A bus that runs on formic acid | Hacker News Reader

A bus that runs on formic acid

bbc.com

It has an energy density of 1.77 kWh/L and 1.22 g/cm^3, or 1.45 kWh/kg (http://pubs.acs.org/doi/pdf/10.1021/acsenergylett.6b00574). Compare to gasoline at 12.9 kWh/kg (https://en.wikipedia.org/wiki/Energy_density) and li-ion batteries at 0.1-0.3 kWh/kg (https://en.wikipedia.org/wiki/Lithium-ion_battery).

Honestly nothing can beat gasoline up front.

but here we have something that can match li-ion, but that can be refueled as easily as one refuel a gasoline car. Can be stored for long periods on simple containers. And can be produced from atmospheric gasses.

Looks like it's up to about 10x better than li-ion.

Gah, sorry for the brainfart.

Interesting implications for fixed location energy storage. A palette sized tote of water is about 1000 liters, so 1.45MWh/tote. That is roughly a month of US household electrical consumption.

I'm not finding numbers for efficiency of creating the formic acid, and for the catalyst I find notes that the good ones use expensive elements. So I guess when my new lead acid battery bank wears out in 8 years I won't be installing a formic acid system.

Formic acid contains 53 g/L of hydrogen[1]. The Mirai has a 500 km range, using 5 kg of hydrogen[2]. So you would need 95 L (116 kg) of formic acid to get the same range. The actual tanks on the Mirai (87.5 kg, 122 L) are physically larger, but weigh less.

[1] http://large.stanford.edu/courses/2013/ph240/yoo1/

[2] https://en.wikipedia.org/wiki/Toyota_Mirai#Fuel_economy_and_...

Seems like a decent tradeoff. The extra weight would reduce the range, but the gained tank space might make that ok?

I imagine the formic acid also has safety advantages: it's stored at room pressure rather than under pressure, so the tank can't explode, and if there's a leak, it won't vapourise.

On the other hand, it's reasonably nasty stuff, although far from Things I Won't Work With levels of nasty:

https://www.cdc.gov/niosh/ipcsneng/neng0485.html

Also, imagine how many ants you'd have to milk to get just one liter of this stuff!

cough

Hope that cough isn't because you tried to find out and now have pulmonary edema from inhaling the fumes.

Very interesting work. What they developed essentially is a way to store renewable energy.

They take CO2, H2O and electricity from renewable sources to create their fuel. The secret here is the catalyst they developed. The fuel is liquid, thus stored easily.

In order to use it they use a reverse chemical process which creates H2 and CO2. The H2 burns with oxygen (and releases part of the stored energy) to produce H2O and thus they end with the elements they used in the first step.

If in its currrent capacitiy can be used for transportation, it probably can be used for many other things as well.

So the catalyst isn't renewable. How much of that do they need? What are the costs, and energy put into that?

> So the catalyst isn't renewable

Is it not? Not being used up is kind of the definition of "catalyst" though, so while it might need maintenance/recycling (due to mechanical changes, or contamination) it probably can be reused after processing.

I didn't make any statement about the catalyst's attributes but I indeed mistakenly attributed its creation to this team.

The catalyst was developed in EPFL and is renewable. I believe this is the one: https://www.nature.com/articles/ncomms5017

"The tailpipe emissions are only CO2 and water," explains Mr van Cappellen. "No other harmful gases like nitric oxides, soot or sulphuric oxides are emitted."

The same is true of the complete combustion of petrol and other hydrocarbon fuels. I remember the same was said of propane when it became the popular alternative fuel several decades ago.

It sounds like the application of this fuel is meant to be alongside carbon capture, so there's no net emissions at all.

I think the core of the idea is that formic acid is easier to synthesize than other hydrocarbon fuels, while being easier to handle than pure hydrogen. It's also split into hydrogen and CO2 in this process, not burned, which could happen cleaner than practical combustion?

The idea here is that the acid is made from elements already floating around in nature, and thus the exhaust do not introduce more than the production initially removed. This unlike petrochemicals because the exhaust gasses is in addition to what is already out there.

The CO2 is also an input; it originally comes from the environment, so this is net-zero emissions in the same way that biofuels are. From the article:

   Although the bus emits CO2, Team Fast argues that the original CO2 used to create the hydrozine is 
   taken from existing sources, such as air or exhaust fumes, so that no additional CO2 is produced
    - it's a closed carbon cycle in the jargon.

True if combustion occurs in pure oxygen. Combustion of petrol fuels in an automobile tends to produce nitrogen oxides from the nitrogen in the atmosphere. I assume fuel cell reactions don't do this.

>The fuel, which the team has dubbed hydrozine (not to be confused with hydrazine)

/facepalm

Why would you cozy up your name next to a horribly carcinogenic rocket fuel? This a nomenclature foot-gun.

Seems reminiscent of the hyper/hypo issue in medical jargon. Not something you want to screw up.

Making up a name "Hydrozine" instead of just calling it "formic acid" makes this quite confusing. Maybe it works for marketing.

Yeah, that was a little too subtle. I had to check it a few times before I realized they weren't talking about hydrazine (toxic, probably carcinogenic if it doesn't kill you right away, and definitely not something you want putting around on public roads).

If I were their marketing, I'd pick something else, fast. Something a good hamming-distance away from anything requiring special suits for handling, and that doesn't include steps in release protocols like "evacuate nearby towns".

Mixing "hydrozine" with hydrazine gives a hydrazone.

"bug juice" seems like a better name.

Formic acid freezes at 8°C. Hooray.

Interesting. What's the catalyst made of? I remember they used to require platinum and other expensive elements.

Also, using CO2 from factories is nice but eventually we need to get rid of them altogether. I imagine taking CO2 from the atmosphere at its natural concentration should be incredibly inefficient.

Doesn't this solve the battery storage issue for renewables? I mean you can produce lakes of this stuff and 'burn it' when needed.

Strategically could be worth shipping/piping from a high sun/wind/geothermal area.

The key is that it is a way to store renewable energy easily and cheaply.

I can't imagine the horrible smell... just one angry ant is enough to make me ill. An engine full of the stuff would be a nightmare.

No mention of handling issues around liters of irritating acid...getting stung by ants is bad enough

How strong an acid is this?

If it's not extreme then handling shouldn't be much worse than petroleum fuels which are mildly irritating, toxic, and flammable. We have built infrastructure to let people handle those products (rather) safely.

Have you been stung by an ant or stinging nettle? It's not fun.

Sure, but I can imagine ants that injected gasoline or vinegar (for example) would be unpleasant too - while having those substances on your skin is fine.

Formic acid is a relatively weak acid (if I can read wikipedia correctly), much more like acetic acid than sulphuric acid.

Yep, from what I can tell it's about 10x stronger than vinegar at the same concentration, but about 1/7 the strength of citric acid (lemon juice). It's often use in wart treatments so it's not too bad in small concentrations.

However, it's flammable and can cause acid burns in the concentrations they're talking about in the article.

It's a weak acid similar to acetic acid (vinegar contains 9% acetic acid) but weaker.

https://en.m.wikipedia.org/wiki/Formic_acid#Safety

On the other hand, it's 100%, not 9%. I'd say it's about as nasty as anything you're likely to come across at home (bleach, white spirit, etc), but small potatoes as an industrial chemical:

https://www.cdc.gov/niosh/ipcsneng/neng0485.html

Hmm. I got it all wrong comparing the acidity figures. The Wikipedia article states "Formic acid is about 10x stronger than acetic acid.".

Isn't formic acid a main ingredient in wasp or bee venom?

Formic comes from the Latin word for ant.

It's what ants spray at an intruder when upset.

It's also hallucinogenic.

Good stuff.

> It's also hallucinogenic.

That's one way to get people to ride the bus more often ... :-)

"The driver said my downtown stop was the one with all the candy-canes, but all I see are walruses with briefcases."

Highly recommend Ender's Game and the many sequels, where the alien insect species is known as the Formics.

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