Re: Ok, let's do this.
Posted by Dale on Feb 25, 2002 at 10:00
(204.212.222.6)Re: Ok, let's do this. (Mike Kremer)
I will even admit that Hydrogen must cost at least 25% more than its equivalent of Diesel fuel.Since hydrogen fuel is created by inserting the energy from breaking up water (or hydrocarbons) and the energy released is what you get going back to water, the economics are that you pay for the energy in another form to break up water plus losses plus profit. Diesel fuel isn’t the cheapest source of energy so I’ll accept that hydrogen could eventually be as cheap as 125% of the cost of diesel.
But you are still thinking and talking diesel or gasoline engines.Either you don’t understand what I’m saying or I don’t understand what you're saying. Combining hydrogen with oxygen and using the energy released is what I’m talking about. The big difference between a piston engine and a fuel cell is efficiency. That is why I have always assumed 100% efficiency and talked about the heat of combustion of hydrogen. The term “heat of combustion” might be confusing but it is the energy released by oxidation in any process. Creating water from hydrogen and oxygen is a combustion (oxidation) process whether done as burning or in a fuel cell. Oxidizing the hydrogen in air generates heat which can be converted to mechanical energy. Oxidizing it in a fuel cell generates electricity that can be converted to mechanical energy.
Admittedly it would be extremely difficult to usurp the conventional oil/gas burning engine since the whole kit and caboodle is tied into our present economy. But the change must come.Why? We can continue the way we have been going for hundreds of years. By that time maybe the environmentalists will have figured out that the end of the world has been postponed and we can get on with doing things that make sense rather than only politically correct to raise funds for environmentalists. Nuclear comes to mind.
Ergo, emmission free autos in California and elswhere?Do we just declare hydrogen as pollution free and ignore the fact that it pollutes more than gasoline?
I dont profess to have the answer...but I like to think I am steering myself or others in the right direction.And I would posit that you are steering the world in a direction of economic and environmental disaster. Get the answer before you decide what is best for the world.
Consider the following truths--Gasoline engines are a lot less efficient than Electric motors.Other than the fact that your fact is false and electric motors are far less efficient than gasoline engines… We went through this before and gave the math. Do I have to repeat where electricity comes from?
(they waste heat, plus reciprocating conversion to rotary)Ever put your hand on a 5 horse power electric motor that has been running for a while? Bet it wasn’t for long. And the conversion from reciprocating to rotary is 99.999% efficient. A quick rule of thumb is that if it isn’t hot, it is efficient. A crank shaft or a cam shaft doesn’t get very hot if oiled even transmitting hundreds of horsepower.
Electric motors are the more efficient option BUT not if they use batterys.That should be LESS efficient AND they use batteries.
Since gasoline stores at least 9 times more energy per kilogram, than a lead/acid battery. I dont think todays Batteries will ever be used, to heavy and not enough lead in the world.That is correct.
You talk about the difficultys of Hydrogen storage. You are right its a problem, but you make it sound more difficult because again you mention Hydrogen/Oxygen combustion...as in, and in comparison with the conventional diesel engine.No, as I have repeatedly said I’m talking about fuel cells. A fuel cell combines hydrogen with oxygen and releases water. The energy released is 326 BTU per SCF of hydrogen.
A Hydrogen storage tank might occupy approx 5 times the volume of a gas tank (storing at 200 atm or 3000lbs) and weigh 250 lbs+ at least.At 3000PSI you would need about 40 cubic feet. A 20 gallon gas tank is about 2.5 cubic feet. A 40 cubic foot tank would weigh several thousand pounds.
Yet I am still thinking Hydrogen.....because inspite of the above disadvantages you can push the gas into a metal, such as Magnesium where it will squash into the spaces between the Magnesium atoms.And how much would that weigh? Do you really think you can get that much hydrogen stuffed in there? And how are you going to get it out again without exploding if you rupture the tank?
And unbelievable as it may sound, you can actually store MORE Hydrogen inside the metal than you can as a liquid.Not at all unbelievable. Yes, you can. How much does it weigh?
They used incredibly thin sheets of Graphite only one third of a billionth of a metre apart, and they reckon they can store 30 litres of Hydrogen on a single gram of graphite, ..If I am thinking of the same research, that was about 5 years ago and no one else seems to have been able to duplicate those results. But let’s assume it can be done. How much is that? That’s 1 SCF per gram of carbon. That’s about what I assumed in my previous post. Since carbon is light, the weight is reasonable but how do you get the hydrogen in an out? You need either high pressures or high temperatures. Either of these constraints eliminates the feasibility of the vehicle.
which works out to an amazing 8000 kilometers per tank with your Hydrogen powered car **HUH? Did we suddenly change from automobiles to tricycles? The range of a vehicle is an entirely different problem. Let’s stick to energy storage and not get lost in new vehicles which take far less energy per Km. If you go that direction than I have to point out that I have a gasoline engine in my closet that would easily drive a model car 10,000 km /gallon.
I am pretty certain that Hydrogen stored as a magnesium hydride, need only be stored at 200lbs pressure, with a pressure release valve leaking a small quantity to atmosphere when not being used by the Fuel Cell.In a huge volume. But I find it fascinating that you intentionally leak hydrogen. Why waste that energy and what is that going to do to the environment?
As I have stated elswhere, Fuel Cells are the subject of intense research today.Yes and so were magnetohydrodynamics 40 years ago. We were told magnetohydrodynamics was the solution to electricity generation. You could burn almost any fuel and generate electricity with almost 100% efficiency. Billions of dollars were invested. Problem was that we ignored the little technical problems of gas volume and materials. Same thing is going on with fuel cells. The majority of researchers are sticking their heads in the sand and ignoring the insurmountable physical, economic, and environmental problems a hydrogen economy would entail.
I like to believe the Hydrogen Fuel cell electric car will become a reality in the near future.How about next year? http://www.bangkokpost.net/News/25Feb2002_news40.html