The Toyota Mirai (FCV) Thread

Leaks as in manufacturing tolerances or leaks due to the gas escaping through the actual tank itself because hydrogen atoms are so small (whatever the technical term for that is)?

The former we have no doubt the manufacturing and quality control will be first rate, but on the latter the risks are quite real.

 

The latter, which are also known as permeation leaks. I'm interested in understanding how quickly (or slowly) the hydrogen leaks out over an extended period of time just sitting in the tank after a full refill. For example, what is the percentage of hydrogen lost from the tank after a day, week, or month in the Type IV tanks being used by Toyota and others.

I've just started looking for this. So far I've found a bunch of information but it's all written from a safety testing perspective rather than energy loss. I'm still figuring out how to convert the permeability ratings into the kind of number I'm looking for. This is all new to me.

I have no idea whether this is a significant issue or not. I'm just curious. There was some initial industry concern that Type IV tanks, which use plastic liners, were more permeable than the older tanks like the previously used Type III that used metal liners to seal in the hydrogen.

The rates I'm seeing would appear to be far lower than required for safety reasons so this is really just about the implied energy loss from storage. It is therefore analogous to Lithium Ion battery self-discharge

 

Hydrogen is a tiny molecule, and tiny molecules have a tendency to find their way out of things with pressure pushing them. Some of the gas molecules found in air can squeeze their way through tire rubber. It might take gold foil to make a hydrogen tank truly 'leak' proof. The seepage rate is likely low enough to only be a problem with cars sitting for extended periods of time, and the loss rate tiny enough to allow the hydrogen molecules to spread out before reaching any concentration.

The Mirai, and I assume other FCVs, has onboard hydrogen sensors in case of leaks in terms of tank cracks.

Which isn't an issue to the user if they are charging at home.

One of the translated Japanese articles I posted in the other threads on the subject. Perhaps there isn't a change in pump hardware, they already have to pump higher than 70MPa. The communication link may allow the car to tell the pump its tank is rated for a higher pressure.

If I happen to pull into a gasoline station still using an original hand pump with graduated glass vessel, I can still fill my tank up all the way. A 35MPa pump will only fill a 70MPa tank to about half. California is spending millions upgrading older stations and building new 70MPa. If these stations require upgrades to fill to 82MPa, it will cost at least hundred of thousands.

The majority of a car's miles are driven within range of home. The majority of plugin owners charge at home. This is a non-issue for them.

For those willing to do long trips in a BEV, they will plan that trip around the available chargers. Long trips generally require some planning. Most will opt for a PHV, ICEV, or HEV for such trips, and use the countries extensive network of gasoline stations

The cost for chargers to have multiple plugs will just be the cost of the plug; $100 to $200, maybe less. In most cases that will mean one more plug for a non-Supercharger charger built in the future. Which might look like a lot in comparison to the charger's cost itself, but chargers are cheap compared to stations.

Tesla has a Chademo adapter available, and is working on a SAE Combo one.

 

Well that shoots down my idea of a plug-in hydrogen car as a stepping stone technology that could great ease the "fuel anxiety" of limited stations and possibly only requiring refueling on out of town trips. Having continual seepage over possibly months would put a serious dent in efficiency and running costs.

 

Everything I've read says that H2 is much more prone to leaking than CNG through tank materials or fittings. The difference would have almost certainly been due to tank construction and not H2 vs CNG.

 

Like batteries, the EVSE prices have dropped. Here's one for under $400, ClipperCreek | EV Charging Stations | EVSE | Electric Vehicle Charging.

Installation will add to that, but how much depends upon the amount of work an electrician will need to do. Some locals of California are requiring EVSE wiring to be installed to the garage with new construction. The cost for the length of heavy gauge cable and high amp circuit breaker is tiny compared to the cost of the house itself. Installing in existing construction can be pricy. It depends on the house. In 2001, many of the homes we looked at had only 60 amp service. Some still on fuses. One still had post and tube still in place. Newer homes already have 200 amp service, and multiple, logical circuits.

Many houses already have a garage, so that isn't an extra cost. Same if the charger is going somewhere that was going to be a parking space to begin with. Parking already has a real estate cost, and private cars aren't motion 24 hours a day. The parking is already needed, and isn't built for a charger; a charger is added on to the parking.

This is from nearly a year ago, but has a break down of EVSE install costs, How Much Do Public And Home EV Charging Stations Really Cost?.

A curbside, fast DC charger costs $60,000. Will use that for a Supercharger station. Away from curbside reduces costs, and so does multiple chargers installed, but Tesla has to pay for the site. I think they are around 8 chargers per location; that's $480k, but we'll call it $500k. They are open 24hrs, and could potentially give 384 cars a 20 to 30 minute charge during the day.

A hydrogen refueling station costs $1 million at best. The cars can refuel faster, but the number the station can service during the day is limited by how much hydrogen they can make and pressurize in that time. Many seem to be in the 50kg to 100kg range. That's 12 to 25 cars with 4kg fills. A station being supplied liquid hydrogen by truck might be able to service 100 cars.

So, for more money, less cars can be filled. The fast charging does have its limits, but people using gas stations expect to be able to fill up right away 99% of the time. Gas station owners expect to be able to fill hundreds if not over a thousand cars during the day. A hydrogen station can not do that.

Where do you get that it was certified under light truck?

 

The SAE has released free partial previews of some of the technical papers being published in conjunction with the annual SAE World Congress convention in April.

Here are the links to the Mirai-related papers that I thought were interesting:

Toyota Mirai fuel cell stack
Development of Compact and High-Performance Fuel Cell Stack

Toyota Mirai H2 Storage
Development of High-Pressure Hydrogen Storage System for the Toyota “Mirai”

Toyota Mirai DC boost converter
Development of Boost Converter for MIRAI

 

Interesting tid bit

Does that mean they plan to retrofit or replace existing pumps?

 

I personally doubt it. Why should an H2 station take on the added expense of pre-chilling the H2? Maybe this will be done in the future when there is real competition between stations but not in the short term unless H2 providers subsidize stations in order to promote fuel cell vehicles.

 

Type A stations are already doing this, and they are the only ones that can meet CARB's 3 minute refuel time. A Type B one(-20C precooled, IIRC) might be able to do a 3 minute refuel depending upon ambient conditions, but their nominal fill time is around 7 minutes.

There is also a Type C(0c precooled), and a Type D, which may only be ambient. These pumps can have a refuel rate reach 20 minutes or more.

 

I saw a Mirai yesterday on the 91 Freeway right around the 710. I've seen a handful of Toyota Highlander FCV's, Mercedes F-Cell, Hyundai Tuscon FCV, but this was the first time I saw a Toyota Mirai around Los Angeles in the wild.

 

Fueled by Bullsh*t | Presented by Toyota Mirai
Published on Apr 22, 2015

 

+1

At least they owned it. And those trucks carrying the bs could run on bs, and so could the digesters, so we could be so deep in bs, we wouldn't even know how much it costs.

Which was of course the problem in the first place. It wasn't that renewables and waste could not be used to make hydrogen, it is that all those truck miles and digesters and refomers cost a lot of money using today's technology. The cars cost a lot of money to. If only all that bs just piled up exactly where people refueled,it would be much easier. Unfortunately the biomass is not stored conveniently near where fueling stations would have to be to get fcv adopted. That means you need to either transport the biomass, the biogas, or the hydrogen, which using today's technology is expensive. It is much cheaper to burn the biogas where it is generated in an inefficient 35% ocgt then drop the power on the grid. I suppose you could use that to displace some natural gas on the grid, that you could more cheaply use to make the hydrogen.

Techonological breakthroughs are possible to reduce the cost of renewable hydrogen. Hydrogen supporters should look there and not concentrated on baffling people with bs.

 

I had to triple check to make sure the video was actually posted by Toyota USA.

 

i got a little uncomfortable when they shook hands after shoveling the $h!#.

i got a guy that runs his diesel on french fry grease. now here's the thing, when he first started using it, the restaurants were happy to get rid of it. but it became so popular, they started charging. he is not happy about that.
not sure how efficient it is to collect hydrogen with these types of methods for mass fueling.

 

toyota's new fcv marketing slogan: 'we're just driving down the road, running on bull$h!t'. couldn't be more appropriate.

 

I think the Jurassic Park quote "your scientists were so preoccupied with whether or not they could that they didn't stop to think if they should" (video clip linked below) pretty much sums up that video. That's cool that their hydrogen fuel cell vehicle can literally run on bullsh!t, but they never bother to explain whether it's actually feasible to financially support it in the future.

(Video should start playing at 1m40s, but I can't get the link to work correctly in Priuschat.)