Super Algae Bio-Diesel Energy
Posted by Jeff Id on November 25, 2008
I received an interesting link from Richard M part of his comment is below the rest is HERE.
I believe there is some hope for one bio-feul … algae. It has significantly better output than does corn, soy, etc. There is a new tecnology currently being test marketed that uses a vertical arrangement to get more output. They claim 33,000 gals/acre/year.
The great thing about comments on a small blog like mine is that I read each and every one. Along with my natural lack of political correctness I also am unafraid of being wrong. I do it quite often as my wife will happily tell you. Check out the link above, it is pretty interesting.
They claim 33,000 gallons per acre of vegetable oil created using a cool structure which stacks the algae in tubes. This is a huge claim considering that corn produces like 50 gallons per acre or something. Pond algae was the previous best at an inflated 900 gallons of oil per acre. Pretty exciting stuff if it’s true really.
Well we know that bio is a form of solar. Typically there is a very low conversion rate for sunlight into the oil, a bunch of light energy is wasted and a bunch more is put into plant proteins and other things not related to the final product – oil. So the first thing I did was check on how much sunlight energy per acre we can count on. These are just estimates- back of the napkin calcs – but they will give us a smell test.
Direct high noon sunlight is about 1000 Watts/m^2 on a clear day.
If we have 12 hours of top quality sunlight
1000 Watts/m^2* 12 hr/day * 365days/yr* 3600 sec/hour = 15,768,000,000 Watt-s /m^2
Then we assume a cosine distribution for daylight intensity of 63% of peak energy (an optics thing, the approximate average of the cos function)
Assume again that most places will only receive 70% of this amount of light. (also high estimate)
15,768,000,000 Watt-s /m^2* .63 * .7 = 6,953,688,000 Watt-Sec/m^2
1 acre = 4047 sq meters
28,141,575,000,000 Watt-Sec/acre or — Joules per acre in proper units.
How many Joules per acre are there in 33,000 gallons of vegetable oil. Well my 5 minute search didn’t reveal any value for algae veggie oil but it did reveal that wikipedia was using my guesstimated value of 1 gal veggie oil to 1 gal gasoline. They are both hydrocarbons after all. Ripping hydrogen off a carbon chain (oils are to my knowledge all carbon chain based) and combining with oxygen produces the nearly the same energy from nearly every oil type fuel. In college grad school I taught a fuels and lubes lab to keep shoes on my feet.
Well gas is about 121,000,000 joules per gallon so we get 33,000*121,000,000 = 3,993,000,000,000 Joules per acre.
This means that 3,993,000,000,000/28,141,575,000,000 * 100 =14.1% of the total sunlight is converted into oil. This is a huge number.
Look at the system they used.
It looks pretty cool, vertical arrays of poly-something tubes with pretty green stuff. But the total sunlight absorbed is the question here. I am an optical engineer so there are definite issues with the structure as to actual use of the light. Note the glare off the plastic in top right corner of the above picture. This is lost light. A substantial percentage of light will be reflected from the surfaces of these bags. In this greenhouse configuration it is especially true for directly overhead sunlight.
Now in the shots below you see a diffuse layer applied to the top of the greenhouse. I am no greenhouse expert but diffuse polymers is something I am familiar with. This material likely reflects, scatters or absorbs 20-50% of the sunlight striking the greenhouse although there are materials which can do better. I suppose it is designed to make sure that plants don’t burn from too much light, but I am not an expert in botany. If you see the shadow inside the greenhouse created by the roof material you can get a feel that more than 50% of the light is absorbed, scattered or reflected. There is definitely a significant reduction in the light striking the algae.
What happens to the numbers if we apply a few more losses?
From before 14.1% of the light is required to convert into oil to meet 33,000 gallons/acre.
If we say the light is reduced by 50% due to the roof. We have 28.2% required to convert into oil.
If we have a loss of 15% due to the plastic bags we get 33.1% of the light energy must turn into oil. Plants photosynthesis has a maximum of 6% efficiency in the link here. A substantial portion of that energy is used to keep the cells alive and not for oil – say half at the very least. So at my original number of 14% these Algae are running 4X higher efficiency than is physically possible. With the other numbers included for 33.1% of the light energy required we achieved an efficiency of 11X the maximum allowed by reality.
My numbers are heavily biased in favor of the company!
Well like many things in the green world, this one has claims that exceed reality. What does this mean?
1 – Will algae from this process exceed the production from a pond style algae farm?
I am not sure, I think a well mixed and fed clean water pond will capture more light energy and may produce the same amount of oil. No proof here though.
2 – Is this a good energy solution?
The numbers provided cannot be trusted. Pond based algae energy doesn’t work because of the massive area required, I suspect this will also have the same problem. There isn’t enough sunlight striking the earth to make this work.
3 – Even if they’re several times off in efficiency isn’t this the best solution?
Yes, if they are only several times off. What I don’t like is that they have presented physically impossible numbers to support their company position and by the numbers my guess is 30 times off. Before I accuse anyone of pulling a Michael Mann, there is one case (besides my inability to multiply or bad numbers) I can think of where I might be wrong (Just because I’m often wrong doesn’t mean I give up easy).
If you remember the water powered car’s that crop up from time to time. People use special fuel cells which convert water into electricity by splitting H20 into hydrogen and oxygen. Well the reality was that a coating is applied to the fuel cell which actually contains the energy, not the water. This coating’s energy is used in the same fashion as gasoline and when it is consumed the car stops running.
The food given to the Algae wasn’t disclosed on the website. If the food contains high energy materials (not a botanist) this could drastically change the energy balance giving falsely high results to an otherwise energy wasting process. If the food was made from scrap such as corn husks or stalks it still might be a good process but the disclosure on the website wasn’t sufficient.
Therefore, if there are high energy foods used (previously stored sunlight) this process has a chance.
If not. — Another myth busted.
Either way, it is easy to believe in these companies, I want them to be true more than I can say. A good comment by Richard made me question my other results and run through them again. I hope my readers understand that I will be thrilled to find other reasonable answers to energy. If other cost effective solutions become available, this engineer will immediately become their biggest supporter. You can see my tone when I started this post, I hadn’t done the calcs yet. Anyway, I’m not buying any stock in this one until they disclose more.