29
votes
Accepted
Why is hydro-electric power still scarce in some places?
Because most of the water is at the lowest point is can be, the ocean.
Second issue is that you need quite a bit of vertical drop for water power to be a viable power source.
There are DIY hydro ...
- 5,741
12
votes
Why is oil used as the lubricant in power generators, while water is the most available, cheapest and accessible lubricant?
Sea water is about the worst thing in the world to put in a metallic mechanical device. As noted , corrosion would be horrendous ; dissimilar metals, stray currents , etc. Wind turbine gearing is an ...
- 6,057
10
votes
Why is hydro-electric power still scarce in some places?
There are two issues, harnessing and market. You need both to be viable.
A market, makes most of the 70% of the land mass covered by water unusable, because even if you could harness the power, it ...
- 2,477
8
votes
Why is hydro-electric power still scarce in some places?
Rivers in a flat landscape are often unsuitable because you need a height difference to make the turbine work. Let's say a 1 meter height difference is required. There are many areas where the river's ...
- 736
7
votes
Accepted
Why are creeks sometimes piped underground in urban areas?
In more developed areas (cities) burying streams is popular because it allows for more land to be developed without the fear of flooding. Also, streams in these areas tend to become very blighted and ...
- 10.6k
7
votes
Can I seal the inside of a water well to use it as water reservoir when the well is dry?
Well liners are generally made to order. One of your issues will be to find a company that can make what you want.
You will need to ensure the liner is the correct size and that it does not tear ...
- 9,527
7
votes
How to divide the water flow into outlets with equal flow each?
Even if you had matching orifices, you might have issues with the pressure drop inside the pipes and corners.
If you are really after matching flow rates, you could look into flow control valves/flow ...
- 24k
6
votes
How do I calculate the density of seawater at different temperatures?
The density depends not only on temperature, but also on salinity, see the wikipedia page on seawater, which has this neat diagram:
Assuming you have seawater of constant salinity, you can use the ...
- 1,831
5
votes
Why are creeks sometimes piped underground in urban areas?
What's the reason for going to the cost and effort of doing this?
In many places, placing a stream into a culvert can be cheaper in the long run. Streams (particularly fast flowing ones) erode the ...
- 364
5
votes
What development possibilities could yet exist in water desalination?
Carnegie, through their CETO device, and others have already looked at using wave power to directly pressurise water for reverse osmosis: a wholly mechanical process rather than converting to ...
- 3,721
5
votes
Accepted
Can I seal the inside of a water well to use it as water reservoir when the well is dry?
I see two ways:
I've had great experience in my pressure vessel design with a 2.3 mm thick liner of polypropylene or polyethylene. In a pinch, you can weld PVC, but I don't recommend it. Thinner ...
- 5,323
4
votes
Can a retention/detention pond and a parking-lot be constructed in the same site foot-print?
Yes, Underground Detention is a thing. That Wikipedia article even mentions placing them under parking lots.
The exact method that you propose is a little different than preconstructed vaults, but it ...
- 10.6k
4
votes
How to calculate hydropower in kW without water head
If you have horizontal water flow (no head) you are extracting its kinetic energy (from its velocity) not its potential energy (from its head).
So you need to know the velocity of that flow as well ...
- 1,610
4
votes
Managing water supply pressure to a building
The best method is to pressurize your tank on the upper floor, then regulate the flow as it goes down. This is because pressurizing will require active components (i.e. pumps, and other devices that ...
- 5,323
4
votes
Accepted
What happens to the sedimentation collected in water treatment plants?
I was part of a team of contractors to remove and spread the dried sediment from a water treatment facility - the sediment was a red cake/ powder and was spread on the fields as fertiliser.
- 15k
4
votes
Why is hydro-electric power still scarce in some places?
In years past I would have been a fan of hydroelectric power but I have read1 about some of the downsides over the years. These include:
Major ecological problems including blocking fish migration. ...
- 9,794
4
votes
Why is oil used as the lubricant in power generators, while water is the most available, cheapest and accessible lubricant?
Great question! Water absolutely is used as a lubricant in some power generating systems. For example many Francis style turbines use their feed water as the primary lubricant and coolant of the ...
- 141
4
votes
Accepted
Why aren't these spokes radial?
Radial lacing "tortures" the spokes of the wheel because when torque needs to be transferred from the hub to the ring when accelerating (or from ther ring to the hub during braking).
Radial ...
- 24k
3
votes
Difference between static water level and water table level
Static water level refers to the level of water (in a well for example) under normal, undisturbed, no-pumping conditions. Static water level is best determined when the well has not been pumped for ...
- 503
3
votes
What happens if one pumps from municipal water supply during power outage?
It isn't just a question of air. When you put suction on a system that's normally under pressure, you're going to draw in contaminants through every available opening — leaks in underground ...
- 6,844
3
votes
How do I calculate the density of seawater at different temperatures?
You could use the Equation of State for seawater. Sources and detailed information on this topic are to be found here, here and here.
Please note that the equation apparently does not cover ...
- 1,734
3
votes
Why don't hydroelectric plants use cascades of turbines instead of single turbines?
The reason why a hydroelectric generator is fundamentally different to a gas turbine is because water under pressure is not a gas, and does not change size significantly as energy is extracted from it....
- 31
3
votes
Accepted
Is it possible to create a sub-surface pond?
I would describe this negative incline portion of the pond as a "shelf". They are common and need to be self-supporting with a material that has compression and tensile strength; concrete and rebar, ...
- 7,784
3
votes
What are these "water fountains" in the middle of a river in North Korea? (Probably also found elsewhere.)
They are merely ornamental.
Near the top of the image you can see the base of Juche Tower (Google Maps), a monument in Pyongyang on the bank of the Taedong river.
(the two large fountains are ...
- 13k
3
votes
How to divide the water flow into outlets with equal flow each?
If the head pressure is any more than just adequate, the problem is very easy. Just ensure that the bottleneck is near the points of exit, that they are of equal diameter and approximately the same ...
- 31
2
votes
What development possibilities could yet exist in water desalination?
For reverse Osmosis
This site gives the minimal required energy for sea water desalination by RO as 2.78 kJ/l (fresh water), this is if you consider only the reversible process. According to ...
- 4,687
2
votes
Low cost, moderately accurate water depth measurement
Measuring water in open channels is a basic element of water conservation. With the increasing demand for improved water management techniques, there is a serious need for low-cost and accurate water-...
- 21
2
votes
Accepted
Low cost, moderately accurate water depth measurement
An alternative could be a barometric chip enclosed in a waterproof container with a membrane, weighed down to rest at the bottom.
A barometer circuit for Arduino is available from Adafruit for under $...
- 6,093
2
votes
Low cost, moderately accurate water depth measurement
I think your actual goal is to measure the volume of water in the tank.
At least for the tank, you could apply strain gauges to the base of the tank. More water in the tank means more weight, which ...
- 123
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