Google answers many questions, if you're just PATIENT enough. just stumbled across a powerpoint on the web, concise design analysis of the problem by a professor of mechanical engineering. The equations show why the patent-office file cabinets are littered with ideas for spring-stored energy for bicycles which never saw a real factory floor.... the energy-storage density just ain't there. His recommendation: optimize the electrical approach.
Ok: who makes the best electrical-assist which encompasses an efficient regenerative-braking?
what's the state of the art of energy-storage capacitors?
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I don't think the electrical means would be the best solution however. I have already found that the cost-per-mile of operating a Bionx is greater than for operating a gasoline-engine of comparable power, and that was assuming flat ground.
The problem with electrical vehicles is that everybody WANTS small lightweight batteries, but they tend not to last very many discharges before failing if they are deep-cycled, and if they aren't deep-cycled, then you don't get much practical energy storage from them.
The only way to make electrical batteries that will last a lot of discharge cycles is to make them lead-acid and make them BIG and only ever discharge them lightly--but you see then,,,, if you want a vehicle that can climb hills, then the last thing you want is a bunch of heavy batteries powering your hill-climbing vehicle.
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I would suggest a gas engine kit, such as a Golden Eagle belt-drive. The belt drive is simple and reliable and a 4-cycle engine is easy to fuel. ~
Mountain topography and type of cargo aside . . . You figure high tech state of the art is going to be less expensive than a piece of wire and some pulleys? It won't take capital?
You wouldn't be the first person wanting to get a weight down a mountain. Or hill - any mountain worth the name wouldn't be bicycle friendly.
I worked a place in Alaska where we wanted to haul supplies up to a mountain lookout, and do it cheaply. We had a very steep cliff face and they were using airlifted supplies. Some guy got the idea to use a rope and buckets. Water filled a bucket and pulled the supplies up in another bucket. Daily re supply with food and equipment versus weekly and at a lot lower cost.
Still needed the copter for changing observers, and no one could take more than a month in the 5 X 8 aluminum box they called home. They were working on a steel cable to lift men up. The idea was to put one guy in a sling at the base another at the top, add enough water to bring the up guy down (if necessary). Plan was to use something like the old style dial telephones - centrifugal brake to regulate the speed - or an off the shelf centrifugal clutch from a riding lawnmower. I never saw that working, but have no doubt they could make it work.
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I had a similar idea to build a small railway on my property which would be used to bring down firewood from the top of a hill (about 50' elevation). I figured I could run it for free, or maybe get extra energy, by using the potential energy of the wood. Probably it would not be economically worth the effort, but the cool fun factor made it something I wanted to try. Having batteries in the vehicle seemed to be a null factor, except that it required bigger motors or slower gearing, and maybe more rolling resistance. I also considered electrifying the rails, or using an overhead hot line, but it would only be efficient at voltages much higher than would be safe.
For energy storage capacitors, try:
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From a previous post, here is a discussion of what to expect:
Energy storage for the capacitors is based on 1/2*C*V^2, so your 210,000 uF
25 V bank will store 65 J (watt-seconds). If you have 800 watts of motors (1 HP), the energy will power the vehicle for less than 0.1 seconds. They are most useful for quick energy dumps from dynamic braking, but you will need more than that to absorb the kinetic energy of a fast stop. Supercapacitors are available, such as Maxwell BPAP1200 ? E270, which are
1200 F at 2.7 V. Ten in series gives you 120 F at 27 volts, and energy storage of 43,000 W-Sec, or 50 seconds run time at 800 watts. They cost about $46 each.
Some interesting high surge current capacitors are:
They obviously haven't seen the proper way to do this...with a really big rubber band, like in the Swedish film, "The Apple War".
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I wish I had screenies, but basically the bicycle guy in the film uses the rubber band to get to the bus stop really fast, and stretches it on the way home in the evening.
I would think the coolest method to use the potential energy of the wood to run the railway would be to burn it in a steam engine. :)
Seriously though, I've seen small "railroads" in shopping malls that are run off 12V running through the rails. They're big enough to carry a bunch of kids so something similar should be able to lug a cartload or two of firewood. It doesn't have to be terribly efficient to be useful. Slow is also probably quite acceptable. If it saves you from having to make several trips then it can be quite slow and yet still faster than the alternative.
You could even go all renewable on this and fit out solar panels on the top of the "engine" for this railroad. When the sun shines the thing will slowly work its way up the hill using whatever energy the panels produce. Add a stop switch at the top (of course) to keep it from going too far. So what it if takes a day or two to get there? It's not like you would have to be driving.
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