Carbon neutral petrol car.

[Buckman]

Don't rush out to buy an EV just yet. It seems that Mazda may have developed a carbon neutral petrol car? I wonder when it will become mainstream within the next 4 years? See https://www.autocar.co.uk/car-news/...-rotary-electric-vision-‘carbon-negative’-ice

 

[Tobes]

Looks like marketing BS to me. A rotary combustion engine combined with a plug in hybrid power train. Nothing new to see here. The "carbon negative" part is some verbiage around an algae derived synthetic fuel that is low carbon, and a CO2 capture device on the exhaust system. That's smoke and mirrors. My personal prediction, its as likely to succeed as a hydrogen based combustion engine in a passenger vehicle.

 

[RogerL]

Looks like marketing BS to me. A rotary combustion engine combined with a plug in hybrid power train. Nothing new to see here. The "carbon negative" part is some verbiage around an algae derived synthetic fuel that is low carbon, and a CO2 capture device on the exhaust system. That's smoke and mirrors. My personal prediction, its as likely to succeed as a hydrogen based combustion engine in a passenger vehicle.

Carbon capture in the exhaust isn't smoke and mirrors, it's real using a mobile form of the same processes used in industry

 

[otherclive]

Carbon capture in the exhaust isn't smoke and mirrors, it's real using a mobile form of the same processes used in industry

I have had experience of the old ICI process where carbon dioxide and hydrogen are catalysed to produce methanol which in some circumstances could be burnt, or used in other chemical processes. Also with molecular adsorption to remove and concentrate the Carbon dioxide. But I cannot envisage either being suitable for automotive use. What process is the Mazda using?

 

[Buckman]

Looks like marketing BS to me. A rotary combustion engine combined with a plug in hybrid power train. Nothing new to see here. The "carbon negative" part is some verbiage around an algae derived synthetic fuel that is low carbon, and a CO2 capture device on the exhaust system. That's smoke and mirrors. My personal prediction, its as likely to succeed as a hydrogen based combustion engine in a passenger vehicle.

Wow so you have no interest in something that may be more environmentally friendly than any EV and require rare earths? I am very surprised.

 

[Tobes]

Wow so you have no interest in something that may be more environmentally friendly than any EV and require rare earths? I am very surprised.

That's a complete misrepresentation of my interest. I am completely interested in engineering solutions that lower the impact of the machine (of whatever type) on the environment. But I am also massively skeptical of anything that claims to be more environmentally friendly than an electric drive train - especially if it involves combustion. Some questions to back up my skeptical stance.
1) If the rotary engine and the as-yet-to-be-manufactured-low-carbon-fuel are so clean, why is the vehicle being touted as a PHEV? Isn't the PHEV bit just expensive redundant hardware if the rotary engine is "110% cleaner". Also - PHEVs have a battery and require "rare earths" (which are not rare).
2) The article says the new fuel will emit up to 90% less carbon than a conventional engine. And then will save an additional 20% at the tail pipe. 20% of the remaining 10% is 92%, not 110%. You can't save 110% of the carbon dioxide produced by combustion. Thats what is referred to a "marketing maths" in my line of work.
3) If the carbon capture process is so effective - run it on atmospheric carbon, at industrial scale, to reduce the impact of other high CO2 emitting processes, and run the car on CO2-free clean energy (using its PHEV side) from zero carbon sources (wind, solar, hydro, tidal) etc.
4) CO2 free fuel is not in-and-of-itself a good thing. We know Hydrogen _can_ be a CO2 free fuel (for combustion, or fuel cell). But it comes at a cost of efficiency and hence price. It's very expensive and inefficient. What is the energy cost to manufacture the microalgae fuel, and what is its actual cost? If it's more than 12year old single malt scotch per litre, I will stick with free electricity from the roof, and buy the scotch to drink.

Carbon capture in the exhaust isn't smoke and mirrors, it's real using a mobile form of the same processes used in industry

I agree - carbon capture is a real thing. But it's hard enough to do at even medium scale in a fixed environment, never mind in a small form factor mobile format in a car.

Don't misunderstand my skepticism for denial or dismissal. I would love to be proved wrong. But here my "if it's too good to be true, it's probably BS" sensor is alarming.

 

[Buckman]

Remember people said all the same things about EVs and although myths are plentiful some of those negative things are probably still correct. However my post was about carbon neutral cars and not EVs so lets not go down that route. At the moment, none of us has enough insight to comment whether it is a misrepresentation, good or bad, but in my opinion it could be a step in the right direction and save thousands of jobs.

 

[Tobes]

A quick search found this. A 2020 press release from Mazda discussing their support for Microalgae bio-fuel.

The 90% reduction in CO2 emissions is a "net" figure as the fuel is grown from atmospheric CO2.

In combustion mode the car will emit "normal" amounts of CO2 (the fuel is carbon chain molecule based), which will be partially attenuated by the carbon capture device.

Net net - The car being discussed is a regular combustion engine car (all be it a rotary engine, not piston) with a plug in hybrid component, that is tuned to run on microalgae fuel directly rather than petrol or diesel.

The "news" here is - IMHO - the fuel, not the car, and that news is 5 years old.

Again - I would very much like to see the reality of the microalgae fuel. How much space does it take to grow (it uses photosynthesis so will need large areas)? Is the energy collection denser than solar panels? Does it need direct or ambient light (could it be co-deployed with solar farms as a space sharing solution)? How much energy does it need to collect and process (what is the net gain)?

I have lots of questions, and can find few answers.

 

[Buckman]

Just in case you missed it, it is now 2025 and not 2020. Carry on asking your questions as that is your choice. I am just happy that we may at long last have a truly environmentally friendly car.

 

[Tobes]

Just in case you missed it, it is now 2025 and not 2020. Carry on asking your questions as that is your choice. I am just happy that we may at long last have a truly environmentally friendly car.

That's my point, in the last 5 years I have not seen any major announcements about this fuel. IMHO the car is a red herring. The fuel is the prize, and if it becomes available it will allow you to continue running your existing car with with the same fuelling mode you have today, but with reduced carbon output. But it may cost you 5 times as much per litre - we don't know.

 

[Hutch]

If you Google Hydrogen passenger cars, there have been over 56k made mostly Hyundai and Toyota,
Also if you research Hydrogen Fuel cell cars, As well as the two manufacturers I have mentioned, BMW, Honda and Mercedes are also developing.

BMW development

Reciprocating engines, are dying away, there is just too much friction involved. Just a case of time and fuel, and emissions.

 

[Tobes]

There are some hydrogen vehicles, and they have been around for a long time, but have never taken off. Toyota have the Mirai, Hyundai the Nexo. Looking at howmanyleft.co.uk you can see how many are registered with the DVLA over time. These are total numbers of that car type on the road that year.




Just for comparison, The BYD dolphin, a Chinese full EV that was introduced to the UK market in 2023.


And the Tesla model 3

And just to make the point - Here is the MG B GT v8. There are more of these on the road in 2021 than there are hydrogen cars.

 

[ProfJohnL]

I agree with Hutch in post #11. Internal combustion engines all have so many inherent losses, that its an abhorrent use of rare fuel when you throw 60 to 70% of the energy it produces away. That aspect will not change regardless of where the fuel comes from.

And the other issues so rarely understood, is that burning any fuel (Including pure hydrogen) under great pressure as in ICE's alway produces a range of pollutants which do affect the environment, and Once the fuel has been burnt, its gone.

I'm not suggesting that EV's are free of all issues, but EV objectively produce fewer pollutants than ICE vehicle over their whole life, and whilst zero pollution would be ideal, a reduction is better than continuing to use a technology when better and less polluting is available.

ICE vehicle also use rare earths and other socio-political compromised materials.