Induced Demand

217px-Supply-demand-right-shift-supply.svg

Image: Wikipedia.

I was on the phone the other day having a conversation about greywater with a person enrolled in an entrepreneurial program. She asked me an excellent question: did having a greywater system cause me to use more water?

She was alluding to a concept known as induced demand. In other words, when you have more of something you use more. Buy a hybrid car and you end up driving more miles since you don’t pay as much for gas. Build a four lane highway instead of a two lane one and so many more people end up driving that you end up with worse gridlock.

I’d never thought of induced demand when it comes to greywater, but it’s a good point. Did I plant more fruit trees because I had a greywater system? Has this caused more water consumption in our current drought? Honestly, I think the answer is yes.

You could probably find induced demand between the lines of David Homgren’s permaculture principles. But perhaps we should insert a thirteenth principle: acknowledge induced demand and work to prevent it. Simply being aware of the phenomenon is a good first step in avoiding its pitfalls.

My original greywater system consisted of a tank and a hose to drag around to a bunch of trees. I’ve since simplified the system. It’s now just a pipe leading from the laundry machine to one tree that needs just about as much water as we do in laundry each week. My second system is more of a 1:1 match between the waste water and the demands of the landscape.

Have you encountered induced demand on your homesteading path? If so where and how?

Tippy Tap, Beta Version

tippy tap1

A tippy tap is a water-saving handwashing device developed for use in areas where there is no running water, usually fabricated out of simple found materials. Erik and I both love appropriate tech, and this is a really good example of the form. The tippy tap literally saves lives by allowing people to wash up after visiting the bathroom.

Erik included a tippy-tap, a rather fancy version of one, it turns out, in one of our link roundups.  I’d never heard of such a thing, and, intrigued, promptly fell down a deep YouHole watching tippy-tap videos.

The basic idea is that a jug of water is suspended from a pole or branch by the handle–so it can tip. A string is then tied to the top of the jug to act like a lever to create the tip. A small hole punched in the front side of the jug allows a thin, controlled stream of water to flow when the jug is tipped. To keep cross-contamination from occurring, you don’t actually touch the jug or the string to use it. Instead, the string which tips the jug is tied to a stick on the ground, which acts as a foot pedal, so the jug is tilted by foot action alone.

I thought it would be cool to have a tippy tap hanging in the garden for hand washing — better than spraying water all over with the hose, especially in these times of drought. It would also be a good handwashing station for camping.  So I made a beta version to test the idea. Long story short, it works well. I made a few mistakes and want to work out some kinks. Also, for use in the garden, I want to design a more attractive tippy tap, perhaps using a gourd or ceramics.

For the how-to, and some links to other tippy tap instructions, read on.

Continue reading…

004 Egg Ethics, Solar Food Dryers and a Question about Earth Ovens

rootsimplepodcastart

On episode four of the Root Simple Podcast Kelly and Erik discuss the tricky ethics of eggs and mayonnaise, what kind of solar food dryer is the best and we answer a question from Ed about earth ovens.

Plans for the Appalachian Solar Food Dryer can be found in an article on Mother Earth News.

We have a detailed post on how we built our adobe oven here.

If you want to leave a question you can call (213) 537-2591 or send an email to [email protected].

The theme music is by Dr. Frankenstein. Additional music by Rho.

A downloadable version of this podcast is here. You can subscribe to our podcast in the iTunes store. Note that it takes a few hours for the new episode to show up in iTunes.

What’s the Best Solar Food Dryer?

Lead-Chart jpg

Appalachian Food Dryer. Image: Mother Earth News.

Dehydration is a great way to put up food. Second to freezing, it’s the best way to persevere nutrition without adding sugar or salt. And if you use the power of the sun, you won’t need to spend any money on electricity.

In a desert climate you can just put your food out on screened trays. But just a bit of humidity in the air makes this approach risky. Food can spoil before enough moisture is removed. That’s why you should build a solar food dryer.

V5380E13

Brace Direct Food Dryer. Image: FAO.

There are two basic designs for solar food dryers: direct and indirect. Direct dryers are just a box with a piece of glass on the top. Indirect dryers use a box to collect the heat of the sun and then, thanks to the fact that hot air rises, take that heat up into an enclosed box that contains the food you want to dry.

The Poistk Dryer

The Poisson Indirect Dryer. Image: Mother Earth News.

Which design works best? Dennis Scanlin, Coordinator of the Appropriate Technology Program and Professor of Technology at Appalachian State University in Boone, North Carolina has been studying solar food dryer technology for decades.  According to Scanlin, indirect drying is the way to go. Scanlin tested three dryers, the Appalachian Solar Food Dryer (an indirect dryer that he invented) against a direct dryer developed by the Brace Research Institute and the Poisson indirect dryer. In an article in Permaculture Activist, “Evaluating Solar Food Dryers: Stocking Up with Solar Power,” Scanlin says,

The Appalachian indirect dryer produced higher temperatures than the other two dryers and also removed more moisture from the tomatoes drying inside each day. In one test, the Appalachian dryer removed 32 oz. (0.95 L) of water during ta day, while the Brace direct dryer removed only 20 oz/ (0.59 L), and the Poisson dryer only 15 oz. (0.44 L). The Appalachian dryer was able to remove as much as 3.73 lb. (1.69 kg) of water in a single sunny day from tomatoes drying inside.

Scanlin also notes that direct dryers degrade the quality of the food and possibly nutritional value due to direct UV exposure.

solardryer

Our Appalachian Food Dryer, badly in need of a paint job.

We built a Appalachian Dryer several years ago and it works great. You do need to remember to bring in the food at night to prevent rehydration and spoilage (for some reason I often flake out and forget to bring in the food). For awhile I had an electric Excalibur Dehydrator on loan and it’s a lot more convenient. But, of course, it uses electricity and makes a lot of noise.

Since I built my Appalachian Dryer Scanlin has decided that it’s not necessary to use insulation. This makes the project even simpler. For just around $200 worth of materials you can easily make an Appalachian Dryer out of plywood nails and screws.

You can find plans for Scanlin’s dryer here.

Journal of the New Alchemists

Screen shot 2014-04-24 at 10.30.39 AM

“Six-Pack” Backyard Solar Greenhouse, 1975. Image: Journal of the New Alchemy.

After reading an article by Paul Ehrlich, “Eco-Catastrophe!,” Nancy Todd turned to her husband John and said, “We must do something.” The year was 1969 and the Todds along with Bill McLarney went on to found the New Alchemy Institute.

History repeats itself. What the New Alchemists did, in response to the 1970s era energy crisis and political instability, sounds a lot like what people have been up to since the 2008 economic bubble: aquaculture, organic gardening, earth building, market gardens, no-till agriculture, old timey music, wind power, four season growing, permaculture, non-hierarchical leadership and goats. Only the 1980s era of appropriate technology amnesia separates current efforts from the work of the New Alchemists.

Screen shot 2014-04-24 at 9.08.03 AM

Aquaponic system. Image: Journal of the New Alchemy.

By accident I discovered the Journal of the New Alchemists deep in the closed stacks of the Los Angeles Central Library. As revealed by their journal, what distinguishes the New Alchemists from other efforts of the time is the Todd’s science background. The Journal has a refreshing research-based approach to its subject matter. The period I reviewed (their last decade of publication) covers mostly their agricultural experiments, but occasionally dips into urban planning and other subjects.

Screen shot 2014-04-24 at 9.08.32 AM

Biodome. Image: Journal of the New Alchemy.

It’s interesting to look back at their work to see what ideas went mainstream and what faded away. What didn’t stick is what Nassim Taleb would call “top-down” approaches to design epitomized by the 70s fixation on geodesic domes and self contained ecosystems (though we’re starting to see a resurgence of the latter via a renewed interest in aquaponics). The more bottom-up work of refining conventional organic agriculture through no-till farming and integrated pest management had more long lasting influence. One could make a good argument that you need the domes and aquaculture schemes to inspire people to work on the more prosaic stuff. But another criticism of the appropriate technology movement of the 70s is that it focused on technology rather than social and political problems (see economist Richard S. Eckaus article “Appropriate Technology: The Movement Has Only A Few Clothes On“). We may be in the midst of repeating that mistake.

Screen shot 2014-04-24 at 9.06.48 AM

Aquaponic system. Image: Journal of the New Alchemy.

One does not need to wander the closed stacks of the library to find the amazing Journal of the New Alchemy. Thanks to the internet you can download the New Alchemist’s publications as pdfs. Aquaponic enthusiasts will find much information. The Journals are a fascinating read and gave me a great deal of respect for the founders of the New Alchemy and their many contributors (one issue features a young Gary Paul Nabhan). They went far beyond talking the talk and walked the walk. They did something.