pulling electricity out of a river

[riverpower]

Hi,

   I think I may have found some decent river flow in a river where I currently have a mooring.  The mooring is probably 80 feet from my dock.   This is a navigable river, so there are boats going up and down it, some will throw down anchors, fishing lines, etc.  

   So, let's assume I can put in a tidal flow turbine and a generator, say mounted on the river bed next to my mooring.  Has anyone found a way to safely get the electricity onshore?  Dropping an electric cable on the river bed doesn't sound very safe, and it would definitely get yanked out/up eventually.  I cannot think of any other way to get the electricity to my house.  

   Anyone else ever faced this?

Thanks

[Nando]

There are ways to bring the power to shore, well protected, but do info about the river, water velocity, seasonal water levels changes, depth of river in area of interest, seasonal temperature, etc.

Nando

[stevesteve]

How about armoured cable? It would be heavy and resistant to most damage.

You would have to find out about your own liability though. Say someone catches some kit and then loses it because it snagged your wire - would you be liable?

Sorry to widdle on your bonfire, I love the idea.

[terry5732]

I fail to see anything unsafe about a couple anchored wires.

You may have to replace or repair damage to them occasionally.

Please explain what you think would be unsafe.

[richhagen]

It seems to me that you are stuck with routing a cable somewhere, and probably on or in the river bottom.  Rich

[Phil Timmons]

mho, I would not worry so much about the electrical issues, that could made safe or at least fail-safe -- so it will "fail" in a safe condition.  One method that comes to mind is to ground-fault the circuit.  You know the plug devices that are probably in your bathroom, kitchen and garage?  Ground Fault Interrupts are not just for small appliance circuits.  They range into the thousands of amps and biggie volts, as well.  We build them into industrial services.  Anyway, a GFI design monitors to ensure that as much current is being returned as waa sent.  If there is a difference between what goes out and what comes back -- a leak as it -- were, the circuit instantly opens.

My concern may be for more mechanical things.  Like at what depth level of river to locate the turbine/generator/whatever device?  I think I noticed you mentioned "bottom?"

The fluid dynamics guys here probably have a better view on this, but the river current on the bottom is rather slow -- like at the edge.  In some rivers, it is so slow on the bottom, that back in Army days, when we would do river diving (scuba type) we could "walk" upstream on our finger tips, get to where we were going.   But to return downstream we would float up and let the river carry us back downstream to the boat -- drifting along at maybe 10 to 15 mph.  You could hit the boat or anchor cable hard if you were not careful.

So anyway, the farther from side or bottom friction, I think the faster the flow would tend to be?  Does that make sense?  I am thinking you may want it drifting (with flags and whatever) from your mooring float?

I guess another caution I can see is debris.  When garbage comes downstream, it can hit and hit hard.  You may want to consider if you would want some sort of "breakaway," with a backup anchor cable to shore.  That would allow the normal mounting point to separate, but the device would still be saved and up next to shore 80 or 100 feet or whatever from the back up anchor point.

I guess the last caution I can think of is stupid people tricks.  Like an anchor dropped through it?  Dunno.  Hard to make anything fool-proof because fools are so ingenious.

[wind pirate]

"I guess the last caution I can think of is stupid people tricks.  Like an anchor dropped through it?  Dunno.  Hard to make anything fool-proof because fools are so ingenious."

We like to say - "we keep trying to make things idiot proof, and they keep building better idots."

W-P

[riverpower]

Wow,  thanks for all the warnings.   You guys clearly have run into many of these problems before.

   A little info.  This is a tidal river.  Where the mooring is, the river is about 25 feet deep at low tide, and over at the dock it probably is 12 feet deep at low tide.  I've estimated the flow to be around 4kt to 5kt at peak flow times.  My hope is to get 1kw to 2kw out of it, if I can overcome these issues.  

   I'm contemplating mounting a turbine (gorlov?) out next to the mooring, and having it be 1/2 way between the surface and the bottom.  Of course mounting it would be a challenge.  It would have to have some kind of mooring base on the river floor, and then either have a solid mounting, holding it vertical 5-10 feet up in the water, or consider hanging it on a line up to a float,

   I had NOT thought about 'stupid people tricks', like dropping an anchor THROUGH the turbine.  I also had NOT thought about large debris hitting it.  While Ive seen all the junk floating on the river surface, I now realize I need to see what junk is moving in the river about 10 feet deep.  I had planned to put a wire cage around the turbine to keep anything from hitting the blades.

   I did have some really stupid ideas to get the power from the turbine to the river shore.  These included having the turbine turn a pump, and have it shoot a stream of water towards a huge funnel on the shore, and create head and flow, to turn another turbine on-shore (stupid, what happens when the wind blows!).  Or, the turbine could turn a generator which would light a really bright light with a directional reflector behind it, and beam the light to shore.  

   I do like the idea of an armored cable with a fail-safe mechanism.  So if something really snagged it, it would pull free, and I'd just lose the cable.  Also, clearly I need to think about making sure if something hit the turbine or caused it to lose it's base, that I'd not lose it completely.  

  THanks for the ideas.  If there are any more out there, please let me know!

Dave

[ghurd]

There is more suspended garbage than I would have expected.

Thousand Islands region has clear water due to the recent introduction of non-indigenous Zebra mussels in the Great Lakes.  The bottom is clearly visible at 25 or 30 feet.

The suspended crap going by was probably too small to bother a Gorlov, but could get something with 'tighter blades'.  Potato chip and bread bags, small twigs...  Bags could maybe stay folded around a blade?

But there is crap between the surface and bottom.

G-

[Instinctz]

Lol.. I have got to say, you have many very interesting idea's.  Just dont forget.. its that sort of thinking that invents things many would never have for seen!