Just joined this forum... already learning tons...

I am trying to put together a small algae-to-biodiesel demo project in Vancouver, Canada. This is very much in the planning stage, and I'm scoping out various technologies and techniques...

One major challenge is temperature control (without significant energy inputs), and a dynamic bubble insulated greenhouse along the lines of solaroof.org and solarbubblebuild.com seems ideal.

Has anyone had any experience with bubbles?  Should I be looking at alternate insulation systems?

Thoughts appreciated,

d

Have you spent any amount of time under a greenhouse sort of conditions 12 months out of the year?

http://forums2.gardenweb.com/forums/load/strucs/msg0217432416706.html

My suggestion would be to learn from the greenhouse plant people. Maybe a greenhouse hort course or work in a tomato hothouse operation or... just to learn the swings that happen. In the summer its 140F and in the winter it will freeze every water pipe u got. Even daytime/nighttime swings can be tricky.

How about an algae that can handle 45F and just use geothermal groundloops? That solves your heating and cooling issues.

Maybe ecogenics seminar would help.

That bubble solaroof is cool stuff, Ive been dreaming of setting something like that up for a while now.

d,

Solaroof has great promise and the few that have been built work.  There are not enough to be able to be dogmatic about the design.  

The complete design does take care of both heating and cooling, avoiding the extremes encountered in conventional greenhouses. 

If you build one, be sure to make the bubble chamber at least a yard thick.

There have been proposals to incorporate the algae growth areas into the Solaroof, leaving the interior for other uses. 

 

our  closed loop ecosystems have functioned winter and summer growing algae and tilapia fish for  close to thirty years now, we have had the opportunity to thoroughly test our systems over a broad range of climatic conditions.  in the summer, we can reach stagnation temperatures up to 160f if we dont ventilate the system, we do this  occasionally to steriilise the interior of the system and make it free of many pathogens. in the winter, we can hold 80 F temps in the system even when temps outside are 20F.

 the water  in the pond maintains a constant 65F due to geothermal heating (cooling)so there is not much of a delta T to reach the 75 or eighty F termps to maintain a high metabolic rate for the fish and algae.

we will cover the details of the Ecogenics ecosystem extensively in our upcoming "How to" seminar. basically our system is a  linear modular air rigid, frame supported polytunnell P.B.R. and can grow 10 LBS. per day (wet) of algae harvested by surface skimming or up to forty LBS (wet) by  harvesting through 500 mesh screens .

check out our website www.ecogenicsresearchcenter.org for pix and details.

 

 

Froggy, thanks for the link...

My bedroom has south facing windows but I guess that doesn't qualify as a greenhouse ;-(

I read through the gardenweb thread and did a couple other searches on the site, and get the distinct impression that single pane greenhouses get freakin' cold at night without some sort of heating... despite getting super hot during the day.

My interest in bubble chambers... aside from the coolness factor... is they sound like they can stabilize indoor temperatures within a narrow range with minimal energy input.... and potentially be built with cheap materials.

Now, geothermal ground loops... or, should these really be called heat sinks? These sound well proven and effective...I'll have to look into this more.  Any favorite links?

...ecogenics, checked out your site... nice stuff...(!)... yet perhaps I'm missing the section on greenhouse design?

d 

Use closed loop geothermal wells to supply lots of low grade heat keep the algae/diatoms from freezing http://geoheat.oit.edu/dusys.htm

Good thread. Glad to see I'm not the only one looking at the solaroof technology . I think there's alot of promise in being able to convert greenhouse space into an active photosynthetic surface. Most of the work I've been doing has been for the MDEQ looking at bioremediation of excessive nutrients by algal (cyanobacteria) growth. I have yet to get out of the lab, but I think that if I were going to build a bioreactor/raceway system I would incorporate a passive flow system that would allow water + algae to run down the surface of a rounded greenhouse, in a cavity that would be covered by a larger greenhouse. This system would trap CO2 and heat, but also seal off potential contaminant strains of algae. This would essentially be a hybrid of an photobioreactor and raceway, having the advantages of a passive system with alot of surface area (raceway) and a closed environment that would be easier to control (PBR). I've looked at the solaroof stuff, but I think it would be too costly to use energy for a bubble-making fan. I think that the system could be cooled by passing water through a heat-exchange pond. One question I have for you guys here (I'm a bio-chem person, not into economics or energetics) is if it would be worth pumping the water/algae mix 10 vertical feet to the apex of the greenhouse system? If I assume that the surface area is 1250 sq ft. (40x20x10) and the water depth is 0.5 in. will I need a 52 C.F.S-1 flowrate to ensure a constant 0.5 in. film of water? (assuming surface is 100% level) Would this flowrate require more energy than I would get back from the algae?

Jordan,

I think the Solaroof proposal was for a trickle of water over the inner surface.  Nothing like 1/2 inch is needed.  You just want to give the algae cells a few moments exposure to the sun as they coast down the covering.

The users of the Solaroofs that have been built have felt the electricity use to blow bubbles is justified.  You do not blow bubbles all the time - only when the old ones have collapsed or you need some heating or cooling.  TheSolaroof includes a heat exchange pool, usually underneath it (it not easy to see, but it is down there.)

The Solaroof algae proposal would involve three films - the outside two define the bubble area and the third layer is for the algae.  So it is kind of a PBR solar collector inside a greenhouse. 

Both of the Solaroofs that I am aware being in operation are rounded.  If you go to a larger structure,it may make sense to make it flat.  There are proposals for large greenhouses with flat, but sloping roofs.  Rounded works, but flat may work also.

Ross is revising his system based on several years experience.  I suggest you look at his next version and at Harvey's before you finalize your plans.

Sorry for the delayed response, didn't see your reply. Anyways, I have recently given this solaroof idea alot of thought, mostly because I'm not an engineer and don't want to bother with testing my own design. I would like to know how the algae gets raised to the top of the lower greenhouse cavity, does a pond pump seem like the only answer or can an airlift pump also be used. The solaroff/algae proposal is essentially a hybrid bioreactor and open pond, somewhat like the solix bioreactor and has alot of strengths to it, with the only significant weakness being that algae has to be pumped vertically to make it work right.

 

By the way, who are harvey and ross? Do you have a link for their website/contact? How do you know so much about solaroofs? have you seen one in person?

 

 

Jordan,

Yes a lift pump will be needed.  And to lift about 10'.  I am not experienced with airlift pumps but assume it could be used.  My wild idea was an Archemedes screw.  We will need to be gentle with most species of algae to avoid damaging them.

Harvey and Ross are the owners of the only two currently existing Solaroof buildings. (I think there have been others, but they have been taken down.)

Harvey is at:

http://www.solarbubblebuild.com/

Ross's company is at:

http://www.sunarc.ca/english/home.html 

I have been following Solaroof - both Yahoo group and wiki - for some time.

 

http://solaroof.org/wiki/SolaRoof/HomePage

http://tech.groups.yahoo.com/group/solaroof/join

 

Harvey was gracious enough to invite me to visit him and his greenhouse. 

Hello dsgirard,

It's great to hear that someone has taken an algae interest in Vancouver.  I'm currently working at the wastewater treatment plant in Whistler and am also interested in setting up an algae to biofuel project for my master thesis over the next 2 years.  

I have been trying to learn as much as I can and these forums have been very helpful.

Where will you be obtaining nutrients for your algae growth?  It is fortunate that our municipal waste stream has plenty of nitrogen and phosphorus for algae growth, temperatures range from 10degC in the winter to 22degC in the summer.  I am now trying to culture some native species in a homemade photo-bioreactor.

I am very interested in collaborations and hopefully we can discuss algae to biofuel more in the near future.

AT