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Carbohydrate-Based Synthesis To Replace Petroleum Derived Hydrocarbons?
someWebGeek writes "From PhysOrg's 'Taking biofuel from forest to highway,' University of British Columbia biofuel expert Jack Saddler says, 'we will become less dependent on fossil fuels and will become more dependent on fuels made from the sugars and chemicals found in plants.' Nothing too new there; the idea of biofuels eventually taking over from petroleum distillates has been around for ages. However, Saddler contends further that 'Similar to an oil refinery that processes crude oil to make thousands of supplementary products like plastics, dyes, paints, etc., the biorefinery would use leftover agricultural and forest material to make many of the same products, but from a sustainable and renewable resource.' I remember my organic chem instructor back in '81 telling us that eventually the textbooks would have to be rewritten. There would be no presumption of fractional distillation of thousands of basic compounds from petroleum, and the teaching emphasis would shift to synthesis from simple hydrocarbons. He noted that we'd all miss 'the good, ole days' when synthetic fibers, plastics, etc. were cheap... or even an economically viable option. I can live without rayon, but, dang, I'm gonna miss polyvinyl chloride!"
The OP said, "I can live without rayon, but, dang, I'm gonna miss polyvinyl chloride!" Rayon is made from wood. We make vinyl chloride from petrochemicals, but the original source was plant material and the majority of world production uses plant material. Acetate, is another one typically from plants. As is nitrocellulose. Casein, is a protein from milk. It is also the plastic that the buttons on your shirt are probably made of. So plastic without petroleum is not that hard to find.
If you have to burn 10 barrels equivalent of crude oil to make 1 barrel equivalent of food grade veg oil
I have read and heard this so many time here on Slashdot now, and I am gonna call you on it.
If it takes a ratio of 10:1, crude to produce vegetable oil. Then how come a cheap vegetable oil can be found for a 3-4 bucks a gallon?
While the cost of 10 gallon of crude costs 30-40 dollars?
Are the producers just giving us all that crude for free out of the goodness of their hearts?
Seriously people use your brains, think for your selves.
If my comment didn't sound as good in your head as it did in mine, then I guess we all know who's to blame
As an agricultural scientist, I always feel slightly uncomfortable when biofuel producers start talking about using 'agricultural waste'. Increasingly, this 'waste' is now used by farmers as an integral part in boosting soil carbon and increasing biological activity as it breaks down, improving soils and improving subsequent crop yields.
The value of this, though often difficult to measure is significant and very real. But I worry shortsighted farmers looking for a quick buck may lose these less tangible benefits, leading to further soil degradation and lower yields in the future.
Right now, I've read we're burning about 400 years worth of laid-down plant carbohydrate per year, in the form of fossil fuels. That's right. To obtain the equivalent amount of energy from non-fossil biofuels as we're currently getting from fossil fuels, we'd have to increase the amount of plant material being grown on Earth by a factor of 400 times
No that is not what it means at all, in any way shape or form.
What it means is that we are using fossil fuel at an rate of 400 times of which new fossil fuel is produced by natural processes. Only a small percentage of biomass will ever become trapped in the correct anaerobic environment and then fossilized over millions of years. So there is lots of biomass available for use as fuel.
If my comment didn't sound as good in your head as it did in mine, then I guess we all know who's to blame
Trees are about as effective in doing photosynthesis as any other plant.
That's not true, there's significant differences in efficiency between various species of plants. Most grasses for example are much more efficient than trees, which is why grassland can support huge herds of large animals, but a forest can't.
See: Photosynthetic Efficiency, where it has a table of some typical efficiencies:
Plants, typical : 0.1%
Typical crop plants: 1-2%
Sugarcane: 7-8% peak
This is because more than one kind of photosynthesis has evolved, with somewhat different chemical processes. Look up C3 carbon fixation and C4 carbon fixation for the differences.
There is a significant research effort going on looking into ways of taking the genes for the more efficient types of photosynthesis and merging that into less efficient plants. This could be used to make fruit trees grow much faster, or to create algae that can be used to produce alcohol or oil at efficiencies approaching those of solar electric power.
A barrel of crude is 42 gallons. So one barrel of crude would make, by your calculations, about 4 gallons of vegetable oil. At current prices of $105/gallon, that would be a cost of about $26 her gallon of vegetable oil.
However, I believe those 10-to-1 figures are for energy, not volume. According to wikipedia, a gallon of crude oil is a standard measurement: 1.7 MWh. Per gallon, that's 40.4 kWh. I can't readily find the energy in vegetable oil from google, however a quick conversion from calories (120 kcal/tbsp = 80,832 kcal/gal) gives us 94 kWh/gal.
That's quite a but more per gallon, giving us only 1.8 gallons of vegetable oil per barrel of crude oil, raising the cost to $56.66 per gallon. Obviously these figures aren't right.
Is that the whole story? Let's consider how vegetable oil is made. Corn oil is rather cheap, so let's look at it. You have to extract the oil from the germ of the corn. Wikipedia again tells us that one bushel of corn yields 1.55 pounds of oil. One bushel is 35.24 L dry. Corn oil has a density of 9.25 g/c^3 (g/mL). Conversions (9.25 g/mL = 77.2 lbs/gal).
Phew! So that 35.24 L (one bushel) of dry corn only yields .02 of a gallon of corn oil! So you need FIFTY bushels of corn to yield one gallon of corn oil!
How much energy is in 50 bushels of corn? Conversions again: one cup of corn (raw) is 132 kcal. So that's 2112 kcal/gal. A bushel is defined as 8 gallons dry, so there are 16,896 kcal/bushel of raw corn. 50 bushels of corn means you need 844,800 kcal of corn to make one gallon of corn oil, which is only 80,832 kcal.
There's your missing energy. You need about 10.5 calories of corn for every calorie of corn oil. Or to put it another way, you need 982.5 kWh of corn energy to produce 94 kWh of corn oil energy.
Take our earlier estimate of 10-to-1 gallon-for-gallon of $56.66, divide by 10.5, and you get a much more reasonable $5.40 for a gallon of corn oil. Figure in some government subsidies, and differences in the two markets and some market fluctuations, and you are very close to your $4 a gallon bulk price for vegetable oil.
Use your brain, think for yourself, but be sure you have all he data and knowledge you need to draw a valid conclusion. The 10-to-1 figure is a general estimate that I just demonstrated is reasonably accurate. Adjust your tinfoil hat and start scrutinizing your conspiracy theories a little more closely. :)