Algae Photobioreactor & Biofuels

What's good with it Lains. I have a question about a project that I'm doing and I'd like to ask for some advice. I'd like to build a algae photobioreactor to produce algae with, ultimately with the goal of producing B100 biodiesel fuel (maybe using hexane for lipid extraction however I haven't gotten to that point yet). Anyways, so far I've been using an aquarium pump for aeration, but I think it'd be much cooler to run the system without any electricity. My idea is to set up a small windmill as the power source and connect it to a small low-pressure air pump (in order to pump air to the bottom of an 8 ft tank I think I would only need somewhere around 5 psi, as water pressure increases cumulatively about 0.45 psi per foot). The problem is, the only cheap air pumps I can find online are all electrical, most likely small linear compressors. I can't seem to find any that solely use a mechanical drive. I don't think it should be too expensive to make a small piston compressor or diaphragm pump, seeing as I don't need to worry about a motor, just gear it up to my windmill and let it run. I really don't want to have to attach an alternator to the windmill just to convert that back into mechanical energy. I have to admit though, I'm out of my depth here. Are there any designs out there for simple diaphragm air pumps that I could make? Or any supplier that sells such a thing? I've checked the usual suspects (ebay, alibaba) and have come up short. Thanks for your consideration.

>>4917 Does your system even work? Once you have a working system then do the novelty mods, not the other way around.

What about photovoltaic cell?

>>4918 My system is a few 2L bottles with an aquarium pump and it works reasonable well. It's pretty low yield though. I'm trying to find a way to glue multiple bottles together, but all of the glues I've tried from the hardware store don't work on PET very well. I have some acrilic sheets also so I might try to make a tank out of those.

>>4920 I think I actually have an old solar charger lying around somewhere that I could repurpose... I don't know if the wattage would be sufficient though

>>4922 Do some calculations, I don't think it is hard to calculate what amount of energy it takes to create a certain amount of pressure by air pump or if that air pump allows for that amount of pressure. Also what >>4918 still holds. Make a small test and grow from there.

if you have a water source you could try to engineer a trompe to create the small pressure you need ( trompin' time - https://invidiou.site/watch?v=3U97A3h7HCQ )

The bubbles is just a way to cause agitation I think. You could just use an Archimedes screw attached to the windmill through a gear system to circulate the algae from the bottom to the top in a cycle.

>>4937 I was thinking he would like the oxygen as well though. There was a man making a sterling engine out of an old automotive air compressor, that could perhaps be adapted to do what you want. I'll see if I can find it

>>6105 "Sterling engine cast iron" throws up a lot of interesting results actually https://www.youtube.com/watch?v=IgWHuhVcLKA This is the video using a Chrysler RV-2 air conditioning compressor which is quite hard to find outside of America. You'd also be driving it with a windmill instead of propane

Not exactly on topic but similar so I won't start a new thread: Have any lains been experimenting with gas production from biological waste? I tried composting kitchen waste with a container that was supposed to store the produced gas, but unfortunately it was pretty hot that day and it composted so fast that my container exploded lmao. So I gave up for the day and only was reminded of my project when I saw your thread. Being able to generate gas from decomposing biomass in a SHTF scenario would be very neat, but I mainly do it for fun I guess.

>>4921 Do you have a heat gun available? You may as well melt them together. It's a bit tricky to get the bottom side right, but if your section is small enough it works great if you slowly turn the two objects while heating the upper side constantly, making gravity do the work for you.

>>4921 Why not pick up a 145l garbage bin? Use glass or plastic to make a clear flat lid, and make some holes for tubing.

>>6107 I think it would fit here, as the thread says "algae bioreactors & bio fuels". As to the problem at hand: I did not do a build yet, but I took some notes, thought experiments and looked up biogas reactor schematics, and it seems that the best way to go about it is to build a reasonably big setup, so that it justifies the additional expenses. For the degradation process you would need a large container, ideally from stainless steel for small scale applications, but I imagine a HDPE container would work well, too. If you absolutely need to cheap out, use thick PET, but watch out for pressure damage. The reactor needs to be sealed, and tubes are needed for ventilation and siphoning off the biogas. It needs to be stored separately, in a pressure rated container, which could be improvised from a fire extinguisher, or using any other pressure rated vessel that you can attach a valve to. For storing the gas, you would also have to compress it after a while, so having a compressor is a must, if you aim for high yield. Also, think about cleaning the gas, as the degradation products include hydrogen sulfate, which can fvck up your setup over a short chain of chemical reactions. As with everything, do research into the topic, and work out critical details before building a setup. It will save you a lot of frustration.

Look up "peristaltic pumps". These are simple mechanical systems that also are reliable, and are easily connected to a small wind turbine. If you use a vertical axis wind turbine, you can feed the compressed air in a small hose straight to your bioreactors without going through electricity or long mechanical axles.

>>4917 You can use pumps meant for bubble baths or peristaltic pumps. Just check what back pressure they can handle, which relates to the depth of your bioreactors. You might not want to make these too tall. >>4918 Not sure about OP but such systems are in use. Some have covered the facade with glass bioreactors and rely on sunlight for energy. >>4923 The energy is force x distance, where force depends on the height of the water column and density of water. >>6107 This is well tried technology but keep in mind that you need anaerobic fermentation to generate methane, otherwise you get a lot of CO2. Farmers have filled fermentation chambers with manure and get a fair bit of methane gas. This is impractical of end of the world scenarios since you need a fair number of animals. Wood gas generators are more feasible.

Thanks for the idea. I just found this site https://farm-energy.extension.org/algae-for-biofuel-production/ I personally was looking into hemp fuel for ethanol and diesel, but this is an interesting alternative. I want to get the highest yield while balancing space and physical labor. This or a combination of this and hemp could be a good solution. That or if this could meet my fuel needs then I could grow less hemp and produce the oil and foliage for consumption and medicine.

>>8234 I just looked over this site I posted last night and wow, 18 gallons of fuel per acre from corn vs 6283-14641 gallons from algae. This chart doesn't mention hemp, but according to a source I just found farmers can net anywhere from 700 lbs to 1200 lbs of seed with a generous 32% oil compared to canola oils 40%. That's 231 gallons of oil from an acre of hemp. Now I'd need to calculate how much fuel i'd need to power a .5 or 1 MWH generator a minimal amount to meet my power and or heat demands. Now a quick search shows that it takes 2 gallons average per day to heat a house where the outdoors low temp is 40 F. Now living in New England I know that I'll need much more fuel since an acre would only heat my house for 115 days at 2 gallons per day and that's certainly not enough considering how harsh the winters are. I could survive the summer without AC though. Then there are my power needs, though power and heat production can overlap since a Combined Power and Heating unit produces both. This just opens my eyes to the fact that even hemp fuel would be costly and require a fair bit of labor to maintain self-sufficiency. I guess I would need to compare upfront costs and labor to algae production since that is the clear winner. I am basically trying to draft up a white paper for totally self-sufficient living where you don't need to give up today's luxuries, rather just adjust your lifestyle a little bit so that you consume responsibly. So my goal is certainly to try to produce all my energy, food and material needs with as little cash and as few hands as possible. Then take that data to scale upwards for small compounds, towns, cities and municipalities. I want to apologize now to anyone that thinks I am trying to steal this thread, I simply felt that this is relevant to OPs needs and thus may help them and others. Here is a link to the hemp fuel article I referenced. http://www.biodieselmagazine.com/articles/1434/hemp-biodiesel-when-the-smoke-clears

>>8236 HAHAHA small correction. an acre would produce 30 gallons of hemp fuel from 231 pounds of oil extracted from 700 pounds of seed. Yeah I was looking at another site that stated that penuts produce 3500 pounds of penuts at 50% oil with a total of 240 gallons of oil which was only 9 gallons more than my hemp oil calculation considering being 4 times the dry weight and a higher percentage of oil. So 30 gallons of fuel per acre proves that hemp isn't viable for small scale production and self-sufficiency. I'd need acres and acres of land with heavy machinery and many hands just to meet one households needs, but penuts on the other hand is clearly better, but algae still comes miles ahead of the others.

>>6105 Old thread, so OP might have already built his system out, but this gave me a thought; >>4917 OP, why not run the entire system off electrical, but from a Stirling engine generator running off part of the biodiesel produced from the algae (once you've got that system set up)? I presume you mean that you don't want to run off the grid, not that you have something against moving electrons in and of itself; If so, it would certainly simplify things in terms of needing to construct a windmill, select a more ""specialized"" pump and work up a connection between them, versus just picking up a generic pump off the shelf and doing a little electrical work. Plus you're not tied to making sure you're getting enough wind at any one moment, and you could up the control complexity if you ever wanted (simple example: https:// youtu.be/64cEmjtwRgw?t=899 ) by just adding more electronics to the same electrical structure. At that point the simpler system would certainly be a matter of opinion, but electricity would have to be more flexible. The whole system could semi-automate itself, including pumping into whatever you've got set up for fuel generation, and you wouldn't need to worry about setting up more windmills or whatever and switching the pumps yourself. Just let an arduino or something handle it.

>>4921 Literally just use clear packing tape bro