I am personally a fan of bioreactors not open pond cultivation.

I am weighing in on the side of MORE algae production per acre not less.  AND all that I am saying is theory not real world.  Someone ELSE do the math or show me some different math.  An acre foot of water ( 12 inches of water covering 1 acre of land ) is about 325,000 gallons of water.

My assumption, working as a “mature” working pond.  Algae growth rates are suggested at doubling on a 24 hour cycle.  If there was a 5% harvest rate per week, ie 5% of the water was taken out as an algae harvest. That is over 16,000 gallons of algae per week.  If you said 20% biodiesel lipids, again, a low estimate.  That is 3,200 gallons a week or 169,000 gallons a year. 

This is spreadsheet math not a real world algae farm AND all these are conservative numbers.

I think that most people are not realizing how much water is on an acre of land.  Please tell me where my math is wrong.

In my opinion, we need to stop with all the hype and accusations.  We have spent billions of dollars on algae research for the last 35 years and are still not off foreign oil.  If you want to throw stones at various claims, I would suggest start ing with ALL THE GRANT MONEY spent on research to date and what has been accomplished. Most government grants have been used for grants, not commercialization.  If you speak with 10 different algae researchers, you will get 10 different opinions.  The same goes for algae producers. Going forward, new algae producers need to benchmark everthing..

Secondly, bullet proof numbers are needed but unfortunately most VC’s do not have any money.  They do not have an IPO market as an exit strategy.  Most investment in algae today is coming from the private sector and not VC’s.

There is a big differnce between growing algae in ponds vs. closed-loop photobioreacors, the.  same way there is a big difference in growing algae in a research setting vs. a commercial scale.

Yeah, I don’t see PIE IN THE SKY numbers being a sound footing to entice VC credibility.  You want to state BULLET PROOF figures. . . unless your selling bridges.  Algae is still the promised price puttin’ petrol packin’.

i grew algae for animal feed.  about 5000 lb/acre/year…  making motor fuel from algae may be costly.  i can make gasoline for 50 cents/gallon by building hydroelectric and windmills electric energy to obtain hydrogen to liquefy residue after distilling gasoline from free wood waste and weeds   i will go any where wanted free
    glen hemerick, 15871 peacock hill rd se, olalla, wa 98359 phone 253-857-7225
      (JavaScript must be enabled to view this email address),  (JavaScript must be enabled to view this email address)

First of all, I am a big supporter of algae farming, so my remarks are not meant to discourage anyone. I would like to point out a few things. There are two types of algae: (1) photo-autotrophic – grown in sunlight or artificial light, and (2) heterotrophic – grown in the dark in tanks. Grow algae in sunlight, and you need a lot more surface area to expose algae to the light. Grown in sunlight: Rex Zeitsman in Africa reports 4 grams of algae per liter per day, which is a pretty high return. This was optimized for ethanol production and resulted in 20,000 gallons per year, based on a 20 square meter open pond pilot plant with a paddle wheel…Grown in the dark in tanks:  Canadian Pacific Phytoplankton Ltd., Nanaimo, British Columbia, CA. reports 10 tons of mixed marine phytoplankton produced every 11 days. That’s 330 tons per year per acre. If you gasified that into ethanol, at about 110 gallons per ton (a middle of the road figure), you would get 36,300 gallons per year ethanol.

Now, if you want to get oil out of algae instead of ethanol, that’s a different animal. Different types or strains of alga to start with. A system and methods optimized for oil production. You have to de-water the algae and then extract the oil. The oil extraction is the thing that is challenging researchers. But it will be solved. Growing alga is the easy part.

Let’s take a look at your assumptions. Rex Zeitsman in Africa is getting the 4 grams of algae per liter per day, which is the highest I’ve seen for algae grown in sunlight in open ponds. Let’s say you’ve got 4 grams in the growth medium to start, and you double that to 8 grams per liter in 24 hours. One liter equals 1,000 grams, so 8 grams of algae in 1,000 grams of water equals about 1%. The question is: How concentrated can the alga get before shading decreases the growth rate?

Grow algae heterotrophically in the dark, and that’s not a factor. So alga can be grown in the dark in much higher concentrations.

Here’s the thing. You’re taking 5% of the water out, but that’s not all algae. It’s mostly water. In fact it’s probably 90% water or more, if it’s grown in light. So let’s say you can get the concentration up to 10% algae in the water, which is on the high side. Your figures are 10 times too high. When you take out 5% water per week, 90% of that is water, not algae.

Another factor is: When you weigh it, has the algae been dried or is it wet? Some researcher are claiming that they can extract algae oil without drying it. That’s great, but when we try to figure out the actual return of algae biomass, it’s a lot easier to calculate dry algae than wet algae. Wet algae is fuzzy math. Calculating dry algae is accurate. Did you know that milk is 90% water and only 10% dry solids? Likewise algae is diluted in water, and even after you extract it, it’s wet and much heavier than when you dry it.

There are a number of OTC bulletin board algae firms and private firms making unsubstantiated and outrageous claims on the oil yields for algae.  Beware, brother, beware.  And although bioreactors can certainly yield more than open ponds - they don’t scale.  Also not considered in all of these “calculations” are the energy and cost inputs for floccing, harvesting, drying, and cleaning the systems.  Also not being folded into these judgments is the enormous embedded water costs for both open and closed systems.  Algae oil has some long-term potential but we are a long way from scale.  Beware of outrageous claims.

Beware of a media person that never built an open or closed loop system making statements without any facts to support them. He must be getting his information from the researchers who rely on grant money.