In India, every power outlet is governed by its own switch, and those switches are monitored with a careful eye. I was sternly instructed to turn switches off when I was done with them. If I vacated the bedroom without turning off the switch to the overhead light and the ceiling fan, I would get an immediate reprimand from the family cook. When I visited the aunt’s place across the hall and wanted to use the Internet, I had to start up the computer from dead because it had been switched to “Off” at the wall. No standby appliances vampiring electricity here.

This thrift extended even to the apartment gym, where I arrived with water bottle and towel to find the lights off and every cardio machine dark. To work out on the treadmill I switched its outlet on. When I finished I turned it off, as the sign next to the the machine instructed.

To contend with Chennai’s broiling heat, it isn’t as simple as pushing a thermostat button and pumping an entire big room or building full of cold air. Instead I turned on the A/C unit by the treadmill, and when I was done with the treadmill I switched it off. Then I headed to the dumbbell area and activated its resident A/C unit. None of this felt like any sort of imposition.

Somehow Indians have an instinct toward electricity conservation. Maybe it has to do with the country’s roots: Like many Indians, Anjali’s family is just three generations removed from its ancestral village, where one tended to the rice paddies and the bullock. Life was too hard to let anything go to waste.

Whatever the reason, it was refreshing to take a break from America’s thoughtless, wasteful use of power and to know that, halfway around the world, a billion people have found another way.

How India Puts Itself on a Power Diet is a post from: The Ferris Files

Thermoacoustic Engine. The thermoacoustic engine is a technology that has some serious explaining to do. Many sources of natural energy, such as wind or solar or wave power, are fairly easy to get your mind around. But what the heck makes a thermoacoustic engine run?  The short answer is waste heat, which our industrialized society (and even rural society) has plenty of.

Efficient Cookstoves: Waste heat in a poor, off-grid community comes from the cookstove that combusts wood, dung, or some other burnable to cook food for the family. There are millions such cookstoves in the world and most are ripe for serious design improvements. A few simple changes to a stove’s design can slash the amount of feed wood, keep children safer, eliminate soot in the hut (and wipe black carbon from the skies), and cook food faster.

Solar Refrigerator: Another head-scratcher. How is it possible that a refrigerator could get cold because it is out in the blazing sun? Students at Michigan State University figured out how, and are doing so with materials readily available in Guatemala.

Windbelt: The windbelt fills a void our wind portfolio: It produces small doses of power very close to where it’s needed and can operate in winds that are strong or weak. It does this without lopping off the heads for birds, and requires almost no maintenance.

Treadle Pump: When I saw my first video of the treadle pump, my first reaction was, “Of course!” A farmer who can’t afford diesel and isn’t on the electric grid could save hours every day with the help of this cardio machine made from steel or wood.  An hour or more on the treadle pump can replace hours of labor for farmers in Asia, Africa and Latin America, and at a price they can actually handle.

New Ideas in Rural-Size Energy is a post from: The Ferris Files

Photo by Nick Hobgood

If there’s one thing I learned from reporting this month’s Innovate column, it’s this: The biggest beneficiaries of renewable energy will be the poor, rural farmers of the Third World.  The billions of people who live off the grid in Africa, Asia and Latin America will use smaller and humbler technology than we will in the urban, modernized world. Yet its impact will be far greater.

In Europe, the U.S. and parts of Asia, the focus is on building massive solar installations and windfarms that are powerful enough to replace the carbon-spewing sources we already have, like coal-fired power plants, and that can feeds into the robust electricity grid we already own. Our power sources will change, but for the most part we’ll use those electrons for the same activities we do now. The developing world doesn’t resemble this equation at all. Entire regions have no money for projects this big, and no grid to speak of.

Traveling in rural Africa and Mexico, I’ve seen that the defining characteristic of the small backwater village is its lack of electricity. During the day a tinny radio powered by batteries plays at the grocery kiosk. At night the town shuts down, except in the orbit of the few businesses fortunate enough to have a kerosene lantern. A person is living a lifestyle of the rich and famous if he has a TV running off an old car battery. Though cellphones have become common, they’re difficult to charge and can’t provide nearly the connection to the world that an Internet-enabled laptop can.

For this month’s column, I looked at small yet cutting-edge technologies that could change this scenario. Some are novel ways of producing a few modest watts, enough to load a battery that can light a bulb in the hut at night so Mom or Dad can prepare for tomorrow’s harvest, and the kids can study.  Just these few hours of productive time could spark dramatic changes in health, prosperity and educational attainment. As we learn to make power generators that are small, powerful and cheap, it will be possible for even poor villagers to have access to computers and the Internet. And with that, the village might achieve just enough prosperity and convenience that its residents don’t have to flee to the urban slums to make a living.

In my next post, I’ll explore what these technologies might look like.

This Issue’s “Innovate” Column: Energy for the Developing World is a post from: The Ferris Files

I’m excited about this assignment because it lets me roam about at the beginning of our new era, the Renewables Age, and bend down to pick up the shiniest objects. The field is suffused with a sense of possibility. Seems like every week I hear about a new idea for capturing electricity from an orphan source, or harnessing it in a  superior way. Trapping windpower (PDF) from passing subway trains! Making ice at night to cool buildings by day! Deriving fuel from our own sludge, or from carbon dioxide in the air, or from a glass of water!

Innovate is eye candy for techno-enviro geeks. The centerpiece is a large graphic about a technology, or a suite of technologies, that could solve one of our myriad energy conundrums. The trick for me as a journalist is to find the inventions and trends, and then work with a graphic artist to turn complex ideas into an illustration that can be understood at a glance. Finally, I do a profile of one of the pioneers of that exciting new field.

Someday a decade or more from now, when the Renewable Age is fully upon us, we will do what humans do: We will glance back at promising technologies that sputtered out and chuckle in a knowing way; we will admire the victorious inventors, who will live in mansions and run businesses that have become boring and predictable; we will drive cars with a battery the size of a tea bag and a tank filled with gas made from old coffee grounds, but we will complain that it doesn’t have enough cupholders.

This is not the column for that day. This is the column for this day, when we don’t yet know who the winners or losers are, but can see with growing certainty that something fantastic is just around the corner.

My New Column Starts This Month In Sierra Magazine is a post from: The Ferris Files

There are many reasons, but one has to do with maintenance. A solar panel requires almost none: Install it and leave it alone for years. But a wind turbine is a finicky device with many moving parts, and the servicing makes a small turbine hardly worth the expense. I’ve always wondered whether we would ever learn to harvest wind on a smaller, simpler scale. Turns out we can.

The WindBelt was dreamed up by 28-year-old Bay Area inventor Shawn Frayne during a trip to Haiti as he tried to figure out how to deliver power to the energy-starved developing world. Frayne dispensed of the turbine altogether and explored a different aerodynamic phenomenon known as aeroelastic flutter. The marquee example of the principle is the so-funny-it’s-tragic collapse of the Tacoma Narrows bridge, aka “Galloping Gertie”:

Frayne asked himself: What if I induce those same forces, but on a small scale, and use that flutter to move small magnets and produce electricity? The result is wind power on a modest, rooftop scale. This video demonstrates it best:

The company Frayne created to improve and market the technology, Humdinger Energy, is marketing three sizes of Windbelts to serve different needs. Deploy a regiment of Windbelts in a windy area, and they could supply power equivalent to a large wind turbine, but without the noise or the rotors that kill birds.

The Wind Turbine’s Tiny Cousin is a post from: The Ferris Files

A solution has appeared in the form of the treadle pump, a sort of Stairmaster that pumps water. The device takes water-carrying work away from a polluting machine and puts in the hands (or rather under the feet) of the farmer.

Invented by in 1981 by an aid worker, the treadle pump has sold more than 1.4 million units in Bangladesh, according to IDE (PDF file), with many more in use in India and Africa. They range in price from $20 to $100 and may be made of metal or bamboo.

Twenty hours a week on the water treadmill will irrigate a quarter-hectare field – enough to empower a farmer to grow an extra crop cycle each year, to make each crop more robust, and bring home more money for the family.

The Treadle Pump: An Exercise in Productivity is a post from: The Ferris Files

The solar refrigerator. The purple box at bottom is the cooler, the solar panel and activated carbon bed are on top, and the condenser is at center. Image courtesy Michigan State University.

The very idea of a solar refrigerator is a contradiction: Use the hot sun to keep things cold. How could such an oxymoron possibly work?

It would seem impossible if a team of undergraduates from Michigan State University hadn’t already built a prototype, out of cheap materials, in Guatemala.

The potential uses for a solar refrigerator are endless, from air-conditioning buildings to keeping a case of Sam Adams cold on a hot Fourth of July day. But its most immediate purpose is keeping vaccines viable for medical clinics in areas of Asia, Africa and Latin America that aren’t served by an electrical grid. The perfection of a solar fridge could significantly reduce disease in the rural developing world.

The Michigan State undergraduates who built one of the world's first solar fridges.

To get a solar fridge going, one needs a material that remains freezing cold even at room temperature. The Michigan State team chose ethanol, though methanol works too. Vacuum-sealed in pipes to low pressure, ethanol’s molecules slow and its temperature drops to about 35˚ F. The ethanol resides in the “evaporator,” a coil of copper tubes just inside the cooler. (Why is it called an “evaporator”? You’ll see in a minute).

By the end of the night, the cooler is 39˚ F, cold enough to keep its contents chilly even through a tropical day. As the ethanol has worked its cooling magic, it’s been doing something else: boiling at a furious rate. Ethanol in low pressure boils and turns into gas, just like that foggy liquid nitrogen you might have played with in science class.

Pipes direct that gaseous ethanol to the top of the box, where it drifts through a sandbox-like bed of powder at the top of the machine. The sand is activated carbon, aka charcoal. (John Barrie guesses that even charcoal from burnt coconut shells could serve this function.) The activated carbon traps the ethanol and holds it tight.

A solar refrigerator in action in Guatemala.

Then the hot sun rises. Sun rays strike the solar panel atop the machine. Directly beneath, the bed of activated carbon begins to heat up, and as it does, the ethanol vaporizes again. Only this time, the expanding gas raises the pressure in the pipes so the ethanol can turn back into liquid form. The ethanol gas fills the condenser, the matrix of pipes in the center of the drawing. The condenser has a large surface area that dissipates the sun’s heat and cools the ethanol back into liquid. As the day wears on, the ethanol trickles back down into the evaporator. By the time night falls, all the ethanol is pooled down in the evaporator, and the cycle can start again.

What if it’s cloudy? MSU professor Craig Somerton, who led the solar-fridge team, says that a fire set under the unit would keep it working.

While the sun-powered chiller is still a long way from reality, its promise is substantial. A well-calibrated solar refrigerator could go for years without maintenance, and most importantly, without ever being plugged into an electrical outlet. Click here to learn more and to find design drawings of the solar refrigerator.

A Refrigerator Powered by the Sun is a post from: The Ferris Files

A Lorena stove in action.

In parts of India they’re called chulhas, in Malawi chitetezo mbaula, in Central America the Lorena, and in East Africa the jiko. The names and designs vary, but the principle is the same:  a low-cost, efficient stove that replaces the open fire.

It’s hard to overstate the difference a better stove can make. In many parts of the world women cook over open fires in unventilated huts, filling the living space with smoke that stings the eyes and creates respiratory problems. Children burn themselves on the embers. An open fire requires lots of wood or other burnables, which means stripping the countryside in order to burn it.

An efficient cookstove requires a fraction of the wood, since it burns only exactly what is needed and sends heat directly to the pot. A flue routes the smoke outside, and the air receives less soot and carbon dioxide.

The building material is anything from clay to metal to concrete, and requires an exacting attention to design. To learn how it’s done, read this PDF.

Toward a Better Cookstove is a post from: The Ferris Files

In short: The thermoacoustic engine uses heat to create sound, and sound to create electricity.

How’s that again? For the statement above to make sense, one has to understand the intimate relationship between sound and heat.

Imagine an impatient driver honking as you amble across the street. As the purple-faced motorist presses his horn, your innocent ears perceive the honk as a sound wave. What is a sound wave? Though we perceive it as sound, in reality it’s a wave of pressure. The crest of the wave compresses air molecules as it travels, while the trough of the wave is a little decompressed. That pressure wave enters your ear and strikes the tympanic membrane like a drumstick on a drum, making you turn and glance at the driver.

Now here’s where the heat comes in. The high and low-pressure parts of a sound wave actually have different temperatures, like the difference in mood between the angry driver and your cool self. The high-pressure part is hotter and the low pressure part is cooler. It’s this gap between hot and cold that makes a thermoacoustic engine work.

A typical thermoacoustic engine is a cylinder with a heat source warming up its middle. (Any of several heat sources will work: flame, an engine’s  waste heat, or solar energy.) As the middle gets hot, the ends stay cool. Observe the flame at mid-cylinder in this video:

Pressure waves of heat and cold begin to bounce back and forth between the center and the ends. If the pipe is the right length and if the heat source is adequate, these chaotic waves fall into a steady rhythm known as a standing wave. Crucial to the engine is the “stack,” a perforated stopper that stands between the hot and cold parts like a cork with tiny holes in it. The stack serves two purposes. It’s an accelerator, causing air molecules to speed up as they move through the small openings. It also serves as insulator, to keep the hot side hot and the cool side cool.

At one end of the cylinder, the pressure waves create motion. Many thermoacoustic engines, also known as lamina flow engines, use the pressure waves to move a piston. That’s the design in this video:

Barrie’s design instead employs a magnet moving on a spring (like a drumstick on a drum). The magnet moves next to a copper coil, and the magnetic field between them creates electricity.

But wait – where does the sound come in? The sound is part and parcel of those pressure waves, though it doesn’t serve a useful purpose. In the same way that heat is a waste product of an internal-combustion engine, sound is a waste product of the thermoacoustic engine. Controlling that sound is part of the design challenge.

An engine could issue a whine of 135 to 180 decibels, which is louder than cozying up to a jackhammer. But if encased in a steel tube, it presents as a low hum, like the sound of a refrigerator running.

The Thermoacoustic Engine, Explained is a post from: The Ferris Files