Toyota Mirai (Hydrogen Fuel Cell vehicle) - Page 1
Forum section: electronics / general

author: Stonent
author_rank: Super Contributor
timestamp: October 27, 2015, 03:29:36 am
content: What do you think? I hadn't heard much about fuel celled vehicles in a while. Seems to me that getting the hydrogen from the methane / landfill gas would cost energy and you could have just burned it in a normal engine, but intriguing none the less.

author: IanB
author_rank: Super Contributor
timestamp: October 27, 2015, 03:33:43 am
content: Hydrogen vehicles seem to be something that Japan (or the Japanese government) is pushing. There is a lot of research going on into hydrogen production, storage and delivery.

author: PChi
author_rank: Frequent Contributor
timestamp: October 27, 2015, 07:27:53 pm
content: It's exciting times, early days but the market is starting to develop.I believe that using a fuel cell is considerably more efficient than buring hydrogen in a normal engine which is important because storing the fuel requires heavy pressurised tanks.Toyota are importing 12 Mirai FCVs into the UK this year and they are all sold. There is money to be made if anyone can produce hydrogen. There is already a hydrogen filling station in Swindon that claims to be solar powered.

author: tom66
author_rank: Super Contributor
timestamp: October 27, 2015, 10:05:07 pm
content: Hydrogen is a bad idea.First, it's only an energy storage mechanism, ultimately it all gets converted into electricity to run an electric motor. Whilst hydrogen is abundant, it is not common in the Earth atmosphere. So forget about extracting it from that. There are many ways to get hydrogen, but the most common is steam reforming of natural gas, which produces CO2 as a byproduct. An alternative is to use electrolysis using electricity to extract hydrogen from water, and this sounds great until you realise the efficiency is less than 30% in the most ideal case. Why not just use the electricity directly? When you take into account the efficiency of a fuel cell you're looking at a round trip efficiency in the 10-15% ballpark, so you'd be using six times more electricity than you would charging an electric vehicle directly.So we either run hydrogen cars from fossil fuels...or we run them really, really inefficiently from electricity.Not to mention the cheapest hydrogen fuel cell car with a 300 mile range is the Mirai, which costs over $150,000 to make, primarily due to the fuel cell cost. Toyota makes a $100,000 loss on every single one they ship. Its fuel cell puts out about 100kW, which is around half the continuous power, and a quarter the peak power, of the 70kWh battery pack in the base, $75,000 Tesla (which Tesla makes a profit on.) And fuel cell cost scales linearly with output power (rather than batteries which scale with capacity.) So they aren't going to be fast, and whilst most people don't care, you're going to have to please the petrolheads too, which means you have to offer a vehicle that's nice to drive too.And not to mention infrastructure! We'd have to build hundreds of thousands of hydrogen stations because unlike an EV you can't charge it at home! Public chargers are nice for EVs, but they aren't required if you've got a sufficiently sized battery, whereas without hydrogen stations a hydrogen car just won't work.

author: helius
author_rank: Super Contributor
timestamp: October 27, 2015, 10:20:38 pm
content: QuoteFalse dichotomy... as you wrote earlier, there are many ways to get hydrogen. Some chemical processes make it as a byproduct. And it can be produced using biofuel processes.https://en.wikipedia.org/wiki/Fermentative_hydrogen_productionThe human gut releases hydrogen under certain disease conditions:https://en.wikipedia.org/wiki/Small_intestinal_bacterial_overgrowthThe reason for the "Mr. Fusion" reference in the video is that hydrogen fuel can be made from waste. And fuel cell technology is advancing, so a $100,000 fuel cell (must be Pt-group based at that price) is not the last word in the conversion of H2to energy. Fuel cells made from ceramic are poised to take over at much lower cost, and without using strategic materials which is still a concern for lithium batteries.

author: IanB
author_rank: Super Contributor
timestamp: October 27, 2015, 11:01:36 pm
content: Quote from: tom66 on October 27, 2015, 10:05:07 pmActually, steam reforming of natural gas is not such a terrible thing.If you burn natural gas directly, you have two equations happening:carbon + oxygen => CO2 + energyhydrogen + oxygen => H2O + energyYou use the energy at source and both combustion products get released into the atmosphere.On the other hand, if you reform natural gas with steam you have:methane + steam + oxygen => CO2 + hydrogenLater on:hydrogen + oxygen => H2O + energyInstead of using the combustion energy at source it is instead used to make hydrogen. You capture the CO2 (don't release it) and save the hydrogen as a clean burning secondary fuel.So the advantage is that you still get most of the energy from the natural gas, only you have a way of capturing the carbon at source and producing hydrogen as a product instead of heat.

author: macrop
author_rank: Newbie
timestamp: October 28, 2015, 04:34:44 am
content: If anyone is interested in the production of the car - below is the video. Personally I'm not a huge fan of this car but nonetheless the video is still great and shows the complexity of the vehicle.

author: tom66
author_rank: Super Contributor
timestamp: October 28, 2015, 09:50:29 pm
content: I do think hydrogen has one really ideal application and that is long-distance transport replacing diesel trucks. It fits well, because a purely electric truck would need a ludicrously sized battery pack, and there isn't a strong requirement for infrastructure as the route can be planned in advance to use specific hydrogen stations. And cost and performance (power) isn't as critical as a passenger car, a 300kW fuel cell could probably do the job with an electric motor providing the low end torque that's typically required to get such a vehicle moving.I'm not a fan for personal vehicles because the most economical way to get hydrogen will be through steam reforming of natural gas which doesn't solve the issues with fossil fuels that conventionally powered cars have. At least electric vehicles can be run off renewable sources. Algae and bacteria can be tamed into producing hydrogen but from what I've heard the production rates are poor so the costs will be very high, even higher than electrolysis. Not to mention the respiration of such organisms will still be producing CO2, the issue with CO2 primarily being releasing it at too great of a rate such that the ecology we have cannot absorb it effectively.I saw a Nissan e-NV200 van today, which is based off the Leaf powertrain. It was being used by a local courier company. For inner city work that's great. It was so quiet, I almost missed it trying to cross the road. (I'm sure a legal requirement for a noise generator is going to come about soon, if only for the blind.)

author: miguelvp
author_rank: Super Contributor
timestamp: October 28, 2015, 10:45:12 pm
content: Aluminum (or Aluminium as some call) reacts with water at relatively low temperatures (300C I believe) and produces Hydrogen on demand, to avoid oxidation researchers use gallium.The reaction is as follows, mix water and aluminum and get hydrogen and alumina:2Al + 3H2O --> 3H2 + Al2O3Jerry Woodall did discover (by accident) how gallium helped maintain the reaction:http://www.purdue.edu/uns/x/2007a/070515WoodallHydrogen.htmlBut Woodall had some problems with the DOE because the DOE rejected to give them fundingWoodall's version:http://www.nbcnews.com/id/18700750/ns/us_news-environment/t/clean-energy-claim-aluminum-your-car-tank/#.VjFGx_mrSUkDOE reply:http://www.nbcnews.com/id/18829531/ns/us_news-environment/t/energy-dept-hydrogen-claim-has-drawback/#.VjFHbvmrSUkBut the DOE is a bit short sighted because you could collect the spent byproduct Alumina while filling in fresh aluminum pellets, then use solar energy at the pumping station to convert it back to aluminum. Yet, the DOE is right on the amount of energy required to extract the oxide in alumina to convert it back into aluminum requiring around 50MJ/Kg on top of having to replace the carbon anodes.In any event, it's not yet economical and it does produce CO and CO2 (on the conversion from alumina to aluminum) so I don't know how green it would be. But it's an interesting concept.