Getting Out Of The Box With Hot Air

One of the reasons that Oriental countries have such high savings rates is that many entire communities lay within single buildings. Many workers travel between factories, residences, day cares, grocery stores, gymnasiums, restaurants, theaters, doctors and more without leaving the building they live in.

All of this adds up to higher savings, much more leisure time and much more energy to pursue both investment and recreation whether on or off the water.

For personal interest I once did a comparison of the savings potential of an unskilled migratory worker in oil rich Alberta versus his counterpart in Metropolitan China.The unskilled worker in Alberta is lucky if his gross income will support a private substandard residence.After paying the rent he will be dependent upon food banks and the charity of others to feed himself.How he gets to work and back is unfathomable. His counterpart in China receives free rent in a factory apartment plus one free hot meal per day. He either rides an elevator or takes a stairwell to get to work.Employers provide many free recreational opportunities ranging from theater to Karaoke and pool.The end result is that the migratory unskilled worker in China is able to save over 90 % of his income while enjoying a vastly superior standard of living.

 

I haven't had time to read all the posts, so forgive if this has been mentioned before.
The foremost exponent of compressed air power and the inventor of a compressed air motor is Guy Negre. They have been developing compressed air powered cars mostly in France. According to their website they are really very good. But I have heard elsewhere there are very many problems associated with them.
Check out: http://www.mdi.lu/english/

 

The MDI Airpod car stores about 29 MJ of usable energy in its 175 litre tank. I guess the carbon-fibre tank weighs about 110 kg when its full. It lasts 12,000 cycles and costs EUR 1,200.

A comparable electric car, the Smart ED, has a 59.4 MJ battery, but in practice can only use about 47.5 MJ. The batteries weigh 385kg, cost EUR 13,000 and must be replaced every 1,000 cycles.

Both cars have an efficiency of about 45% (pump-to-wheel, or grid-to-wheel).

The petrol-engined Smart holds 33l, or 1,155MJ of energy, but its motor has an efficiency of about 11%, pump-to-wheel.

As the airpod is light, and recovers energy on braking, it nevertheless has a range of 220km (according to the manufacturer), compared to 634km for the Smart petrol (urban, inc. reserve tank), and 110km for the Smart ED.

So the energy density is not too low for a short-range urban car. Furthermore, it is inexpensive to buy and run, and as it does not pollute, there is no road tax.

I still don't think it will be very successful here, though.

 

Ahh,

we are talking cars again.

Well, this is the boatdesign.net, or not?

Now, how do I put this great technique in a boat?

 

See attachment ...

 

Being that I used large compress air motors for cutting and grinding, I can tell you the following; Compressed air is the worst method to transfer or store energy as far as efficiency. It takes 90 hp to drive compressor to generate air to power 30 hp engine. A lot is lost into heat, removing moisture, and motors that are design to operate at a certain rpm only. Hydraulic in contrast can be 95% efficient. That said air motors have uses. I love my air starters. I need 5 gals of 120 psi air for each start minimally. No problem I have a 40 gallon tank. I could convert to higher pressure system and have backup system that I can start engines with scuba tanks feeding 40 gallon tank. but would have to convert whole boat to air tank to travel a few miles. But it takes a great deal of time/energy and cost to refill tanks.

 

Ok, shot.

The boat you have stolen from my thread, where did you steel the car?

 

If this air system was installed in an Albin 25 Motorsailer what range would it have at a speed of 4 knots under air drive only ?

 

The car came from a car exhibition photo.

You are looking for ideas for equipping your boat aren't you? I thought that would be a useful addition for running around the port, and you have a source of compressed air on board already.

 

No,

I am searching for the opinion of other members what they call a capable passagemaker. (within the given parameters)

And that sort of wasted energy is sure not part of my plans. I live in reality, dreaming is not part of my business. Though allowed of course.

 

DISCLAIMER - All figures here are rough approximations !!!!!

I am not sure what the hull drag of this boat is, but lets say 50N/ton at this speed, and say it weighs 2 tons. The speed is 2.1 m/s, so you need 200 W of motive force, which translates to, let's say, 400 W at the shaft, or 1 kW to the motor (40% efficiency motor and gearbox). There's 29 MWs of energy in the compressed air, so you can run the motor for 8 hours (29,000 seconds). The range is 60 km on one cylinder of 175 l (75kg) of air compressed to 350 bar. That's on a lake with no winds.

You could always add more cylinders, of course, or up the pressure - using liquid air would double the range in the same size tank (and double the weight to 150 kg of air per tank).

Bear in mind the exhaust is at -40 °C - useful to drive the airco, fridge-freezer and ice machine.

 

60 km per fill is a pretty good range. Lets picture the air powered Albin 25 as having 2 draw lines on opposite sides of the boat, each of which is attached to a 40 pound anchor resting on the bottom of the lake. Let's say that once every 2 seconds at least one of the draw lines will apply a 20 pound force to an air compressor for 1 second as it rocks in the harbors wave action with a little help from a 6 foot by 6 foot square sail. How long will it take to fill the air tank ?

 

Rough guess?

12-24 months...

That is a good range on the compressed air though.

 

I was hoping for 3 or 4 days. I think my theoretical boat is going to need bigger anchors attached to the draw lines. I'm also wondering about the possibilities of capturing more energy by setting a single anchor and draw line through a hole in the bottom center of the hull.

On Monday I'm going to try to get some more definitive answers from a local industrial air compressor supplier.

 

Can you take a video camera along and film his face when you explain what you are trying to do.

Also every air system I have ever seen with exception of aerospace stuff will leak, add that to your equations.