Saturday, March 21, 2009

appropriate infrastructure development


Saturday morning we woke up and had a proper look around Will´s place, made some eggs (which i was told had too much salt- a recurring complaint) and then headed out for AIDG´s workshop.

There was a group of chickens hanging out in the back yard. Though i don´t think this is where our eggs came from, they very well could have. From what i gathered the chickens subsist entirely on compost, which seems like a good system.

Erin was very excited about this brick oven, she has been pining to do some baking ever since she got here. In fact, she decided we would build one on the roof.

Will gave us a great tour of his office and the connected workshops. Everyone there is totally engaged in awesome low-tech projects, a lot of them seemed connected to water in one way or another.

The first thing we got to see was a testing bench set up to monitor the optimal usage of a micro-hydro design that one guy, Sam, had invented. (Micro-hydro is for small scale, personal use, electrical generation) His design is pretty ingenius, it basically channels water through PVC pipes to a bucket with a generator inside. I don´t know exactly how it works, but somehow through physics alone the water is forced to a higher velocity than it would reach normally and then streamed through the bucket. Sam admits the design has some obvious inefficiencies, from a purely scientific standpoint, but its not designed to be the most efficient generator possible. More than efficiency it is going for effectiveness- its designed to be built by anyone, out of materials readily available and easy to use- two points which are at the heart of appropriate technology.

The bench Will is pointing to simulates the conditions under which the bucket would operate. The bench is designed to allow detailed monitoring of electrical output and tight control over water speeds and (i think) pressure. They are currently running tests to find the optimal operating scenario for the generator. I don´t know much about hydro, but this design is unlike anything i´ve ever heard of- it could be revolutionary for personal electricity generation. Sam said its really big with survivalists.

Inside there was another bench designed to do "dry runs" of the generator inside the bucket. I can't remember exactly how it functions, but i think there are a variety of voltages and amperages that the generator can be tested on. Also, i gather its easier to test it dry if you're wanting to tweak the machine's innards.

Next we got an explanation of a device that had counfounded us all the night before. It turns out this thing is a water pump built by some MIT students some time ago. You literally stand on the two planks and step up and down to pump water. The AIDG folks were impressed with how quickly the students had built it, a matter of hours if i remember correctly. Though they didn't entirely trust it, they said it was a little wobbly to work and none of us were allowed a go. Supposedly it pumps out enormous amounts of water, and very quickly. Maybe even too quickly.

Next we got to see the "safe stove." Its called a safe stove because it contains and channels smoke very well. One of the leading causes of death amongst children in developing nations is smoke inhalation from indoor cooking set ups. The safe stove dramatically reduces the amount of smoke that is emmittted indoors. This type of stove is also sometimes referred to as a rocket stove because of the way that it intakes air- when it really gets going it makes a whirring noise like a quiet rocket. There is a small opening in the front of the stove to put in twigs and other small wood pieces, the wood sits on top of a small shelf which allows air to flow strongly up from underneath it. The air and flames are then channeled up through the highly insulated stove, heat the top elements and then exit out of a pipe in the back. For whatever reason, constricting the air flow to a small channel increases the efficiency of burning substantially. And the heavy insulation retains a great amount of that heat to use for cooking instead of dissipating out into the atmosphere. I'm a big fan of rocket stoves, and this one was particularly impressive.

Will's co-worker Vergel did an awesome job of explaining the stove to us. I was blown away when he said that the flames can get so hot that the shelf glows red. They worry about it melting sometimes- talk about efficiency!

Our final stop on the tour was outside to the bio-digester. I think i had startled its creator, James, earlier that morning with a barrage of questions. I was really eager to learn all about it and he was as gracious as one could be at 8:00 in the morning while making eggs.

Basically the bio-digester is an anaerobic (lacking oxygen) processor of organic materials. It utilizes certain microbial life forms to break down plant material into methane. (If there were oxygen present it wouldn't make methane, or at least not at the smae levels). The device is made up of two tanks, the first is the digestor, which is essentially a cement lined hole in the ground with a big 55 gallon drum floating on top and an underground pipe connecting it to the second tank. The second tank, form what i gather, is really just there to be the place where the excess spills over, gets collected and then used as fertilizer. In the first tank the big blue drum is pushed all the way down, as the methane is created it rises to the surface and lifts the tank- a good visual indicator of how much you've got. A tube comes off of the top of the tank and, eventually, will be connected to a special gas stove that can burn uncompressed methane. For every week's worth of compost James guesses they'll be able to cook two to three meals. I was impressed but James said this was nothing to more complex systems that are better sighted (to optimize sun exposure) there are versions in Haiti, he said, that can cook two meals a day.

The gas is kept from escaping by pinching the the tube, as well as putting in a small amount of water to act as a gas trap.

Dory looking excited, as per ususal.

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