Air Cars and Hydrothermal Vents

Air cars are already being made :

http://www.mdi.lu/english/

Thanks for the comment, but that's not why I posted what I did.

There have been numerous back-and-forths about the feasibility of air cars. I had hoped to provoke anyone from either side to prove that air cars can compete with other technologies or to prove that air cars cannot compete with other technologies.

This is from a Google Search for "compressed air+energy to produce" There were 507,000 hits in 0.21 seconds

This paragraph is an eye opener:

"A 1.17 rated horsepower air operated mixer uses 45 cfm at 80 pounds-per-square-inch (psi) and operates 40 hours per week. The cost of the compressed air to operate this motor over a year is $1,292. A comparably sized electric motor of Energy Policy Act (EPACT) efficiency, rated for hazardous locations, is around $350. The cost to operate the EPACT motor under the same conditions is less than $100 per year. Including installation, payback is under one year."

12-1 difference between an Air Motor powered by an electrically driven compressor and an Electric Motor doing the same amount of work is not very economical. Read the whole article to see if Compressed air is an economical way to transmit energy.

Thermal Vent power is not one I can comment on.

I didn't start this thread recently -- I merely started a new thread. I don't necessarily agree that tapping hydrothermal vents in the deep ocean is feasible, and my gut feeling as an engineer is that air-motor powered vehicles are not feasible, but if anyone can design and build one that is, then why not?

My comments here are to challenge anyone who believes strongly one way or the other to do something rather than beat it to death with mere words in this forum.

Go back to your textbook and review thermodynamics. You will answer your own question. It really is a no-brainer unless you are one that anticipates a point in time when we learn how to violate the laws of thermodynamics.

Apparently I'm not making myself clear . . . I DO NOT think air-powered cars are feasible, nor do I think tapping into the energy spewing out of hydrothermal vents is very practical or feasible either.

I guess this is the part that confuses me:

" my gut feeling as an engineer is that air-motor powered vehicles are not feasible, but if anyone can design and build one that is, then why not?"

It seems to infer that you don't know for sure that it is infeasible and what I'm saying is a review of the facts might help you resolve that uncertainty. To be clear, what I am saying is that, short of someone changing the laws of thermodynamics, there really is no ambiguity about the unfeasibility which makes the notion of "why not?" invalid. I'm pointing to why not. There isn't any hidden magic. We've already beat this one to death.

I have not done any thermodynamic calculations because my gut feeling tells me that air cars are not feasible. If my gut feeling had told me that air cars may be feasible, then I may have done a little investigating. So, the inference that I "don't know for sure" is, at least partly, true.

The "why not" question leaves open the possibility that someone may invent or discover a way to compress gas (to a liquid state perhaps) using wind or wave power (free energy after amortization of capital costs), design an efficient air motor, etc. But, you won't see me working on such a thing.

And I agree, this one has been beaten to death long ago.

The air car thing is really retro tech. This concept was tried with trains well over a century ago:

http://www.dself.dsl.pipex.com/MUSEUM/TRANSPORT/comprair/comprair.htm

Yup, beaten to death, but there are still companies trying to sell this idea.

As for Hydrothermal power, a novel idea, perhaps with potential. But I don't see it happening anytime soon. Greenpeace would tie it up in the court for decades, (and if built, would be crashing their boats into it).

The compressed air car concept has already been covered in depth on CR4 in quite a few different threads (ken and I have assessed the different techniques and written quite a bit on the subject).

http://cr4.globalspec.com/comment/315311/Re-new-air-powered-car

Also search "air car" along with "jack of all trades"

Unlike compressed air vehicles, hydrothermal vent use for power generation is actually promising.

OK, I'll tell you once again.

Air powered vehicles have been around for more than a century; they are much like steam powered vehicles, but they use compressed air. Like steam powered vehicles, they tend to be only about 15 per cent efficient. Steam cars are inefficient because they lack a condenser. The exhaust is steam at atmosphereic pressure, and the heat of vaporization is wasted warming the atmosphere. Air cars are inefficient because the air compressors are inefficient; they are air cooled and waste heat warming up the atmosphere.

The trick is to conserve heat. Cool the air compressor by injecting water, which turns to steam, absorbing gobs of heat. The output is a mixture of air and steam, which I call wet compressed air, WCA. the patent goes into detail on the thermodynamics.

Assuming the compressor and the WCA storage tank are insulated, little energy has been lost. Upon expansion through a "steam" engine, the air expands and cools, and the steam condenses, reheating the air. So, the input is air and water at ambient temperature, plus mechanical energy, and the output is air and water at about ambient temperature, plus mechanical energy. Where did 85% of the energy go? It didn't; the system is thermodynamically reversible, "perfectly" efficient. (Obviously there are losses to friction) In 1930 the diesel-pneumatic locomotive pictured below, but a box cab added, was tested against a diesel-electric locomotive and was found to use 26% less fuel pulling the same train over the same route on the same schedule. The compressor-air motor were more efficient than the electric generator-motor. Surely air tanks are cheaper and more efficient than batteries.

I could easily convert a diesel crew cab pickup truck (4 seats to qualify for the auto xprize) by converting the engine to air (new cam) and putting tanks in the back. About 70 cubic feet could contain 70 kWhr, equivalent to 2 gallons of gasoline, and should be able to drive it 200 miles. (My Prius consumes about 20 kWhr/ 100 miles)

Obviously, I haven't built the vehicle, nor won the$10 Million prize, but show why it can't be done.

ESBook wrote:

"Obviously, I haven't built the vehicle, nor won the$10 Million prize, but show why it can't be done. "

You are not listening. However, I will gladly change my mnd when YOU build you're design and an independent test outfit documents/proves you're system actually is even 85% efficient. The old saying "Put your MONEY where your MOUTH is" still rings true today. A prize of $10,000,000.00 should make any donor, you convince of your systems viability, put up the price to build your contraption. After all, the way I understand your idea, you would not have to design and build anything that is not already available. Assemblling off the shelf ncomponents ca't be that expensive.

Until then I still believe "Hope Springs Eternal" for an efficient compressed air drive. ESPECIALLY SINCE ALL THE EXAMPLES YOU GIVE ARE FROM THE PAST. Why are they not resurrected and running today whle electric drives are in use in several applications.

"Until then I still believe "Hope Springs Eternal" for an efficient compressed air drive."

How many demonstrations do you require? The locomotive worked.

"ESPECIALLY SINCE ALL THE EXAMPLES YOU GIVE ARE FROM THE PAST."

Future exmples cannot be posted at present.

"Why are they not resurrected and running today whle electric drives are in use in several applications."

1. The details were kept as a trade secret, no patents that I can find.

2. The German railroads in 1930 were not about to dieselize. Perhaps if they had captured some oil fields...

3. When you are a hammer salesman, everything looks like a nail. Screws are not wanted. When you are General Electric, all locomotives look like electrics. Pneumatics are not wanted. When you are President and have just announced $2 Billion for battery research, you are not about to fund competing "low tech" schemes. It would be embarrassing. (I've been through this with Dept. of Energy. They say WCA would work, but they have "something better." They would not tell me what that was.)

I would love to build my own air car, but at present I put off grocery shopping until payday. To win the prize, one not only needs a car, and a professional driver, and an entry fee, one needs a business plan to produce 10,000 cars in one year. Respectfully, even General Motors would have trouble introducing a new model in less than a year. If someone (an auto dealer?) wants to team with me, I'm available.

the WCA is all wet, it doesn't work. The metalurgy limits the compression when you add water into the air. A two stage air compressor can only make 150 psig air. after 5 stages you get 1200 psig.

I did a simulation that limited the metalurgy to 450F. A 40 HP expander requires a two stage 70 HP compressor and a 26 HP water pump to get the water into the discharge to cool it. The final exhaust from the expander is air at 125 F and 1/2 half your injected water goes into the air, so you'll be consuming 8 gallons per hour of water.

"the WCA is all wet, it doesn't work."

Golly, it worked in 1930 in Germany. Perhaps they employed Harry Potter? It was a trade secret, so details are unavailable, but no one disputes that it did work more efficiently than a diesel-electric locomotive.

"The metalurgy limits the compression when you add water into the air."

How so? Corrosion? Do I need to use a bronze compressor?

"A two stage air compressor can only make 150 psig air. after 5 stages you get 1200 psig."

Why use multiple stages? What is the peak compression pressure in a single stage diesel engine cylinder, say 30:1 compression ratio? Intercoolers between stages are wasters of energy and are not necessary if the temperatures are moderated by water. The diesel-pneumatic locomotive used single stage air pumps and, judging from the size of the "steam" engine cylinder, the pressure was at least 200-300 psi.

"I did a simulation that limited the metalurgy to 450F. A 40 HP expander requires a two stage 70 HP compressor and a 26 HP water pump to get the water into the discharge to cool it. The final exhaust from the expander is air at 125 F and 1/2 half your injected water goes into the air, so you'll be consuming 8 gallons per hour of water."

The water goes into the intake of the compressor at atmosphereic pressure. Gravity feed and a carburettor should do the trick. 26hp?? The input is ambient temperature air and water, and the expansion is the inverse of the compression, so the exhaust is ambient temperature air and water. Granted, it you input dry air, low relative humidity, you lose some water, but water is cheap. In the 1930 locomotive, they were used to pouring water into locomotives, and water is cheap, so they made no effort to recycle it. In a car, one would not want to leave a cloud behind, annoying the guy who is tailgating you, so you filter the drops out.

Your analysis used 96 hp to get 40 hp out. Where did the 56 hp go? When you limited temperature to 450F, was that peak or average?

Consider this thought experiment. I have a pile driver and a length of drill pipe, closed at one end and with a piston and rod in the other end. The pile driver weight drops and pushes the piston in, compressing the air quickly (so as to minimize heat conduction) to some high pressure. The kinetic energy of the falling weight has compressed the air. The air then expands and throws the weight back up. This is not unlike the air springs used on busses and trucks. However, the bottom of the pipe will get very hot, so we should water cool it. If the water is outside the pipe, the hot water represents waste energy. If the water is inside the pipe, it will absorb heat, cooling the air, and, as the air expands, the water (steam) will reheat the air, cooling the water. If the pipe is insulated and things happen quickly, little heat energy is lost. Except for friction, it is a perfectly reversible process.

I'm quite willing to be proved wrong, but I would want to see the assumptions and calculations involved. For example, you might assert that the water droplets entrained in the air will not change phase as the air is compressed. I would expect that assertion to be backed up with data from steam tables and so forth. As I read the tables, the critical point for water, at which the liquid phase cannot exist, is somwhere near 450 F. Please correct me if I'm wrong. If you have a good algorithm for computing the temp and pressure of the mixture during adiabatic compression, please post it. I've been trying to sell WCA for years, and if it really BS I'll stop and be quiet. But no has yet convinced me it is BS. Even the NIST and the Dept. of Energy said it would work, but they were busy funding batteries.

I already assumed 100% staurated air coming into the first stage. Air can only hold 4% by weight of water, you don't really make any sizeable amount of "steam".

Diesel engines do not do 30 to 1 compression ratio. 22 to 1 is normal. At 30 to 1 compression ratio on a air compressor, 1 stage, the discharge temperature is 1500 F at 420 psi. That would call for tungsten alloy. Dropping back to 22 to 1 drops the discharge temp to 1200 F at 280 psi, a 304 stainless might be used. If you inject nearly stociometric diesel fuel, the temperature drops from 1200 to 350 to 400 F. adding water to saturation drops the temp by 100 Degrees on the discharge.

Cylinder size is not an indicator of pressure in most cylinders, rod diameter is the weakest link as it compares to cylinder.

How do you cool the interstage on the compressor, by a water cooler or in your case, injecting water to cool it? Have you never run a shop air compressor before? I've run fire floods where we injected air into the ground at 1000 psig, with extra cooling, it takes a 4 stage air compressor.

Where does the missing energy go, to entropy and to boiling the lost water. The temperatures are steady state, there will be slightly higher and lower conditions as the valves on the compressor open and close.

Again, the closes we can get to reversible would be to have 10,000 stages of compression, the higher the compression ratio, the less "reversible" the process. I suggest you look up polytropic efficiency.

H2O at 450F is still liquid at 422.16667 psia.

Here join one of my organizations, http://www.iapws.org/.

Here is my general purpose thermodynamics simulator, you can download and try it for two weeks, then lease it for $10,000/year.

for free you can do single point enthalapy and entropy here. http://webbook.nist.gov/chemistry/fluid/

I picked 30:1 as an example, because the VW Rabbit diesel, with an auxilliary chamber, is 26:1, and I figured by filling the pre-chamber a bit 30:1 would be reasonable.

The idea is to use water inside the cylinder to absorb heat by vaporizing. (A century ago, large gas engines, that's producer gas, were cooled by injecting water)

If, as you suggest, the water won't vaporize, therefore won't cool the cylinder significantly, then the idea fails. But it worked in Germany, at lower pressures.

My guestimate of the operating pressure of the locomotive was based on eyeballing the cylinders. If the loco used steam at 200-250 psi, I would expect a larger diameter. You may note in the illustration the double-acting cylinder with cross-head, relatively low speed because it's directlly coupled to the wheels, no separate crankshaft. Otherwise, everything looks like a stock steam loco. The compressor, as far as I can see in several photos, had no visible cooling jacket or fins, and there was a reference to injecting water to cool it.

Thanks a lot for the site references. I'll have to take some time to use them.

"The input is ambient temperature air and water"

Not to nit pick, but the temperature here last night was below freezing. How am I going to start my air car if it's a popsicle?

Air cars are an obsession of mine, at least those using liquified air as fuel. (check my website darlap.com ) As to whether they are practical, this depends upon your definition of practicality. If a powered rickshaw or golf cart sized automobile making 3 miles per gallon and traveling at 30 to 35 MPH and creating NO pollution qualifies, it certainly is. It seems to me that after ruling out the use of burning hydrocarbon fuels, that cryogenic energy storage is the next most practical.

Dr. Mitty Plummer built a similar vehicle out of an "off the shelf" air motor, and some baseboard heaters. He was using liquid nitrogen, but liquid air would work as well plus offer the lubrication characteristics of liquid oxygen. A century previously, it was discovered that a normal steam car with it's boiler filled with liquid air and a fan instead of a burner would run quite well for a short period until it frosted up.

Actually, I have been working on the feasibility and methods of portable storage of power through cryogenics for better than two years, and believe I have it pretty well "all figured out". Considering that we are evaporating the liquefied air with atmospheric heat which is without cost to us, the efficiency figures don't seem too bad.

If we are interested in having a discussion involving what seems to be facts and their interpetation, I will take the trouble to go through the process step by step if anyone seems interested. If we want to ridicule (the term "jab" bothers me) I may not wish to play the game. (this certainly doesn't mean that if I am in error what I would not want it pointed out) Ayyon

"If a powered rickshaw or golf cart sized automobile making 3 miles per gallon and traveling at 30 to 35 MPH and creating NO pollution qualifies, it certainly is. "

That means a 30 Gallon tank of the Liquid Air would about 90 miles. If it could be produced at 0.03 cents a gallon that would be a reasoable ride. People living close to their work could certainly benefit.

Where does the energy to run the "baseboard heaters" come from?

How much does it cost per gallon to produce the Liqud Air?

What energy is used to produce the Liquid Air?

How is the liquid air tank filled at the end of the 3 mile journey?

"it was discovered that a normal steam car with it's boiler filled with liquid air and a fan instead of a burner would run quite well for a short period until it frosted up."

Evidently he did'nt have any Baseboard heaters on that design.

Define "Short Period of Time." before it frosted up.

Sounds like a "Barn Burner" plan as my friend George so eloquently put it when he heard of a new innovation.

Hello Bud:

Energy storage through liquifaction and reevaporation of ordinary air is in no way comparable to energy storage through burning hydrocarbons. In most cases it is more expensive, certainly more bulky and heavy, must be stored in well insulated containers, presents a problem with solidification of lubricants at -300 F, and under most designs eventually insulates it's heat exchanger surfaces through frost formation. It's only redeeming feature is that if you take hydrocarbons off the table it comes in a distant second best, and that you don't require third rails, broadcast power, or very long extension cords to power a non-stationary device.

It is a liquid and can be poured or pumped which gives it, besides the other advantages over batteries of lower cost and less weight almost instant recharge simply by refilling the tank.

It can be made from ordinary air with anything which can be made to turn a shaft; geothermal, hydraulic, solar, tide, ocean temperature variations, wind, "off peak" electricity, or nuclear. As a rough idea of it's cost to make, app. 2 KWH of electricity gets you a liter of liquid air. If you are hear a large power source and can get electricity for 2 cents per KWH, an argument can be made that it is cheaper than gasoline. If you pay 8 cents like I do here in the midwest, or 20 cents like on the West coast, it isn't.

I used the wrong terminology in describing the devices used by Dr. Plummer as "baseboard heaters". While this was the purpose for which they were built, in his application they are heat exchangers (boilers if you prefer) and work by pumping liquid air into one end, letting atmospheric heat transfer through the fins and walls causing evaporation and an increase in volume of at least 800 X and using the now gaseous pressurized air run an air motor.

Clearly the amount of time to produce a layer of frost of sufficient thickness to impair heat transfer would depend on the humidity of the air, but I am guessing it could be as little as 15 or 20 minutes. This is why I designed a rotary heat exchanger which keeps itself frost free by shearing the frost from the cold surfaces through centrifugal force.

How effeciently I can turn the compressed air into power remains to be seen. An old of rule of thumb was that a good steam engine was 90% efficient at utilizing already formed steam. Some of the modern air motors claim something like 98% efficiency. (before getting too serious about literally applying conventional thermodynamic formulas and ratios to liquid air applications, please keep in mind that negative values in "normal" calculations such as heat loss through cylinder walls or friction become plusses when collecting heat from the atmosphere)

bill_michaels

i took 100 pounds per hour of air, compressed to 15 psig and cooled it to liquify it. It took 1.5 ton of refrigerant at -312 oF. that takes about 100 Horsepower. I pumped the liquid air to 300 psi, that took about .5 HP. I heated the air to 700 oF which vaporized and took 3 tonnes of heat (which use $5 of electricity at $.02/kw-hr everny 24 hours it ran). The 75% expander turbine would then put 7HP to the wheel of your car.

so you run over 100 HP in equipment taht costs about $500,000 and you end up with 7 HP in your air car, 7% efficient in my book

Dear Vincini:

Respectfully, I find considerable discrepancy between your perspective and mine, and although I have found considerable support for my position, It is certainly possible that I may not fully understand the problem.

First, it seems to be an article of faith that just cooling gaseous air will not liquefy it; that it takes pressure plus cooling it. I admittedly haven't tried it, but I believe it to be true. The "Stirlair" company makes relatively small portable units for creating fog in stage illusions and in their Indian facility for freezing sperm. They advertise a production of roughly 1 liter of liquid air at atmospheric pressure from the expenditure of roughly 2 KWH of electrical power plus water cooling. I believe them.

You say "pumped the liquid air to 300 PSI". Why? evaporating liquid air in a confined space will produce pressure. Why add heat to 700degrees F? Anything greater than -312 F will evaporate the liquid air causing a great increase in both volume and pressure. As far as the liquid air is concerned ambient temperature represents 350F+ degrees of heat.

The atmosphere is full of solar heat which makes the ambient air temperature what it is. This heat energy is free for the taking, and exactly how efficiently it can be used is of little concern of mine.

Now, compressing the ambient air to make more heat available from it would be a good idea if the energy thus gained exceeded the total energy required to compress it. Theoretically this is quite feasible, as witnessed by the "heat pumps" currently in operation, but is not part of my initial design.

Please help me to understand your perspective on this.

bill michaels

Hi bill_michaels:

Interesting idea

Because it doesn't take much energy to compress a liquid, you could use a small pump to compress the LA (liquid air) to a high figure which, when evaporated and heated to room temp would give very high pressure compressed air and hence a high energy density.

I'm thinking of pressures like 150MPa (about 22,000psi - an arbitrary figure of no special significance except it is far higher than any sane person would normally try to store bulk compressed air). The energy available from this would be huge, and it might even make the scheme feasible.

s a machine prototype (motor), which could be used in any vehicles, industry, buildings, robots, etc, and it doesn't produce any pollution because it uses the thermal energy from the environment for working, as only fuel.

you could visit : www.tonson-motor.com for more information.

The site link you have provided is for special application air-powered motors. These work of compressed air and are designed for applications where electric motors are not suitable (such as hazardous areas). They don't produce any pollution but they still require a source of compressed air to run, and therefore are less efficient than existing electric motors (by their very design).

and it doesn't produce any pollution because it uses the thermal energy from the environment for working, as only fuel

What thermal energy ? This is mentioned no where on the site.

The Dept. of Energy and others will say that air cars are inefficient, because commercial air systems are only about 15% efficient, energy in vs. energy out. You know that compressing air need not be that inefficient. For example, when your Toyota drives over a bump, the air in the tires is compressed, then expanded. If it were not almost perfectly efficient, what would happen? The tire would heat up and explode? (That can happen) Go flat? Another example is a thunderstorm.

now you getting just plain silly. What's next, the DOE hiding a 101% eff engine and the oil companies bought up all the patents on super eff car engines. Comercial air systems follow the same thermo laws as home and industrial, as in India, as in the USA. The energy needed to compress air is about 75% efficient. The energy released from compressed air will recover 70%. Then couple the whole thing through gears, drive shafts pulleys or whatever and the net eff for the cycle is under 50%, assuming no losses going into the compression.

If the energy going into the compression is its self from a power plant, ant that power plant is at best 40% ef, then the whole system is under 20% eff. If you burn gasoline directly, the whole system is about 25% eff.

OK, consider that when Chrysler wanted to cut out four cylinders of their V-8 engine, to save fuel, the most efficient way was to A. cut off the fuel, and B. disable the valves. That way the air in the cylinder was compressed, consuming energy, but it gave back the energy on expansion. Apparently the engine didn't know it was so inefficient (.75x.70= .52).

The important thing is to manage heat transfer, which is generally wasteful, and when things happen quickly, like the compression stroke in the engine or your tire hitting a bump, the heat transfer is minimised. When commercial compressors are air cooled, of course they waste energy heating up the atmosphere, in India or in the US or in the MIDI car. Some people just never learn.

The efficiency of the power plant will be egually bad for the electric generator or the compressor, so for "zero-emissions" the question is the comparative efficiency of compressor, storage tank, and air motor vs. generator, battery, and electric motor. Consider also the economics; batteries and copper are expensive and will not easily scale up for utility load leveling or such. Air, on the other hand, does not have to be mined or smelted (EPA and OSHA compliance), is non-toxic (again, EPA and OSHA compliance), and does not get more expensive as demand increases.

As for DoE and NIST, when you have invested $Billions in battery technology, you don't want to admit that air is a competitor. They evaluated the referenced patent and said yes, it would work, but they had something better. They would not reveal what the something better is.

in thermo dynamics we have a law called the first through third laws of thermo. During compression in you example of the DiamblerChrysler V12, the intake and exhaust are closed. During compression the cylinder consumes energy. Then during expansion it gives off energy. In you thinking the energy in = energy out, NOT TRUE. During compression some of thenergy heats up the gases and the heat is removed via the water. During expansion, more energy is added to the cylinder from the water system.

the equation for temperature rise across a compressor is approximately Td = Ts *(ratios^((k-1)/k)). So at a compression ratio of 10 to 1, and k=1.25 (k is Cp/Cv), and T= 600 degrees rankin, the compression temperature is 600 * 10^1.25 or 950 degrees R or 490 degrees F. the coolant removes energy and the cylinder sees a peak temperature of 300 F Then on expansion, the 300F gas is expander and the temperature in the cylinder drops and if there wer no cooling, the cylinder temp would be 10 degrees F, but we add energy to bring the temperature up to about 140 F, where we started.

So we reject heat out of the radiator and then add heat. SO this process looses energy, but it loses less than letting the cylinder run, it is better, but not a 100% offset.

read about reversible, if you don't believe it, try taking an air compressor and remov the after cooler, then blow the air back into the air intake of the compressor. According to your theory, the compressor motor would stop using power and the piston would run for ever. What happens is the compressor would meltdown to a pile of molten steel in a few minutes. all the lost energy goes into melting the steel.

Yes, of course. As noted previously, the heat transfer to the cylinder walls is not complete, as it takes time. Obviously, nothing is 100% efficient, but allowing a fixed volume of air to be compressed and expanded (much as happens in a tire) is more efficient than having the valves open, when the frictional losses of pumping air in and out (as Sceptic proposes in the next posting) are worse than the thermal losses.

Just to jolly up the thermodynamics, imagine that there were water droplets in the air. As the air temperature rose toward 490 F, the water would absorb heat but, not being connected to the radiator, the heat would remain in the cylinder, and the actual peak temperature would be lower. On expansion, the water/steam would reheat the expanding air. Since the air/steam temperature would not greatly exceed the cylinder wall temperature, the heat transfer would be minimal, and, after several cycles, there would be, on average, equilibrium, with the heat in equalling the heat out. (Since the heat in the cooling water is free, don't count it as a loss) If you look for energy losses, it's mostly in the shearing of oil films on the piston rings and bearings, not much.

A century or so ago, some large gas (coal gas) engines were cooled by injecting a spray of water into the cylinder and onto the cylinder walls. Instead of heating the atmosphere with a radiator, the heat (of burning gas) was used to make steam which, mixed with the combustion gasses, helped move the piston, thus increasing overall efficiency.

Just as a general observation: About 99 % of good ideas never get very far, in the real world of bureaucracies, etc. Things have to be reinvented several times, on average, before the managerial clods will accept them. Also, many good ideas which did go somewhere get lost "in the march of progress" and are neglected, a case of "better" supplanting "good enough", when "good enough" may be the economical solution. For example, for centuries, wind mills (wind turbines) pumped water and ground grain. They were replaced with, mostly, electric motors, long tranmission lines, big power plants, etc. Only comparatively recently have people recognized that, especially if you are miles from the grid, old technology may be more appropriate (say for pumping water for your grass-fed cattle).

A bit more than a century ago, wooden merchant ships were being replaced with steel ships, mainly because wooden ships leak, especially in storms. One needs a big crew to man the pumps during a storm. Wooden American ships were selling for practically nothing, scrap value, and were being bought up by silly Norwegians, who did not realize that wooden ships required big crews. What the Americans did not realize was that the canny Norwegians had wind-driven pumps, which worked great during storms, removing the need for a big crew and making the ships economical to run. Soon the Norwegian merchant fleet surpassed the American one.

Again, about a century ago, there were street cars in Chicago which were powered by compressed air. The car would fill up with air at the downtown terminus, run out to the suburbs and back, to refill again downtown. The performance, average speed, even including the recharge time, was better than the electric cars, and there was no need for overhead wires. But the wires were already in place, and the air compressors were "lo-tech." Electric cars became the standard. Now, however, people are designing "light rail" systems from scratch, where the overhad wires are long gone and not desireable (nor are third rails, from a liability viewpoint). Maybe it's time to reconsider air? However, today's engineers, if asked to design an air powered street car, would probably use air to drive a turbine which drives an AC generator, and then solid-state rectifiers would supply DC to the motors on the wheels. A "steam engine" would be so retro.

The Department of Energy was created during the Carter era to reduce our dependence on imported oil. (Consider how successful they have been!) They did a fairly expensive study to find alternatives to oil-fueled diesel locomotives and, after months of effort, rediscovered that trains could be pulled by coal-fired steam locomotives. Of course, they would have to look like diesels.

Vacuum tubes, the last century's technology, "are obsolete", and most electrical engineers are taught little about them. NASA spent $millions trying to replace vacuum tubes with solid state amplifiers, because vacuum tubes are so passe'. NASA never was very successful, because vacuum tubes are more efficient and are radiation-hard, for use in space. The B-1 bomber has several vacuum tubes in it, but the Air Force will try to deny it. Every microwave oven has a vacuum tube in it.

The RAND Corp. once did a report suggesting the use of lances, vice rifles, because they are inexpensive, require little maintenance, do not need to be resupplied with ammo, don't jam in the mud, and are pretty good at inflicting mortal wounds. It was, of course, satirical, meant to make fun of the McNamarra-era fashion for life-cycle cost as a measure of merit.

you are in the conspiracy theoy mode now. No, adding water does not increase thermal efficency, it allows more work at the expense of more fuel for a given size engine. This has been beat to death as not an efficiency gain, just a way to get extra power when needed at an expense to efficency.

You can buy water and methanol injection system for your car on ebay. The Army used this to get extra power for take off on overloaded P51's, way before Carter created your DOE conspiracy department.

Look up entropy on compression and you will see the loss. Do a thermo model tracking the enthalpy and entropy and post it, then you can get some one's attention.

Water injection in P-51's cooled the intake air (to get more mass in) and may have prevented pre-ignition, but the intent was not to increase efficiency, just raw power. They didn't block off the radiator.

It may be that those guys who built the big gas engines, a century ago, were ignorant of thermodynamics, or perhaps they just didn't want to have to build a bigger, more complex cooling system. The point was that injecting water prevented dangerously high temperatures, and if you are going to cool an engine with steam (Steam cooling was common then, just let the water in the cooling jacket boil away), you might as well let it do some work. Probably they were deluded.

I don't know exactly what Chrysler do, but if I were designing it I would lift either inlet or exhaust valves on the "idle" cylinders so the only loss is friction and a small amount due to uncompressed air being moved from the inlet (or exhaust) manifold in and out of the cylinder.

I wouldn't be allowing the air to go through it's compression cycle, that's simply wasting energy for no reason.

With respect to the original thread, "Power from hydrothermal vents", I would see no fundamental reason why this wouldn't be possible, but why?

Surely it would be easier to extract power from hot rocks and magma, which aren't sitting under umpteen feet of ocean.

A possibility is to drill down to a source of magma, pump in sea water, then the resultant steam can be used for power, with the water condensed and used for irrigation, general municipal water supply etc.

Eventually, a thick crust of salt would form over the magma so a new hole would have to be drilled.

Incidentally, where water is short and power is being generated near the ocean, why not run the steam plant at reduced efficiency and use the waste heat to distill water. I'm sure it could be as cost effective as reverse osmosis, as it gives a use for the reject heat.

http://www.energy.ca.gov/geothermal/index.html

Here is where they lots of geothermal. The local greenies protest because there are earthquakes caused by this activity.

There is no useable waste heat in steam turbine operation, the water returning from the turbine is not hot enough to boil water, they condense the water under a vacuum.

There is no usable waste heat in steam turbine operation, the water returning from the turbine is not hot enough to boil water, they condense the water under a vacuum.

That's why I mentioned "reduced efficiency". If the water to be distilled is used as cooling water and used at higher than normal temp, part can be distilled and used as fresh water. the penalty is a reduction of efficiency of the power generation, the bonus is reduced cost of water distillation.

Obviously there is an optimum balance to be achieved, and under the prevailing conditions, this can be calculated.

It is always cheaper than burning fuel for distillation alone, as reject heat from the steam plant contributes. You need to plot it on a Mollier or TS diagram to see the advantages.

No free lunches anyway you slice it. You ought to see the old Naval ships boiler systems. We had one on land. The ship was decommissioned and the whole set of boilers were transported to the site and reinstalled exactly as they were on the ship.

The triple effect (3 stages of steam ejectors) water distillation system was intact and we made pure water from the brackish produced water. We boiled the water at 80F. Guess what, it still takes 1100 BTU/lb to boil the water at 80F.