Pedal Power and Micro Hydro
This is a quick summary of my talk and shop tour at the Farm Hack event Sunday April 29, 2012
Pedal Power Pedal power is useful for off-grid and small scale applications.
Power output for humans 50 Watts (easy effort- can maintain for hours) 100 Watts (strenuous effort- can maintain for minutes up to 1 hour) 200-500 Watts (intense effort- can maintain for seconds up to 1 minute) Helpful tips flywheel helps with momentum (mass x radius x velocity squared) heavier and faster is better chains are more efficient for low speeds (less than 1000rpm) but v-belts are easy and ubiquitous humans pedal 50-100rpm gearing is needed (grain grinding 90rpm, electric generators 1,000rpm, blenders 10,000rpm) permanent magnet DC motors are also generators (like in a treadmill) find cheap/free parts on craigslist/ebay or in dumpsters (old bikes, exercise equipment, etc)
Small and micro scale hydro power is the most cost effective (and best energy return) renewable energy source by an order of magnitude.
Site survey: measure head: elevation drop from top to bottom (of spring or stream) measure flow rate in gallons per minute potential power (Watts) = head(ft) x flow(gpm) / 10
Case study Full and By Farm: Pre-existing spring fed water on farm head height 100ft (elevation) existing 2in pipe distance 1500ft flow rate 5.5gpm (gallons per minute) power output 75Watts power output per month 53kWhr water pipe was existing, hydro system cost $400
I will post more details on the Tools section of this site, and feel free to contact me for any more details, questions or help with your project: andy[at]pedal-power.com