OLPC Experiments With Cow-Powered Laptops

An anonymous reader writes "The One Laptop Per Child Project (OLPC) is toying with a novel source of power for its low-cost XO laptops: cows. "We plan to drive a dynamo (taken from an old Fiat) through a system of belts and pulleys using cows/cattle," wrote OLPC's Arjun Sarwal, in an October 21 e-mail posted to one of the group's discussion lists. Sarwal and others are now finalizing the design of the cow-powered generator."

Being Thrifty

[WillRobinson]

After looking at the generator setup, this is something that would work. Generator from taxi's ready available cheep, a couple of front wheels from motorcycles also ready available. Ditto for 12 volt regulator and batteries. Driving farm animals around in a circle to run mills or other equipment for food processing has been done for centuries.

My question of this working is that I would expect the cow section to run probably 1 RPM. I would expect that the generator must turn somewhere above 400 rpm to put out a full 12 volts. (alternators usually above 700 rpm). So that is a pretty good gear ratio. Hence you see the double gear increase. Seems like it would be better to use a horse, which walks a bit faster, for several hours a day to charge the batteries instead of a cow.

Re:Something doesn't smell right

[slart42]

No, it's pretty real, they've made a deal with the OCPC project (One Cow per Child). They give the cow needed to power their laptop! It's a pretty sweet deal, you get a laptop and a cow! Now that's marketing!

On a more serious note, OCPC is actually called Send A Cow (http://www.sendacow.org.uk/ [sendacow.org.uk], they try to aid farmers to support themselves by donating livestock.

Re:Cows don't walk much

[duggi]

Farming and watering the fields with cows is pretty much a common sight in India. Event after the green revolution of the 60's many farmers still use cows(Bulls too) for farming, and it works like a charm for the Indian media when showing the stereotyped poor farmer. That apart, using them as an energy source? Have they even thought of solar powered batteries? I am no expert, but I live in India, and I can make an approximate guess as to how much energy these cows can generate(they do live in slow motion world) and surely it would be cheaper, cost efficient and it would simply make more sense. It would have helped if they posted in the same article what they were smoking.

Re:One Cow per Child Project (OCPC)

[ZachPruckowski]

You might be joking, but Heifer International [heifer.org] isn't [heifer.org]. They give animals to low income third-world areas, and when the animals mate, they pass some of the offspring on to other poor people. My grandparents donate a Flock of Ducks [heifer.org] or Chicks [heifer.org] from every grandchild in our family at Christmas.

Torque

[Algorithmnast]

When you consider the use of a cow vs. the use of a small animal (like a hamster) you start having to understand how we turn physical motion into electricity.

A small animal like a hamster is really cute, but they don't produce much usable electrical power. They only run long enough to get a workout, and if they get tired... they stop running. Yes, someone actually turned their hamster's wheel into a generator. [otherpower.com] The hamster could light up LEDs, but that's nowhere near powering a laptop.

A cow, on the other hand, will produce excellent torque - if you can get it to walk - but then you waste some of that power changing the low-amp high-volt power into higher-amp lower-volt power. Remember - pumping water is essentially a high-torque/low-speed process, but most electrical generation is low-torque/high-speed. (But that's because most electrical generation is for AC power, not the charging of DC batteries. For DC charging, high-torque/low-RPM might work nicely.)

However, what they're probably going for here isn't the optimal conversion of animal power to electrical power. What they're probably trying to do is transform into electricity what they perceive to be widely available power.

Cow Solar Adapter

[Doc Ruby]

The "cow power" is just solar power collected first by the grass (or whatever) the cow eats, then by the cow. By the time the cow pushes the dynamo, the efficiency of using the 1KW:m^2 that falls on the growing stuff is in the hundredths of a percent. Sunlight might not be "consistently strong", but it's evidently strong enough to grow whatever the cattle eat. What it needs is a battery, which the OLPC has.

Instead of a dynamo of belts and pulleys, which requires a lot of maintenance and isn't portable (like many nomads and people who herd cattle), how about they work on fermenting that grass for fuelcells? The cattle won't have to work as hard, so they won't need as much grass, which extra grass can power the OLPC. The dynamos they're proposing must be supplied elsewhere anyway, even from Fiat taxis, so why not get fuelcells instead? And why not use the demand for them to grow local fuelcell production industries?

And if fuelcells are too expensive or complicated, why not just some standard PV cells, feeding the OLPC batteries? A PV collector the size of a cattle pen could power several OLPCs.