(from an email)

I think that there are maybe four dozen plausible solar cooker designs, tops, of which three or four are head and shoulders above the rest and have become standards.

They’ve been shaking this stuff out for 30 years. Doesn’t mean there isn’t room for innovation, but the field is much, much smaller than you’d anticipate and a lot of pre-filtering has already been done.

Likewise improved stove designs: wood gasifications stoves, of which there are maybe three approaches, rocket stoves, darfur stoves… biogas diigester systems of various kinds… steam injection stoves (as far as I know not yet practical)… less than a dozen basic technologies are in play, of which only three or four models are common. The Stove Community has been working on this for about 30 years too, and they’ve written off most of the space as unworkable.

For water purification, there are half a dozen systems: SODIS with plastic bottles, SOPAS (solar water pasteruization) using solar cookers, large array UV/solar, sand filtration (not portable for the most part), potters for peace filtron (bacterial recontamination issues) and the lifestraw (can’t be used by children, the very old, or the very ill == all your most vulnerable groups go unprotected.) There are a few options worth looking at that I haven’t explored, but the general shape of the field is well understood.

Same for shelters. Three or four standard relief tents, the shelter systems domes, the global village shelters, these unifold things (new to me), hexayurts, and various “local materials” options which NGOs have asked people to build from time to time.

I went through the field broadly and did a survey from 2003 -> 2006, generally working through what was understood to be State Of The Art and picked the Hexayurt Project Infrastructure Package from the best stuff I could find.

The “aesthetic” of the Hexayurt Project package is forward looking – Wood Gas Stoves are *wonderful* but not *quite* ready for field use in lifesaving situations yet – but we also have pretty good options for fallbacks to established practices.

It’s not that I was beating off options with sticks, it’s that there were large periods of time when I couldn’t find *ANYTHING* that looked like it would work, then I stumbled on one or two decent ideas.

The reason that the developing world is not using these technologies is because almost none of them actually work in practice in field conditions well enough to spread like the cell phone did. The model here isn’t sifting through piles, it’s picking three or four things, making sure they’re well tested and accredited, and then getting them **finished** – polished, tested, refined and then rolled out. Nearly nothing **actually** makes the grade – we’re looking at things which are *close* and hoping for future refinements.

We don’t want to re-invent the wheel: there are already large, established, highly capable and technical communities of practice that are working in these fields. We’re just picking a few things they recommend, and trying to get them through the validation processes so the NGOs etc can use them.

I do not believe that anybody alive understands the actual network of interconnections well enough to produce a useful taxonomy of appropriate technology solutions at this point – for example, the Sustainable Settlements Charrette neither produced nor used such a taxonomy. RMI doesn’t regularly use a taxonomy for infrastructure that I’m aware of.

Taxonomies are incredibly difficult and require profound thinking on the fundamental questions, and that thinking has not been done yet. It’s the work of years.

It’s a spectacularly hard problem. It *looks* simple, right up until you consider a story like the kids who were given reverse osmosis water, got adapted to it, then the filters went away and they got stick.

That, right there, is an *incredibly* important example of how precisely understanding the parameters of the problem is much, much harder than people think.

You can say “water purifiers” and, if you wire that into the taxonomy, it’s wrong before you start. The actual category is something more like “prevention of water-borne diseases.”

Now you’re into the space of public health. What did we discover? Reverse osmosis purifiers **CAUSE** water borne diseases **when you take them away.**

This is **vital.** RO turns out, in some situations, to be a problem, not a solution.

Here’s another hoary old classic from the archives of mishandled interventions: Operation Cat Drop.

http://www.strange-loops.com/scicatdrop.html

This is our enemy, right here: partial understanding that looks like complete understanding, followed by mayhem.

We cannot just drop the gear into categories and not break the entire cognitive space which exists for doing whole systems based optimizations of the problem space. It’s a mistake from Day One to think that we know how to model these processes.

Loose binning, yes. **very very very loose binning** reflecting a well-understood common format, sure.

But not **anything** that pretends to be a taxonomy. We are not there yet, and it’s hard to imagine how we get there without several years of work on public health and technology issues, another extremely poorly understood area.

If it was simple, it would have been done already. I’ve been at this for *five years* and the longer you spend with appropriate technology, the more complex the field becomes. First class engineers have been working on improved wood stoves for 30 years and still haven’t come up with something which is good enough to have spread all over the planet in the same way cell phones did.

This stuff is hard. Harder than we know. Getting started is easy, but getting to completion and actually having a tangible impact on the world is hard.

I should say, though, that a taxonomy of **PROBLEMS** is much more tractable, and a taxonomy of infrastructure is also a lot more tractable. It’s not an insoluble problem, but progress has to be exceptionally carefully thought out!

I think that a *functional* taxonomy based around simple classes of problems: “purify water from bacteria” “purify water from chemicals” is plausible. It’s the mapping of those atomic solutions into healthy patterns of life which is the incredibly hard part!!!

Over to you, Woody 🙂