rotarygod

Hydrogen is crap for an ICE. Period.

EdwardsB

Cool, well if you ever back in town let us know...there are a few of us in town, maybe all go get some adult beverages.

globi

Thanks for the info - I'm Swiss and German is my mother tongue - so I don't have any translation needs. So maybe its KH then - he often likes to get riled up in his own forum.

Actually to give Hydrogen some credit - I believe mixing Methane with a small amount of Hydrogen has some promises:
http://www.greencarcongress.com/2007...ctio.html#more

This way it is still easier to store more energy in the same tank and you still get the benefit of a quicker and thus more efficient combustion and this with more power too.
Also Methane is cheap and opposed to ethanol can more easily be produced from any biomass (even us humans produce methane). A gas station could actually produce the extra hydrogen needed on site and thus there wouldn't be any hydrogen distribution necessary (only natural gas).


However I still see more advantages in plug in hybrids. Electricity produced with photovoltaics on ones roof is sufficient to power an electric car. What else can one ask for than produce the electricity needed to power ones car one ones roof? And the gas stations for the long-distance trips are already in place.

PoorCollegeKid

I disagree. Hydrogen is good fuel for an ICE. It burns quickly (especially beneficial for Wankel engines), has a high energy density, and doesn't require expensive, power-robbing and efficiency-reducing emissions equipment to be placed in the exhaust of the engine. At the current time, however, it's a crap fuel for an automotive ICE due to the issues with storing it, especially the energy required to compress or liquify it, and the very low displacement specific output of current H2 powered ICE vs a fossil fuel powered ICE of the same design. I think that distinction is very important in this discussion

rotarygod

It makes HALF of the power of gasoline in an ICE. It burns way too fast. How is that not a crap fuel? It IS!

HD-Paschke

M7E0052.pdf is the RX-8 HRE
M5-H2 is the M 5 alias Premacy HRE

PoorCollegeKid

How is fast burning a bad thing? It increases efficiency by making the burning process closer to the isometric ideal. In fact, it seems to me that this feature of H2 is one of the big reasons why Mazda is looking into hydrogen rotary power. Gasoline powered rotaries are put at a great disadvantage compared to a gasoline powered piston engine due to gasoline's "slow" combustion speed. It takes so long for combustion to occur in the rotary that much of the energy of the fuel is spit out the exhaust because it is released too late in the expansion stroke to be extracted as work. With hydrogen, this effect is much less pronounced, since it burns roughly 10 times faster than gasoline.

Hydrogen engines make less power/L, but they can run at a higher efficiency. In a stationary application, this is wonderful because you can simply increase displacement and still put out the same amount of power, all while using less fuel. In automotive applications, you need to find some way to keep the engines from growing in size and weight. Going with a pushrod engine rather than an OHC one would be one way to do this (fitting twice the displacement into an engine of the same size/weight to make up for the 50% lower Power/L), but you're always going to lag behind a gasoline engine of the same design unless you find some way to utilize H2 in a way that gasoline cannot be. Could you use high boost to offset the air displaced by hydrogen? H2 is supposed to be more knock resistant than gasoline, so this could help even the playing field.

Now, I'm not saying that H2 is God's gift to humanity in fuel form. There are many problems that must be overcome, but that's the reason why companies and universities around the world have R&D budgets. People are working on these problems as we speak, and I'm certain that some, if not all, of them can be solved with a little ingenuity. I'm not sure that hydrogen will be the fuel of the future (I don't think anyone could support that assertion at this point), but it seems silly to just dismiss it at these initial stages of its development because it's not as good as the established, well-developed fuel of the present day.

rotarygod

How is fast burning a bad thing? Go do some homework. Do I have to teach everyone everything?

PoorCollegeKid

Everything I've ever read or been told about fuels, especially about H2, states that its high burn speed is a good thing, not a bad one. Since you're the only source of "Fast burn = bad" that I've found, I'm really curious to hear your reasoning behind it. The only drawback I can think of is high pressures due to nearly isometric combustion, but that can be taken care of by simply using beefier parts (like diesel engines do, since they need very high cylinder pressures to make decent power at their low operating speeds). Most discussions about the negative aspects of H2 fuel focus around the production and storage of the stuff, especially with regards to the efficiency penalties associated with each.

Edit:
1.) I meant "only drawback besides emissions," because H2 engines tend to produce a good amount of NOx when under load.

2.) By "read," I mean "read in a scholarly, peer reviewed journal like ASME Journal of Gas Turbines and Power, or International Journal of Hydrogen Energy." I'm not just some punk kid trying to get RG to explain something that should be obvious to anyone with experience. I have some limited experience and I'm just wondering why what RG is saying seemingly runs counter to that.

3.) There are H2 ICE designs that are competitive from a power density standpoint with gasoline engines. A properly designed liquid H2 ICE is a practical way to get power densities around that of a gasoline engine (the cooling effect of LH2 injection is substantial, and cooler air = denser air = more power, estimates of power densities are 100% to 115% that of gasoline engines), as are DI H2 ICEs (DI removes the issue of H2 gas displacing air in the cylinder during the intake stroke, estimates and actual measurements peg this one at 115% of gasoline power/L). These are only two of many H2 ICE designs that are theorized or have already been shown to be competitive with gasoline engines from a power/L standpoint.

sosonic

Hydrogen is crap from a consumer perspective as well.

Look around you. Your T.V. runs on electricity, your computer, your microwave, etc... So why not have that same convenience with your car.

Why can't I just plug my car into ALL THE AVAILABLE OUTLETS, charge it, and be on my way? That is the epitome of convenience.

Battery and hybrid technology have advanced to the point that electric cars are becoming very practical. The ultimate fear of the gasoline mafia is more investment in battery technology.

Unfortunately, despite the efforts of the gasoline mafia to buy patents, threaten inventors, have electric cars destroyed, etc... The technology to make practical electrical cars that can compare with traditional gasoline cars and can compete on price is HERE. Ask Toyota about it, it can be done. Furthermore it can continue to be done better.

By creating a market for electric cars the PRICE will go DOWN for them and the technology will be PUSHED to become MORE ADVANCED.

If California and other states were allowed to mandate low pollution alternate solutions at 10% or so of the market, we will have even more KILLER electric cars on the market as a result of the competition and pushing the technological envelope.

Furthermore allowing all the electric cars to hit the market may allow us to come under our emission level caps and allow some room for muscle cars to stay on the market as gasoline cars are displaced by their electrical alternatives. The way the situation is now, ALL cars are being pushed to reduce emissions, thus making it harder and harder to have muscle cars on the market. Some car companies may stop even making muscle cars. If they do, than what is the point on running cars on gasoline? You are going slow anyway. By the way, there are some really fast under 5 second 0-60 electric cars...

With electric cars and hybrids running around, you can focus on using green methods to generate electricity. Solar, wind, hydro, and even nuclear. By the way, newer designed nuclear power plants can be multiple times safer and you can continue to improve the situation. Countries like Japan, already get 40% of their electrical power from nuclear power plants right NOW and provide 15% to 20% of the electrical power in the world NOW. I have no beef with nuclear power as long as you can make it safer.

We don't have to ridiculously pollute ourselves into extinction or melt our polar ice caps through the stupidity of burning too much fossil fuels. I love to go fast like the next guy, but I would not mind going fast in a good looking hybrid electric car.

Hydrogen is inconvenient for the consumer, in addition to being less efficient than gasoline. The gasoline mafia will attempt to control creation and distribution of hydrogen. Instead of plugging into an electrical outlet, you will have to drive to their hydrogen service station.

The gasoline mafia will block efforts to use green methods to produce hydrogen, so they can burn all the gasoline, coal, and gas possible to create hydrogen. That is crazy to pollute, to create a non-polluting alternative. To continue to perpetuate the same problem... That is why they have a hard-on for hydrogen and love it so much.

If you argue for using green methods such as solar, wind, etc... to produce hydrogen, then WHY NOT produce the electrical power and send it to a battery? Why use a green method to produce hydrogen, when it is also less efficient than gasoline? You should just transfer the power to a battery.

Any effort and expense that you make to advance hydrogen, is effort you can make to advance battery technology and electric cars. The time of the electrical car is NOW. Mazda would be better served making a hybrid electric car.

kartweb

Imagine how 40 years ago Mazda was probably hearing the same pessimism about wankels as there is today over hydrogen.

If they think it can be done, my hat's tipped to them for trying.

zoom44

why is it they cant work on an alternative. there are plenty of people working on hybrids and electrics/batteries etc. Mazda is abotu to launch a hybrid in the new Tribute. THe Rotary Hybrid Mazda5 is capable of burning gas /hydrogen/ e85 and is Hybrid also. someone has to work on the now, the immediate future and the long term future.

They work on alternative technologies all the time- just dont put your eggs all in one basket.

globi

Fast burning is particularly useful at low loads. At high loads pressure and temperature would be unbearable by the engine parts.
Keep in mind Diesel burns relatively slowly and Diesel engines still do not inject all fuel at once at TDC (despite the fact that these engines can handle much higher pressures). Also, detonation is principally fast burning and efficient too, but obviously also destructive.

Ideally Hydrogen would only be injected at partial and low loads in a gasoline engine - not only because it speeds up the combustion (and therefore increases efficiency) it also allows to significantly increase the a/f ratio and thus reduces pumping losses.

Methane has even a slower burning speed than gasoline and power density is also lower. Therefore, there are obvious benefits in mixing Methane with Hydrogen (Hydrogen in the mix at all loads).



If a small gasoline or diesel engine is simply used as a gen-set for an electric car (e.g. GM Volt), the engine can always be operated at high loads and therefore high efficiencies. So being able to operate an engine at low loads and high efficiencies is completely irrelevant in this scenario. (Same applies to the Prius with its relatively small and low power gasoline engine combined with a CVT and thus low load operation is basically inexistent).

A hydrogen engine or fuel cell can also be used as gen-set for an electric car, but this would automatically require a larger and heavier engine and a larger and heavier hydrogen tank (not to mention the missing clean hydrogen generation, the missing cheap hydrogen and the missing hydrogen distribution etc.).

As battery technology improves we'll see more plug-in Hybrids and as the gen-set is only used for long distance trips, it has to be light and small in order to reduce costs and to improve efficiency of the entire car. If 90% of your driving is without gen-set operation you want to carry as little unused weight around as possible (otherwise the batteries and e-motor again need to be larger etc. - a vicious circle). Having a hydrogen gen-set with hydrogen tank as opposed to a gasoline gen-set with a small tank would probably be like carrying an extra 4 wheels in ones trunk.

PoorCollegeKid

See, that's what I initially thought. I found that there are hydrogen engines that operate at high loads (about the same specific output as a gasoline engine) that handle the loads fine and still operate in the 30-50% efficiency ranges, however. The high load pressures and temps are definitely harder to deal with than a gasoline engine, but it seems that people have found a way to do it, though the engine may or may not be commercially viable at this time.

A slight off topic, but diesel and gasoline engines have roughly the same combustion lengths (~50 crank angle degrees). Diesels see much higher pressures due to their high compression ratios (upper 10s - low 20s) and high intake pressures (due to their throttle-less, turbocharged operation), so they must be built beefier to withstand the increased forces. Knock is destructive mainly because it causes intense local heating of the piston and cylinder wall (which helps cause more knock - bad), sets up high local pressures (as opposed to an overall, symmetric high cylinder pressure, which is easier to deal with), and also sets up strong pressure waves (up to 180 atm, compared to peak pressures in the 30 atm range for gasoline engines) in the cylinder. Knock is not always destructive, however - HCCI engines are designed to knock everywhere in the chamber at the same time, and though they're very difficult to control, these engines are showing quite a lot of promise.

I really like this idea. One of the things that I see as being a huge problem with hydrogen is its creation and storage. If less hydrogen is used to get its benefits, then less has to be made and stored, so things are better off.

I agree with you on the storage part, but I do not think that a hydrogen engine necessarily has to be any larger or heavier than a gasoline engine. I believe that both hydrogen and gasoline engines hit peak efficiencies at roughly the same operating regimes (lowest rpm that can use full timing advance, ~80% peak load at that rpm), so they'd both be utilized in the same way if you were looking for peak efficiency or peak power. However, hydrogen engines are consistently more efficient than gasoline engines at a given load, so they have an advantage in a hybrid setup where peak efficiency is your concern. Price is a big downside, I would imagine. It seems likely that a hydrogen engine that can attain this kind of power density and efficiency would cost far more than a conventional gasoline engine. If mass produced, though, it doesn't seem as if it should cost a whole lot more than a diesel engine does, especially with the expensive emission regulation equipment a diesel must use. However, as I mentioned before, the increased engine efficiency is somewhat (maybe even entirely) offset by the energy cost of making hydrogen and then compressing or liquifying it so it can be stored.

Whenever distribution networks (or a current lack thereof) are brought up for any fuel, I'm reminded of a lecture given on the future of energy systems by a lead engineer for Shell. He opened by projecting a picture on the board, taken in 1908. In this picture are the 4 main ways to power the transportation used in those days: horse, electric, steam, and gasoline. He told us that people really didn't like gasoline powered engines back then because they were loud, noisy, dangerous, smelly, had poor powerbands, and, very importantly, the fuel was difficult to obtain because there was no widespread network of gas stations like there is today. However, after much R&D was done and gasoline engines really started taking off, roads were built, gas stations were opened, and the distribution network for the fuel was built pretty quickly. His message to us was that a present-day lack of a massive distribution network doesn't mean we should immediately discount a potential fuel because such things can be built well within a single lifetime, or even a single career. Just something to think about

I completely agree with this. In my mind, the big problem with hydrogen ICEs (as long as we have fossil fuels, anyway) isn't an inherent issue with hydrogen as a fuel, but rather how to store hydrogen in a way that doesn't add a large amount of weight or size to the vehicle. Even if the tank is made fairly light, hydrogen's low density means that it's going to have to be pretty big to maintain the same range as gasoline, so the vehicle will have to be made bigger to hold this tank. If the tank is small, then your range is going to be proportionally short, which isn't a very attractive option for consumers that probably won't be able to find a hydrogen station until hydrogen goes mainstream, if it ever does.

globi

Actually HCCI engines also have a limited load range, because high loads and detonation is a problem. But for this reason a HCCI engine might also be a great Hybrid engine, because high loads are not needed (again reducing the potential of hydrogen).

Btw Honda already built and sold a 2 stroke engine based on autoignition: http://www.motorcycle.com/manufactur...xp2-14293.html
(Again autoignition operation was only applied at low loads.)



Maybe they'll develop more powerful hydrogen engines in the future, but so far their specs are not impressive at all:
From the M7E0052.pdf HD-Paschke posted:
Power H2: 80kW
Power gasoline: 154kW
Range H2: 100km (the tank uses up the entire trunk space)
Range gasoline: 549km (the tank sits underneath the rear passenger)

auzoom

Interesting article on BMW's Hydrogen guzzling 7 series http://www.spiegel.de/international/...448648,00.html

HD-Paschke

Nano-graphite may store H2 gas
http://www.physorg.com/news5180.html