In the early 1960s, when I was a Peace Corps volunteer on the Caribbean island of St. Lucia, I had a colleague who, like me, grew up on a farm in Iowa. In St. Lucia, he worked with small farmers in a remote area. He was really out there in the field, more isolated than the rest of us.

When he returned to his hilly, southeast Iowa farm, his father suggested they clear some timber from their bottomland to have more pasture for their cattle. George thought that was a good idea and immediately went to town and bought a machete.

“Gosh darn,” his father told me later, “I thought it was a good idea for George to go to St. Lucia and help those farmers get ahead, but now he comes home and wants to set me back 200 years.”

Sometimes I think technology developed in a first-world country like the United States and taken to Africa would, in fact, set the people who were to use it back at least a bunch of years, if not quite 200.

The question comes up often today, in light of the literally thousands of highly creative, motivated persons from many nations who are doing an astounding amount of work in the area of appropriate technology.

I define the activity of “appropriate technology” as designing a tool to be used in surroundings and for a lifestyle completely different from that of the designers’ everyday environment. In other words, designing a tool appropriate to the lifestyle in which it will be used. Indeed, the tool is for use in surroundings completely different from anything the designers may have ever experienced. As is the case when American engineers and scientists develop products for use in rural Africa and for populations in developing countries.

Appropriate technology is today a worldwide home for professional engineers who want to put their knowledge and background to use helping others. Appropriate technology, if you will, is a form of socially redeeming problem solving.


Done right, appropriate technology pays special attention to the variables that affect the users, such as their gender and state of health, the power sources available to them, and fabrication materials they’re familiar with.

Tweak or Shift

Overall, most engineers follow two basic strategies when it comes to “doing” appropriate technology. They either tweak an existing technology to make it better for the user in one or more respects, such as making it more durable, more reliable, more efficient, or more effective. Or, they’ll shift the technology in some fundamental way.

To tweak existing technology might be to take the Corona or Porkert food grinders, used by hundreds of thousands of the world's poor, and check for their weak points. The cast iron hand grinders, made by Corona of Colombia and Porkert of the Czech Republic, are what might come to mind when you are asked to envision the meat grinder your grandmother or great-grandmother might have used. These units, still in wide use, are general-purpose workhorses. They use steel cutters to grind grains, as well as legumes, coffee beans, nuts, and sesame or sunflower seeds, and also to mince dried fruits and vegetables.


To tweak the grinders for better use, an engineer might ask: Do the burrs wear out quickly? Does one part seem to break too often? Is a part prone to being lost? Tweaking these weaknesses might make the grinders more durable, stronger, better secured, but without the need for significant design changes.

A shift, on the other hand, might be simply to push, rather than to pull a tool; to use one's legs rather than one's arms to power a tool; to rotate a shaft around a vertical axis rather than a horizontal axis to operate a tool.

Take the example of the foot-powered treadle water pump. Invented in the 1970s by Gunnar Barnes, a Norwegian engineer, for use in Bangladesh, the pump is now widely used in arid regions of Africa. The pump is composed of two metal cylinders with pistons that are operated by walking, or treadling, on two treadles the way one would operate a pump organ or, in modern-day terms, a stair-stepping machine at the gym.

Previous to the treadle water pump, many rural people used tools that called upon the arms, rather than the legs, to pump water from the ground. But humans find it easier to treadle— as in the pump organ example—rather than pump a handle up and down with their arms. They tire less easily when using the larger, leg muscles. So the move to the natural walking motion was a major shift for the water pump.

Designers at the San Francisco nonprofit KickStart Inc. tweaked the treadle pump by changing its design from a suction-only pump to a suction and pressure pump, greatly expanding its impact on small farmers.

Or is the KickStart addition of pressure yet another shift? Regardless, the great advance gained from the KickStart treadle pump is that it sucks water out of the ground and pushes it up a small hill. Further, it increases the area that can be irrigated from 0.2 to 2.0 acres—amazing!

Small Shift

The problem is that shifting appropriate technology is particularly difficult to do well. It's hard to keep the end user in mind, when the designer comes from an entirely different viewpoint, an entirely different environment.

The challenge for those shifting appropriate technology is to answer the question: “What is the best next technological step given the current technological state at the place the technology will be used?” Does the location have electricity? Do residents commonly use draft animals, or call only on themselves to power simple tools?

There are three important criteria for a potential technology to be accepted and used by those for whom it's designed:

First, it must be a natural next step to the people who will use it. That is, it must fit rather seamlessly into their current system of doing the larger process.

Second, this next-step technology must yield a large increase in output from the existing process, such as a significant reduction in the food-particle size, when a food is ground with the next-step technology.


And third, it must mirror the steps previously moved through in already developed countries. So a next step in African food crop processing must be analogous to the step that was taken in, say, Europe or North America, when farmers there were using the same technology as Africans currently use. So African farmers will need to pass through the same stages of technologies as farmers did in Europe, North America, and parts of Asia, but of course, at a much more rapid rate. Steps cannot normally be skipped.

In my short time doing appropriate technology, I’ve seen elegant systems that weren’t adopted because they didn’t move the intended users sufficiently far forward in terms of output per unit input. Why should the intended users bother?

So what is sufficiently far? A good goal is at least one order of magnitude increase, a small jump in the technology the users currently employ. Too much of a jump and introducing the upgraded system in a developing area might be the equivalent of a group of alien scientists and engineers landing on U.S. soil and asking their Earthling counterparts to adopt the telescope they’ve developed, which far outstrips our Hubble's capacity.

Our scientists and engineers wouldn’t have been aware of any of the middle steps in the evolution from the Hubble to the alien scope. They wouldn’t be able to operate the alien telescope and—no matter how nicely asked by the alien engineers, no matter how many times they were assured that this telescope would allow them to see further into the universe than ever before—they’d likely abandon the project. Not to mention that, should the new telescope break after the alien engineers return home, no one would have the tools or the know-how to fix it.

Great Gains

To better get the idea of the one-order-of-magnitude increase and the effect doing appropriate technology can have, take the following examples.

The Universal Nut Sheller, allows a person to shell 125 pounds of peanuts per hour, up from the traditional 25 pounds that can be done by hand, said Jock Brandis, founder and research and development director of The Full Belly Project of Wilmington, N.C., which designed the sheller ( The nonprofit project works to allow manufacture of tools, including the Universal Nut Sheller, where they will be used.


The jump in peanut-shelling production represents an order of magnitude increase appropriate for the user.

The nut sheller features only one moving part for easy manufacture and use. It comprises a concrete, solid cone within another cone that's open at the top and bottom. The cones allow for the process of shelling, which works by centrifugal force and friction. The interior cone, with its attached handle, acts as a rotor and rotates on a shaft. The user turns the handle around fast enough to spin the nuts to the outside through centrifugal force, Brandis said.

The nuts fall between the surfaces and are rolled and squeezed, allowing the nuts and shells to fall through to the bottom. This mix of nuts and shells is then winnowed out. The sheller is adjustable and can shell coffee berries, shea nuts, and jatropha seeds.

Likewise, in the 1990s Compatible Technology International, a St. Paul, Minn., nonprofit that develops technologies for use in developing countries, introduced its manually powered 4.5-inch diameter Omega steel burr mill into Zimbabwe for grinding roasted peanuts into peanut paste. The paste is used daily in many African households.

At the time, most local groups used the time-consuming mortar-and-pestle method for crushing the nuts, and followed that up with manually rubbing the nut meat between a smooth glass bottle and a stone to produce a fine, thin paste.

Working with the University of Zimbabwe's Development Technology Center, CTI volunteers gauged the Omega burr mill to increase paste output in rural women's cooperatives about one order of magnitude, moving from linear to rotary motion.

The very early history of post harvest food processing in many nations includes a period when mortar and pestle type linear motion was important. This period was replaced early in North America by rotary motion from mill dams, followed by rotary motion from steam engines, internal combustion engines, and most recently by electric motors.

Shifting from linear and reciprocating motion to motion that rotates a hardened steel burr against a fixed burr was very effective at increasing peanut paste output. Rural Zimbabwe's peanut butter groups that adopted the manual Omega increased the amount of peanuts processed each day from four kilograms via traditional methods to around 50 kilograms of peanuts per day with the manually operated burr mill.

The mills’ early adopters made significant profits, because the price of paste made the old way was very high. Profits declined as more grinders were introduced, but citizens ate better because peanut paste was less expensive, hence more could afford it.

To ensure replacement parts would always be locally available, CTI provided Development Technology Center a pattern for casting the Omega housing and a special apparatus to form the auger helixes. Former CTI volunteer Mark Kooiker, a machine-shop operator, worked with a Zimbabwe foundry and machine shop and with fabricators to develop precise production techniques. CTI began working in Zimbabwe in 1995 with the Omega II. In just three years CTI went through the II, III, IV, and V versions of Omega grinders to the VI, which has been distributed for over 10 years now. Grinders and parts distributed in Zimbabwe are locally made.

Following Up

But the grinding technology wasn’t embraced without tweaking. Women agriculture workers in Africa are known to be strong, so grinding roasted peanuts to a creamy consistency in a single pass through the Omega grinder was technically feasible. But it was over-taxing physically for the women. Follow-up ergonomic studies by the Development Technology Center at the university, showed that heart rates in women hand cranking roasted peanuts with the manual grinder exceeded accepted international standards set by the Food and Agricultural Organization of the United Nations, according to a report by the Technology Center. Further, the switch from linear motion to rotary motion caused significant increases in lower back, chest, and upper arm pain among workers, according to the report.

So tweaks had to be made to produce creamy peanut paste in a single pass, yet maintain the cranker's heart rate and muscle exertion within acceptable limits. CTI and technology center engineers and scientists reduced the feed rate by developing a metering device mounted inside the hopper.

Another Axis

A different option to overcome cranking difficulty would have been to shift from a horizontal axis to a vertical axis grinder akin to many of the original wind power grist mills in Europe and many modern burr mills.


In fact, several appropriate technology post-harvest foodprocessing devices feature vertical axes. These include the breadfruit shredder developed by engineers and engineering students at the University of St. Thomas in St. Paul, the peanut sheller from the Full Belly Project, and the maize crusher from the Agriculture Research Council of South Africa (

Vertical axis machines enable several persons to crank at the same time using design principles from radial engines. Each person replaces a piston, though the person pushes and also pulls his or her own rod—whether a master or an articulating rod—to help in the job of generating torque to accomplish the needed work.

Post harvest food processing in rural Africa seems still dominated by vertical linear motion—pounding a wooden pestle into a wooden mortar, while most of the world has moved on to rotary motion. It would appear, given the relative abundance and collaborative mindset in African village food preparation, one appropriate technology route forward might be to put greater emphasis on small, vertical axis rotary motion machines.

These machines would employ radial engine principles, wherein several pistons are replaced by three to five people engaged in coordinated linear motion—pushing and pulling—but in a horizontal plane. Master and articulating rods for these radial “engines” could, perhaps, be fabricated locally from the wooden pestles they replace.

There are many ways forward with appropriate technology, just as there are many communities of people, many countries, many environments, many needs. The challenge is to keep design criteria in mind when designing for the users. And to always ensure technology designed will be appropriate for their use.