Sounds great and no doubt would reduce emissions alkaline fuel cells operate at 250 degrees celcius hence no NOx would likely be produced, but not only does hydrogen become a energy carrier in this setup but so does the nitrogen. Is obtaining nitrogen from renewable source a problem, I would imagine not? but how many places do this already and of course it will be important to know what is the result of not obtaining the nitrogen from renewable sources.
Alkaline FC are still susceptible to CO poisioning, so the old question of durability still comes to light.
Another lame one. Ammonia's made from hydrogen and nitrogen. The hydrogen is made from, you guessed it- natural gas. Ammonia is therefore just a hydrogen carrier, one that's easy to crack- but one that's energetically expensive to make. It is a liquified gas at modest pressures but it's also very, very toxic.
The most energetically efficient way to run a vehicle off fossil fuels is still a hybrid IC engine running on liquid fossil fuel. Want to use natural gas as that fossil fuel? Carry it directly as a compressed gas.
Agreed that any pure-hydrogen power would be less efficient than something you pump directly from the ground into your tank, for many reasons. Natural gas distresses me only because I know so much of it gets burned off as a waste product while pumping more marketable crude. And hydrogen power is no guarantee your primary fuel source is non-toxic or renewable. Look at this company patenting new battery technology using lead and cobalt - major non-renewable hazardous waste materials, but they store more power with less cost, fitting the bill for the 300-mile range requirement.
Instead of the promise of efficiency, safety, and resource conservation, it seems to me that hydrogen instead offers zero-emissions and an end to dependence on foreign energy sources. Safety is just a set of engineering requirements to address the toxicity and voltatility of things like ammonia. Efficiency can be gained in other areas such as weight, aerodynamics and regenerative braking. The carbon released when you make the ammonia or hydrogen can be sequestered.
Ammonia is the second-most produced chemical in the US, can be made with domestic fossil energy sources, and filling stations can be set up for pennies on the dollar it would take to erect hydrogen filling stations. It's not perfect but it can work in the short term. In the context of an earlier revolution: we'll need to run with steamers (wood, coal) before building engines (gas, diesel).
Hydrogen can be had fairly easily from coal and natural gas, two plentiful domestic energy sources. In both reactions CO2 is a product, and if done in a factory the CO2 could be captured more easily for sequestration. Organic sequestration at this point (without emission) is possible now but requires a lot of capital and a little imagination. Inorganic sequestration has a long way to go. I envision it could be done with solar energy in a similar way plants do it, but would require huge advances in electrochemical nanotechnology.
Organic sequestration is already being done on a wide scale as lumber companies plant and harvest their owns trees, which are selected based on how quickly they can grow. Use of kenaf as a raw material is also on the rise. These materials trap carbon naturally and are mainly produced for markets in developed countries. If the Kyoto treaty also looked at our rate of carbon sequestration, we would not be seen as the bad guys they make us out to be. This free market of carbon, where it floats through the atmosphere between the points of emission and organic sequestration, must make them nervous.
It is my opinion that cars powered by internal H2-combustion engines will become practical and widely used long before fuel cell vehicles.
Re "It is my opinion that cars powered by internal H2-combustion engines will become practical and widely used long before fuel cell vehicles."
I agree with you on that one.
The big question in my mind, though: wouldn't an H2 IC engine be just as bad with NOX as today's gasoline-fired engine? Are there ways around that?
And, as we tend to run the engine leaner (to gain efficiency), don't we also increase the temperature and therefore the NOX generation?
I suspect that ultimate theoretical efficiency of fuel cells might be better than IC -- can anyone confirm?
Other than NOX output and efficiency, I don't understand why more people aren't talking about IC engines fired from natural gas or hydrogen (rather than fuel cells fired from natural gas or hydrogen). And everyone could still get all excited about drinking the water that comes out of the tailpipe.
Nitrogen - Hydrogen carrier in the form of ammonia,
Nitrogen makes up 78% of our air, forgive my lack of all things chemical, but why cant you liquify air and bleed off the nitrogen, with no NOx created in the low temp FC then the nitrogen is released into the atmosphere and the life cycle of the nitrogen has little or no effect on the atmosphere.
expensive maybe but liquid oxygen as a bi product could reduce this cost.
Liberty,
Quote,
Safety is just a set of engineering requirements to address the toxicity and voltatility of things like ammonia
- I think one of the reasons we have been using liquid fuels for so long and now bio diesel and ethanol are taken seriously is because, liquids are safer than gases. nat gas and LPG are now being used increasing more and safely, but you can not change the laws of physics and a liquid fuel will always be choosen if all other things are equal. I am a fan of hydrogen but am not a fan of a 10,000psi tank in my car, although I beleive they have a place on the roof of a bus, if a bus rolls over you going to be stuffed anyhows!!
The australian government is set on implimenting carbon sequestion (make them feel better about exporting so much coal, well it is the best quality in the world), I know of people working for CSIRO on projects of the manner. Put into simple terms it will be 20 years before any sequestion is done on a scale large enough to have an environmental impact, and they still dont know if once in ground it will have sesmic reactions or simply leak and prove pointless.
A 5MW wind turbine has just been installed in germany, the largest in the world.
from a quick internet search I think drax power station in the UK is the largest power station creating 400MW (10% of UK total demand) thus 80 5MW wind turbines will do the job. and yes they are really are cost competitive with coal fired power espically if you are going to use sequestion, so why bother?
trying to confirm the high efficiency of a FC system is difficult, at
you can download a table listing every FC vehicle built thus far. you will notice the highest efficency is the equivelent of a 80MPG vehicle and has a pathetic range.(other milages given are simply targets and have not been achieved.
This is not such an uncommon milage figure for small diesel powered vehicles and some of the the new TDI cars(turbo high pressure common rail Direct injected diesels) with all the mod cons i.e power steer, air, elec winds, 6 stacker cd can get 3/4 of this figure. but with a massive driving range on one tank and performance close to naturally aspirated petrol.
prototype diesels are even better again, check this out. .
The phrase you are looking to describe hydrogen by is "energy carrier". It is commonly refered to as this and it is the correct description untill we find a large trapped source for the taking ;o)
NOx generation is temp depend and if a hydrogen engine is running lean (low temperature) less than equiv ratio 0.4, no NOx is produced. above this closer to stiocheometric conditions the temp rises, read "the inevitability of engine out Nox - lawrence livermore laboratory for more info. it's floating on the web somewhere.
Univ. of Melbourne has a hydrogen powered Ford cortina, on a FTP-75 drive cycle 51% less NOx is produced
I am keen on the use of hydrogen but the use of hydrogen in automobiles ties directly with the technology available for it storage. Carbon nanotubes are considered the best possible system, low pressure, low adsorption and extration energy needed, but there is a great debate over what is really possible from them.
Hydrogen from renewable electricity (ex wind turbines) piped to residental and commerical areas for the use in SOFC's to generate not just electricity, but heat and water(likely not drinking but irragation, washing etc.) in my mind is much more likely the first step.
Biodisel can be home grown, mixed with crude oil diesel or used on it's own, it holds just as much energy as diesel (cannot be said for ethanol, hydrogen and many other alternate fuels) and diesels engines of today are soooooooooo much better than yesterdays smokey ones.
To second guess the future is the hardest thing to do while the US DOE only has a target of 6% Wt hydrogen storage system for the 2010 it is going to be a long time before hydrogen will be used widley for practical reasons.
Here in aussie looking at the levels of pollution over the last 20 years, the toxins in the air have all gone down and not up, becuase of catylitic converter on cars. I don't think we need zero emission vehicles we just need low emission vehicles.
Hydrogen will make up part of the future energy distribution but not all of it. and unlikely to be the automotive industry execpt where mandated like california. But as earlier stated we all ready have capacity to have zero emission vehicles i.e. battery powered ones, they may even be better environmentally wise when you consider the quantity of platinum in PEMFC's, and what platinum mining will do to the third world countries it exsists in.
Hydroscope: Ammonia's a terrible hydrogen carrier from an energetic standpoint, and if you throw out energetics out the window, the best hydrogen carrier is liquid water.
Hydrogen reacts with ammonia reversibly and with difficulty, resulting in a high temperature high pressure process with lots of recycle. Ammonia's "cheap", but only because natural gas is "cheap".
The cost of the nitrogen has little to do with the cost of ammonia. To make ammonia you first make hydrogen- that's the trouble.
As far as NOx emissions are concerned, the problem of removing NOx from the steady output of a fossil fuel or renewable hydrogen-fired IC hybrid are trivial compared with the problems involved with the generation and storage of hydrogen as an energy carrier, or the manufacture of fuelcell powerplants.
Until you have a renewable source of hydrogen, fossil-derived hydrogen-fired devices don't generate substantial energy efficiency benefit (if any) to compensate for the enormous costs of the fuelcell and hydrogen infrastructure/storage. Focus on replacing a large percentage of our fossil fuel driven electricity generation with renewable sources first, before you focus on making hydrogen to substitute for fossil fuels in transportation applications.
The roadmap to a hydrogen economy is going to have difficulties and the destination is still going to be imperfect. After all, even ignoring the relatively insignificant NOx emissions, any hydrogen power plant would not have "zero-emissions" - water vaper is one of the greenhouse gases
Renewable power has its advantages but in reality the problems with mining Pt in 3rd world countries may be dwarfed by the NIMBY pressures you'll run up against with implementing renewables in their current forms.
Ammonia, while not perfect, offers one path on that "road" with liquid fuel, cheap infrastructure, and FCs that rely less on precious metals.
Diesel has come a long way, with higher available rail pressures & valve speeds, and better particle filtration. But upgrading from 30mpg to 70mpg won't ultimately solve our dependence on Middle East crude, just prolong it by making oil reserves last even longer. If they were really our friends that might not be a problem.
I know this is all getting slightly off-topic, but you've got me thinking about the biodiesel now.....
How good does the whole biodiesel model look? How much energy does it take to turn corn (or whatever they use?) into oil? I assume there's positive net energy available here? (I understand that ethanol takes more energy to make than it provides when burnt?)
I understand that biodiesel is sold at some gas stations in CA now -- how does the cost compare to standard diesel? Are the prices real market based prices, or is biodiesel being subsidized to keep the IL farmers happy (like ethanol is)?
Just how clean is a modern diesel? We still have the CO2 problem, right?
Re "Biodisel can be home grown" -- no doubt I can grow corn -- can I really turn it to oil in my bathtub? Or am I missing the point on that one?
It seems to me that maybe biodiesel is potentially a realistic solution to reduce our foreign oil dependancy. But it would not seem to do much to reduce greenhouse gasses. Comments?
there are thousands of biodiesel sites on the net check them out for all infomation. I believe you need to replace all rubber materials in your engine if you want to run it on 100% biodiesel. But you can apprently run your standard deisel on 20% bio without any problems, as oil prices rise and environmental concerns increase, biodiesel is being considered world wide.
The CO2 produced from burning biodiesel was first removed from the air by the plant that was processed. But you are correct to ask about the energy input needed. These senerio's are commonly termed "Well to wheels" and "life cycle analysis". I'm sure there are some on the net for all alternative fuels, I can point you in the direction of some hydrogen ones. but currently don't have any for biodiesel, I'm thinking this will change soon ;o)
liberty,
changing the ave of all cars on road from 30MPG to 70MPG while mixing in 20% biodiesel would have a major effect I'm sure but those figures would likely not be seen. . ..
hmmm maybe I will investigate biodiesel a little more, I starting to really like the sound of it too. I know you can cook it up via used cooking oil too.
The downside to diesel engines (from the environment) is they don't tend to burn their fuel as well, creating particulate emissions (but they getting much better), apart from that they burn at lean fuel rates, and suitable catylsts have not been found which means more NOx, CO, and unburned HC's make it to the atmosphere even though less are produced in the cylinder. The catalitic converters in petrol engine only work in a very narrow band of combustion conditions i.e. stiocheometric + - very little. There have been many attempts to fix this via fancy catylsts and particulate traps, also useing a sacrifical redundant usually diesel fuel itself, as it's already on the vehicle and cheap. But it turns out hydrogen is an excellent redundant to be added to the catylsts for these non stiocheometric combustion conditions.
I think I just thought of an excellent project biodiesel car with hydrogen addition in cylinder and in catylst ;O). now all I need is the money and motivation :O(.
Re "there are thousands of biodiesel sites on the net check them out for all infomation" -- yeah... but I don't trust most publicly available information on energy, I've occasionally noticed, um, a slight bias in some of the numbers. On eng-tips, you can usually cut to the heart of the matter a bit more quickly.
Interesting point on the plants pulling the CO2 from the air already. So we should be talking zero net CO2 with biodiesel (or more accurately, a net reduction in CO2 assuming steady growth in the usage of bio).
Regarding "diesel engines ... don't tend to burn their fuel as well" -- I just read somewhere that there is a keen interest in getting gasoline engines to burn something more like a diesel, apparently they are getting closer using sophisticated computer control and limiting the speed range of the engine... The whole point being to make them burn cleaner...
Would it make any sense to use a biodiesel engine running at a fixed optimized speed to drive a hybrid vehicle? Sorry if the scope's starting to creep on your project already....
Not showstoppers, but problems I see with biodiesel: Water, fertilizer, fuel, labor, and capital are all needed to make biodiesel, and there problem is not enough arable real estate in existense to support our needs (or wants).
I was wanting to convert a motorcycle to burn used cooking oil, but diesel-powered motorcycles only currently exist as military prototypes in support of the "one-fuel-forward" tactical requirement. Someday there might be demand for these commercially, they get 120mpg and have less emissions than their gas-powered cousins.
