- Local groups
- All groups
- Upper North Island
- Bay of Islands
- Opotiki Coast
- Lower North Island
- South Island
- National network
- Add your group to this web site
- Offer Support
- Contact us
Digest Colonizers, Make Gas, Cook Beans...
I’ve been wondering for a while how much work and resources would be required to build a prototype for a neighbourhood scale organic-waste-to-energy plant, with a pedal-powered mulcher. I’ve heard a lot of theory about biogas digesters, but this article entitled ‘DIY Methane Generator‘ seems to be based on the experience of some people who have actually experimented with it on their permaculture farm, with some success.
“Just about any organic waste can be decomposed as a methane generator - plant (soft material is better than woody material) and animal wastes, and even human waste.”
This got me thinking. Soft material. Like convulvulus and periwinkle? Twitch? Grass clippings? Animal waste, who has a dog and feels guilty putting its do-do into landfill, and weird about putting it in the compost? Human waste. Hmm. I wonder how many kilograms of humanure a household produces each day?
“Each kilogram of biodegradable material yields around 0.4 m³ (400l) of gas… 2 gas rings for a couple of hours a day will use between 1-2 m³”
So that means you’d have to be able to process about 2.5kg to 5kg of colonizing weeds, dog poo, and humanure per day, per household, to supply enough gas for daily cooking needs. I presume this material would need to be mulched fairly finely for efficient digestion. Maybe this could be done with wind power, where it’s available, but what about cycle power?
Cycle power has the benefits of being available when it’s not windy, and providing an exercise opportunity for humans (assuming you have humans around who want some exercise). Think about all those people at the gym, riding exercycles which aren’t hooked up to anything! Turning human pedalling power directly into mechanical work is much more efficient than turning it into electricity and back into work, and there is almost certainly more embedded energy in the various hardware needed for electrical generation and storage than there would be in a pedal-powered machine. Also, according to this article in Low Tech Magazine, a stationary bike custom-built to provide energy from pedal-power is much more efficient than hooking up a standard bike, whether you’re trying to generate electricity, or power a machine directly.
So what I’m thinking is this. Each neighbourhood could have a gym, with exercycles designed for ease of harvesting the energy output of the person exercising, using a direct mechanical drive with some sort of gearing system, to allow riders to work their way up to the force necessary for a given job. A standard socket could allow a variety of mobile machines to be hooked up to it, anything from a smoothie maker to the mulcher discussed above. When nobody is using the energy directly, the exercycles could be set up to store it by charging banks of communal electric batteries, or even by winding up clockwork, compressing air, or charging electromagents.
This is something the energy group of a Transition initiative could start working on right now.