Oil from algae

Hello!

Woke up in a visionary state of mind today and thought I'd put my thoughts out for display!

In order to achieve world dominance, or rather crush it, we need infinite supplys of raw material apart from the ultimate meta-fabber that makes itself on all levels.

Obviously supporting dictatorships in oilproducing countries is not the solution.

Most biofuels also suffer from the problem of eating up farmland and thus, direcly or indirectly taking food away from poor people.
Apart from the moral aspects of driving your ethanol-gulping SUV to the grocery
store to buy some mayonaise (how many bowls of rice did you make not happen going back and forth?) we also have the problem of nitrides and over-fermentation.

Nukes and fusion is all nice and dandy but before we get there we are likely to have nothing to make stuff out of left (read: no oil no plastics)

It seems that green algae could be the solution to all of the above.

According to www.oilgae.com the green algae run on sunshine and CO2 and nothing more. The nourishment used to grow them can be filtered out and recycled infinitely!

Also the algae can make use of dirty water or even saltwater, deserts would be a great place to grow if the systems could be made closed-loop.

Another California based company (Sapphire Energy) has made claims that they will make crude oil from algae, suitable for the present-day refineries, making diesel and gasoline just as usual, currently they say at prices of refining hard-to-get-to oil.

My question to the brain-trust in this forum: Doesn't this knowledge belong in the public domain? Anyone in for growing green slurry in their backyards this summer?
(Or the coming summer for the southern hemisphere)

Energy figures for those interested, calculating roughly at 1kW per m^2 of land
and conservatively at 2000 hours of sun per year gives us a potential of
20 liters of biofuel assuming an energy content of 10kwh/liter and a 10%
effieciency of conversion rate.

It seems that a moderate 100 m^2 rooftop reactor could heat a home for a year.

I know there are some talented people here, please tell me what you know about this!

Especially I like the pragmatic approach of people on this forum!

Hi mimarob,

... similar ideas with generating food-basics, energy and all sorts of ressource-materials (for building and fabbing too) from algae, bacteria or funghi are common in many SCI-FI-novelles since 50 years or so.

Some clever folk made several efforts to realize this in reality too, but until now generating the needed stuff from mineral-oil was cheaper and more supported by funding and common (industrial) interests

Maybe with rising prices for the ressources this would change, but i think it's a problem we have to encounter some years more ...

There are many clever ideas for receiving energy, ressources and other stuff 'free' from our local surrounding, but without a broader interest they tend to 'dissolve' in the information-swamps.

Viktor

I believe most photosynthesis is about 1% efficient. Remember that's just at first stage carbon fixation. Much of the energy captured must then be used to run the cellular machinery. It would take bioengineering on a level not currently known to turn 10% of incident sunlight into hydrocarbon products.

Quote

Energy figures for those interested, calculating roughly at 1kW per m^2 of land and conservatively at 2000 hours of sun per year gives us a potential of
20 liters of biofuel assuming an energy content of 10kwh/liter and a 10%
effieciency of conversion rate.

10% is a bit keen for photosynthesis. It's somewhat less than that (someone on another thread quoted 3% as being quite good for a plant).

Quote

It seems that a moderate 100 m^2 rooftop reactor could heat a home for a year.

I'd say that's quite a big pond to stick somewhere, especially on rooves which aren't really intended to bear serious loads Maintaining such a thing could prove tricky too.

Photovoltaic cells are a far better way to extract power from sunlight; modern cells are getting quite efficient. I was reading [www.extremetech.com] this morning, by a strange coincidence. What they can't do is provide you with useful materials to use elsewhere; alcohols for your fuel cells, for example. Or feedstock for handy organic thermoplastics, which would be very useful to the project!

Oh well, one pipe dream at a time. I live somewhere with weather unfriendly to solar projects, limited roofspace, poor wind levels (and no space to put a turbine anyway!) and no workshop. You'll no doubt have better luck with these sorts of projects!

For use as energy, algae is incredibly wasteful in that respect. As has been already stated, the efficiency of photon-to-fuel is, at this point, be around 1%, and that's at the high end. It's much better to heat a home using solar tubes, and power it with photovoltaics. Fueling cars is problematic because fossil fuel is still comparatively less expensive (though not by much, and there's definitely room for improvement on the algal feedstock end).

I'm the administrator of www.phyco.org, and I've been researching algae for the past few years. However, there's one thing that I keep coming back to-- the economics. Although algae is very prolific (it doesn't spend time building plant parts such as flowers, stems, and leaves; it's all about reproduction & production), corn and soybeans already have a large amount of established infrastructure and subsidy that facilitates their production as fuel.

However, after discovering RepRap, I read somewhere that your goal is to use plastic in the price range of $0.02/cubic centimeter. That comes out to $20/liter of material. That's about an order of magnitude the price at which it would be economical to sell algae as fuel. In addition, it would make RepRap self-sufficient.

The only problem is that no one has produced fuel from algae on a commercial scale-- (ie, you cannot buy it), much less plastic. I can look into papers on if anyone has produced any sort of plastic such as PLA from algae, however. It is also technically possible to gasify the biomass and use the resulting syngas to produce stronger plastics.

I'll look into it. You guys have some great ideas here!

The big problem of algae isn't the efficiency of photosynthesis. The problem is the evaporation from the body of water needed to keep the algae in. Think about just about every home needing it's own olympic-sized swimming pool and you will get the idea. That much water surface loses a lot of water to evaporation. It's an expensive proposition, never mind the health implications of deliberately creating that much stagnant water.

Hi, Forrest!

Water is generally an issue with open ponds such as raceways, but not with bioreactors. In general, you only put in what you take out (in a properly engineered system). This actually makes these much more economical for fuel production than any sort of agriculture available today.

For a home system, it might make more sense to use a photobioreactor; though they cost more, they produce a higher algae density, and are better for growing high yield monoculture crops.

I consider a photobioreactor to be more DIY than a raceway pond, since you can more easily tweak productivity on a small scale, and still get the end result of a pond ten times its area.

Another thing about ponds; you mentioned stagnant water-- any raceway enthusiast will tell you that you need a paddle wheel. This is important for many reasons; it mixes the algae so you get better aeration and light coverage, so you don't bleach the top layer of algae (algae need only about 10% of regular sunlight. You need to let the photosystems recover under bright light).

Um... and just how are you getting the sunlight to the algae?

Hello Forrest,

There are many different configurations for photobioreactors. Some use tubes, some use bags, some use aquarium-style vessels. I'd suggest a combination of tubes and aquariums for a DIY, homebrew kit.

As a disclaimer, I've never put this into practice; I've only studied algae in the lab and in textbooks. Yes, I'm one of those... You're right to be skeptical of this, as it's still in experimental stages.

The take-home is, eventually someone, a DIY, backyard tinkerer, will get it right. Hopefully they'll share their ideas with the community. There are a lot of resourceful people here building RepRaps, that I think this might be the ideal place to spread the word.

I did some research into bioplastics, and I found an excellent article about using renewable feedstocks from biomass. A good deal of these could be grown at home, if using the proper techniques and equipment. I will give an example. Here is the article:

[www.nt.ntnu.no]

The R-1 portion of synthesis diagram of Rilsan 11 (Nylon-11, PA-11, you may have heard of it...), specifically, the one found on page 8 and described on page 7, is already done by biodiesel homebrewers and co-ops. This is part of a larger process that ultimately ends in creating the polymer, which I will summarize below:
* Algae produce starches and lipids. (not in the diagram, but let's use this as a basis)
* Starch can be fermented into ethanol, which can be used as a substitute for expensive and harmful methanol, and lipids can be extracted from algae (exactly how is a discussion for another day) (this is not in the process diagram, either)
* After esterification, aka "the biodiesel process", (R-1, using lipids, ethanol/methanol, and sodium or potassium hydroxide... aka lye, caustic potash, as a catalyst), biodiesel (methyl/ethyl esters) are sent to be washed in sulfuric acid (S-1, to remove the basic NaOH or KOH catalyst; some homebrewers I know handle this regularly) in order to neutralize the pH.
* The esters are purified (C-2) in order to get the desired biodiesel with a carbon chain length of 18 (C18, which is longer than the average carbon chain length found in diesel fuel, but less than motor oil; however, this is still the stuff of vegetable oil, please don't confuse it with fossil fuels.) The mixture of methanol and catalyst, as well as the quality and properties of the lipids in the esterification step will determine the chain length of your methyl esters. This is to be experimented with, and is why it's handy to have some lab equipment available, such as a gas chromatograph, in the beginning stages, until more commonly available tests, such as the pHLip test, are created for homebrewers. If this is going to be done on the co-op scale, however, a GC is good to have in order to optimize production and get quantitative feedback.
* Next, the C18 methyl ester is send to a pyrolysis chamber (R-2), which is basically a 570-degree F oven. Some perfume gunk is removed from the chamber, dunno what to do with that. More perfume gunk is removed in C-3 and C-4. We really don't want that perfume gunk to be in our polymer.
* In R-3, saponification takes place, which is the same process used to make soap. You can get methanol out of this, since that's what esterified that lipid in the first place.
* In R-4, hydrobromic acid (this may prove to be a challenge due to its acidity constant of -9, which makes it a much stronger acid than H2SO4, with a acidity of -3. For reference, acetic acid (you know, from vinegar) has an acidity of positive 4.76, and water is 15.76.), is added to the result of R-3, to add bromine to the mix. Bromine is present in salt, especially sea salt.
* Finally, in R-5, we're reacting the product with ammonia, which is sent to be cleaned in C-5, and results in your polymer, 11-aminoundecanoic acid.
And I'll bet you thought making biodiesel was hard!

---

~~~~
[phyco.org]

Yeah, I guess I'm a little skeptical. If you are depending on sunlight going through a transparent media to get to the algae you've got problems. Glass, which won't come apart in sunlight is going to be hideously expensive given your 1-3% max conversion efficiency. I know of no transparent polymer that can stand direct sunlight for more than a few months. It doesn't sound anywhere near practical. Wish it was, mind.

Forrest Higgs Wrote:
-------------------------------------------------------
> It doesn't sound anywhere near
> practical. Wish it was, mind.

*sigh*
I know how you feel, man. Some days it feels that way too. Did I mention that algae is only about as dense as 1g/L? That's usually doubles every day, mind you, which is great, prolific even, but it's still 0.1% of the total volume, and harvesting is only one of the issues involved in sorting all this out, in addition to finding the right strain and growth conditions, production of the algal culture, recycling medium, extraction of starch and lipids, processing... The list goes on.
I try not to get too down about it though, since the possibilities are there, and maybe by the time I get my PhD, things should look more promising in the field.

PhycoFalcon Wrote:
-------------------------------------------------------

> I try not to get too down about it though, since
> the possibilities are there, and maybe by the time
> I get my PhD, things should look more promising in
> the field.
>

ROTFLMAO! I remember thinking exactly the same thing about algae harvesting when I was finishing up my Master's thesis on solar energy conversion efficiencies...

...back in 1974.

Hmm, so I'd better lower my expectations one order of magnitude or so, damn I have to stop reading thoose news-from-a-startup-company texts...

So we are down to a 10W/m^2 production rate and that is in a closed tank under optimal conditions... o well, back to the drawing board :-)

Edited 1 time(s). Last edit at 06/02/2008 03:46AM by mimarob.

... there were some recent ideas to enhance the productivity of algae-growing with many communicating water+algae-filled glass-tubes surrounded by focussing solar-mirrors (similar to focussing heat for hot-water-devices) or UV-emitting lamps.

For optimal results you have to arange two separate areas - one exposed to the light, another fully darkened, as most algae needs day-night-cycles ...

Maybe for generating fabbing-material you should focus more on funghi than on algae?

You can grow many kilograms of (some tasty too ) mushrooms in your basement, when wetting some straw-blocks and seeding the right spores ...

Viktor

mimarob Wrote:
-------------------------------------------------------
> Hmm, so I'd better lower my expectations one order
> of magnitude or so, damn I have to stop reading
> thoose news-from-a-startup-company texts...
>
> So we are down to a 10W/m^2 production rate and
> that is in a closed tank under optimal
> conditions... o well, back to the drawing board
> :-)

That measurement you posted is used as a measure for solar insolation; you didn't give any period of time for this "rate"; and you only get 10W/m^2/day around the equator. Here (Colorado) it's more like 5W/m^2/day (averaged throughout the year). Plus, that's only really relevant towards solar panels, since with algae production, it's often measured in g/m^2/day. Spirulina, when grown in tubular photobioreactors, typically yields 25g/m^2/day, as can be found in the paper "Microalgal mass culture systems and methods: Their limitation and potential", by Yuan-Kun Lee.

Viktor, I'm wary of systems that focus solar energy onto algae, as that is liable to overload their photosystems and bleach out the algae. Algae need only ~10% of full sunlight. I would never use UV bulbs to grow algae, either.

I can't say I know much about fungus, other than that it is a heterotroph, meaning, it eats food rather than makes it. That might make it more productive than algae, but I like algae since it adds energy to the system rather than reducing it by another trophic level as the fungus would.

Hi Alex,

the mirrors shouldn't focus the sunlight to much, they should better distribute the light between the tubes, otherwise the tubes would shadow each other.

Tubes because of the same reason - in a big tank only the outer algaes receive the full sunlight - with tubes you have better distributing ...

For the funghi: - besides of energy you need fabbing material too, so maybe it's easier and more efficient to use dried/baked and powdered funghi as fabbing powder?

Viktor

The algae should still grow even if they're somewhat shaded. As long as it's not in total darkness. Usually algae are CO2-limited, but unfortunately that's a problem that is difficult to solve in a renewable manner.

If the the fungus powder can be extruded as something resembling the properties of a polymer, that's cool, but I'm not sure that would work. You should do some research into that.

I've heard of fungus being used to turn oil and alcohol into biodiesel, which is the first step of the renewable Rilsan process I detailed in an earlier post, however, you still need a source of oil and alcohol, which algae can provide.
[blog.wired.com]

25 g/m^2 and day..

So assuming good sunlight we could get around 9 kg of it per square meter and
year.

My rooftop example would then give about 900 kg of biomass for a year.

Is that dry substance and oil or is it before we remove the water?

Any guess on its energy content?

I made some rough guesses and ended up about at about 10W assuming it could be
burned as fuel (and the smell didn't kill you :-)

What other refinements are needed to make a useful product out of this?

Assuming it could make into behaving like crude oil, all other processing stages would already be well-known.

BTW, I talked to a guy from the middle east a few years ago. He told me that it was possible through some crude process to make some kind of plastic "glass" out of oil, which was then used for greenhouses to grow food. The plastic glass would only last about one season under the dessert sun though.

Bioreactors reproducing themselves...

Erik.. Dreaming away at work...

I've never heard of that glass, Erik. If you can, please look into it some more.

The 25g/m2/day figure is simply for dry biomass. If you are clever, you can get about 30-40% of that as oil. Since a gallon of vegetable oil weighs about 3.4kg, you should be able to extract about 1 gallon vegetable oil from the algae per meter per year.

Now, let's say we've got a 100m^2 area, like your roof, and we effectively covered this with tubes. Assuming that your bioreactor will produce 1.6g of biomass per liter (as per the paper I mentioned earlier, referenced to the 25g/m2/day spirulina figure), you'd need to process half of the 15.6L of algae per m2 of reactor space. You process half because you harvest half the solution, fill it in with fresh medium, and then let the culture double again (usually over the course of one day). So, we're processing about 781L of algae each batch, about 200 gallons per day. Out of those 200 gallons should come about 1.25kg of algal biomass (which makes sense; that's 0.625% of the solution, as algae is very dilute, even in the dark green stuff). This means you can get about 67 gallons of biodiesel from your roof-top system per year.

You might be able to get starches from some of the rest of the processed material, which can then be used for ethanol production, to make up the other 10-20% of your biodiesel (the Renewable Raw Materials paper recommends using 'an excess' of methanol to produce Rilsan plastic).

At any rate, let's say we can use 50% of the algae in making your biodiesel. That's 1.38lbs of biodiesel, or less than .2 gallons per day. Also, accounting for glycerine loss, you take 10% off of that figure. You'd need an entire week to produce 1 gallon of biodiesel from your reactor.

Most people would stop here, and say-- damn, algae makes so little fuel, it's impractical for powering my big SUV. That's true. But we're in the RepRap community now, and RepRaps can be solar powered, so they don't need expensive fuel. But they do need plastic, and plastic is much more expensive than fuel! I read somewhere on this forum that PLA costs $75 / 2kg spool. B100 fuel costs, today, in Denver (Courtesy of Shoco Oil), $5.43/gallon. So, that's $1.60 / kg. The economics work out to be in much greater favor for plastic production. Even ABS plastic is $20/kg, according to the rrrf.org site.

I don't know the losses in the Rilsan plastic production process, but let's just guess and say we can turn 80% of the biodiesel into plastic. So, if we can make 164kg of biodiesel per year, (that's with esterification, glycerine, and extraction efficiencies accounted for), it would be valued at about $5000. That's enough plastic to make about a 100 RepRaps, and if you sold those as parts, you could double your money. And all that off of one roof!

If the process is not economical, in a capitalist economy, it's not sustainable. It's a good idea to think about sustainability, since even if the process is renewable (which is a tough enough feat to achieve by itself!), you may find it's not possible to do it in a sustainable manner; such as using flue gas from coal plants as a CO2 source, or chemical fertilizers to make your culture medium; or using biosolids from wastewater treatment plants (wastewater treatment uses 1% of our total energy resources here in the USA.); these sort of things aren't sustainable in the long run. You've gotta be thoughtful about how you do this, and cover all the angles.

mimarob Wrote:
-------------------------------------------------------
> BTW, I talked to a guy from the middle east a few
> years ago. He told me that it was possible through
> some crude process to make some kind of plastic
> "glass" out of oil, which was then used for
> greenhouses to grow food. The plastic glass would
> only last about one season under the dessert sun
> though.

It's not glass. Greenhouse growers without a lot of capitalisation often use plastic films like polyethylene. They last about one season. Around here, they cover whole open fields with polyethylene and gas the root nematodes with methyl bromine. For high value crops like strawberries they cover the fields and plant the sets in holes in the film. That cuts way down on the amount of cultivation to keep weeds under control that they have to do and thus the number of illegal aliens they have to hire.

Apparently, there is a grade of Rilsan that is transparent! This could possibly be produced to make more material for a photobioreactor. Basically, the PBR could produce more of itself, just as Erik was thinking.

Check it out here:
[www.omnexus.com]

RepRap

Almost none of the corporate proprietary stuff is in the public domain.
I've just written a book: Green Algae Strategy: Engineering Sustainable Food and Biofuels
that summarizes both the food knowledge and biofuel knowledge that's public.

some algal species are 84% lipids (oil) but they grow very slowly.
others at 60% oil can be grown quickly.
other species are 60% protein while others are 90% carbs

whoever posted the piece on open ponds was right: too much evaporation plus opportunistic algae invade pond, create weedy algae which must be replaced. Closed cultivated algae production systems, CAPS, are the way most firms are going. Far more productivity and more control over growing variables.

Very little exists on actual production outside of academic papers and one edited book by Amos Richmond (Israel) on actual production metrics.

My book Green Algae Strategy will be availabe on Amazon in August.

Mark Edwards
Professor, Arizona State University
drmetrics@cox.net

Thanks, Mark. I look forward to reading your book. It's been a long time since I've seen anything on the subject aside from academic papers and blue sky activism from envirocrazies with no technical grip on what they propose. It will be good to see something solid and maybe even practical for a change. BTW, do you recall the title for the Richmond book?

Edited 1 time(s). Last edit at 06/02/2008 01:28PM by Forrest Higgs.

Forrest Higgs Wrote:
-------------------------------------------------------
> I know of no transparent
> polymer that can stand direct sunlight for more
> than a few months. It doesn't sound anywhere near
> practical. Wish it was, mind.


There is at least one. It's called Tefzel and it isn't cheap.

[www.rwgrayprojects.com]
[www.rwgrayprojects.com]

Now if you could produce it yourself that might be a different matter.

Hi,rodzite. I posted earlier a link to a type of Rilsan that is transparent. Here's another link, straight to the manufacturer:
[www.arkema-inc.com]

Using the process described above, that may be a starting point towards creating Rilsan on your own.

Interesting stuff.

Sorry, when I said "glass" I meant something like plastic transparent sandwich wrap.

Anyway if one could get a way with a material that thin, it might not be so much of a problem to replace it every season.

So is it the photons in the sunlight that is the limiting factor to the photosynthesis or is it the limited amount of CO2?

I read somewhere that they where going to try leading the CO2 from nearby powerplants into the algae, but thats obviously not sustainable.

It is anyway most certain to need a ventilation of some kind and so a filter to keep the alien algae away and a few pumps so we need another field of electriciy solar panels *sigh*

Obviously the algae also needs to be circulated, which leads to a question I had for some time: How deep does the pond need to be to make optimal use of the sunlight?

Another thought I had was about growth, we know the repraps can grow quite quickly.

When it comes to filling space, suppose we can make a 1m^2 bioreactor complete with a plastic box weight 1.64 kg, we could double the amount of reactors each year, provided we don't make any repraps.

Considering I spent 5 liters of fuel this morning just getting to work (and an unknown amount just being there) we'd need a pardigm shift to go with it :-)

mimarob Wrote:
-------------------------------------------------------
> So is it the photons in the sunlight that is the
> limiting factor to the photosynthesis or is it the
> limited amount of CO2?

It's usually CO2 that is the limiting factor, but other limiting factors could be macronutrients (NPK-- nitrogen, phosphorous, and potassium), trace metals such as iron, sunlight (though algae need only 10% full sunlight), high oxygen concentration, and even competition from contaminant algae, bacteria, and protozoa, just to name a few of the challenges one might face when growing algae in a photobioreactor.

> It is anyway most certain to need a ventilation of
> some kind and so a filter to keep the alien algae
> away and a few pumps so we need another field of
> electriciy solar panels *sigh*

It would be wise to install a good, replaceable filter on your air pumps.

> Obviously the algae also needs to be circulated,
> which leads to a question I had for some time: How
> deep does the pond need to be to make optimal use
> of the sunlight?

If you're going with a pond, most commercial raceway operators use depths of only 20-30cm. That's 8-12 inches. They use a paddlewheel to keep the mixture circulating, and this setup works very well and is proven. There are, however, issues with evaporation and environmental factors, as we have discussed.

> Another thought I had was about growth, we know
> the repraps can grow quite quickly.
>
> When it comes to filling space, suppose we can
> make a 1m^2 bioreactor complete with a plastic box
> weight 1.64 kg, we could double the amount of
> reactors each year, provided we don't make any
> repraps.

Where did you get that number? One cubic meter is 1000 liters. You could produce 25kg of biomass per day from one cubic meter of medium given the numbers established in my earlier post. Your entire rooftop system of tubes, 100m2, would contain about 1500L total volume, or 1.5m3. It's not that much, but that's good, since that keeps medium preparation costs low!

> Considering I spent 5 liters of fuel this morning
> just getting to work (and an unknown amount just
> being there) we'd need a pardigm shift to go with
> it :-)

It takes 25MJ of energy to make one kilogram of plastic. One liter of gas has 34MJ of energy, so making plastic is good too.

> Where did you get that number? One cubic meter is 1000 liters. You could produce
> 25kg of biomass per day from one cubic meter of medium given the numbers
> established in my earlier post. Your entire rooftop system of tubes, 100m2,
> would
> contain about 1500L total volume, or 1.5m3. It's not that much, but that's good,
> since that keeps medium preparation costs low! smiling smiley

Hello Alex!

I was probably mis-quoting your previous post, you mentioned a figure of 164 kg of bio-diesel per year and I assumed it was for the 100 m^2 rooftop example so I divided it with 100 to get the per-square-meter yield, hence the 1.64 kg.

Looking back at these figures make me feel I would get better yield growing old-fashioned potatoes so obviously I made a misstake somewhere...

What exactly do you mean when you say 25g/m2/day ? At which pond depth is this achieved?

Hmm, but wait now, if the pond is 20-30 cm, say 25 cm. Then the volume of the
arrangement would be 0.25*100 = 25 m^3 ?

I to will have to read prof. Edwards book when it comes available :-)

Actually-- I'm wrong, you're right. I got confused and used the 25g/m2/day figure, when I should've used the 1.6g/L/day figure when dealing with volume. So, your calculation, double-checking my math, is actually not far off at all!

I was doing this calculation off of a tubular photobioreactor that could be mounted on your roof.

But if we're talking about ponds, the 25g/m2/day figure is what you want to use.

Your math towards the amount of medium in a pond isn't right though. I had trouble with that one the first time I took a crack at it too, but it's good to think in terms of liters. 1000L in a cubic meter, 25% of that is 250L.

Also, some very good books already available are:
[www.amazon.com]
[www.amazon.com]

Oh I meant the volume for the total pond, 100 m^2 x 0.25 m is 25 m^3 or I'll have
to go back to primary school...

So anyway.

Am I right to assume that people doing ponds that are 25 cm deep could expect to get 1.6g/liter/day which means that in "my" pond structure I could get
100 [m^2] x 0.25 [m] x 1000 [l/m^3] x 1.6g = 40000 g = 40 kg of green goo a day?

Assuming I would live near the equator take [40 kg/day] x 365 [days] = 14600 kg
which would be almost 15 tons of the stuff in a year?

Then assuming half of it can be made into oil. I would have about seven tons
of plastic?

Energy content of the oil would be about 10kwh/kg (just a wild approximation)

In one year we "produce" 70000 kwh (sorry for being to lazy to convert to Joules)
Assuming again in the equator example a sun influx of about 1kw/m^2 we would end up with about 4000 sun hours under ideal conditions.

The energy input would be 1 [kw/m^2] x 4000 [h] x 100 [m^2] = 400000 kwh

Now with this calculation we end up with an efficiency fo 70000/400000 = 17.5 % which is way to high by an order of magnitude!

Any comments?

Edited 2 time(s). Last edit at 06/04/2008 08:03AM by mimarob.