Water power!

[gt40]

I just had a look at this video, and what it claims is just amazing.
I haven't had any time to research the claims, but Id thought I'd post it here for others to critique.

http://www.ebaumsworld.com/2006/06/waterfuel.html

[Dr Mordrid]

Aquygen website....

Aquygen = "HHO" = "Brown's gas" = highly dubious.

HH2 etc. are a mixture of hydrogen and oxygen gas prepared by electrolyzing water. HH2/"Brown's gas" generators are sold for welding, but as in that video its also been proposed as a fuel for internal combustion engines and fuel cells.

Let's take a look at using it in IC engines. Considering the amount of electricity used by the generator, how many moles of gas it outputs/KW and the typical efficiency of an IC engine it takes >1 KW of electrical energy to get ~1/3 KW in mechanical energy, an overall efficiency of ~33%.

Given that the efficiency of an electric motor can be >85%....

As for any special properties of this incarnation (HH2 has been circulating here and in Australia for >20 years) that's so controversial that Wikipedia has pulled its article.

[Brian Ellis]

Dr. M may not have said it all, but he has said most of it. The most important point not made is that of the electrolyser efficiency. They can be made up to 75%, on condition that they be run 24/7 and is of the most suitable very large-scale design. More typically, they run at 50-60%. The energy wasted is dissipated as heat. Reason: in a perfect electrolyser, a given current will always supply a certain weight of gas in a fixed time. For example, you need 26.59 Ah to produce 1 g of hydrogen or 3.35 Ah for 1 g of oxygen. Let's say that a given water electrolyser has a current of 10 A flowing for an hour: this will produce 0,376 g H2 and 2.99 g of O2 or 4.18 l and 2.09 l respectively. Typically, you will require a voltage of 3-4 V in practice, in order to push this current through (this will depend on the electrode geometry and water conductivity), so the power consumed is ~35 Wh. The heat of combustion of H2 is 141.79 kJ/g, so we shall obtain 53.3 kJ by burning the gas or 53300 W-sec = 14.81 Wh, giving an efficiency 42% of energy. The other 58% is dissipated as heat in the electrolyser. Under the best conditions, you may be able to reduce the voltage somewhat, but you will always get less energy out than energy in (2nd law of thermodynamics).

Let's say, for the sake of argument that a small-scale casual electrolyser runs at 55% efficiency (and this is pushing it) and, taking Doc's other figure and a mechanical train efficiency of 85%, this makes the overall efficiency 0.55 x 0.33 x 0.85 = 0.154 or 15.4% from your electric supply to your wheels. However, it doesn't end there. Your fossil fuel power station has an efficiency typically between 30 and 35%, so the fossil fuel to wheels efficiency now falls to about 5%, compared to 30-35% for a conventional car or 40% for an equivalent hybrid car with an Atkinson motor. This is why the hydrogen car is just a pipedream, or a bottomless hole for GM, Ford etc. to receive taxpayers' money offered by governments wishing to appear environmentally-friendly. OK, a fuel cell will be slightly more efficient than an IC engine (typically 50-55%, as opposed to 30-35%), but hydrogen is not a fuel: it is just a poor means to store energy. The same goes for the very hypothetical Brown's gas. If you wish a good laugh, read http://www.phact.org/e/bgas.htm

[Dr Mordrid]

I almost typed something similar, but I knew your hyperkinetic fingers would jump in to fill in any gaps

Hydrogen fuel cycles only make sense if there is some kind of reactor for pre-converting some more portable fuel into something the fuel cell can use directly, and even then with the rise in Lithium Ion battery efficiencies and the cost/complexities involved, why bother?

As it is now a Tesla (you've gotta love Elon Musk ) can do 200-300 miles/charge, several times the average daily miles driven even by Americans (36) and the next generation of Li-Ion batteries could double that with shorter charge times. The big automakers are working on similar plug-in systems; GM, Daimler-Chrysler, Toyota etc. They'd be stupid not to.

Using a more complex/expensive system (fuel cells) massively violates the K.I.S.S. principle.

[gt40]

interesting links.
Afte a little reading I have decided that Brwon's gas is much more combustible when it come out of Mr Brown's a$$