FW: Re ethanol
Mackey David [EMAIL PROTECTED] wrote: Most Ethanal is manufactured from agricultural crops such as sugar cane, corn and wheat starch. Ethanol can be produced from trees but the production costs are very high and have only been experimental. Brazil uses sugar cane to produce most of its ethanol. Yes, that makes sense to me. I'm puzzled by a number of things in the article Ed posted. Generally ethanol is produced by aqueous fermentaion of sugars, then it must be distilled by application of considerable heat, which severely encroaches on the efficiency of the process, unless one can arrange for heating by otherwise waste or unused heat such as sunlight or industrial waste heat. As to "cellulosic biomass", that is protein, and while it will give off methanol as part of its decomposition under application of heat (this is where wood alcohol comes from), I haven't heard before of any means of yielding ethanol from it (chemical synthesis of ethanol from methanol is not trivial). I'm rather curious about the mechanism and efficiency of this process. Potentially, one could get a fair amount of ethanol out of cellulose, just in terms of counting atoms, but it doesn't look to me that there would be an easy way of getting a high yield. Of course, the organic waste coming out of the process might have other uses which could feed back into the process to increase its energy efficiency, but still I suspect a lot of cellulose would have to go in relative to the amount of ethanol coming out. Another item in the post which has me puzzled is this question of CO2 output. I can't see why ethanol should put out only 1% the CO2 of gasoline. There is a higher ratio of hydrogen to carbon in ethanol, which I could see giving an improvement, say decreasing CO2 to around 65-70% that of gas, but You're still burning carbon, and you've got to end up with CO2. -Pete Vincent
Re: FW: Re ethanol
Um, this is straying kinda far off topic, but when Pete Vincent wrote: As to "cellulosic biomass", that is protein,... I hope you were making a thinko/typo. I suppose any aggregate biomass contains some protein but cellulose is a polysaccharide -- a sugar polymer -- not protein -- amino acid polymer. If you bust cellulose up, you get glucose. Raw wood contains a bunch of other stuff, particularly lignin, but it's around 60% cellulose. - Mike
Re: FW: Re ethanol
Michael Spencer [EMAIL PROTECTED] wrote: Um, this is straying kinda far off topic, but when Pete Vincent wrote: As to "cellulosic biomass", that is protein,... I hope you were making a thinko/typo. I suppose any aggregate biomass contains some protein but cellulose is a polysaccharide -- a sugar polymer -- not protein -- amino acid polymer. If you bust cellulose up, you get glucose. Raw wood contains a bunch of other stuff, particularly lignin, but it's around 60% cellulose. Ack. Clearly a major brain lapse on my part. Don't know where it came from, but fortunately I never have to make any claims that I'm a chemist. OK, so presumably we can cook up a good broth of enzymes and biomass and get out glucose, which then allows the fermentation process to proceed. This doesn't answer my other questions, though... -Pete Vincent
Re: FW: Re ethanol
Just be sure you don't heat it.As I found out heat or micro-waves kill enzymes. REH pete wrote: Michael Spencer [EMAIL PROTECTED] wrote: Um, this is straying kinda far off topic, but when Pete Vincent wrote: As to "cellulosic biomass", that is protein,... I hope you were making a thinko/typo. I suppose any aggregate biomass contains some protein but cellulose is a polysaccharide -- a sugar polymer -- not protein -- amino acid polymer. If you bust cellulose up, you get glucose. Raw wood contains a bunch of other stuff, particularly lignin, but it's around 60% cellulose. Ack. Clearly a major brain lapse on my part. Don't know where it came from, but fortunately I never have to make any claims that I'm a chemist. OK, so presumably we can cook up a good broth of enzymes and biomass and get out glucose, which then allows the fermentation process to proceed. This doesn't answer my other questions, though... -Pete Vincent
