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Correct me if I am wrong in my thinking, but using an average of 270,000,000 barrels per month from EIA finished motor gasoline report works out to 136,080*10^6 gallons per year. Divide this by 4,000 gallons/acre/year production by an algae farm equals 34,020,000 acres or a land mass about the size of Iowa at 36,013,440 acres or 56,271 sq miles. Doesn't seem like that large of an area, once spread out over the nation, to replace all of our gasoline (and I know thats just gasoline) with this potential solution. We just need action, over business as usual. I figure I can meet all of my needs with the area in my back yard. Can anyone tell me how to make my own algae pond to make diesel fuel? I believe there was a site out there were Savinar was trying to debate some of these biodiesel guys, I felt they held their own, in theory, I have yet to see any results yet though. Ah yes, found the link, it was this guy, Michael Briggs:
http://www.unh.edu/p2/biodiesel/article_alge.html
It seems like a lot of water. 56k square miles is bigger than Lake Superior and Lake Huron combined.
yes but how deep is it?
I don't think it has to be very deep to be a problem. If you're talking about flooding an area the size of the state of Iowa to a depth of several inches, and then replacing the huge amount of water that evaporates every day, you're talking about water use on a scale that is mind boggling. We're already having trouble getting enough fresh water to irrigate the crops we already grow.
Profitable algae to biofuels has not been accomplished. It is like solar photovoltaic cells and making electricity. It can be done but is not practical or profitable on a large scale compared to more competitive power generation. Cellulosic ethanol is so far from profitable it might bankrupt any nation attempting to convert to it.
One idea I saw took advantage of the fact that algae only needs around 1/10th of the amount of sunlight to grow, the rest causing the algae to need agitating to bring the algae which has not been exposed to the surface up and submerge the stuff on the top that has had its dose of sunlight.
That takes energy, and makes the process expensive.
the idea is simply to pipe the sunlight in with optic cables in the right amount, so you would have a building with several levels, each with tanks of algae, and each would get the correct amount of sunlight and would simply need skimming to harvest, and then drying.
Doing things indoors would also reduce evaporation.
homebrew -
I've looked into algae only superficially, but I think that with regard to the large scale production of biodiesel from algae, several questions are highly pertinent to its feasibility and cost-effectiveness.
1) While high-lipid strains of algae can be grown in enclosed bioreactors under highly controlled conditions, can an algae 'monoculture' realistically be maintained under steady-state conditions in an open pond, where a natural 'ecology' of various strains of algae plus other oganisms will eventually establish itself?
2) What is the maximum algae concentration that can realistically be grown in an open pond under the conditions of a) no mechanical agitation, and b) mechanical agitation provided?
3) Related to (2), what is the maximum algae concentration that can realistically be grown in an open pond while still maintaining aerobic conditions with a) no mechanical aeration, and b) mechanical aearation provided?
4) What are the nutrient requirements in terms of lbs NPK per dry-weight lb of algae produced? How are these nutrients to be provided?
5) What are the best methods for extracting the lipids from the algae, and what are the material handling considerations and energy requirements of such?
6) If we assume an algae lipid concentration of say 25 % by dry weight, then after lipid extraction we are left with 75% dry weight of organic algae mass. How is this large amount of highly biodegradable (and hence oxygen-demanding) material
to be handled and disposed?
My gut feel is that the large-scale growing algae in enclosed reactors will prove to be a technological deadend due to economic reasons and that unless high-lipid algae can be successfully grown entirely in open ponds, biodiesel from algae will go nowhere. Having said that, I am more than willing to be proved wrong.
Great list of questions, to which I add: How much energy is used in the process of drying the algae, which must occur before any additional processing?
At ASPO-USA Denver, I talked with one of the NREL reps who spoke there and being very interested in algae biodiesel production asked his opinion. He identified joule's list and my addition as the big problems in getting a decent EROEI for the process. He thought cellulosic ethanol more realistic IF a lowcost enzyme process could be established instead of the very costly--both in $ and EROEI terms--acid process (there's a process using water, but it takes too much time for the reactions to occur for any degree of high throughput/yield/scale).
I know of at least one company trying to prove you wrong. They plan to used large ponds covered by an inflated plastic dome. Separation of the oil does not require the algae to be dry. Simply dissolving the cell walls or mechanically breaking them to release the oil allows the oil to rise to the top. The remaining wet fraction could be fermented into methane.
I was very hopeful of algae-biodiesel to the point where I wanted to build my own "refinery" in 2005 prior to my talk with the NREL man. Have any you seen this popst at RR's blog, http://i-r-squared.blogspot.com/2007/05/algal-biodiesel-fact-or-fiction....
thomas deplume -
Yes, you can cover a large pond with an inflatable plastic dome, but the practical limit for each dome is probably not much more than an acre or so. However, algae biodiesel production facility of even modest size would require hundreds or thousands of acres.
The more I learn about these algae schemes, the more I'm convinced that there are very daunting scale-up obstacles, particularly in the area of material handling.
For example, let us take a quite modest algae biodiesel operation with a production capacity of say 100 barrels per day. At about 7 lbs per bbl 100 bbl/day is about 29,400 lbs/day of oil. If we assume that the algae we're growing has a lipid concentration of about 25% by dry weight, then we will need to grow about 118,000 lbs/day of algae.
I don't really know what the maximum algae concentration is practical for large pond, but I tend to doubt that it's much more than 1% by dry weight (doesn't sound like much, but 1% is VERY green and opaque water). If so, than that means we will have to handle 11.8 million lbs/day of algae-containing water. To harvest the algae that amount of water would have to be put through some sort of liquid-solid seperation step (or steps) prior to lipid extraction. The concentrate (say 30% solid by weight) would then go through lipid extraction and separation, and the spent algae cells sent to their final disposition (perhaps anaerobic digestion.
We are thus handling a very large quantity of aqueous goop to produce just 100 bbl/day.
Algae will contain on the order of 6% nitrogen and 1% phosphorus (give or take). Thus, in order to grow 118,000 lbs/day of algae we will need to supply over 7,000 lbs/day of nitrogen and almost 1,200 lbs/day of phosphorus. If these nutrients are to be supplied by sewage treament plant effluent, then a very large flow rate of sewage will have to by pumped through the pond each day.
Again, all this is just to produce 100 bbl/day of oil.
While, the above numbers can be noodled around with, I do think I am at least in the right ball park. My main contention is that while material handling and algae separation may be trivial on a lab scale, it becomes a very big deal once you are in the realm of even modest production levels.
errata:
Should read " ... at about 7 lbs per gallon, not 7 lbs per bbl.
You make some good points. But how do these factors compare to the water and natural gas used by the Alberta tar sands or the 99% water cut in some oil fields? Whether it is biofuel or rock oil there are enormous capital investments involved. As for a limit on the size of an inflated dome the Pontiac Silverdome covers 13 acres. Not that I believe anything that big is necessary the minimum practical size needs to be worked on. The different methods of production different companies are trying will answer all your questions in the next few years. Even if one method proves to be a big success the area that needs to be covered each day for the next few decades according to my calculation is around 10 square miles. Fortunately the ponds can use land not suitable for agriculture, uses only 10% of the water per acre that corn or beans would, and can utilize brackish water sources which are in abundant supply. Unfortunately there is not enough time left to upscale any method found to be practical.