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botsapper 09-21-2016 02:08 PM

#Two to Go
Current hydrogen production methods require non-renewable fossil fuels but Toyota found a plentiful source, poop.
A sewage processing plant in Fukuoka, Japan in a primary treatment, physically separates the 'solids' in settling basins. In the secondary treatment they treat the sludge with micro-organism/biodigesters using anaerobic digestion to breakdown the biological matter creating biogas. Instead of burning it off, the Fukuoka plant filters out the CO2 and catalyses hydrogen gas formation to be used by Toyota Mirai fuel cell vehicles.
Additional benefits from the human waste process; prevents algal blooms, red tide, and dead zones, conserves nutrients (especially nitrogen compounds) and reduces anthropozoonotic pathogens. Actually an old technology, India uses this bio-sewage treatment to produce biogas, an important part of their energy infrastructure.

Toyota's project in Fukuoka will use human waste to create the biogas needed to power their Mirai hydrogen fuel cell car

Stubby79 09-21-2016 03:28 PM

Had to read the article. The hydrogen is coming from water being added to the mix. Ain't no catalyst going to change one element to another!

Which makes me wonder...if it's coming from something being added to the mix, why bother with the mix in the first place?

RedDevil 09-21-2016 03:29 PM

Ehm... from that article:

The process is pretty simple. At a wastewater treatment plant ... sewage is separated into liquid and solid waste. ... microorganisms are added to the mix. These microorganisms break down the solid waste, creating biogas, about 60% methane and 40% carbon dioxide. Then, workers filter out the CO₂ and add water vapor, which creates hydrogen and more CO₂. They extract the CO₂ again, and voila: pure hydrogen.
Mixing methane and water vapour does not produce hydrogen and CO₂ just like that.
If it were that simple we would already be doing that from straight methane.

I bet the Mirai can use methane as a fuel instead of hydrogen. It would be easy enough - methane is less volatile anyway.
Burning it produces some CO₂, of course, but that would otherwise be released in some way too (like if the H₂ scrubbing did work after all) so it should not matter.

I guess Toyota prefers profiling the Mirai as a hydrogen car rather than an methane car. Which is a pity, as straight methane seems more easily providable than hydrogen.

If we accept methane cars and infrastructure the sky is the limit.
If we persist in using hydrogen (and having the capability to use that, including the special tanks etc) the cost will stay prohibitive.
The Toyota Mirai will remain a mirage and the Honda Clarity a rarity.

jamesqf 09-22-2016 11:45 PM


Originally Posted by RedDevil (Post 523247)
I bet the Mirai can use methane as a fuel instead of hydrogen. It would be easy enough - methane is less volatile anyway.

Which of course raises the question of why they don't just use the methane directly, either in fuel cells or natural gas power plants, rather than converting it to one of the most difficult to store & transport elements? Or react it with a bit more carbon, and produce liquid hyudrocarbons?


Burning it produces some CO₂, of course...
But the CO2 would be released anyway, as the sewage decomposes. The problem is not CO2 per se, because that's just part of the normal carbon cycle on which life depends. It's the addition of fossil CO2 that's the problem.

RedDevil 09-23-2016 03:28 AM

There is a thing called steam methane reforming which produces hydrogen:

There are basically 2 ways of doing this:
Steam (Methane) Reforming which uses methane and steam and a lot of heat, and
Autothermal Reforming that adds oxygen, effectively burning part of the methane to produce the required heat.
SMR can be more efficient that ATR, but only in large scale plants.
It is no rosy cheeks tech.

But Toyota just served reheated bull in a new format, see their 2015 release:
Toyota Explains Exactly How Mirai Fuel Cell Car Can Run On BullSh*t!

Which the EV community debunked:
Toyota Mirai fueled by bullsh!t ad total BS

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