form of power is that it becomes possible to heat water up to boiling temperature. Exercising humans never reach boiling temperature no matter how hard they try.

Fair point, though that is arguably the only situation involving electricity (besides heating the room itself which doesn't involve heat capture) in which you're actually trying to generate heat.

A single square meter solar panel which costs on the order of $100 will outproduce a human. If you're camping or in a power outage and want to charge your phone or some led lights, sure, a bike charger makes sense, but you'll never be net positive with the energy you create vs. the energy needed to produce the generator.

Solar panels only outperform a human when the sun is shining. From the article:

"But what if skies remained gray for many days in a row? Rather than trying to purchase enough battery storage to cover all reasonable eventualities, I decided that my backup source of electricity needed a backup itself, one that I could use to charge that battery during times when my photovoltaic panels won’t function"

As a primary source of energy a cycle generator doesn't make a lot of sense. But as an on demand source to cover occasional periods of low solar generation it's a great hack.

Not only that, but human power is incredibly inefficient, especially if the food you are converting into that power is not plant-based. It's significantly better if you eat plant-based, but nowhere near a bunch of solar panels covering the same area that the plants did.

If you get above 400w, consider turning pro.

Even though it won't run your refrigerator, I would have been pleased to be able to plug an external mobile device battery into a smart trainer during a recent power outage so i could continue to work on a book manuscript while power was out.

The winner of the Giro d'Italia stage today was doing nearly 600W for just over 17 minutes.

I don't think you can have a 400W bike FTP without already being a pro.

There might be a handful of time trialists here in the UK with day jobs that could do that, but yeah no one is doing that without dedicating a huge part of their life to training.

More importantly, I bet your hour a day user never comes close to the energy nessesary to build the bike and associates electronics in the first place

But, but, but... you're ruining the movie "The Matrix"!

;-)

Apparently the original story had the AI use the network of human brains as a giant neural network.

As the story goes, the movie executives thought this would be too difficult for most people to understand, so they switched it out and used the thermodynamically unviable power source motive instead.

I wish The Matrix had humans in virtual reality cages because the AI had a mandate to keep them alive and well, and this was simply the most efficient mechanism for doing this. This would have made the resistance far more ambiguous as they would actually be fighting for freedom but against the well-being of humanity.

>I wish The Matrix had humans in virtual reality cages because the AI had a mandate to keep them alive and well

Humans have finite lifespans, right? So all the AI has to do "relieve" itself of the burden of keeping humans alive would be to not let them reproduce. This would be pretty easy considering that it's pretty hard for people to spontaneously become pregnant while hooked up to those pods.

It's even crazier if you start comparing the energy used for training massive AI models vs. the paltry wattage required to keep a human brain operating.

Agreed, but my son's crank flashlight is a great teaching tool and it never runs out of batteries!

When you think about it, humans are really energy efficient at moving their limbs.

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