Energy Use in America and The World - Today and into The Future
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Yes, Hydrogen can be demonstrated in experimental vehicles, and they can have impressive acceleration and speed. But that's with a rather small Hydrogen tank aboard. If you ever see an impressive demonstration like that of a Hydrogen powered vehicle, make sure to ask how long that vehicle could continue to perform like that. The answer is certain to be no more than a few minutes at most. So, as a demonstration, Hydrogen can seem quite impressive, because it is! But in actual practical applications, the details probably make it never to be usable in our vehicles.
Hydrogen (H2) plus Oxygen (O) makes H2O, water, or actually, water vapor, at higher temperatures. And Hydrogen is actually capable of nearly meeting those high expectations.
And there is even a concept, and somewhat of a device, called a Fuel Cell (originally conceptualized in the 1830s), which can use this reaction to generate electricity. During the 1960s, NASA developed Fuel Cells which produced electricity for spacecraft. They worked reliably and fine, but they were horrendously expensive. There have been people trying to make inexpensive versions ever since! In the early 1990s, some breakthroughs were found. The concept of a Fuel Cell is actually pretty simple. You provide a supply of hydrogen gas and oxygen gas (which is usually from the air) which are separate, with a unique barrier between them. The simplest version of a Fuel Cell is to allow the NUCLEUS of the hydrogen atom to pass through the barrier while not allowing the electron to also pass through. The electron is then caused to follow some DIFFERENT path to eventually get to where the nucleus had gone to, where the end result will be water molecules. The electrons are negatively charged, and when they are forced to follow that alternate path, they are MOVING CHARGE which is the same as an electric current. In words, it therefore seems quite simple to have a Fuel Cell produce electricity. However, in practical terms, there are lots of complications! It may still be ten or twenty years before any reliable technology will exist which has tolerable cost.
But Hydrogen itself has an ENORMOUS disadvantage, as well as many smaller ones. It cannot really be considered a "fuel" at all! Yes, it IS, but it isn't! It IS because of the exothermic chemical reaction described here. It ISN'T because it does not occur naturally. We have such an attachment to petroleum and natural gas and coal and uranium BECAUSE they exist naturally. We actually have the technology to manufacture petroleum, but it would be so involved and expensive to do that it would never be worth it. Hydrogen is very different. It is so chemically reactive that it IMMEDIATELY combines with nearly any other atom (ion, actually) that happens to be near it. So there is NO natural supply of Hydrogen, anywhere on Earth.
This really changes the equation A LOT! Essentially, Hydrogen should be considered to be similar to a battery, where electricity is produced somewhere else and then STORED in it. And it turns out that the chemical properties of Hydrogen are such that it is rather difficult to pull hydrogen atoms out of any of the molecules that it exists in. That means that a lot of power is needed to separate out the hydrogen. The obvious primary source is water.
You can look up something called the Electrochemical Equivalent of Hydrogen in many Reference books. It is the amount of electrical energy that exists in the chemical bonding of Hydrogen atoms inside of the molecules it exists in, such as water, H2O. Those Reference books show that 12,062.183 ampere-hours of electrical energy is required to release a single pound of Hydrogen from any chemical compound. It turns out that there are no "perfect" devices to do this, and the best tend to be around 20% efficient at getting the Hydrogen released, regarding the electricity used. So we actually need to use up around 60,000 ampere-hours of electrical energy in order to get one pound of Hydrogen released (and therefore available as a fuel). That is a LOT of electricity! Your kitchen toaster uses around 15 amps of electricity, for maybe 30 seconds. Here, we are talking about 100 amperes of electricity being used continuously for 600 hours or 25 days!
So, proponents of "the coming Hydrogen economy" brag about the fact that Hydrogen CAN be produced by electrolyzing water to separate it into Hydrogen and Oxygen gases. Then they brag about the fact that when Hydrogen burns, it combines with Oxygen to create "lots of power, and just water vapor". Those statements are totally true, and nearly everyone seems to totally trust the people pushing Hydrogen and Fuel Cells, without asking the next, VERY IMPORTANT, question! Didn't Newton prove to us that we cannot have energy simply appear? That there is a Conservation of Energy? So, if we have to SEPARATE the Hydrogen from the water to start with, doesn't it seem obvious that it has to require AT LEAST AS MUCH energy as will later be released when the Hydrogen again winds up as part of water? How come nobody asks this really obvious question???
In fact, there is another closely related Law of Nature, regarding something called Entropy, where NO actual process can be 100% efficient. So, as discussed below, to provide all that electricity needed to release Hydrogen from any chemical compound: (1) coal must first get burned in a power plant; (2) it must heat water into steam; (3) that steam must drive high speed turbines; (4) the turbines must drive alternators; (5) the electricity must then travel through wires and transformers to get to your house; (6) an electrolysis apparatus must use (a LOT of) electricity to produce Hydrogen gas; (7) that gas must be tremendously compressed to be of manageable size; (8) THEN you finally get to the Fuel Cell technologies that are still being developed!
The result of this is that Hydrogen power for vehicles might SOUND amazingly Green, but the reality is that the power consumed (at that distant electric power plant that you never see) to create the Hydrogen is at least seven times the amount of power associated with a gallon of gasoline! For now, no one seems willing to tell the public these things, because they REALLY want to get the public to buy a zillion Hydrogen powered vehicles! This exact same situation occurred a few years back when Battery-powered vehicles were supposed to be the FUTURE! Battery power is GREAT, IF you only consider the vehicle itself. It gives off ZERO pollution! But these same issues regarding the massive amount of electricity needed to re-charge those batteries (even for golf carts) already costs about double what the equivalent amount of gasoline would have cost! And at the distant power plant where that electricity was produced, a LOT of pollution, carbon dioxide and atmospheric heat was created and released; you just don't see it! Ditto, with Hydrogen!
It seems fascinating that two technologies that are promoted as GREEN, are each horrendous when the whole picture is examined, because that distant power plant has to burn ferocious amounts of coal to produce that much electricity! And people who optimistically think that they will be able to use a few solar panels or a windmill to produce a thousand amperes of electricity for 24 days to generate one pound of Hydrogen? I have a Brooklyn Bridge that I think you may want to buy!
There is a more technical name for this relationship. It is called the Electrochemical Equivalent. For hydrogen, one can look up that value in many reference books, as being 12,062.183 ampere-hours per pound. One can easily see that at a rate of ten amps, the 1206 hours is slightly over 50 days, as noted just above. With actual existing equipment, around 250 days of continuous use and consumption of a lot of electricity, just to produce that one pound of Hydrogen.
People who promote hydrogen seem to imply that by simply snapping one's fingers, all sorts of hydrogen can be obtained! Note these comments and calculations just above had assumed that all equipment was perfectly efficient, which is never even close to being true in real life. YES, they are technically correct that you could take a glass of water from your kitchen tap and generate hydrogen gas from it by electrolysis, which might then be used as fuel in a vehicle. But see that they have sort of left a LOT of important details out?
In addition to NOx production, if the device in which the burning occurs has any lubricants, like oil, there are also oxidation products of the Carbon in them, which can contain CO, carbon monoxide. When Hydrogen is burned in a decently designed device, these environmental problems are fairly minor and they are rarely considered to be any great danger.
However, a pound of Hydrogen is HUGE! At standard atmospheric pressure and temperature, it takes up around 190 cubic feet of space. In contrast, that pound of gasoline only takes up about 1/50 of a cubic foot. Hydrogen gas takes up around 10,000 times the space that gasoline does!
For the record, we are NOT suggesting that gasoline is any great fuel source. It IS convenient, and compact, true. But it causes pollution of many sorts, including adding large amounts of carbon dioxide to the atmosphere which directly contributes to global warming. So this is NOT a fan letter for gasoline! It is instead intended to present an accurate scientific discussion of Hydrogen as a fuel, where all the press reports we hear in the news seem to always leave some really important stuff out!
Consider a mid-sized car, traveling at 60 mph down an Interstate Highway. It is well known (and easy to calculate) that roughly 40 actual horsepower is needed to maintain a constant speed. A horsepower is equal to 2544 Btu/hr, so we are talking about 102,000 Btu/hr of "actual" energy/work. For an hour's driving, we would therefore need 102,000 Btu of output energy. (A gasoline engine would use maybe 3 gallons of gasoline during that hour's driving (20 miles/gallon) which actually contained about 378,000 Btu of energy, but the engine/car efficiency is only around 25% to create the 102,000 Btu of output work.) Consider now that a cubic foot of Hydrogen (not compressed) only contains 319 Btu per cubic foot. That hour of driving would therefore require over 1,000 cubic feet of the Hydrogen.
We can say this same thing in terms of "gallons". A gallon of gasoline contains around 6 pounds, and has 126,000 Btus of energy in it. A gallon of hydrogen (gas) only contains around 40 Btus in it. Quite a difference! Instead of a two cubic foot gasoline tank (15 gallons) in your car, you would need a tank more than 3,000 times bigger, over 6,000 cubic feet, for the equivalent Hydrogen! That's a little more than TWO standard semi trailers (8'wide x 8'high x 45' long or 2900 cubic feet each). Pretty big gas tank!
Well, that is obviously not going to happen! So, the many ongoing explorations into using Hydrogen as a fuel always involve carrying HIGHLY COMPRESSED Hydrogen in very thick, heavy tanks. If you have ever seen the kinds of tanks used for the Oxygen for a worker's oxyacetylene cutting torch, that's the kind. Such tanks can hold Hydrogen at around 100 times atmospheric pressure, or 1500 PSI, an extremely high pressure (or even higher) (We will later mention even higher pressure hydrogen tanks at 3000 PSI).
Well, at 100 times atmospheric pressure, the Ideal Gas Law tells us that the Hydrogen would now only take up 2900/100 or 29 cubic feet. That works out to around 60 of those (fairly large) high pressure storage tanks (to match the effective capacity of the 15 gallon gasoline tank.). Each tank is very massive to withstand the very high pressure, and each weighs nearly 100 pounds empty. (And around 1/4 pound more when filled with Hydrogen!) So the normal American car which presently weighs around 2800 pounds would have around an extra 6,000 pounds added, so the vehicle would now weigh more than three times as much as current cars! (This tremendously affects acceleration, handling and other performance, and it would be like that car pulling a huge 6,000 pound trailer behind it.
Those 60 very high pressure tanks present another complication. If industrial workers ignore proper safety rules when working with a high pressure Oxygen tank, it could fall over. As the hundred pound tank falls over, it quickly develops a lot of momentum. If there should happen to be something in the way on the floor, where the neck and valve of the tank hit it, the neck and/or valve tends to just snap off. Suddenly, 1500 PSI of compressed gas has an easy way out, and it all goes out almost immediately. Isaac Newton told us about the Law of Action and equal Reaction. The hundred pound body of the tank then zooms off at extremely high speed in the other direction. There have been many industrial accidents where such Oxygen tanks flew many hundreds of feet through the air and passed completely through many concrete walls.
Most suppliers of industrial Oxygen display photographs of vehicles where ONE such Oxygen tank had not been strapped down properly and the neck wound up snapping off. Usually, the vehicles shown in those pictures are hard to tell as being vehicles, except for maybe a tire somewhere in the picture.
Get the point? Imagine having 60 such tanks in a car. Either one vibrates loose from its clamps, or the guy who last replaced them didn't strap them all down properly, or an accident occurs where you hit another vehicle or a tree. If even one of those tanks ruptures, bad things would result. And have you ever even seen what happens to any car when a semi hits it?
Notice that this issue is not actually related to any hazard of Hydrogen itself, but rather the fact that it would have to be stored at extremely high pressures due to its very low density. Whether it was a high-pressure Oxygen tank or a high-pressure Hydrogen tank, this danger is virtually the same, and is entirely due to the pressure that the gas is compressed to.
Because of this extraordinary safety hazard, which is only due to the very high pressures involved and really has nothing to do with the Hydrogen itself, there is no imaginable way that the US Government would ever allow such vehicles to be licensed. It would conceivably be safer to drive a dynamite truck!
However, even if there was some way to do all that compression, it takes a good amount of electricity for the compressor motor to drive the compressor. A significant cost would be involved for that compression, even if you somehow had your own compressor.
In addition, free Hydrogen does not exist. All of the Hydrogen that might be collected is now in various compounds. The simplest to deal with is water. If you had Chemistry in High School, then you hooked up some electricity to an apparatus that contained water, and you saw little bubbles of Hydrogen form in one upside down test tube and Oxygen form in the other. That is called Electrolysis, or the Dissociation of water. It is obviously pretty easy to do.
But those are just little bubbles of Hydrogen that you collect. Remember that you are going to need an amount of Hydrogen that would more than fill two semi trailers, to just equal one tank of gasoline! It is possible to calculate the amount of electricity needed for that, but you must get the idea that it is a LOT of electricity! So, you get to pay your electric company for that, too.
So, you would wind up paying for the electricity to Dissociate the water in the first place, plus the cost of the electricity needed for the extreme compression. Of course, all of this would be after you bought the necessary equipment! It turns out that all this will increase your electric bill by at least $7 (and likely much more) for the equivalent of one gallon of gasoline. Also, roughly 60 pounds of coal have to be burned at a distant electric power plant to produce that same energy that a single gallon of gasoline contains. Which causes roughly NINE TIMES the amount of global warming carbon dioxide (165 pounds) to be produced at that power plant than if you had simply kept driving the gasoline powered vehicle (18 pounds)! (See the Battery-powered vehicle presentation linked at the bottom of this page for the complete details on that.)
An alternative, of course, would be to buy (rent actually) tanks of industrial Hydrogen that is already compressed. Current prices for Industrial Hydrogen (the lowest purity available) are around $42 for a standard K cylinder, a very high pressure tank which contains 197 standard cubic feet of Hydrogen, plus a monthly rental fee for the tank. The 6,000 cubic feet that we had earlier determined were equal to one 15 gallon tank of gasoline, would therefore be around 30 of these tanks, which would cost around $1260 for (one gasoline tankfull!) the compressed Hydrogen plus the monthly rental of around $300 for the tanks themselves. (Using the single gallon of gasoline scale we discussed above, you would need to buy/rent only two K-sized tanks, for around $85 plus cylinder rental costs, for the equivalent to that single gallon of gasoline.)
We complain today at paying $3 per gallon for gasoline, which would be $45 for our 15 gallon tank. How many people would be willing to pay $1260 and more for the same driving distance, using Hydrogen?
Consider the inside of an engine cylinder in a normal car engine traveling down the highway. The engine may be rotating at 2,000 rpm, or 33 revolutions per second. The piston must therefore move upward and downward 33 times every second, and its speed in the middle of its stroke is around 45 feet/second. If a fuel burning in the cylinder is to actually push down on the piston, in order to do actual work in propelling the vehicle, the fuel-air mixture needs to burn at a speed faster than the piston is moving! Otherwise, the slow-burning mixture would actually act to SLOW DOWN the piston! It would not only not do productive work, but it would require work FROM the piston.
The fact that a Hydrogen-air mixture has a flame-front speed of around 1/10 that of a gasoline-air mixture seems to indicate that only a very slowly moving mechanism could be used. That might be possible, but it suggests that yet another hurdle might lie in front of Hydrogen ever becoming a common motor fuel.
So, even ignoring the problems discussed above regarding having to compress the Hydrogen to actually be able to use it, we now have maybe 100 cubic feet of Hydrogen. We noted above that each cubic foot contains 319 Btu of chemical energy. So we have 31,900 Btu of energy available. Maybe that sounds good, but your house furnace probably uses up 125,000 Btu/hr in the winter, so that Hydrogen would only provide heat for a single house for around 15 minutes! But if we look at the energy consumption of the whole United States, each year, it is a little over 100,000,000,000,000,000 Btu.
Our energy amount above is equivalent to around 31 cubic feet of natural gas (at a little over 1,000 Btu/cubic foot). But each year, the US consumes around 30,000,000,000,000 cubic feet of natural gas!
See the problem? Even if the Hydrogen techlology could be scaled up by a factor of a MILLION (extremely hard to do!), it would then still only represent one one-millionth of our gaseous energy needs! (We have another web-page in this Domain that presents government and industry data on energy supplies and consumption rates, and it shows that, without imports, the US would completely run out of natural gas in a little over EIGHT years!) So that need for a gaseous fuel will certainly exist. But it is hard to see how Hydrogen could provide but the tiniest amount of that need.
Yes, I realize that the public and politicians seem fascinated with Hydrogen as the "answer to all the energy problems", but it is really hard to see how that could happen. We humans have gotten spoiled by being able to consume and waste unbelievable amounts of coal, oil, natural gas and uranium. There seems to be no care at all regarding what people of 20 years from now will do! Some people say that "science will find solutions" but I ask that you note that I AM a Nuclear Physicist! If the US is not able to rely on friendly countries for Uranium, oil, and natural gas, we may all wind up in a Medieval United States! We already used essentially all the Uranium that was under the US, nearly all the oil (4.3 years supply left), and nearly all the natural gas (8+ years supply left). This is bad. Very, very bad. But I truly doubt that Hydrogen can provide any significant alternate source, mostly because our total energy consumption has been so amazingly high!
Another politically popular "energy solution", wind-generating of electricity, has many problems of its own, primarily transporting the electricity hundreds or thousands of miles, because very little actually gets to the end of those very long lines! Even with impressive government funding of wind-generation, it seems very unlikely that such systems can realistically provide more than the tiniest part of the US electricity usage. But it seems likely that politicians will go crazy and authorize a thousand times as many windmills than already exist. And the windmills will soon after be discovered to cause weather changes in the climate, because so much wind is slowed down such that normal weather patterns cannot occur.
So the rather casual comments that "our technology will find ecologically sound ways to make electricity in the future" as the future source of the power to drive Hydrogen generation, is pretty close to Easter Bunny and Santa Claus sort of stuff.
It is really hard to see how the US will be anything other than a total-coal powered country within a few decades. We DO have a lot of coal!
Yes, Hydrogen can be demonstrated in experimental vehicles, and they can have impressive acceleration and speed. But that's with a rather small Hydrogen tank aboard. If you ever see an impressive demonstration like that of a Hydrogen powered vehicle, make sure to ask how long that vehicle could continue to perform like that. The answer is certain to be no more than a few minutes at most. So, as a demonstration, Hydrogen can seem quite impressive, because it is! But in actual practical applications, the details probably make it never to be usable in our vehicles.
In other words, one of the resulting products is the carbon dioxide that is blamed for much of global warming. But it is really NOT a fault IF the methane is PRODUCED as on a farm, as in that case both the production and oxidation of the methane is part of the natural Carbon Cycle. It is ONLY if the methane being burned had been brought up from being stored underground for millions of years. In THAT case, when it is burned, it releases NEW carbon dioxide into the atmosphere that had been removed millions of years ago.
It sure seems to me that methane is a FAR more attractive possibility regarding solving future energy needs than Hydrogen has any chance of accomplishing.
By the way, chemically, Methane is CH4. Another immensely popular concept (but an incredibly expensive and foolish idea!) these days is Ethanol (or Ethyl Alcohol or Grain Alcohol) which is CH3OH. Methane and Ethanol are therefore quite similar chemically, where a Hydrogen atom is in one and a Hydroxyl ion in the other.
(Ethanol requires not only immense amounts of corn to be grown, at the expense of food crops, which has already [2007] caused grocery prices to rise tremendously, but it requires the heating and fermentation processes of a still, and then has to be trucked around, together USING UP about as much (fossil fuel) energy that the Ethanol can eventually provide! AT BEST, we are simply WASTING all those millions of acres of corn crops! Interesting, huh?
C Johnson, Physicist, Physics Degree from Univ of Chicago
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