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56 comments on Pond Scum or Planet Savers?

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odograph on January 16, 2006 - 9:19pm Permalink | Subthread | Comments top
I'll have to follow those links and listen to those mp3s when I have more time.  The algae systems are interesting, but I'm cautious about the maintenance required by these tube-based system.  My intuition as an ex-chemist, aquarist, and goldfish pond owner is that they will be high maintenance.  And certainly, they can't touch a pond for photon capture.  No matter how you stack your tubes, you're still going to have light hitting racks, mounts, struts ...

On the other hand, they look really zippy, and no doubt serve to attract funding much better than a boring pond.

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odograph on January 16, 2006 - 9:26pm Permalink | Subthread | Parent | Comments top
BTW, the advantage of tubes in an experimental setup is that you can monitor inputs and outputs more carefully.  There is no pond surface to atmosphere transfer to be guessed at.  So, a loss in efficiency is balanced(?) by an increase in monitoring.

I suppose covered ponds would give you an ability to measure surface transfer, but you have to maintain your pond cover.

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ericy on January 16, 2006 - 10:16pm Permalink | Subthread | Parent | Comments top

The people who first started looking at algae were considering open ponds - I imagine because of the low capital costs.  These days people have given up on that approach, for several reasons.

First of all, some strains of algae have a high oil content, but many do not.  In an open pond, what would happen is that you get competing strains growing in the pond which you don't want.  A closed system makes it much easier to keep out unwanted strains of algae.

Secondly, it is harder to maintain the optimum growth temperature in an open pond.

Finally, I gather that an open pond would lose a lot of water from evaporation.  A closed system wouldn't have this problem.

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odograph on January 17, 2006 - 9:17am Permalink | Subthread | Parent | Comments top
I hadn't heard that you need to limit growth to certain species.  Certainly a pond evloves over time ...

That would absolutely be enough to require a closed system.

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TJ on January 17, 2006 - 9:22am Permalink | Subthread | Parent | Comments top
I'd guess that this will never happen unless they figure out how to make a pond work.  Miles of plastic tubing would be a maintenance nightmare; any blockages would have to be cleared by hand.

A bioreactor might work for a furnace output, if you could find people willing to pay for the installation.

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Magnus Redin on January 17, 2006 - 10:28am Permalink | Subthread | Parent | Comments top
Pump cleaning plugs thru the pipes at regular intervalls. I would be more worried about finding a long lived transparent plastic that is not turned brittle or opaque from UV radiation.  Long lived tubing is important for good economy.
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TJ on January 17, 2006 - 12:49pm Permalink | Subthread | Parent | Comments top
Won't work.  Phytofermentans did the math.  You're talking thousands of 20' plastic tubes all manifolded together in parallel.  To prevent blockages you would have to regularly backflush each tube.  The piping and valving alone for the gas, water, and cleaning would cost several times what the tubing would.
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