Featured Nissan takes a different approach to fuel cells: Ethanol

I think the SOFC is used by Bloom Energy and other stationary fuel cells. They have a high operating temperature; 500C might be the coolest running out there. Unless Nissan has gotten one to run cooler, expect a big warm up penalty, and maybe a bigger battery pack.
Solid oxide fuel cell - Wikipedia, the free encyclopedia

Using a separate reformer means less work in converting the car to using a different fuel. Technically, there is no reason why this system couldn't use gasoline, diesel, or natural gas. Ethanol is just easier to get as a low carbon emission fuel at this point.

At this point, ethanol will pollute more than electrolysis hydrogen simply because of the trucks and tractors being used to harvest and transport the feedstock to the ethanol plant. The flip side is that little hydrogen is made commercially by electrolysis; most is coming from a fossil fuel of some sort.

A liquid fuel will always be better economically than a gaseous fuel. They are just easier to handle and transport. This also makes FCEVs easier to design. The pressure that hydrogen is stored at on a FCEV means the tanks are heavy. In order to not be any heavier, the engineers are stuck using tanks that are a sphere or cylinder; this makes the tanks bulky, and limits how they can be packaged. With a liquid fuel, they can go back to using the tanks they were using for gasoline and diesel cars. So it saves weight and space. Some of those savings could be taken by the different fuel cell type, possible larger battery, and the reformer, but those are all components that are easier to pack into a car body with little compromises than a hydrogen tank.

With diesel, gasoline, and maybe butanol, the US could use the existing petroleum fuel infrastructure and stations. So no extra cost beyond normal growth and maintenance. Ethanol will require the pipelines, tanks, and pumps to be upgraded. All the gaskets and seals likely can't handle high levels of ethanol. The ethanol will clean out the system, and decades of gunk stuck to pipe walls is now moving through out the system. Then the ethanol itself will corrode the steel.

So major upgrades are needed, but it will be cheaper than building hydrogen infrastructure.

 

Interesting. A couple of thoughts:

Where does the energy to heat the ethanol in the reformer come from?

This concept, " Compared to vehicles that require hydrogen as fuel, the so-called "e-Bio SOFC" system can approach carbon neutrality, Nissan said.

That's because the carbon dioxide emitted during the process of reforming the ethanol into hydrogen has previously been removed from the air by the plants used to produce ethanol—whether corn, sugar cane, or other feedstocks." sounds little like hoccus-poccus accountability to me.

 

I like it but would prefer to see anhydrous ammonia or methanol. Regardless, the technology of reformulating the hydrogen carrier in the car from something easier to transport makes a lot of sense. That is it 110 proof makes it an excellent base for other things.

Bob Wilson

 

Who knew Willy Wonka was so far ahead of his time with the Wonkamobile?

 

I suspect it would quite a technology breakthru to have the necessary reliability to make small scale H2 from ethanol. if that worked well, there could be many other uses besides cars.

Also the ethanol would still have the problem of low energy density compared to gaso, especially as they seem to talking about further diluting with water. So they'd probably need like min. 20 gal tank to equal range of a Mirai.

Not sure if they need the extra water chemically or just trying to make ethanol more cheaply (easier to make 95% ethanol/water than 100% ethanol). Recently we had a post mentioning use of 95% ethanol/water in some Europe E10 gaso fuels. This is possible since about 1% water is soluble in E10 gaso blends.

 

From the battery and the fuel itself on start up, which is why I think the pack might be larger than what PEM FCEVs use. After that, the heat from the fuel cell could be used.

The basics are pretty straight forward. The hocus pocus comes in on how to account for the fuel for the tractors harvesting the plants, the electricity used at the plant, etc.

We know Toyota's plan for hydrogen in Japan involves using Australian coal. The ethanol has better odds of a lower carbon footprint.

I think Nissan is going with ethanol for that green cred on carbon emissions. Methanol has the same counter point as hydrogen; most is made from natural gas or petroleum. Ammonia has the same with natural gas.

On top of that, anhydrous ammonia requires pressure vessels for fuel tanks. Not to the extreme pressures that a hydrogen tank needs to withstand, but enough to put limits on packaging them in a car. With a SOFC, it might not need a reformer though. Small molecules, like methane, could be broken down right in the fuel cell.

Volvo already had a fuel cell with reformer run on diesel for over 10k hours. The home power fuel cells also use a reformer with natural gas. The issue isn't one of reliability, but more of miniaturizing the reformer to the point that it can be packed into a car without taking up too much space.

Putting a 20 gallon tank into a car the size of the Mirai is a breeze, and it wouldn't require losing the middle rear seat. The HHR, a size class down, had a nearly 16 gallon tank in it.

If the reformer is using steam, then having it mixed with the ethanol is the simplest approach. In which case, the water is also supplying hydrogen to the fuel cell, so the aqueous ethanol is providing some more energy than the ethanol in it alone.

 

I tend to rank hydrogen carriers by the molecular weight and liquid density at room temperatures. Liquid ammonia is right up there and was X-15 fuel. As for handling, many of these hydrogen carriers are already carried about in common tanking.

Since I spent a summer working in an ice plant that used ammonia refrigerant and relatives who use it in their fields, I am fairly sanguine about it. Ammonia can be carried in water at room temperature although the density makes it not so good.

Bob Wilson

 

OK right I forgot about the water needed for steam reforming, however, the FCV is making loads of water so we are converting water to water need recycle stream I guess.

 

Long term thinking, if this won out and there was massive need for more ethanol, we flat wouldn't have the water. Water is going to become the premium natural resource of the future.

I just got back from a trip to the Big Bend and saw the end result of both the US and Mexico sucking the Rio Grande/Rio Bravo dry just for current needs. It's barely a foot deep in most spots and the flow is so slow you can no longer raft down it; a river no longer grand nor brave and no longer reaches the gulf of Mexico.

 

Ammonia is only liquid when chilled or kept under pressure; it boils at -33C. For storage on a car, it will need to be in a pressure vessel. Granted, not one nearly as strong for hydrogen or even CNG, but one that still has a weight and space cost over a tank for liquid fuels.

Anhydrous ammonia can be used to fuel ICE cars, too. Which can be a plus in expanding the infrastructure while FCEVs still are expensive. But it is nearly all made from natural gas or coal, and apparently the amount we make now uses 1% of global man-made power.
Ammonia - Wikipedia, the free encyclopedia

Looks like I'll get to play with it in the lab this afternoon.

For fertilizer, the ground needs to be moist. In bone dry soil, most of it will just float off. Apparently, AA has potential as a lifting gas in airships(in the Wiki). It will also dissolve in ethanol and methanol.

That is probably how the Nissan release claims 100% ethanol is possible in the system. Any water the alcohol picks up along the way is likely enough to replenish any lost from the system.

There are two other methods to steam reforming, Partial oxidation - Wikipedia, the free encyclopedia and Carbon dioxide reforming - Wikipedia, the free encyclopedia. The CO2 reforming is a new field, but the partial oxidation one has been around for a while. Sounds like it is what is going on in a wood gas system.

Perhaps the bottled water companies have the correct price for it.

There are reasons to use another fuel over ethanol, but even renewable diesel will consume some water in production, and likely anything we come up with to replace petroleum. It is just a convenant source for hydrogen, or the lifeforms we use need it.

 

coal?


.

 

probable outputs are carbon dioxide and water vapor. With the CO2 poison the fuel cell? Who knows, probably do c2h5oh + 3h2o (from tank either with ethanol or separate) + heat -> 2CO2(waste)+ 6H2, Then 6H2 + 3O2 (from air) ->6H2O + electricity + heat.

You could recycle the Water, and use half of it for the catylitic reformation of ethanol, but nissan is propossing the water either goes in the same tank as the ethanol or a separate tank depending on how you build stations. My guess is you could build a reformer that works with methanol or ethanol gasoline blends, then have a separate water tank.

Now key savings here are Nissan is proposing ethanol which is currently in the US is $1.60/gallon, you need about 1.4 gallons to be the equivallent of a kg of H2, meaning you could carry the equivallent of 5kg of H2 in a 16 gallon tank filled with an ethanol/water mix, or in a 7.2 gallon ethanol tank and a 8.8 gallon water tank. Current price of ethanol is about 2.30 for a GGE ($1.60/gallon). I'm sure you would need to mark it up to $3 to add filtered water and dispense, but this is much less expensive than hydrogen/kg.

lol. Answer is above. Battery will provide initial power to drive the reformer. After that waste heat from the fuel cell will drive the reaction. If the car has a small h2 storage tank, it could be filled at end of the drive while cooling the SOFC.

Note SOFC may be less expensive than PEM, but they run hotter. Maybe ethanol or methanol reformer get rid of the waste heat.

But here is the billion dollar question.
Say you put a 9kwh battery in each, how much greener would a enthanol fuel cell phev compare to a prius prime? Mercedes, Nissan's fuel cell partner is using a 9 kwh battery in their next gen fcv. Toyota a 8.8kwh battery in their next phev. A phev can easily be modified for ethanol burning, and I'm guessing if they export it to brazil there will be an ethanol version.

If they went the same distance on the battery, and the gasoline hybrid got 50 mpge on a GGE of ethanol but could use gasoline to any ethanol blend, and the fcv got 60 mpge on a gge of ethanol but needed it to be pure and mixed with water, I think most would just choose the flex fuel phev and be done with it.