Sustainable Design Update

I have been working this week on a universal LED circuit board. The concept is to create an inexpensive circuit board that can be filled with LEDs and other electronic components in the field. Background: Over 2.1 billion people live without access to electricity. Another billion people live with unreliable access to power. The great majority of these people illuminate their homes and businesses with fuel-based kerosene lamps. Kerosene lamps are inefficient and unhealthy, causing fires, burns and lung disease. Kerosene lamps produce more greenhouse gasses per unit of illumination than any other common light source. Moreover kerosene lighting is expensive, more expensive for a unit of light than what we pay in the developed world. A small percentage of the people who live without electricity have access to light using photovoltaic panels, batteries and fluorescent lights provided by non-profits. This combination of technologies (photovoltaic panels + batteries + fluorescent lights) has proven to be economically feasible based on published data about a program in rural Bangladesh underwritten by the Grameen Shakti Foundation.

A new development in lighting technology is LED lighting. Some LEDs are more efficient than fluorescent lights and much more efficient than incandescent lights. It takes less power to provide a given amount of light using LEDs, and thus LEDs require smaller photovoltaic panels and smaller batteries to make a complete lighting system. In squatter cities where there is often “bootleg” power LED lights can be powered by recycled cell phone chargers to provide high quality high efficiency lighting. Based on our research and prototype lights, the cost of an LED + recycled charger light is between $2.40 and $4.60 depending on the light output desired. This inexpensive LED light may qualify for carbon trading credits in some applications. Right now, individual high output, high efficiency LEDs are relatively cheap, but getting an LED on a circuit board so you can use it with a photovoltaic system is expensive. We are designing a universal LED circuit board that will work with a wide variety of power supplies. Once we are satisfied that what we have is both very efficient and very inexpensive, then we will publish the design and make it available, licensed through Creative Commons – Developing Nations.

Progress:

This last week I have been working with Jose Ordonez at the Xela Teco workshop in

Guatemala. We have been prototyping the universal LED circuit board described above. We successfully created several boards plus a quick proto board to identify a problem with some inexpensive resistors. I will update SDU on this project when I have had time to crunch some numbers. Posting from the road in

jsbarrie

We arrived in Guatemala City last Tuesday night.  The flight was uneventful.  We stayed a couple of nights in Guatemala City and then took the ¨chicken bus¨ to Lake Atitlan.  Mass public transit is easy here if you don´t mind sitting 3 to a seat on what was once a US school bus.

Everyone uses mass transit.  In Guatemala City I marveled at the crowded evening busses taking people home from the business district.  Now, if they could clean up the emissions a bit Guatemala would have a very sustainable transport system.

In San Pedro and other towns on Lake Atitlan, it is easy to catch a Tuk Tuk, which is a small 3 wheeled taxi that takes people up the steep and narrow streets.  The most popular type of Tuk Tuk here has a 4 stroke engine which is much cleaner than the 2 stroke counterpart.  I will post photos when I get a chance to upload from my camera.

There are some signs of eco-tourism here, but Guatemala is decades behind Costa Rica in terms of eco lodging, recycling and jungle / forest preserves. 

This is just a short post to catch up with everyone.  I have to get back to errands here before we head out tomorrow to Quetzaltenango (aka Xela, which is pronounced Shay-La).  I have a small project working on a universal LED circuit board design.  I will post photos of that work here as it progresses.

Posting from the road,

John Barrie

Hi All-

I will be out of the States for several weeks.  I will be spending most of this time working on a project to replace kerosene lamps with LED and photovoltaic lights in Guatemala.  If all goes well, the project will also cover the “Squatter City” parts of Mexico City.

I will be posting from the road.  I will not be taking my laptop so I will catch up with you all via internet cafes.

I’m taking my trusty digital Nikon and I’ll send along photos of all things Sustainable as I see them in Guatemala.

Cheers

John Barrie

Afrigadget is one of my favorite websites. Its all about how Africans are making their own technology. If you haven’t yet checked out Afrigadget, you can catch up by watching this nicely made video.

Afrigadget at TED Global

The Piaggio Avanti is a turboprop business jet. The radical design has propellers facing backwards and a small wing in the front. The Avanti is 40% more fuel efficient than the latest crop of business jets. Better yet, its faster too!

Piaggio designed the Avanti after the first oil embargo when it seemed fuel prices would dictate the future of aviation.

Oven on MSN website, and soon on Ecogeek is a new proposed commercial jet, the EcoJet which is a schematic design for a jet that has 50% fewer emissions than the best jets of today.

The Ecojet has much in common with the Avanti, including rear facing engines and propellers instead of turbofans.

Dr. Orest Symko

A few weeks ago I reported here on a thermoacoustic stove that also provides cooling and electric power. The device that makes the thermoacoutsti stove work is a closed pipe that when heated creates high volume sound waves. Now a Prof. at the University of Utah has taken that idea on a slightly different tangent. Prof. Orest Symko uses the thermoacoustic effect to create pressure waves in a tube that vibrates a piezoelectric material that converts the sound energy directly into electricity.

“We are converting waste heat to electricity in an efficient, simple way by using sound,” said Symko in a Science Daily interview, “It is a new source of renewable energy from waste heat.”

Piezo electric devices create electricity when subject to mechanical stress. Most piexo electric materials are crystals.

Here are summaries of the studies by Symko’s doctoral students:

– Student Bonnie McLaughlin showed it was possible to double the efficiency of converting heat into sound by optimizing the geometry and insulation of the acoustic resonator and by injecting heat directly into the hot heat exchanger.

She built cylindrical devices 1.5 inches long and a half-inch wide, and worked to improve how much heat was converted to sound rather than escaping. As little as a 90-degree Fahrenheit temperature difference between hot and cold heat exchangers produced sound. Some devices produced sound at 135 decibels — as loud as a jackhammer.

– Student Nick Webb showed that by pressurizing the air in a similar-sized resonator, it was able to produce more sound, and thus more electricity.

He also showed that by increasing air pressure, a smaller temperature difference between heat exchangers is needed for heat to begin converting into sound. That makes it practical to use the acoustic devices to cool laptop computers and other electronics that emit relatively small amounts of waste heat, Symko says.

Student Brenna Gillman learned how to get the devices — mounted together to form an array — to work together.

Gillman used various metals to build supports to hold five of the devices at once. She found the devices could be synchronized if a support was made of a less dense metal such as aluminum.

– Student Ivan Rodriguez used a different approach in building an acoustic device to convert heat to electricity. Instead of a cylinder, he built a resonator from a quarter-inch-diameter hollow steel tube bent to form a ring about 1.3 inches across.

In cylinder-shaped resonators, sound waves bounce against the ends of the cylinder. But when heat is applied to Rodriguez’s ring-shaped resonator, sound waves keep circling through the device with nothing to reflect them.

– Student Myra Flitcroft designed a cylinder-shaped heat engine one-third the size of the other devices. It is less than half as wide as a penny, producing a much higher pitch than the other resonators. When heated, the device generated sound at 120 decibels — the level produced by a siren or a rock concert.

“It’s an extremely small thermoacoustic device — one of the smallest built — and it opens the way for producing them in an array,” Symko says.

Note: This story has been adapted from a news release issued by University of Utah.