THE REVOLUTIONARY DUALMODE TRANSPORTATION SYSTEM
On the Streets
In the early years the guideway network won’t yet be complete and not everyone will have true dualmode cars, so we will still need to use the old highways. With pallets we can run conventional cars on the first of the new guideways. And if there is any fuel left we will continue to use internal-combustion-engine automobiles for a while longer for another reason: Unless there are some breakthroughs, battery-powered, fuel cell, or other environmentally clean cars will have inadequate range and performance for highway use.
However, batteries or fuel cells will be quite adequate for the short distances to be traveled in street mode when the guideway system is complete. True dualmode cars with internal-combustion engines could be built and sold during the transition period. This would be optional to renting pallets for use with conventional automobiles. As the guideway system nears completion we will gradually go almost exclusively to true dualmode cars using sustainable “green” energy on the streets. On the guideways dualmode cars will use electricity from the power-grid; but it would be prohibitively expensive to equip all streets and back roads with trolley wires to provide grid power to the cars in street mode. After the transition period, for street-mode the cars must carry some form of portable energy other than gasoline, diesel oil, or any other carbon-containing fuel. Most of the time (and miles) the cars will be running on the guideways and using grid power, so fortunately they won’t need to carry a very large amount of portable energy.
Not many environmentally undesirable conventional cars will continue to be used after the guideways are available, because the guideway mode will be much faster, safer, and less stressful than the highways. And as we will very soon be down to the dregs of the world’s petroleum reserves, gasoline and its substitutes will be priced so high that few will be able to afford them. So in addition to the many other advantages of the guideways, they will be cheaper to use than the highways.
Going way back, in the first two decades of the 20th century, battery-electric cars were fairly popular, especially with women. Some “little old ladies” liked them because electric cars were clean, quiet, and didn’t have to be hand cranked to get them started. (Electric starters weren’t standard equipment in most regular automobiles until about 1928.) How do I know that? I was there. My Dad’s first car, a Model T Ford, required cranking. The second one, an Erskine (a small Studebaker) purchased in 1929, had an electric starter, a remarkable invention at the time. But just in case the starter failed, it also had a crank.
Most present storage batteries are heavy, expensive, and have limited capacity and limited life. They are only moderately better than the ones the little old ladies used a century ago. There is a lot of research going on to develop better types of batteries, but the technical problems are difficult and progress has been slow. Some recent developments show great promise, however.
Toshiba recently announced a major breakthrough in rechargeable lithium-ion batteries. A great increase in capacity is claimed as well as a charging time of only one minute, and a battery life of a thousand charge/discharge cycles. Lithium-polymer cells are a closely related and equally promising recent development. Lithium is the lightest of all of the metallic elements: It is half as heavy as water and twenty one times lighter than lead. That fact allows lithium battery cells to be many times lighter than “lead-acid” battery cells (the type used in cars) of comparable ampere-hour capacity.
But “ampere hours” aren’t the only thing we need: We need power, not just current, and power is current times voltage. The voltage of a battery is determined by multiplying the number of cells it contains by the voltage per cell. Lead acid batteries provide 2.0 volts per cell. Lithium is not only the lightest metal it is also the most active metal electrically. As a result, lithium cells put out a generous 3.0 volts each. Present 12-volt car batteries have six lead cells, but a 12-volt lithium battery needs only four cells. That fact allows lithium batteries to be even lighter, and also to be more reliable (since there would be fewer cells to fail).
Because of environmental and fuel-depletion pressures there are current efforts to bring back battery-electric cars. But so far they are not good enough in a very vital respect; they can’t carry enough energy between battery charges to begin to compete with engine-powered cars. Fifty pounds of gasoline can deliver about ten times as much energy as fifty-pound lead-acid batteries. If the current lithium-battery developments continue to show their great promise the gasoline-to-battery advantage will be reduced markedly, but gasoline will likely still win out in “energy-density” contests. The author knows of no full-size battery-electric cars currently on the market, mostly because their range and performance would be too limited for use on modern highways. But for the street mode of a dualmode system, even the standard lead-acid type of battery would be adequate, since neither high speeds nor long range is required on the streets. So batteries (probably lithium) will likely power our dualmode cars in their manually driven mode, but we should consider other portable energy candidates as well.
HYDROGEN AS A FUEL
An appealing feature of hydrogen is that it is the only practical fuel that contains no carbon; therefore burning it or otherwise using it can’t generate carbon monoxide or carbon dioxide, that evil global-warming gas. When pure hydrogen is used in internal-combustion engines the exhaust gas contains nothing but nitrogen-rich air, steam, and maybe a little NOX (oxides of nitrogen). If we use hydrogen in fuel cells for generating power to run electric motors, we avoid the NOX as well. Therefore hydrogen, like an electric battery, can be used as an environmentally clean portable energy supply.
But the earth has almost no natural hydrogen gas; we have to make the elemental gas from some hydrogen compound by one of a number of different methods. We can electrolytically decompose H2O, but that is an inefficient process, and electricity itself will be in short supply. There are microorganisms that will break down water, but only on a minuscule scale so far.
However, research on decomposing water directly by solar radiation and using photocatalysts is showing considerable promise. According to an article in the May 2006 SCIENTIFIC AMERICAN, research teams at Pennsylvania State University and at University of Texas have been making titanium dioxide nanotubes that have 12 percent efficiency in releasing hydrogen using ultraviolet radiation. Penn State has added carbon to the titanium nanotubes and broadened their response into the visible spectrum, doubling the hydrogen making efficiency. This development sounds well worth watching.
Currently almost all of the hydrogen that we use is made from oil or natural gas. That is doubly wasteful from an energy standpoint since both oil and gas are already in short supply, and the processes for making hydrogen from them are inefficient. If we must use fossil fuels to make hydrogen we should use coal, since its depletion is considerably further off.
The problem in making hydrogen from fossil fuels is not only the accelerated depletion of these fuels, but there are no developed economical ways of making it in quantity without also dumping huge amounts of carbon-dioxide gas into the atmosphere. Because of the low efficiency of the conversion processes, for the same amount of useful energy over twice as much CO2 is generated and twice as much fuel is used in making hydrogen from fossil fuels as is generated by burning the fuel directly in existing automobiles.
There are some undeveloped proposals for “sequestering” the carbon dioxide generated at fuel processing and power plants, but until we can economically do that and find suitable places to put the CO2, we would only be shifting the generation and release of the undesired carbon dioxide from the highways to the processing plants.
Hydrogen is the lightest element and gas. That fact presents another major disadvantage of hydrogen as a fuel. It is the weight of a quantity of fuel that determines the energy it contains, not its volume. It would take an enormous tank to carry an adequate supply of hydrogen gas at atmospheric temperature and pressure. We currently have two marginal solutions to that problem: We can hold the hydrogen at very high pressures in an expensive, strong, heavy, and potentially dangerous tank; or we can liquefy the hydrogen and store it in an expensive large super-insulated thermos bottle (Dewar vessel). Excellent insulation is required to keep the liquid hydrogen from boiling away at an excessive rate. (It boils at 253 degrees below zero centigrade, or 420 degrees below zero Fahrenheit). These hydrogen-carrying methods can’t begin to approach the energy-to-weight ratio of gasoline in a tank at atmospheric pressure and ambient temperature; and both methods introduce more significant safety issues than gasoline tanks do. There is a safer method for storing hydrogen that could possibly become practical. Some “hydride” compounds, such as sodium-boro-hydride, will release hydrogen upon demand. Daimler Chrysler has done work in this area.
But currently there is no really satisfactory method of storing an adequate amount of hydrogen in a vehicle for highway use. However, the much lower range and performance requirements for the street mode does make hydrogen a viable portable energy source for dualmode cars, if we can get an affordable green source of hydrogen.
But “energy source” is a poor choice of words in connection with hydrogen. Coal, petroleum, natural gas, the sun, etc. are true energy sources, because we have them available. But we should not look upon either hydrogen or electricity as sources of energy, because we don’t have them naturally—we have to make them from some true source of energy. Hydrogen can be used as a “carrier” of energy, along with electricity, steam, springs, elevated weights, flywheels, and storage batteries. But none of these are sources of energy because all of them require that we put energy into them before we can take it out.
We must not believe all of the grand claims being made by those promoting hydrogen power. For instance: I have seen the claim that we have unlimited hydrogen fuel in the water of the oceans. That is fraudulently false, since it currently takes much more energy to decompose water to hydrogen and oxygen than we can get back in using that hydrogen in a fuel cell or in a hydrogen-powered internal combustion engine. Water can be seen not as hydrogen, but only as raw material from which to make hydrogen. There is no free lunch. When we develop controlled nuclear fusion the price of “lunch” may go way down, and “oceans of fuel” would then be less of a stretch.
Fuel cells are comparable to storage batteries, except that instead of seemingly “storing” electricity by means of internally reversible chemical reactions, fuel cells generate electricity through the oxidization of hydrogen gas. Fuel cells, which are not reversible, must have hydrogen fuel delivered to them. Like internal combustion engines they use oxygen from the air, but they don’t “burn” the fuel in the usual combustion sense. And since hydrogen contains no carbon, the exhaust from fuel-cell reactions contains no carbon dioxide, just water.
Cars powered by fuel cells have electric motors for propulsion, just as battery-electric cars do. Most environmentalists like fuel cells because they supposedly eliminate pollution and save fossil fuels. (“Supposedly” is emphasized because as we discussed, the only currently affordable way to get hydrogen in quantity is to make it from fossil fuels; but then we still have the problem of the carbon dioxide generated at the hydrogen plant.) And because of the inefficient processes, that will be over twice as much CO2 as we get when we use the fossil fuel directly in cars. We would make more CO2 because we use up more fossil fuel. Seen in these ways, hydrogen and fuel cells are currently a lose-lose proposition.
There are also “reforming” fuel cells that run on alcohol or methane gas (the chief ingredient of natural gas) instead of hydrogen. But these two fuels contain carbon; so reforming cells would again produce carbon dioxide that would be released along the highways. That would still be a loser.
ENVIRONMENTALLY CLEAN INTERNAL COMBUSTION
Instead of using fuel cells, street-mode cars could burn hydrogen fuel in internal combustion engines similar to the engines that now power our automobiles. It should be emphasized that internal combustion engines per se aren’t the bad guys; it is the hydrocarbon fuels we use in them that cause most of the environmental problems. But again, we don’t have the hydrogen. And if we did, carrying enough of it in the vehicles would be a problem.
WHICH STREET-MODE POWER?
None of these low-pollution power systems could provide the range or performance of present automobiles because the “energy densities” of all of these alternate power sources are much lower than that of gasoline. Therefore none of them would be widely accepted for highway use. But any of the alternate power systems discussed above would be adequate for the street-mode of a dualmode system since there the cars will not have to travel either far or fast, and “passing power” isn’t needed on the streets.
We might choose to pass laws that would require car manufacturers to limit the street-mode speed of dualmode cars. This would reduce accidents and save lives of drivers, passengers, and pedestrians as well as save energy. Such laws would doubtless be unpopular with many but they would not be violated, because the cars themselves would be set to obey the speed limit. Greater pressure on the accelerator pedal would have no effect.
Service stations could carry hydrogen and/or charge batteries. Batteries could also be charged at home, at public parking spaces, at parking lots and garages, and while traveling on the electric guideways. We could also charge the batteries by simply parking the cars over buried electric battery-charger coils instead of using charger cords and plugs.
It has also been suggested that the cars could be designed so a discharged battery could be removed and replaced with a recharged one at a station in less time than it now takes to pump a tank of gas.
There will be competition among rechargeable batteries, fuel cells, hydrogen engines and perhaps other portable energy systems. Early cars may use one system, and later cars use another. And different manufacturers may build and sell cars with different street-mode power systems. Experience and further developments will improve all of these systems. But based upon what we know today, the author predicts that lithium batteries will prevail over other means for powering our dualmode cars in street mode.
Next: CHAPTER 7
On the Guideways
Back to: CONTENTS
Last modified: August 01, 2006