Can vehicle exhuast pipe emissions serve a positive purpose? An Indian researcher working in the United States has developed a system that captures exhaust pipe emissions and transforms them into ink. The long-term objective is to reduce the rate of pollution-related illness.

Anirudh Sharma is a researcher from Bangalore, a city in southern India. He works at the Massachusetts Institute of Technology (MIT), a prestigious university in the United States.

Sharma in his lab.

"Our system prevents the carbon emitted from tailpipes from ending up in the atmosphere and in peoples' lungs"

I had the idea while traveling in India a few years ago, when I was still a grad student at MIT. Some cities were really quite polluted from cars and chimney smoke. In the street, when people would wipe their faces with a handkerchief, it would turn brown or black. So I thought it would be interesting to make ink out of this.

Actually, in the past, ink was made from soot [Editor's note: Soot is rich in carbon], notably in China. And it's precisely soot that cars emit. So in 2013, I started doing some research at MIT.

Video shot by Sharma two years ago, at the start of his research..

We developed a device that can be attached to a vehicle's tailpipe, so as to filter the soot it emits, or more specifically the carbon. This system – which works by an electromechanical process – doesn't interfere with the operation of the vehicle, of course.

Next, we recover the soot to purify it, which is to say we remove the heavy metals and carcinogens it contains. Then we mix it with different vegetable oils. This gives us a sort of oil-based paint, similar to other paints that already exist.

The device, attached to a car's exhaust pipe.

The device, attached to a crane's exhaust pipe.


"We've already made 150 litres of ink"

We first tested our system in the lab, to be sure the ink wasn't toxic.

Then, this year, we started to use it on a larger scale, after getting Graviky Lab [Editor's note: An MIT-linked lab, cofounded in Bangalore by Sharma] involved in the process. Over two months, we collected carbon emitted by trucks, cars and chimneys in Bangalore, and by fishing boats and forklifts in Hong Kong. We used the device we had developed, except with the chimneys, where we collected the soot manually. This allowed us to produce 150 litres of ink. That's what you can get from a car running on diesel for 2,500 hours, or about 104 days.

The device, attached to the exhaust pipe of a boat in Hong Kong

We've made pens and spray cans with the ink, and we've filled ink bottles with it. To fill an ink pen, for instance, you need a diesel car to drive for 30 to 40 minutes. This ink was then used by street artists in Hong Kong.

Spray cans and pens filled with the special ink.

The ink being used by street artists in Hong Kong.

Street art in Hong Kong.

The advantage of this system is that it prevents the carbon emitted from tailpipes from ending up in the atmosphere and thus in peoples' lungs. By cleaning up the environment, we can reduce rates of lung cancer. When it's converted into something useful, pollution can thus be seen as 'black gold.'

Incidentally, when this ink is produced on a larger scale, which is the goal, it should be less expensive for the consumer. Currently, the makers of 'classic' ink cartridges are making incredible margins.

Sharma with his invention.

Lung cancer, pneumonia, bronchitis, asthma...India is the country with the largest number of deaths linked to respiratory illness in the world, with 1.6 million such deaths per year. Indeed, six of the world's ten most-polluted cities are found in India, according to a recent World Health Organization report.