A Bamboo Carbon Filter for Diesels Could Reduce Emissions

Diesel cars are a popular choice for those looking to buy a used vehicle in Asia, Europe, and elsewhere. After all, diesel cars cost less to maintain, burn less fuel, and have a longer engine life. Although the pollutant emissions of a diesel engine are less than those of a gasoline one, it still emits carcinogens, nitrous oxides, and soot. Older models don’t even have the emission-control features that newer ones do.

To reduce pollutant emissions, modern diesel engines use catalytic converters, similar to those of gasoline engines. In addition, they use filters to catch exhaust particles.

In a project to make replacement particulate filters more environmentally friendly and affordable, a team of engineering students from the Bangladesh University of Engineering and Technology, in Dhaka, designed a carbon-based version with bamboo. The Green Warriors idea won the US $300 prize for best impact in the IEEE Women in Engineering Climate Tech Big Idea Pitch competition. The contest’s goal is to encourage female engineering students and researchers to become more entrepreneurial as a way to boost the number of technical startups led by women.

“Our groundbreaking activated-carbon-based filter represents a significant leap forward in environmental and economic efficiency,” team leader Tasmiah Afrin an electrical engineering student, said in an email interview. The filters contribute to immediate improvements in air quality, she added.

A carbon-based particulate filter

Diesel engines produce more polluting particulate matter than gasoline engines. Because the particles are so small, they can pass easily through a catalytic converter, which is designed to reduce a vehicle’s toxic emissions. Diesel particulate filters therefore are installed in the exhaust system, generally at the exit of the catalytic converter. The most popular type of catalytic converter forces the exhaust through a ceramic honeycomb structure coated with a thin layer containing a precious metal such as platinum, palladium, or rhodium.

“Our project,” Afrin says, “is based on a modified air filter for incoming air into the catalytic converter.”

The Green Warriors’ prototype filter is made from bamboo and uses carbon granules to further reduce emissions.

Activated carbon granules in an absorption chamber and metallic mesh form the filters, Afrin says. Gases pass through either double or multiple chambers. Their prototype is more aerodynamic and lightweight than existing designs used for carbon filters, Afrin says.

“These filters offer a remarkable 5 to 7 percent cost efficiency improvement compared to existing filters, making them a more cost-effective solution,” she says.

An IEEE Fellow who specializes in catalytic converters contacted by The Institute found the idea intriguing but questioned whether the bamboo-based filters would survive the standard process used today to clean the particulate filters. In this process, called regeneration, the units are heated to…