Hydro-electric Power

n7axw wrote:

phillies wrote:It is perhaps of interest that the first powered airplane to obtain considerable net (of weight) positive lift, though not controlled flight, was Maxim's steam aeroplane.

I went back and read about the test of that, and it was rather humorously noted that as soon as the pilot felt the lift, he (wisely) cut the power...

Don

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On one hand, the pilot was entirely aware that there were no controls for affecting roll, yaw, or pitch. On the other hand, the airplane was prevented from flying by a series of outriggers attached (I infer to the underside) of rails. All outriggers were engaged. In particular, over a fair distance, the rails had been pulled from the ground. The pilot acted barely in time to save his neck.

Even skipping the electric part, a large dam with turbines powering a hydraulic distribution system could supply dramatically more power than a bunch of water wheels.

The industry using that power would have to be right nearby of course.

Expert snuggler wrote:Even skipping the electric part, a large dam with turbines powering a hydraulic distribution system could supply dramatically more power than a bunch of water wheels.

The industry using that power would have to be right nearby of course.

A few years ago I read a paper on an archeological dig on a "Roman" industrial site in N. Italy. A river naturally ran downslope at a 20-30 degree angle and the Romans constrained the river and built a series of manufacturies on either side of the slope with water wheels. On either side, 10 or more separate mills lined the river, stepping down following the slope. There were large, fairly automated smithys, and well as mills of all sorts. It was one of the most advanced industrial sites found in the Roman world.

phillies wrote:
On one hand, the pilot was entirely aware that there were no controls for affecting roll, yaw, or pitch. On the other hand, the airplane was prevented from flying by a series of outriggers attached (I infer to the underside) of rails. All outriggers were engaged. In particular, over a fair distance, the rails had been pulled from the ground. The pilot acted barely in time to save his neck.

The pilot acted wisely indeed.

Don

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Expert snuggler wrote:Even skipping the electric part, a large dam with turbines powering a hydraulic distribution system could supply dramatically more power than a bunch of water wheels.

The industry using that power would have to be right nearby of course.

Actually no, you would be better using shafts and belts, unless you needed the power in a way that was mobile (beyond moving along a shaft). For real life example of the power loss involved in hydraulic power transmission versus belt drive, stump grinders tend to get engines about 50 HP greater on hydraulic cutter powered models versus the belt driven models.

Castenea wrote:

Expert snuggler wrote:Even skipping the electric part, a large dam with turbines powering a hydraulic distribution system could supply dramatically more power than a bunch of water wheels.

The industry using that power would have to be right nearby of course.

Actually no, you would be better using shafts and belts, unless you needed the power in a way that was mobile (beyond moving along a shaft). For real life example of the power loss involved in hydraulic power transmission versus belt drive, stump grinders tend to get engines about 50 HP greater on hydraulic cutter powered models versus the belt driven models.

The various forms of power have similarities: Something that pushes, something that changes, something that produces losses due to the changes. Mechanical and electric are low on losses, although pneumatic and hydraulic can have losses lowered by increasing diameter and shortening length (more expense). For long distances, electricity, since it can easily be transformed to high voltage (thus low flow and losses) combined with the relative ease of making power lines, is at present the best. Each of the others has an advantage in certain circumstances.

The hydro-pneumatic power system would have the disadvantages of low efficiency (except with more complications, such as Stirling, Erickson, and a few other engines) and "bounciness," both coming from the fact that it can compress.

BTW, one mine got very high efficiency in compression: they had a waterfall nearby, ran a froth of water and air downhill through pipes, and got nearly isothermal compression with liquid and gas separated at the bottom. There was no charge for compression energy either

DDHvi wrote:SNIP
BTW, one mine got very high efficiency in compression: they had a waterfall nearby, ran a froth of water and air downhill through pipes, and got nearly isothermal compression with liquid and gas separated at the bottom. There was no charge for compression energy either

So they got streams of compressed air and the water would have the same pressure as any water falling that distance? Do they have to do anything special to separate (capture?) the air?

A retired Geography major who uses Google a lot when browsing here

I'm imagining a really big dam, 100 megawatt class. Would belts and shafts do the job? Could hydraulics distribute power to useful industrial distances, hundreds of meters from the dam?

Once you have the dam, once the Proscription are defeated, swap out the hydraulic pumps and replace them with generators.

Expert snuggler wrote:Once you have the dam, once the Proscription are defeated, swap out the hydraulic pumps and replace them with generators.

I've been binge-watching the Time Team archaeology series; they've explored a couple of old water mills. The "leaks" to fill the mill ponds and power the mills sometimes ran a couple of dozen miles to get sufficient elevation to power the mill.

If 12th century flour mills can manage with open "leaks" for hydraulic power, I'm sure a couple of miles around a major dam would be no problem for a closed conduit. In fact, I suspect that a closed conduit system could be too powerful for a belt-driven distribution system and require reduced efficiency to operate reliably.

EdThomas wrote:

DDHvi wrote:SNIP
BTW, one mine got very high efficiency in compression: they had a waterfall nearby, ran a froth of water and air downhill through pipes, and got nearly isothermal compression with liquid and gas separated at the bottom. There was no charge for compression energy either

So they got streams of compressed air and the water would have the same pressure as any water falling that distance? Do they have to do anything special to separate (capture?) the air?

A retired Geography major who uses Google a lot when browsing here

This was read decades back, part of an engineering course encouraging outside-the-box thinking. IIRC, the mixed stream went into a cavern, and the water could be drained out of the bottom of the mine. Of course, this implies the mine was up a hill or something.

Assume: a deep salt dome, made by solution mining. Run a brine/air froth down a pipe into the center of it. Have a low bottom end return pipe for the brine, and a high bottom end pipe return pipe for the air. You would need to supply some pressure at the top to cause the brine to return, given the density difference between the froth and pure brine. Most of the compression would be done by the brine - at almost isothermal efficiency. You would need to supply extra volume at a relatively low pressure, but would be trading that for extra output pressure. Voila, a very large compressed air energy storage