Posted on 01/24/2007 12:18:48 PM PST by WestTexasWend
It was my understanding that tilled crops turn something like 10% of incident solar energy into useable chemical energy, in which case, algae couldn't possibly be 100 times more efficient. You point out that algae can be grown year-round, as opposed to during one season, and now that you say it, I doubt that that factor was included in the 10% number that I recall. It might also be that tilled crops convert 10% of *absorbed* light into useful chemical energy, which is an additional inefficiency compared to *incident* light, and the algae could score another win there simply by being darker (which they often are).
Saw a similar setup on TV last night--I think on the History Channel.
It was in Arizona. The algae is/are (?) in transparent tubes angled to receive sunlight.
It sounded quite interesting.
I thought they just baked the manure to kill off the seeds. Does that add too much to the cost?
Composting manure can kill some seeds, but baking won't work...if it gets too hot, it burns, and, in fact, if piled too deeply it will heat up on its own and spontaneously combust. Feedlots have to keep spreading it to keep this from happening...so, even after composting-in-place or mixing with other organics, weed seeds survive. The bigger knock against it is that chemical fertilizers are so much easier to apply, give more uniform distribution and usually require no tilling in, which saves on fuel/labor. Also, unlike manure, they don't stink for days or draw flies.
Okay, so what are these chemical fertilizers made of, and how much energy does it take to produce them? Are those energy costs factored into the cost-benefit analysis?
Did anyone else read "pond scum" then AlGore instead of Algae?
Chemical (inorganic) fertilizers are made up of components you'd find in organic fertilizer, minus organic matter. (That's why they can burn plants if there's not enough organic matter in the soil.) It's sort of like the difference between vitamins in pill form as opposed to vitamins present in food. (Here's a decent overview: http://en.wikipedia.org/wiki/Fertilizer)
Whatever money and energy is spent producing chemical fertilizers is easily recouped by being easier to store, transport, and market. Chemicals also let you control and customize the NPK ratio (among other things) for your specific crop. You can't be certain of the chemical makeup of organics, even from one truckload to the next.
Organics have great benefits, certainly, but just aren't clean, convenient or consistent enough for most modern growers.
Okay, but where do you get those components? Don't they need the organic matter in order to chemically extract the nutrients? If not, where do they get them?
http://www.freerepublic.com/focus/f-news/1116843/posts
Similar topic, pig manure and turkey guts.
Gensets being run off of offgas methane from digester ponds.
As far as energy production, I would count Democrats about the same as singularities. Beyond the end of the road.
No, you don't have to start with organic fertilizer to get fertilizer. Many components are mined from soil (sodium nitrate, mined "rock phosphate" and limestone...a calcium source, but mostly used to reduce soil acidity), while others are manufactured (some as by-products) or chemically-synthesized inorganic fertilizers. Those would include ammonium nitrate, potassium sulfate, and superphosphate, or triple superphosphate by-products.
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bttt
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