Renewable Energy Is The Future

[Vman455]

Originally Posted by Hersbird

That is more the exception than the rule most of the main stem dams are under 200 feet. There are dams on the feeder rivers with less than 30 feet drops. The Columbia river watershed is the example for hydro, but not the norm. Imagine what potential lies in the Missouri although we do have a few dams on that too. Or the oregon and California main rivers.

Yeah, but they're very wide--the smallest are a couple thousand feet, and the largest more than 8,000 feet across (Hoover dam, in contrast, is 1,200 feet wide). I imagine being able to make a dam that wide in order to get enough volume to offset the low height only works in a few places where the topography lends itself to that. Also, 200 feet is still pretty high, and most of the Midwest wouldn't support that kind of dam height without significant berms.

[redpoint5]

The Columbia fascinates me. The average flow rate is 264,900 ft^3/s... or nearly 2 million gallons per second. 3 olympic size swimming pools, every second. It has been measured at almost 5x that rate. The Amazon discharges 28x more than that.

[freebeard]

Late to the thread.

Originally Posted by Permalink #9

I like freebeard's idea to tunnel to the ocean from Death Valley and throw a turbine in between to generate electricity. Let Death Valley become the Dead Sea, which always looked like fun. The evaporation will drive a continuous need to backfill from the ocean. Perhaps the evaporation will produce more rainfall, a natural desalination process.

Algae!

Actually, the proposal was to use the seawater to grow algae. The inline turbines and OTEC would be secondary.

The Columbia fascinates me. The average flow rate is 264,900 ft^3/s... or nearly 2 million gallons per second. 3 olympic size swimming pools, every second. It has been measured at almost 5x that rate. The Amazon discharges 28x more than that.

Imagine when it was filled to the brim!

The generally accepted theory as to the cause of the Missoula Flood, or floods, is that a dam of glacial ice, moving out of Canada, filled the mouth of the Clark Fork River just east of its present day confluence with Lake Pend Oreille, near the Idaho-Montana state line. This glacial dam blocked the westward flow of the Clark Fork River causing it to rise against the dam until it eventually reached a depth of close to 2,100 feet, all the while backing up hundreds of miles into the mountain valleys of western Montana. Eventually the lake held over 500 cubic miles of water. At this point, so the theory goes, the dam gave way, allowing the impounded water to flow out across the Idaho Panhandle, through the valley in which the city of Spokane is now located, then to spill out over the great Columbia Basalt Plateau of eastern Washington, carving a series of branching erosional scars and canyons, flowing south until it reached Wallula Gap, a topographic bottleneck at the southwestern margin of the plateau, from whence it entered the Columbia River Valley to begin the final leg of its journey to the sea. Finally, having traversed the gorge from Wallula Gap, the waters crossed the area where Portland is now located, then flowed north and west into the Pacific Ocean. But so great was the volume of flood water that the valley north of Portland could not convey all of it, causing the excess to back-flood far south into the Willamette Valley of Oregon, forming a temporary ponding of water 400 feet deep.

[aerohead]

Originally Posted by Hersbird

The big Columbia River dams don't have that much height to them, you can have height, or you can have volume. The turbines can be designed to work with either.

The new British Columbia hydro projects use the heights and lower volume and don't pool a reservoir at all. Well maybe a little one or just a diversion dam, then pipe the water down the mountain. Lots of pressure, not as much volume.

The turbine/generator load,plus internal wall friction of the inlet/outlet piping would introduce a flow restriction which would have to be overcome by the momentum of the water in order to produce any power;which in itself,would be dependent upon dynamic pressure of the rivers velocity. In the absence of additional gravity head,there would be a load point,beyond which the water would just stall behind the restriction,and the water would just flow around the penstock opening as if it were a choked-down valve.

[aerohead]

Originally Posted by redpoint5

My understanding is that glaciers would not normally contribute to rivers because they are roughly thought of as static, or persisting over many years. It's the annual snow melt that feeds our waterways. My thought is that a more energetic (hotter) world would cycle more water, resulting in more rain/snow cycles. Perhaps rivers could see a net increase in volume globally? After all, a stream is simply the release of sun energy that moved the water to a higher potential energy in the first place.



That was my impression of the Grand Canyon. After having spent a week in Bryce and Zion, the Grand Canyon was a bit of a let down. Zion frames in the smaller features to give everything perspective, whereas the Grand Canyon was too expansive to be be amazed by it's much larger size. Then again, I didn't hike into the canyon or anything, so that probably makes a big difference.

I believe that,the Ganges,Yellow,and Mekong rivers all originate from time-release,mountain glaciers,and will all vanish,along with those who rely on them for year-round water supply.And we know from archeology that,all civilizations who rely on irrigation perish.It's cyclical.Albeit on large timescales,which are no longer valid as the planet warms,non-linearly.
South America has already lost some of their Andes Mountains hydro resources.As tropical mountain ice caps are the first to go.And are.

[aerohead]

Originally Posted by Vman455

Yeah, but they're very wide--the smallest are a couple thousand feet, and the largest more than 8,000 feet across (Hoover dam, in contrast, is 1,200 feet wide). I imagine being able to make a dam that wide in order to get enough volume to offset the low height only works in a few places where the topography lends itself to that. Also, 200 feet is still pretty high, and most of the Midwest wouldn't support that kind of dam height without significant berms.

Niagara Falls is only 160-feet.Con Edison continues to harvest it for power.

[Hersbird]

A turbine is just a reverse pump. The impeller runs the motor rather than the motor running the impeller. You can have a tiny amount of power associated with tremendous head, or a huge amount of power and almost no head. Take a 5hp pressure washer making 2700 psi but only 2.3 gpm, compared to the main condensate pump on an aircraft carrier only making 8 psi but could fill an olympic sized swimming pool every 5 mins. I can't remember their HP rating, but they are huge.
In a way they are sad because that is all waste heat. My buddy went to work at a power plant in the great lakes area (non nuclear btw) and all of their waste heat is used to heat the town's sidewalks in the winter.

[aerohead]

Originally Posted by Hersbird

A turbine is just a reverse pump. The impeller runs the motor rather than the motor running the impeller. You can have a tiny amount of power associated with tremendous head, or a huge amount of power and almost no head. Take a 5hp pressure washer making 2700 psi but only 2.3 gpm, compared to the main condensate pump on an aircraft carrier only making 8 psi but could fill an olympic sized swimming pool every 5 mins. I can't remember their HP rating, but they are huge.
In a way they are sad because that is all waste heat. My buddy went to work at a power plant in the great lakes area (non nuclear btw) and all of their waste heat is used to heat the town's sidewalks in the winter.

The point I was trying to make is,that a river is system open to the atmosphere and any power harvested will be limited by available kinetic energy.We could gang a lot of low-power turbines,side-by-side,but without a lot of hydraulic head available,they'll remain low-power in comparison to a 'tall' dam.

[Hersbird]

There are 2 different potential energies involved. The height is the main but there is energy in the velocity of water as well. I remember the first time I encountered a ram pump lifting water without any power input. I thought it was some kind of perpetual motion machine or an optical illusion. You can have a stream on you property with only a few feet of elevation change but then lift a smaller portion of that water to a pretty good height above the stream without any input of outside energy.

[aerohead]

Originally Posted by Hersbird

There are 2 different potential energies involved. The height is the main but there is energy in the velocity of water as well. I remember the first time I encountered a ram pump lifting water without any power input. I thought it was some kind of perpetual motion machine or an optical illusion. You can have a stream on you property with only a few feet of elevation change but then lift a smaller portion of that water to a pretty good height above the stream without any input of outside energy.

It's a very cool invention.HOME POWER Magazine used to cover some of the installs and owner experiences.My late neighbor 'crazy' Bob and I built an undershot water wheel on pontoons,which we tethered in Clear Creek.It turned,produced torque,and might have generated modest power,but flotsam was always a risk,easily capable of trashing our little engine.Floods,which are more abundant now,would just sweep any 'improvements' like it away.It's great though,that some live with conditions conducive to water power.