Mineral Accretion using Solar! HELP!

[Solar_Marine]

Hi Guys,

I am brand new to this forum and am really looking for some advice,

Here is the back story; I am a marine biologist working in Fiji, basically I am setting up a mineral accretion system, commonly known as BIOROCK, the idea is you run a low current/voltage to an anode (+) and cathode (-) underwater, cathode in my case being a steel rebar structure (normal for this technique) and I am using an aluminium anode. What happens is the reaction taking place at the cathode promotes coral growth and creates an alkaline environment via OH-, the anode errodes, lost of information about this via the net.

My problem is more to do with my power delivery system, which is why I am posting here....

I am using a 50w solar panel, max amperage at 2.93, max voltage is around 20v. Now i am running around 60m/197ft of 16mm copper cable. Ideally at the structure I want around 1 amp. Now Fiji is nice and sunny so I connected up my panel to the cable first, tested it and I was getting around 19v from the panel through all the cable.

I have connected everything up now to the anodes & cathode and it does seem to be working (the anode is bubbling as it should and looks like it is corroding) GREAT! BUT, the cathode is not doing anything after 3 days, I should be seeing something.

Now it is all connected when I test the voltage at the panel in full sun I get around 1.5v, am I right in thinking the anode/cathode 'load' coupled with distance travelled is causing this huge drop....? If i am getting 1.5v at the panel does that mean 197ft away is seeing very little voltage or is 1.5v the whole system?

I haven't tested the Amps in full sun but did it in cloudy conditions today at the panel and was only 0.06 on a 20m setting on my multimeter!!!!

Can someone please confirm my huge drop in amperage and volts is due to the distance and the anode/cathode causing load (they are a load correct?)?

I am a but stuck of what to do next basically, should I get another panel, should I move the panel closer to the structures (very tough), should I buy a battery to be cooer to the structures (easier).......

I really hope somebody can shed light on the problems I am experiencing from the PV point of view,

Any help would be greatly appreciated,

Thanks,
Luke

[OperaHouse]

Solar panels are current devices, power point current is about the same as a short circuit current.  It is doubtful that the length of cable drops the voltage.  In low light conditions the current drawn can drop the panel voltage.  Ideal situation would be some electronics that keeps the panel at its power point voltage.  Your very low current is likely due to a bad connection.  The connection at the aluminum may not be there anymore.

[Solar_Marine]

Thank you for the reply Operahouse,

Ok so i sealed the connection to the aluminium, and the aluminium is bubbling/looks like it is corroding. Could it be a bad connection at the cathode...? I just have the 16mm copper wire jubilee clipped to the rebar,

Maybe a stupid question but can the anode be too close to the cathode and possibly shorting the system?

I m just pretty stumped at all of this, the best voltage to use is 1.23v for biorock, but can use anything up to 12v,

[OperaHouse]

A lot of bubble action may be impressive, but it is likely the last thing you want.  As bubbles form around they act as an insulator, gas doesn't conduct.   The  current is also producing hydrogen and oxygen.    Review the power chart for a solar panel in this article, http://www.egr.unlv.edu/~eebag/Solar%20Cell%20Shading.pdf     A switching power supply can exchange current for voltage for the same amount of power.   For example, Your panel may be able to produce 5A at 15V.    A switching power supply could change that to 15A at 5V.    This would allow you to greatly increase the surface area of the aluminum and produce more of what you really want.

[Flux]

Opera House is on the right lines. Your panel is a current source and in full sun it will give near the 3A. Not in sun but in light conditions it will be way below the 3A. The .06A you measured may be correct, you won't get near an amp without direct sun.

Now the reason why your panel is down to 1.5v is that your system is looking virtually as a short circuit to the panel, the cable loss is not the problem, as a high cable resistance would limit current but not restrict the panel volts.

I don't know what voltage you need to make the process work but you would be better off with nominal 6v panels. In theory you can use converters to better match the panel, if you convert down to about 9v you will have the potential of supplying twice the current on a sunny day.

You still have the problem that you are unlikely to get results in other than full sun.

I suspect that either you need a lot more panel watts or you need to change the electrodes to match the present panel. Try reducing the electrode area until the panel volts comes up to something realistic, in which case you will be using the panel effectively.

I don't have any idea what is required in terms of volts to get things working, there will be polarisation and depending on the way round it is connected the aluminium will likely be forming an electrolytic capacitor when you go much over 1,5v. This will reduce the current and let the volts rise but will restrict the current.

Unless you can find details of the process when working properly you ought to be sorting this out with with a battery or bench supply. When you know what you want then you can look at suitable panels.

Flux

[Flux]

I had a quick look but found no real details of the electrical requirement.

Making a guess I would expect that you need to exceed the hydrogen/oxygen potential so probably need 2v or more at the cell, In addition you have the cable loss, so I suggest you reduce the electrode area until you get 5v from the cell in full sun.

If you want it to work in other than full sun you may need to charge batteries and use a step down switching psu to say 5v to push the system efficiency up greatly.

For now reduce the area and get up to 5v or more and see if it starts working, that should give us a starring point.

Flux

[OperaHouse]

I figure it will take a while before you understand the numbers. Patterns will emerge. real understanding comes from
being in the genba for a while.  Sure, you can load up with a bunch of solar panels but you won't save the oceans by being
inefficient.  There is an ideal voltage the solar panel works at and an optimum voltage for your process.  Electronics
that makes this happen does not have to be expensive or complicated.  You are in a severe environment and despite best
efforts corrosion of connections is going to be a problem.  A method to monitor the process is necessary for research
data and to keep the system operating. An interestin project, I'll be happy to help.

[Bruce S]

Solar_Marine:
Welcome aboard!!

ALL;

The link is a mother earth news story about it the 1980s and I think somewhere in my stack of magazines is the original story from back in the 1970s.

http://www.motherearthnews.com/nature-and-environment/underwater-building-zmaz80mazraw.aspx

It is pretty good overview of what and how.
Solar_Marine
Careful with the name dropping BIOROCK is the name of a company who has restrictions on what can and cannot be shared without their expressed permission.
Sorry had to put that in there .

It is a very mature science and quite an interesting field!

Cheers;
Bruce S

[Frank S]

I'm no marine biologist,  I am a retired industrial engineer, in the past I have been associated with many engineers of all fields some marine engineers as well.
  In most of their projects they wanted the opposite of what you are trying to accomplish  IE  protect metal structures in marine environment to increase their longevity. by using sacrificial anodes
  Since coral is a living organism I suspect that you will be seeding what ever artificial habitat you are  trying to accomplish with several  pieces of corals. on various artificial habitat base structures, which  later once a thriving colony is established could be placed in permanent locations 
  good luck  watch out for  Millepora, Stylaster, and  Distichopora  nasty sting those

[tanner0441]

Hi

I assume you are in sea water, do you know the conductivity of the sea water? Then use a test anode and cathode of known surface area so you can work out the current density in amps per square foot.;l Then you can calculate the voltage required to give you the correct current for your process , also as the sacrificial anode degrades your current will drop. You need to know the surface area of the anode and and the cathode when you start, then move one or both of the electrodes to change the distance between them.

I would look at monitoring the current and voltage at the point of use, or as close as possible.  I spent several years in my distant past designing electrophoretic painting plant, and we used to encounter similar problems but we used a none sacrificial stainless cathode, (and bubbles were the last thing we wanted). I will stand correcting but we measured the conductivity with two electrodes 10mm square and 10mm separation, it was measured in MHOS or seimens. You can do it with a standard multimeter but you have to be quick before the electrodes polarise, the meters I designed used AC at 1Khz.

I hope this helps in some way.
Good luck with your project..

Brian

[tanner0441]

Hi

I have just done a bit of reading on the process and it seems to be the brainchild of one professor Wolf Hilbertz. He uses a ferrous anode (unless your looking to collect hydrogen) and low voltage, he also uses the process to repair underwater concrete structures, the process is also similar to electrolytic protection on underground pipelines, they only use around 9 Volts.

He states in his brief that if you contact him and share your findings he will give you assistance.

Brian

[Bruce S]

Hi

He states in his brief that if you contact him and share your findings he will give you assistance.

Brian

Brian;
Unfortunately, he passed away in 2007 , tho possibly someone could answer for him.

[tanner0441]

Hi

If no help is available then I would look at doing a couple of pilot plants on a small scale then see how they scale up taking lots of measurements and seeing what gives not necessarily the maximum growth but the most stable and predictable results.

Notes of the conductivity, salinity, Ph, and dissolved and suspended solids in the test water. If there is a tidal range or flow past the test area the rate of change. Once you have a base line you can then prove your results in the future.

Reading more on the subject I would think there has got to be lots of information out there and somebodies lab notes somewhere.

Brian

[dnix71]

You don't need voltage applied. There was article on Yahoo this week about manganese nodules being found on the ocean floor about 400 miles east of Barbados. There was the usual millions of years old speculations, but these nodules are found all over the world in deep water and some were found accreted around Budweiser cans that dated from WW2.

It's obvious that warmer water is circulating down and the excess manganese is accreting around something acting as a crystal seed. You can't control ocean current, pollution and mineral densities, but you could paint the surface of your sunken object with something the coral needs (nutrition) and give it a reason to attach itself and make a home. You also have to keep starfish and lionfish away.