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!"

Wood wasn't enough to fuel the Middle Ages

[tp1024]

Who are you kidding? Wood for heating and charcoal for iron smelters was responsible for deforestation of large parts of Europe long before the industrial revolution. People turned to burning coal and lignite for lack of trees in the comparably sparsely populated countries of the 17/18th century. What exactly do you expect this around, with 8 times the size of population and much larger energy needs?

Another couple of factors

[presidenteloco]

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 current production, and use all of that for biofuels. (Assuming various conversion factors work out roughly equivalently for the two processes.)

Second, people need food more than cars, and forests need trees (and the Earth ecosystem needs robust biodiversity as opposed to massive tracts of mono-culture biofuel tree-farms).

Re:End of oil for fuel != end of oil.

[MetalOne]

"Oil isn't going away any time soon". You know I really hope you're right. However, according to wikipedia, the 17 largest reserves total 1.3 trillion barrels. If I divide that by world usage of 88 million barrels per day, I get 40 years. Plus population growth is still happening and the third world is becoming more advanced. Of course eventually this oil will become harder to get, driving up its price and possibly slowing consumption. I believe expensive oil is going to severly impact this world. So while there still might be oil, will it be cheap enough and plentiful enough to prevent the complete collapse of society within the next 100 years. I would really like it if somebody could point me to a decent resource that will alleviate my fears. Sure we might find more oil. Everytime I hear about a big new discovery though, I just divide it by 88 million barrels a day, and I quickly realize that it is a truly insignificant discovery. Sometimes I hear the Canada tar sands will save us, but those reserves are in the above wikipedia figure. Some of the reserve life figures on wikipedia have a longer life time, but that is because the production is low relative to the 88 million barrels per day. In the next 70 years we could have twice as many people on this planet. How much oil will we need then?

Interesting, Rayon and PVC

[Maintenance Goof]

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.

Wait, this is new?

[Daetrin]

It's called thermal depolymerization [wikipedia.org] and you can do it to just about anything organic. So unlike what some other posters are saying, you don't have to devote huge agricultural areas to producing stock just for this process, you can use preexisting waste for the job. There was a company running prototype plant in Carthage, Missouri. They situated themselves right next to a turkey processing plant with the hope they could "process about 200 tons of turkey waste into 500 barrels (79 m3) of oil per day". The plant ran for a number of years, and was supposedly able to produce oil for about 10% less than the price of crude ("supposedly" as in the oil was definitely produced, the question was exactly how much it cost them and how much of a profit they were making.) However they suffered from a number of lawsuits and eventually had to declare bankruptcy.

It seems like they jumped into the game a little too early, or just weren't able to find enough venture capital to perfect the system. Certainly as the price of oil continues to rise and the technology improves this is a process that could certainly be brought back. And note that since they're using organic waste the process is carbon neutral.

nutrient cycling

[proclomeesius]

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.

Re:Factor in one more thing though?

[Anonymous Coward]

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. :)