Zazzle Shop

Screen printing

Tuesday, July 1, 2008

In-Depth look at the DIY "Bucket Hydroelectric Generator"

Sam Redfield on Pico-hydro at La Florida

by Catherine Laine
June 29th, 2008

The pico-hydro system we’re working on just got featured on MAKE and Gizmodo so I asked Sam Redfield, the primary developer on the project, to send over some more info on his invention and time with us in Guatemala.

I recently returned from a 3-month stint with AIDG Guatemala. As part of their program in Central America, they are pursuing an ambitious project to develop cheap, small hydroelectric systems under one kilowatt known as Pico-Hydro. Prior to my arrival in Guatemala I had developed a small hydroelectric system housed in a 5-gallon bucket. Using a Permanent Magnet Alternator as the generator in the system and made almost entirely of PVC, we conducted field tests in the small community of La Florida to determine what the possibilities were for generating power with the device. La Florida had lost its primary source of electricity and was depending on candles and batteries for their energy needs.

Pico-hydro system test at La Florida, Guatemala
Pico-hydro system test at La Florida, Guatemala

Pico-hydro PVC Turbine

La Florida is a small community based around a coffee plantation on which a group of landless campesinos ceded from ruin after the previous owners abandoned the property. It now runs as a collective producing excellent organic coffee. Set in the foothills below a semi-active volcano near the Pacific coast in the tropical lowlands of western Guatemala, La Florida offered a temperate climate with easy access to water. Our work in la Florida focused around the prospect of charging cellular phones using the Pico-Hydro system that I had developed in the States.

Charging 10 cell phones off the battery
Charging 11 cell phones off the battery

To charge cell phones, members of the community have to take an expensive and time consuming taxi ride an hour each way to pay a service for charging. Cell phones have become increasingly important in small isolated communities as they give these communities access to medicine, the market and family. Our field tests began by identifying a site with access to abundant water and a steep incline for the pipe to feed the generator. After a site was identified, we laid the pipe and tapped into an existing stream. In all we laid 80 meters of 2- inch pipe to achieve a head, or drop in elevation, of just under 30 meters.

The generator was then installed with a voltage regulator, car battery and inverter. The regulator insured that the battery was not overcharged, the battery stored the energy for use and the inverter bumped up the power to 110 volts. Three power strips were then attached to the inverter. After we determined that the generator was producing electricity, we began gathering cell phones from the community. In all we gathered 18 phones. The generator was producing 60 watts, not a whole lot of power, but enough to charge 10 cell phones at a time without depleting the battery. Because the car battery could remain fully charged with a load of ten cell phone chargers working, we would be able to charge ten cell phones at a time 24 hours a day without depleting the car battery. Alternatively, we could charge considerably more cell phones simultaneously and allow periods for the car battery to recharge. The system produced enough power to charge all the cell phones in the community and potentially could provide a service that would save the people of La Florida considerable time and money.

Micro-enterprise schemes are being investigated to provide an individual with the generator as a business venture. The owner of the business would charge a small fee for charging cellular phones that would be affordable. The cost of the generator would be paid back over time with the proceeds of the charging service. Another application of the generator being explored is for household lighting. With the emergence of high output super efficient LED’s the prospect of creating small-scale lighting utilities is within reach. Again, people would be charged a reasonable fee to receive four to six high output LED lighting fixtures in their homes. The provider of the service would make a modest profit, and pay for the generator over time.

Duration: 1min

Work continues. One of the issues that we face in deploying the system is cost. The Permanent Magnet Alternator that generates the electricity in the system costs more than $300.00 US and has to be imported from the States. As part of my program with AIDG in Guatemala, I investigated the possibility of rebuilding a Toyota alternator to function as a Permanent Magnet Alternator. After investigating several possibilities, I am happy to report that we now have a working prototype, which is being integrated into the system. Other improvements include integrating the voltage regulator into the device and improvements in turbine performance. In the coming months trials will continue and no doubt improvements in economy and performance will be made. My work with AIDG Guatemala was invaluable to me in understanding the energy issues people face in the developing world and provided me an excellent opportunity to develop my technology in an environment that fosters innovation in a setting where peopleÂ’s lives are positively effected. Thanks AIDG!

-Sam Redfield
Sam Redfield

Sam is building a generator for Professor Brian Thomas at Baylor University to be installed in Honduras as a cell phone charging micro business.

He’s going to try to get me a parts list with general specs to post on the blog in the next few days. Until then if you have pressing questions, you can email him a samredfield [@} earthlink {dot] net