City College of New York - Engineers Without Borders to Provide Chimneys for Smoke-free Kitchens.
By Joanna Bonfiglio (Second-degree Mechanical Engineering student at CCNY)
It’s lunchtime in La Nueva Suiza, a Honduran mountain town some 50 minutes by car from any major roadways—not because of a great distance, but due to the dilapidated infrastructure in the CIA-ranked second-poorest Central-American country. There in a villager’s kitchen, the student members and faculty advisor from the City College of New York chapter of Engineers Without Borders (CCNY EWB) are taking a break from the construction of their water tank and distribution system project.
Not surprisingly, in an area where people do not have access to clean drinking water, homes are also not equipped with electricity. Still, it being midday in a country along the equator the kitchens should have plenty of light—except they don’t; as you enter your eyes have to adjust to the dimness from the soot-covered walls and ceiling that absorb sunlight like a proverbial black hole and to the haze from lingering smoke. It’s not the engineering problem the volunteer group signed on to help with during their January 2007 trip; they thought they would tackle water issues as a club theme. But it is clear that this town is also battling in-home air quality concerns because of chimney-less wood burning stoves with completely open burning chambers, which allow clouds of grey smoke to escape and blacken the interiors.
Like the smoke, the memory lingered. “I can recall in a couple of homes getting up from lunch to get some fresh air when the wood was a bit wet and would smoke up the room,” says Martin Nolan, CCNY ’09, a second-degree student in mechanical engineering, now serving as the current project manager for the Honduras ventures.
Plancha and exposed burning chamber.
Fast-forward to 2008, the water tank and piping have been up and running successfully for almost two years now and the group is planning to address the town’s ventilation problem on an upcoming January 2009 trip.
The tradition of this village is to construct stoves out of adobe mud brick that have exposed burning chambers where wood is inserted and a metal plate, called a plancha, sits above the fire. Many of these homes are not equipped with chimneys and the temperature for proper wood combustion of 1400 degrees Fahrenheit is never achieved, meaning that carbon in the form of soot is produced but is not being vented out of the living space. This essentially lowers the level of air quality. In fact, according to Amy Smith, a mechanical engineer from MIT, the number one cause of death in children under five is inhaling smoke from indoor cooking fires. During a presentation for fuel alternatives available on TED.com, the Technology, Entertainment and Design Web site, she said that such air particulates claim the lives of more than two million children in the developing world each year, in extreme cases.
In everyday cases the escaping heat and smoke make it difficult to be in the kitchen area and a health survey conducted by CCNY EWB reported 18 percent of the approximately 400 residents mentioning eye problems and 46 percent complaining of a heavy cough.
“For the villagers, they make the fire in the morning and it runs all day,” says Nolan. “So they get that smoke in their eyes and lungs every time they walk into the kitchen and as it is the main room in the house, it has to be 50 percent or more of the time they are in the house.” The impact on young lives is especially significant as many households are comprised of eight or 10 children.
Other not-for-profits had offered to help La Nueva Suiza retrofit their stoves; one group came through with some materials but the others did not return. Ultimately, only a handful of homes were converted and experienced limited success. Although the single-walled stacks are less than two years old, the metal is already disintegrating due to the quality of the materials used and the fact that they were constructed without drains, so when the shaft cools and contracts, condensation forms on the inside and has no where to be released, effectively rusting the chimney from the inside out.
To combat the ventilation problem the student chapter is trying to make certain design improvements and learn from the other groups’ mistakes. This includes implementing National Fire Protection Association code by utilizing double-walled chimneys and also applying the principles behind the Onil stove, (http://www.onilstove.com), a popular Third World cooking model that recommends better burning chamber insulation to achieve greater temperatures and ultimately increase combustion so that both the wood and its smoke burn as fuel. In general the stove, called horneas, are between 3-and-4 ft. tall and typically 2-by-4 ft. in length and width. Some are flush with the wall while others either jut out in a more perpendicular position or are completely freestanding in the middle of the room. Using concentric cylinders for the chimneys will help manage the heat for those freestanding stoves, making them less hot to the touch and safer for children to be around. The crux of this work pivots on classical mechanical engineering topics such as heat transfer and offers what CCNY EWB calls “raw engineering” problems for student volunteers.
And there are problems.
The project faces two main obstacles, the first of which was known about from the club’s multiple trips to the region during their water tank work; mainly, that seven of the 13 homes in need of chimneys have thatched roofs.
“To circumvent the roof, we thought we could send the chimney out the wall,” explains Nolan. “The wall is adobe so no risk there, so we thought. Huge impact, easy solution. Or maybe not.” On closer examination they identified that the walls are reinforced with bamboo beams.
“The NFPA Code requires 18 inches between the chimney and a combustible material,” he continues. “With the outer pipe at 4 inches, we would need a wall section with no wood in a 40 inches circle, over 3-ft. of space. No way. The wood is at 1-ft. spacing.”
This made the decision for the group—the palm roofs have to be replaced with corrugated metal, as is the custom for those that have already made the home improvement.
The second complication took CCNY EWB by surprise when one local man asked if he could just have his roof replaced but did not want a chimney; he said he needed the smoke.
La Nueva Suiza is a predominantly agricultural community with many families supporting themselves by growing beans and corn, the latter of which presents a problem for the chimney project. The thatched roofs have a typical triangular exterior construction and on the interior there is a flat, dropped ceiling made of bamboo and wood beams. In this space between the ceiling and the roof the villagers keep their corn because the smoke that collects keeps insects from attacking their produce and works as a natural pesticide.
Martin discusses the project: the soot on the ceiling is obvious and between the cracks, the stalks of corn are visible.
The solution is supplying families with a small, 6-ft. tall “silo” to keep their corn away from insects and allow their houses to become smoke-free environments.
However, this growing project has significant financial implications. The cost of the chimney pipes are about $65, add a cap to prevent rain from coming in and other odds and ends and it’s still under $100. But replacing the roof alone is roughly $175 or 3,200 Lempiras, the local currency, and the silo is another $25.
This pushes the limits of the school club’s budget, which relies on funding from their college as well as grants and private donations from local Rotary clubs and professional organizations.
Recently, the local parish started offering loans to replace thatched roofs and CCNY EWB hopes that if they work progressively by providing for the homes that already have metal roofs, other villagers will have a strong incentive to take out the loan and the club will still pay for the chimney materials, silo and one-quarter of the roof conversion.
Fundraising will always be a bigger hurdle for the group than any of the engineering obstacles—especially they feel with the current state of the economy.
“But we’ve done well so far as there is a big bang for the buck with a project like ours,” says Nolan. “For a small sum, we do a lot and for a lot of people.” So CCNY EWB remains ever optimistic and will keep with their motto, “improving daily life, one home at a time.”
