[Carbon dioxide emissions from cars. Photo Credit: Pixabay]

Japanese automaker Mazda unveiled a prototype exhaust system in the last week of October that it claims can capture up to 20% of the CO2 emissions from its internal combustion engine vehicles' tailpipes.

While the 20% capture rate is modest compared with stationary carbon-capture systems, it is notable for an onboard device small enough to fit within a passenger car’s exhaust system.

Mazda CFO Jeff Guyton told reporters at the Japan Mobility Show in Tokyo that the prototype mobile carbon capture technology's testing was very promising.

A crystalline zeolite substrate in the new exhaust system collects CO2, which is subsequently kept in a small onboard tank. 

When drivers stop to refuel, they can swap out a special CO2 filter cartridge in the exhaust for a fresh one, similar to exchanging a gas cylinder.

The used cartridge, which contains the captured CO2, would then be taken away and the CO2 inside it could be processed and turned into a raw material for other products, such as fuels, chemicals, or materials in different industries.

Mazda’s strategy focuses on practical, modest-scale innovations that aim for incremental and tangible improvements.

Later this year, Mazda plans to publicly test the technology in an endurance racing car, gathering data under full load before determining whether it might be scaled for road use.

Although Mazda hasn't announced when or if the technology will go into production, the idea suggests a novel approach to reduce vehicle emissions, one that might prolong the life of internal combustion engines even as political support for electric vehicles (EVs) grows.

The carbon-capture prototype is part of Mazda's broader "Multi-Solution Strategy," which also includes biofuel tests, rotary-range extenders, and plug-in hybrids. 

Other major automakers, such as Citroen and Ford, have developed plans to phase out European sales of new internal combustion engine (ICE) cars by 2030 in favor of electrically powered vehicles. 

Mazda's ambition to develop technology to capture exhaust emissions points to a different approach to other manufacturers' decarbonization goals. 

The EU law that will forbid the sale of new ICE vehicles starting in 2035 is the driving force behind this.

If other methods to make ICE cars carbon-neutral are devised, some automakers expect that the EU would loosen the regulations to permit their continued sale. 

At the Japan Mobility Show, Mazda CEO Masahiro Moro introduced a new plug-in hybrid that would be equipped with their exhaust pipe carbon capture system. 

He informed reporters that the vehicle is in line with the company's strategy for  “2035 and beyond."  

Mazda is also a supporter of synthetic fuels or biofuels in addition to carbon capture technology, and it was the first automaker to join the "eFuel Alliance" in 2021. 

So far, Mazda has been able to produce 1 L of fuel from an 11,000 L culture tank in two weeks. 

The company is presently developing its own carbon neutral fuel, which is made by refining oil collected from microalgae. 

According to Mazda, the oil-depleted microalgae could be utilized as organic fertilizer or as a source of protein in food production.

The new vehicle with carbon capture technology would be carbon negative when powered by synthetic fuels, meaning that the more it is driven, the less CO2 is released into the atmosphere.

However,  air quality advocates have expressed concern regarding synthetic fuels. 

Tests conducted in 2021 on behalf of the European Federation for Transport and Environment revealed that engines running on synthetic fuels emitted comparable amounts of nitrous oxides and more ammonia and carbon monoxide than those running on regular gasoline.