Pedal Powered Power

When you have a solar-powered web server, where do you go next for a source of power? Instead of lazily mooching off the sun, you can use your muscle with a bike generator. [Ed note: The site is run on an entirely solar-powered server, so if it’s the middle of the night, you might have a better web experience here.]

We’ve covered bicycle generators before, so what’s new? For starters, the accessibility of chargers and batteries has changed significantly. Rather than just charging a phone or putting out a measly 5V, this bike can be integrated into an existing solar PV system and output many voltages. This guide goes over building one with hand tools with great detail.

It starts with a 1950’s vintage exercise bicycle, no hacksaw required. A friction drive connects a generator and makes for an incredibly compact generator/exercise machine. Calculating the correct gear ratio is crucial to getting the 12 volts out at an average pedaling speed. You want your range of voltages to be between 5 and 24 volts. With the help of a control panel provides 5v, 12v, 14.4v, and 220v to power a variety of devices. Boost and buck converters output these voltages (depending on whether the voltage needs to be set for a maximum or a minimum). A potentiometer allows you to dial back the power draw of certain appliances (an electric kettle, for instance), making a workout a tad easier on the human component of the generator.

Another key takeaway from this guide is using a wind charge controller to charge batteries. A solar charge controller will just cut the circuit when the batteries are full. A wind charge controller will increase the load until the motor breaks. Some controllers are also hybrid wind and solar, allowing you to connect a small panel like the one running the webserver this guide is posted on and then charge up the batteries when it has been overcast for a few days in a row.

19 thoughts on “Pedal Powered Power

    1. Yeah. Small wind turbines would overspeed if the load is suddenly cut in high winds, so the best option is to just throw a bearing in the motor, which jams the turbine and renders it safe.

  1. Hmm, fascinating and potentially perplexing although with a prevailing propensity for perception towards productivity pursuant to the art of prescience enhanced by the inherent proclivity to be prepared for progressing the professional prize, one can of course be plaint all to easily to provide presumably potentially perfect personal unless one becomes a pariah in the peurile political paradigm :sigh:

  2. I”m just going to nitpick the title and say it should be been “Pedal Power” because “Powered Power” is redundant. However, if you wanted to imply that it supplied electricity then it would be “Pedal Powered Electricity”.

    If you were going for the alliteration then “Pumping Pedals Powers Personal Pad” would have been a good route.

  3. 24% efficiency (good for food to work ) it will be 7100 kcal per KWH. (This is a very in shape athlete level of efficiency)
    Carbon footprint for 7100 Kcal food on average U.S. diet is 13.5KG co2.
    Carbon footprint for 7100 Kcal with U.S. vegetarian U.S. diet is 6.39 KG co2
    Average U.S. grid is 0.947 KG per KWH,
    Coal plant is 2.23 KG Coal per KWH.
    Natural Gas is 0.91 kg/kwh

    So if you are an athlete is really good shape with very high efficiency, and eat a low carbon vegetarian diet,
    this bike assuming 100% efficiency from pedals to plug is about 3 times worse than a Coal fired power plant at Co2 per Kwh.

    If you eat a normal U.S. diet and compare to a Natural gas power plant then this is 14 times worse.

    1. by that metric, exercise without attempting to capture the power is EVEN WORSE, because then 100% of the energy used to make/transport/cook the food is “going to waste”.

      Point being, I don’t think anyone’s suggesting you convert your house to 100% human caloric power, but if you’re gonna hop on an exercise bike regardless, why not also get some useful energy out of it?

    2. One thing to remember is that a degree of energy consumption is required for life anyway for things like keeping yourself warm – so the increase in energy consumed by a person that spends a while on this bike vs doesn’t is potentially very low.

      And if you account for the need to exercise to remain healthy its easy to spend way more carbon driving to the gym/rockface/lake etc AND you still need the increased food intake for that exertion!

      Also worth noting the Carbon cost of a diet is a very nebulous thing to pin down – for instance we manage to grow a good amount of beans and peas (among a few others) under the Pear tree – that is a vast vast volume of fruit and some veg that has no food mileage (or carbon costs of any sort – watered when needed with captured rain water etc), and there is a butcher and greengrocer that source all their stuff only from the local farms nearby (not that we can afford to go there for everything) again very very low food milage. And if your source isn’t farming in a really CO2 intensive way it will have vastly different energy/environmental costs to the farm that is still farming like its the 70’s shacked to a cheap petrochemical industry…

      More importantly still there is one thing your comparison to fossil fuel misses entirely – at least a reasonable portion of human powered CO2 emissions are a closed loop created by growing the food in the first place – so net zero – its indirect and inefficient solar power really. Where the Coal plant is entirely ‘new’ carbon in the atmosphere, which makes it a bigger problem (though how such things really break down is nearly impossible to really trace unless you can source everything with short vendor chains so know the true costs involved)…

    3. It looks like you got coal values from the FAQ page of the EIA. They aren’t explicit about it, but it seems that they don’t consider externalities, as they consider wind, solar and hydro to be carbon-neutral, which they aren’t when you consider externalities.

      Looking at “Carbon footprint and nutrition of self-selected US diet”, Rose et al, I get 6.39kg CO2 (Table 2, line 1) for a low-impact diet (quintile the lowest impact diets) and 15.69kg CO2 (results, sentence 1) for an average diet, using the 7100kcal value. This seems to be your source. By my understanding, this study only considers the externalities of eating, and not direct emissions from human biology

      Apples: Emissive externalities of dietary energy without direct emissions

      Oranges: Direct emissions from coal power generation without externalities

      Coal has massive externalities, both from emissions and pollution. I’d wager if we summed both direct CO2 emissions end CO2 emissive externalities of both, coal would be much higher than human power. No easy resources are popping up on searches for coal externalities, as the field is a very deep one, and I simply don’t have time to wade through all the papers to parse out indirect CO2 emissions.

    4. If it’s cold weather and you need to heat your house, it’s 100% efficient. All the energy that _isn’t_ turned into electricity will move as heat from your body to the room you are exercising in.

  4. Except when those energy sources are on line. This brings to mind that scene in Soylent Green. Shame of it is I have a very back burner project on my porch. AMF made an excersize bike in the 80’s with a Chrysler Alternator(TM) and a computer that sets the load on the user. The absurdity is it has a power cord to run it and a sizable power resistor inside to bleed off that ready to go 12V. At the time this was made AMF owned Harley-Davidson. That would make this the Harley of generator-bikes. What sent it to the curb was it’s timed life plastic belt from the 20inch plastic rim to a V pulley on the alternator.

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