PHOTOS COURTESY OF CONAMA
* The project showed a very tangible result and shows if you put regulations in place, this works.
—Orlando Gonzalez, U.S. Environmental Protection Agency
Chile's capital, Santiago, is widely regarded as one of Latin America's most modern cities. Located in the center of the Santiago Basin, it's surrounded by mountains on all sides. But that beautiful view combined with rapid urbanization has led to thermal inversion, a meteorological phenomenon that holds colder air close to the ground beneath a warmer layer, causing high levels of smog and air pollution.
Indeed, Santiago holds the dubious distinction of being a regular on the World Health Organization's list of most polluted cities.
“In 2007, Santiago's PM10 measured 55 percent above the present Chilean air-quality standard,” says Nancy Manríquez Donoso, chemical engineer at the Chilean National Environmental Commission in Santiago. PM10, or particulate matter, refers to solid or liquid particles found in the air. These particles originate from a variety of sources—including dieselburning vehicles.
So if you can't move the mountains …
In 2006, the Chilean National Environmental Commission joined forces with the U.S. Environmental Protection Agency (EPA) for a pilot project developed under a free-trade agreement between the two countries. The goal was to demonstrate how filling vehicle tanks with fuels that have a sulfur level below 50 parts per million (ppm) can improve air quality. As a comparison, most diesel fuels in Chile have a sulfur ppm of 300 versus an average of 15 ppm in the United States. The project would also entail retrofitting vehicles with the technology to boost the cleaner fuel's performance.
The EPA had launched a similar project in Mexico. So members of the Chilean delegation traveled there to learn from the experiences of the project team and talk about how to select the fleet, choose equipment and manage data.
But Chile went in with one big advantage.
“When they did the project in Mexico, it was more challenging because, at the time, Mexico was not producing the cleaner fuel and it had to be purchased and brought in from Texas,” says Orlando Gonzalez, international environmental program specialist at the EPA, Washington, D.C., USA. “In Chile, this project was a little easier because the country already uses the cleaner grade of fuel.”
Funding for the Chilean project was coming from the U.S. government—but it had an expiration date attached.
“After the money had been appropriated, we needed to move it from the United States,” Mr. Gonzalez says. “But it took a long time to go through the bureaucratic process.”
Fortunately, Chile is a member of the United Nations Environment Programme's Partnership for Clean Fuels and Vehicles, and the team was able to move the money through that group.
With funding secured, the next glitch came in identifying the fleet of vehicles to be used. That process sucked up four months of the project's anticipated nine- to 12-month schedule. Initially, the idea was to retrofit a fleet of Coca-Cola trucks to increase the project's visibility. But that plan didn't work out.
“One of the problems we ran into is that sometimes those trucks travel in and out of Santiago limits, so they wouldn't have consistent access to the cleaner fuel,” Mr. Gonzalez says. Putting dirty fuel into the new technology would clog up the filter, negating the benefits of the retrofit.
Plus, a fleet of trucks going about the same tasks wasn't going to provide enough of a sample. “We needed trucks with different work cycles, that were different sizes and models and had unique emission standards,” Ms. Manríquez says.
Finally, the team settled on a mix of 10 commercial and construction trucks that would stay within the city limits. But given the diversity of the fleet, it took longer to determine how to properly outfit each truck with the specific mufflers, converters, filtration systems and other items approved by the EPA. “One of the stipulations with the EPA being involved is the technology must be verified,” says Mr. Gonzalez. “It's a pretty long list.”
80% to 95% Drop in emissions among the test fleet of vehicles using diesel-particle filters
To retrofit a truck, a large canister is installed into the muffler so the emissions coming out are cleaner.
“The temperature in the engine is a key element when dealing with retrofitting a truck,” Mr. Gonzalez says. For the particulates trapped in the canister to regenerate and for the technology to do its job, the engine must be hot—between 500° and 650° Celsius (932° to 1202° Fahrenheit).
With the equipment installed, the retrofitted trucks hit the road, going about business as usual.
During the eight months that followed, the trucks' emissions were constantly tested. The fleet made regular stops at Santiago's Vehicular Certification and Control Center Laboratory for checks of hydrocarbon emissions of nitrogen oxide, carbon monoxide, carbon dioxide and particulate matter.
There, the pilot trucks were tested in simulated driving cycles on a dynamometer, a machine used to measure torque and rotational speed. “These cycles were representative of real Santiago city driving conditions, including weight, speed and acceleration,” Mr. Gonzalez says. “During the cycle, the gas emissions were collected through a tube and funneled to the dilution tunnel where the gases were mixed with air properly filtered to generate a diluted sample. The sample was then tested through different specialized analysis equipment to determine the level of concentration of each pollutant.
” The $150,000 project closed in May 2008—and the success was clear. The trucks in the retrofitted fleet produced 80 percent to 95 percent less emissions than their traditional diesel counterparts. “That's a very tangible result and shows that if you put regulations in place, this works,” Mr. Gonzalez says. And Ms. Manríquez sees even greater potential.
“Chile and Santiago have done a reasonable job in identifying emission-reduction measures,” she says. “However, there is significant potential to reduce emissions [even more]. In the short term, we want to establish a program of widespread use of filters in trucks. And by September 2010, each new diesel truck should also be equipped with diesel-particle filters.” –Libby Ellis
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