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 emissions, diesel vehicles use filters that catch exhaust particles and other contaminants. The filters can cost thousands of dollars to replace, however, because they're made with precious metals.

Looking to make replacement 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 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.

We found that old diesel cars are a significant contributor to CO emissions, and we wanted to do something about that," team leader Tasmiah Afrin said in an email interview.

Our groundbreaking activated-carbon-based filter represents a significant leap forward in environmental and economic efficiency," the electrical engineering student added. The filters can rapidly and effectively capture carbon-based gases from vehicle emissions, contributing to immediate improvements in air quality and reduced carbon emissions."

A carbon-based particulate filter

Diesel engines produce more polluting particulate matter than gas 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 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 for carbon capture in vehicle exhaust systems," she says. Not only are they cost-efficient, but they also boast an impressive absorption speed. This means the filters can rapidly and effectively capture carbon-based greenhouse gases from vehicle emissions, contribute to immediate improvements in air quality and reduce carbon emissions."

She says she believes the team's diesel particulate filter would cost less than a current filter, which because of its precious-metal content can cost a few thousand U.S. dollars.

A system for replacing filters

The filters are just one part of the team's vision for reducing auto emissions. The students' pitch also included a transport-management system they would build called CarGreenTech and its accompanying smartphone app. Using the app, owners of older diesel cars could purchase the replacement filter or arrange for one to be installed. Another option would be for CarGreenTech to buy the older car, outfit it with a new filter, and resell the vehicle. The goal is to extend the life of these older vehicles, Afrin says.

CarGreenTech is a platform to make existing vehicles more climate-positive-which provides an all-in-one solution," Afrin says. It captures carbon from the diesel engine exhaust by utilizing layered active carbon filters, upcycling older car parts through a car buying/selling/upgrading business-to-business and business-to-consumer solution." A motivator for student-led startups

The team also includes Ishman Tasnim, Fahmida Sultana Naznin, and Nusrat Subah Shakhawat. Tasnim is studying industrial and production engineering, and Naznin is pursuing a degree in computer science and engineering. Shakhawat recently graduated from the university with a degree in electrical engineering.

The team's mentor was IEEE Member Toufiqur Rahman Shuvo, a lecturer at the university.

The students are all members of the IEEE student branch at the Bangladesh University of Engineering and Technology.

IEEE WIE has a great impact on giving motivation to student startups like us," Afrin says. Entering the IEEE WIE pitch competition was one of our best decisions. We were greatly motivated by the judges and getting an award for our work."

The IEEE WIE competition was sponsored by the IEEE Life Members Committee and Smart WTI, a provider of IoT/artificial water management solutions. The company supports initiatives that aim to contribute to a greener, more sustainable future.