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To: Casaubon who wrote (5790)	4/16/2005 9:26:21 PM
From: Moominoid	Read Replies (1) \| Respond to of 12411

"plants are more efficient at capturing sunlight than solar cells." That is very far from the truth! But they are cheaper... however, the truth is that ethanol from corn is an energy sink not an energy source. I takes more oil to grow the stuff when all inputs are considered than is obtained.

To: Casaubon who wrote (5790)	4/17/2005 2:10:29 AM
From: J-L-S	Read Replies (1) \| Respond to of 12411

Prove it in a scientific way and I will believe you. Otherwise, I don't think you know what you are saying. For instance, calculate the number of BTUs produced by burning an acre of corn (which was the original subject), then compare that with the number of BTUs that can be obtained from an acre of solar cells. Be sure to subtract the number of BTUs it takes to manage a field of corn. This would include the BTU content of nitrogen fertilizer which must be applied, and also the BTUs burned with the use of farm machinery driving up and down the field all year long (spring tilling, planting seed, applying fertilizer, applying herbicide, harvesting corn, taking corn to the elevators, and fall tilling). ----- Allow me to help you get started with a calculation using typical plant matter. One pound of cellulose at a moisture content of 20% has an energy content of 7,700 BTUs. This stored energy is not released as heat until the cellulose is processed (burned). Processing efficiency varies from 45% to 70%. Most people making a comparison between different energy sources will use a conversion efficiency in their calculations of 50%. Therefore, one pound of cellulose will yield 3,850 BTUs of heat. On the other hand, the conversion efficiency of electricity is 100%. A conversion table will tell you that there are 3,415 BTUs in one kWhr. So, a quick calculation will tell you that burning one pound of cellulose will give you the amount of heat equivalent to about 1.13 kWhr of electricity. A typical solar panel (of 13.8 sq. ft.) will produce 167 watts of power. For purposes of calculating energy output of solar cells, it is common to assume that a typical day is equivalent to four hours of solar exposure. Using this number, a solar panel will give you 668 Whr of energy per day. Now we have everything we need to know to calculate that burning one pound of cellulose (with 20% moisture content) will provide the same amount of heat that can be derived from one solar panel in 1.69 days. I don’t think you can grow (and dry) one pound of cellulose in an area of 13.8 sq. ft. in 1.69 days. Do you?