Really? Never took a physics class?

[Triple J]

I do realize that the water cycle is a closed loop system. The thing is, some places get more water than others.  Or rather, some places get more water than they use while others use more water than they get.  Who is to say that the hydrogen making plant in Las vegas will get the exact same amount of water that it uses up from rain?  May be in 50 years or so the water levels of the hoover damn may go back up to previous levels.  You do have to give nature some time to work things out but now your adding to the equation where you are quite possibly using exponentially more water than previous consumption levels.

That is my concern.  If one city uses up X amount of water, it is not guaranteed that they will get the same X amount of water through rain. 

So just replace oil refineries with desalination plants.  Hydrogen generation facilities can get their water from them instead of from the fresh water supply.

[Ducatiloo]

So just replace oil refineries with desalination plants.  Hydrogen generation facilities can get their water from them instead of from the fresh water supply.

The cost of desalination plants are so high no one uses them for anything but drinking water.

[Triple J]

The cost of desalination plants are so high no one uses them for anything but drinking water.

I understand they are expansive...but so are refineries, and so is oil.  If people are worried about the hydrogen option depleting our fresh water supplies, which is a very valid concern IMO, I would bet that a desal plant would work financially.

Compare the cost of a desal plant to a new refinery.  I'd bet they are similar.

[ducatiz]

The cost of desalination plants are so high no one uses them for anything but drinking water.

i was under the impression it was just the opposite-- that the expense to produce potable water is so great means only light brackish water is produced for crop use (i.e. is cheaper to produce)

that's what Israel is doing with their desalinization plants.

[OwnyTony]

So just replace oil refineries with desalination plants.  Hydrogen generation facilities can get their water from them instead of from the fresh water supply.

What i was addressing is that someone mentioned that a hydro plant be in every major city.  Not every major city is near the ocean. 

Better yet, we can make a huge man made river/canal that transports ocean water inland, use that water to cool nuclear reactors.  Collect the steam and make fresh water.  Build a hydro plant next to the nuclear plant so that it can use the steam/fresh water to produce hydrogen while the nuclear plant can provide electricity for the the electrolysis needed to produce the hydrogen.  GENIUS!!

[zedsaid]

why would you desalinate water to extract hydrogen?

Pure water isn't particularly conductive, it's when it's got salts/minerals in it that it carries current.  I learned this in chemistry 15 yrs ago.

Electricity is what you run through water to break off the hydrogen.. so why not just run it through saltwater?

I remember the experiment we did, and no salt = no hydrogen. 

No one's mentioned the happy bi-product of the hydrogen plants... all that oxygen that can go to your local "oxygen bar"... did i mention i live in LA?

[Popeye the Sailor]

Er....easiest way to get more mileage out of any given motor.....is change the gearing of the rear end/transmission....

[OwnyTony]

why would you desalinate water to extract hydrogen?

Pure water isn't particularly conductive, it's when it's got salts/minerals in it that it carries current.  I learned this in chemistry 15 yrs ago.

Electricity is what you run through water to break off the hydrogen.. so why not just run it through saltwater?

I remember the experiment we did, and no salt = no hydrogen. 

No one's mentioned the happy bi-product of the hydrogen plants... all that oxygen that can go to your local "oxygen bar"... did i mention i live in LA?

Im not for sure but i thought that if the water was pure, the byproducts of electrolysis would be just oxygen and hydrogen.  Im not sure if the salt in the water produces a different gas that would be mixed with the hydrogen or oxygen.  I could be wrong but that was my thinking in needing fresh water.

[acalles]

I was led to believe the NOx levels of the PD were pretty modest in comparison to most.  I love my car, it runs beautifully.

we test drove the '09 "Loyal Edition" Jetta TDI.  Very nice, probably get one to replace the Volvo since they won't bring the D5 to the US.  Which sucks since I love Volvos (4th, all 850/S70s) and we liked the D5 that we rented in Italy...

From what I understood, they fired much leaner mixtures, at significantly higher pressures.. so the combustion was very hot, burned up most of the particulates.. but the cat was to reduce the NOx.

the SO2 problem was mostly a fuel issue, it should be resolved now (or significantly reduced) with the newer ultra low sulfer fuels. It also makes it possible to run the new cars at even higher pressures.

I looked it up http://en.wikipedia.org/wiki/Fuel_efficiency
RUG 125,000 btu's / gallon......Diesel 138,700 btu's / gallon............Ethanol 84,600 btu's / gallon
Diesel has about 15% more energy per gallon. But diesel cars tend to get 30 - 40% better mileage.
As injection pressures climb and get more refined the smoke and clatter will go away. The worst offenders that I see are grossly overfueled pick-ups ( trying to get the last Hp / ft lb, who cares about a little smoke)

one is more energy, two is the ability to run very lean, since fuel is injected causing the burn, at light loads (cruse) the fuel can be injected at very lean levels (I believe it can burn at up to 40:1), and since the injection is what causes the ignition it only burns very small amounts of fuel with little to no danger, especially once you add the EGR, and fill 30-40% of the cyl with exhaust gases, which will not burn again.
basically makes the cyl smaller. get all these things right and you have a awesome running vehicle, power when you need it, and great efficiency when you just want to put around.

even with the high efficency of the newer diesels (like the PD) there is still quite a bit of unburnt fuel, much more then with gasoline.. don't belive me? check out the EGR cooler. the higher pressures of common rail systems should help get rid of this problem.

[NAKID]

Er....easiest way to get more mileage out of any given motor.....is change the gearing of the rear end/transmission....

Only for higher speed cruising. Too high of a final drive ratio will lead to load too high for the lower rpm and tq. The engine will bog. Now if you keep the first few gears normal, and go real high for the higher gears for highway cruising. Problem is though, most of the wasted fuel is due to high traffic in city driving. Idling wastes tons of fuel...

[zedsaid]

Im not for sure but i thought that if the water was pure, the byproducts of electrolysis would be just oxygen and hydrogen.  Im not sure if the salt in the water produces a different gas that would be mixed with the hydrogen or oxygen.  I could be wrong but that was my thinking in needing fresh water.

There'll be corrosion  and whatnot, but i don't know if any impurities would escape into the gas... besides, there'll be valves and such to sort any contaminates...

here's a page with info about the conductivity of water at least...

http://www.lenntech.com/water-conductivity.htm


and a quote from it...

Pure water is not a good conductor of electricity. Ordinary distilled water in equilibrium with carbon dioxide of the air has a conductivity of about 10 x 10-6 W-1*m-1  (20 dS/m). Because the electrical current is transported by the ions in solution, the conductivity increases as the concentration of ions increases.
Thus conductivity increases as water dissolved ionic species.

Typical conductivity of waters:
Ultra pure water     5.5 · 10-6 S/m
Drinking water        0.005 â€" 0.05 S/m
Sea water             5 S/m

[junior varsity]

when you talk about numbers of gallons of freshwater, you must think large scale. I was just reading about this the other day.

The city of Memphis has more than a quadrillion gallons in one of the cities underwater aquifers. Clean water. (Some of the best tasting right out of the tap too, of all the cities I've visited).

Quadrillion. A number I can't fathom. Then again, it rains a lot in Memphis and its stupid humid, and referred to as "the jungle" (for many reasons).

Its not the only aquifer for the city either.

That's a lot.

[Triple J]

when you talk about numbers of gallons of freshwater, you must think large scale. I was just reading about this the other day.

The city of Memphis has more than a quadrillion gallons in one of the cities underwater aquifers. Clean water. (Some of the best tasting right out of the tap too, of all the cities I've visited).

Quadrillion. A number I can't fathom. Then again, it rains a lot in Memphis and its stupid humid, and referred to as "the jungle" (for many reasons).

Its not the only aquifer for the city either.

That's a lot.

Not all cities get their water from underground aquifers though.  For instance NYC and Seattle (the supplies I'm familiar with) get theirs from lakes.  These rely on yearly rainwater for replenishment.  Add in a few drought years and things can get tight.  Add in millions and millions of gallons of fresh water being used to create fuel, and you could feasibly have a downright crisis.

Just to present an intteresting #...NYC uses approximately 960 million gallons of water per day.  This is quite a bit below the "safe yield" of their watersheds, i.e. the amount that is replenished by rainwater; however, they're currently looking at system expansion to ensure they can always meet their goals.

I'm just not a fan of ever using something people need to live (i.e. freshwater or food) for the production of fuel.  It causes the cost of said commodity to go higher, and raises the possibility that survival needs will have to compete with energy needs.

[zedsaid]

Not all cities get their water from underground aquifers though.  For instance NYC and Seattle (the supplies I'm familiar with) get theirs from lakes.  These rely on yearly rainwater for replenishment.  Add in a few drought years and things can get tight.  Add in millions and millions of gallons of fresh water being used to create fuel, and you could feasibly have a downright crisis.

Just to present an intteresting #...NYC uses approximately 960 million gallons of water per day.  This is quite a bit below the "safe yield" of their watersheds, i.e. the amount that is replenished by rainwater; however, they're currently looking at system expansion to ensure they can always meet their goals.

I'm just not a fan of ever using something people need to live (i.e. freshwater or food) for the production of fuel.  It causes the cost of said commodity to go higher, and raises the possibility that survival needs will have to compete with energy needs.

They don't need to use potable water.... there's plenty of waste water wherever there's settlement.

[NeufUnSix]

Er....easiest way to get more mileage out of any given motor.....is change the gearing of the rear end/transmission....

That's basically what many manufacturers are doing as a half-assed attempt at improving mileage. The latest generation of 6+ speed autos are programmed to upshift into the highest gear possible as fast as possible - some are into 6th by the 30-40 mph range if you are light on the pedal. What results is horrible shifting and dreadful response because the 'box is constantly aiming for the highest gear rather than a gear that would be optimal for acceleration and exploiting the torque curve. The only way they'll hold a gear and shift acceptably is if you have a lead foot, which of course kills the fuel economy gains.