Hydrogen Fuel
Posted by:
Peter Heid (IP Logged)
Date: February 20, 2002 04:08PM
<HTML>We are coming into an age where zero emission vehicles (Ha Ha!) or super low, emission specific vehicles will be introduced, by government mandate, on our highways. I believe President Bush has called for the use of hydrogen powered vehicles by the year 2012, saying the hybrid is a dead end, like that of the all electric automobile. For the steam vehicles to remain a viable, economical solution to our transportation needs, they must also continue to reduce exhaust emissions with further technological developments. The developments in this direction are as important as gaining system efficiency and their progression on a parallel path only seems logical.
It seems to me, that common practice in the steam propulsion field tends to dictate the use of existing technologies to enhance proven techniques. The cracking or reforming of hydrocarbon fuels is not a new idea, not even in the automotive industry, where it would likely lend its self well to steam propulsion. Methanol can be reacted with steam under the action of a catalyst such as zinc oxide or copper oxide, at about 600 degrees F. in a endothermic reaction. CH3OH + H2O = 3H2 + CO2 A catalyst weight of about 7 pounds can produce 500 cubic feet of H2 per hour. The mixture of methanol and water contains from 1.4 to 1.5 times the hydrogen as liquid hydrogen per unit volume. Sure methanol has only 1/2 the power density of gasoline but it has almost twice the power density of liquid hydrogen and it can easily be made it at home. Power loss would be a trade off, giving up sports car performance for an environmentally acceptable vehicle, besides have you driven one of the new hybrids ? Up a hill ? With future development, the efficiency to extract power could be raised.
The production and distribution of H2 external to the vehicle would be very difficult to implement and makes very little sense for many reasons. Production of liquid H2 can be costly and storage has its own difficulties including the use of about 1/3 of the contained energy to condense it, and continueous evaporative losses can not be eliminated. Compressed hydrogen gas requires a pressure vessel to contain it that weighs 100 times the weight of the H2 and would not seem practical for transportation needs. Hydrides have made many advances in the storage of H2 but these systems are still quite bulky and exhibit a finite life in use. To convert fuel stations to sell H2 products would be very costly and could be accomplished, but at a very slow rate, where as methanol can be pumped with existing equipment. The onboard generation of H2 will also reduce the parts in the system that need to be protected from hydrogen embrittlement.
To continue the use of fossil fuels, means to continue our dependence on foreign oil that must be transported many more miles per gallon than it will make your car go and it is not a renewable resource, not to mention the other environmental impacts involved when extracting it from the ground and refining it. The refining, transport and storage of petroleum products is done on a large scale in few locations and the supply is dependant on continued output. In a war or terrorist situation larger targets may not always be easier to hit but they do produce far greater negative effects when they are. I don't think the home still would be bothered, and the usual by-products of methanol production are, CO2 and a water-mash mixture that can be used to produce livestock feed. In 2010 when known reserves of petroleum start to dwindle and production slows, what do you think will happen to the price of gasoline and other petroleum products ? At that time, production costs for methanol may be reduced by greater efficiency from increased production and improved methods. Do you think they will let you burn wood chips or coke in your car as you cruise through town ? Besides wood is only about 7300 Btu per pound and methanol is 8600 Btu per pound. I would like to see a wood burner hooked up to a smog tester !
Methanol ignites at a temperature of 1340 degrees F., hydrogen about 1080 degrees and gasoline ignites at 563 degrees, hence methanol and hydrogen are very hard to ignite accidentally with something such as a cigarette, you need an open flame. Even with a higher temperature of combustion, H2 requires only about 1/10 of the energy to ignite as do most other fuels. Hydrogen has a flammability range from 4% to 75% by volume with air, far greater range than any hydrocarbon fuel but the minimum is about 2% higher than gasoline making it a little safer in that respect. With the great range of flammability H2 exhibits, there would be very little unburned fuel when starting and stopping a burner. Also the flame speed of H2 is 8.9 feet per second compared to gasoline's 1.0 foot per second so less unburned fuel would be ejected by the draft of starting the burner and that did, I would not hesitate to breathe. When burnt, the by-products of hydrogen combustion in air can be as little as CO2, excess air and water with the water possibly being condensed and reused. The dispersion rate of hydrogen is very high in any state which negates the use of high pressure injection or vaporization to atomize the fuel when fired in a burner. The use of hydrogen in a IC engine has proven somewhat successful at reducing exhaust and overall engine emissions but some problems do occur, including high NOx emissions due to high combustion temperatures, fuel burning in the manifold by flash back and ignition timing concerns. Even with the super clean burning characteristics of hydrogen, in an IC engine you can’t get away from burning the cylinder lubricating oils and the resultant pollution.
The use of methanol as a fuel alone is not without its problems, methanol is quite reactive and can corrode some metals and it has a very specific point of combustion which prohibits ignition at low operating temperatures. Methanol based IC engine projects have included about 15% gasoline to overcome this problem. The use of pure methanol does however prevent the undesirable components of most petroleum based fuels, such as nitrogen, sulphur and heavy metals from entering the combustion process. And yes methanol is poisonous but what would you rather see spilled on the ground, gasoline or kerosene ? Non synthetic methanol production is part of an enviromental cycle in which carbon is first stored in plant matter, it is taken in by the plant as CO2 and the carbon alone is stored. The production of methanol and cracking it for fuel only releases the same CO2 as natural decay of the material it was made from. New synthetic processes can consume more than 300 pounds of CO2 for every 1000 pounds of methanol produced, and they are running with reduced energy consumption over previous methods.
In conclusion, I believe this method of obtaining a cheap source of very clean fuel, with a low environmental impact, is a practical alternative to fossil fuels for powering the steam vehicles in the coming decades. The power available per unit volume is lower than today's fuels and some energy must be expended to crack the methanol but at a cost of creating a practical, super low emission vehicle, running on a renewable resource fuel that can be produced tomorrow by almost anyone with the desire (and money) to do so. The H2 generation by this type of vehicle could be used to replenish the home supply for appliances running on hydrogen.
Sorry about the length again but I wanted to make sure I stated myself clearly, also note the use of the term “fuel cell” would be out of context in this discussion. If you have seen this posted elsewhere I’m sorry to be repeating it.
Remember this is a dream and I am not a chemist so the information may not be completely accurate but I welcome any corrections. And while I'm dreaming, why can't we just burn hydrogen with pure oxygen to produce steam at 6000 degrees F.....
Hydrogen fueled dreams
Peter Heid</HTML>