Sciencemadness Discussion Board

BIODIESEL - cheapen your gasoline

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YT2095 - 18-5-2008 at 00:02

some further experimental data that may be helpful to someone, Using IPA instead of EtOH doesn`t seem to work at all, the KOH takes Ages to dissolve in the alc, and then when the oil is added it almost instantly forms a thick emulsion that even after 15 hours of stirring and 1 hour rest, refuses to split.

hydrocarbons from plant oil

GI Caesar - 6-7-2009 at 00:40

Hi, I'm new here so I don't know if this is total nonsense, but I've got two ideas to get hydrocarbons from plant oil:
1.Kolbe electrolysis
2.Hydrogenation of esters
This is usually done with Lithium aluminium hydride, but hydrogenation is also possible.
I hope this thread wasn't dead before; in that case I'm sorry.

JohnWW - 6-7-2009 at 00:47

LiAlH4 is too expensive as a reagent to be used for industrial-scale hydrocarbon production from vegetable oils; crude oil is far cheaper than oil synthesized in such a manner. I have an idea that Kolbe electrolysis may consume too much energy to be economic for the purpose.

GI Caesar - 22-7-2009 at 04:19

Look at the link! I wasn't talking about LiAlH4 reduction.
I have no idea how much 2000-3000 psi is and how easy Cu2Cr2O4 can be obtained, but it's worth a shot, isn't it?
Anyways, I was thinking about dehydrating the fatty alcohol and cracking the alkene.

not_important - 22-7-2009 at 05:19

You can directly thermally crack the fatty acids, avoiding the reduction step. This is the basis of a number of patented processes for producing hydrocarbons from waste fats, other organic waste such as from meat processing, or Aunt Molly. There are problems with net energy balance, some implementations never produced more fuel stuff than the equivalent in energy consumed running the plant.

Kolbe electrolysis is rather energy inefficient, as well as often being inefficient at converting the feedstock to hydrocarbons. In the case of starting with fatty acids from typical fats and oils, the resulting hydrocarbons are much too long (~ 26..30 carbons) to be useful as motor vehicle fuel, either Otto or Diesel cycle. This means that you'd have to crack the products from the Kolbe process, much cheaper to just start with the oils or FFA and skip putting energy into the Kolbe step or some reduction of the fatty acid.

ammonium isocyanate - 22-7-2009 at 14:27

I have a pretty awesome job as a home chemist. I intern at a biodiesel lab at the University of Kansas:). We make biodiesel from used cooking oil, but at the same time we do experimental research on making biodiesel from various strains of algae.

For the biodiesel from used vegetable oil we do the following:
1. Filter
2. Heat up to 60*C and let sit for ~8 hrs
3. Filter again
4. Add methanol and KOH
5. React at 60*C for ~48hrs (varies alot by batch)
6. Seperate out the glycerin and distill off excess methanol (usually without anything catching on fire;))
7. Acidify with HCl
8. Let sit and seperate out any soaps
9. Run god-knows how many tests on the biodiesel
10. Scratch our heads about what to do with the glycerin (which we currently have sitting around in 55 gallon barrels, they'd probably give me some if I asked for it)

Unfortunately we can't put the biodiesel in road vehicles because we can't do enough tests. For now, we just use it to run all the mowers and other stuff on campus off B10. However, we got some bailout $ :D so we are finally getting a corporate research engine that we can use to test the cetane number.

bdgackle - 28-3-2010 at 07:00

I often wonder if ethanol/biodiesel should be viewed as an energy transfer mechanism, like hydrogen, as opposed to an energy production mechanism.

Agriculture on the scale it exists today requires massive production of artificial fertilizer to sustain -- the biosphere simply doesn't fix as much nitrogen as we need it to to sustain the yields we get today. Breaking the N2 molecules in the air, to get us to NH4 is an inherently energy intensive process. According to Wikipedia, 1-2% of the world's entire energy output is consumed by nitrogen fixation in the Haber-Bosch process. This is on top of the (mostly fossil) fuel used to run the farm equipment, transport products, etc. The fact is, as oil prices rise, food prices will rise right along with them. I don't know whether a closed system using only biofuel to support agriculture is possible or not... has anyone ever found any good numbers on this?

Then there is the land-use question. In much of the world, we have forests that are finally expanding. If we have to cut them back down to till more land, we are disturbing a rather large carbon sink. Granted, forest growth to lock up carbon is not sustainable, but it is a factor in current global CO2 balance.

Now, I would think that any biofuel production from purely waste products is a pure environmental gain, but I have deep questions on the utility of growing crops specifically for fuel production.

Now, liquid fuels are the ONLY viable alternative for aviation, so if nothing else, we may have biofuels well into the future for the simple purpose of converting fission energy (or whatever) into something that jets can make use of.

None of this changes the fact that fossil fuels are clearly not a sustainable solution – I just have doubts about this source of fuel as a viable replacement. I’d be very interested to hear the opinion of someone more knowledgeable though.

12AX7 - 28-3-2010 at 16:43

As far as biofuels go, I expect the most profitable direction to persue is harnessing plant metabolism directly, so we can divert all the photosynthetic energy to making fuel, without wasting it on cellular reproduction and indigestible plant matter.

Better still, find a way to introduce electrodes into the process and do it electrically without any need for light.

As forests go, they don't have to be unsustainable sinks. Clear cut a forest every ten years or so (replanting it, obviously) and you've got a tremendous amount of lumber, plus biowastes (leaves, branches, bark, etc.). Lumber is a net sink of carbon, because most construction refuse is buried.

Tim

bdgackle - 29-3-2010 at 01:41

Good point about construction materials, and certainly the lumber industry in general. The part I was referring to as unsustainable is the carbon sinking achieved by the growth of natural forest over areas that were formerly farmland. In North America, at least, rising yields have led to reduced acres under tillage. As the number of acres falls, additional carbon is sunk over and above what the lumber industry already does for us (most lumber comes from farmed trees) – but this process cannot continue indefinitely, since there is finite land being changed. I operate on the assumption that this will not directly result in an increase in lumber demand, and therefore is independent of the effect of the building industry. The end result is that the carbon balance in North America shifts more toward emission once the changing process is complete.

Where we could really make some gains, at least in the United States, is coming up with a dessert plant that either produces lots of oil or lots of fermentable carbs. The Southwestern desserts here are largely barren and receive tremendous amounts of sunlight. Hard to say, though, if this would be a more efficient use of these resources than simply building solar-thermal power plants there (giant pools of molten sodium, just plain cool).
My main problem with ethanol, and again my experience is limited to the US, is that the industry has become entangled in the politics surrounding it. Decisions often seem to have more to do with profit for ethanol plants and corn growers than with real economic or environmental gain. A situation that is not terribly different from that surrounding oil politics, I suppose.


[Edited on 3-29-2010 by bdgackle]

bdgackle - 29-3-2010 at 01:47

Hmmm... I think I meant "desert" plant, instead of "dessert"; however, getting tasty things as a by-product of the process is acceptable, so I'll let it stand.

JohnWW - 29-3-2010 at 01:59

Quote: Originally posted by bdgackle  
(cut)Where we could really make some gains, at least in the United States, is coming up with a dessert plant that either produces lots of oil or lots of fermentable carbs. The Southwestern desserts here are largely barren and receive tremendous amounts of sunlight. Hard to say, though, if this would be a more efficient use of these resources than simply building solar-thermal power plants there (cut)
Where would the irrigation water needed by those American desert plant crops come from? The water in the Colorado River and Rio Grande and their tributaries is already all spoken for. It would have to be pumped hundreds of miles from somewhere, which could only be either the Mississippi River (untreated), or from giant solar-powered sea-water desalination plants (which would also produce drinking-quality water) on the coasts of California and Texa$. Just putting in the water pipelines and pumps to do that would be an enormous up-front co$t by itself.

12AX7 - 29-3-2010 at 11:42

Obligatory dessert content: "fermentable sugars" include sucrose, fructose and starch, key ingredients in cake. :D

I'd be fascinated to see a coal burning plant in the middle of a greenhouse. Instead of building a stack, cool the exhaust further and vent it into a vast greenhouse. Nothing is really going to grow there, but give it some time, first at maybe 1% CO2, then gradually increasing from there. In a decade's time, the greenhouse should be filled with an astonishing growth of hyperactive weeds. Mow it down and toss it in a vat of cellulase, repeat. Because it's a greenhouse, the water requirements should be modest, and if it's built on poor soil, you probably won't have to worry about soil depletion because only poor-soil-tolerant species will thrive. If a decade isn't fast enough, play the genetics game, mix-and-match species and see which does best.

I know they're researching this right now using algae, which is probably a fairly productive material, but I don't like how much pumping is required. To bubble CO2 through a series of tubes requires that much water head pressure, and the tubes have to be made, and sealed, and pressurized and all, which is way the hell too much infrastructure for something that could be done with steel beams and plexiglass.

Tim

12AX7 - 29-3-2010 at 11:52

Quote:
Quote: Originally posted by bdgackle  
Good point about construction materials, and certainly the lumber industry in general. The part I was referring to as unsustainable is the carbon sinking achieved by the growth of natural forest over areas that were formerly farmland. In North America, at least, rising yields have led to reduced acres under tillage. As the number of acres falls, additional carbon is sunk over and above what the lumber industry already does for us (most lumber comes from farmed trees) – but this process cannot continue indefinitely, since there is finite land being changed. I operate on the assumption that this will not directly result in an increase in lumber demand, and therefore is independent of the effect of the building industry. The end result is that the carbon balance in North America shifts more toward emission once the changing process is complete.


Ah, so lumber already constitutes an approximately constant sink for carbon, so it's already spoken for? (In whatever definition of 'constant' you want, either in absolute terms, or relative to other CO2 production, etc.) Yes, I can see that.

You proposed that this newly forested area (which although it doesn't constitute a continuous sink, does contain a lot of carbon) would have to be removed to free up more tillable land in order to support a biofuel economy. I suggest that, rather than clearing it as CO2, simply add this forest material to the lumber supply, and what material cannot be used for lumber (leaves, branches, bark, undergrowth, etc.) should be mulched (probably not a great idea, since it decays, but may be nutritious for other plant purposes) or digested as additional biomass.

So the transitional phase, when reforested land is being cleared, would probably cause a depression in the lumber market. Perhaps lumber could be advertized during that period, to increase usage of whole timber and such; use plywood instead of OSB, wood flooring instead of composite, etc. After all, it wouldn't be helpful to force timber farms out of business.

Tim

Biodiesel

Dr.Bob - 14-4-2011 at 13:16

NH4NCO gave a fine summery of biodiesel production with MeOH.

Getting back to the earlier questions on ethanol based biodiesel: If you want to use EtOH, it has to be dry (100% alcohol, no water), you need more of it, and the base catalyzed reaction runs at about 10% of the rate of methanol (methoxide is smaller than ethoxide as a nucleophile, so much less steric strain). So you have to have higher temps, longer reactions, more alcohol (molar ratio) and more catalyst. Also, remember that ethanol's MW is almost 50% higher than that of methanol, so you need more alcohol for that reason as well.

So while methanol needs about 20% volume to oil, ethanol requires about 40% alcohol to oil, and ethanol costs more as well (quite a bit more it turns out). so making biodiesel with ethanol is not practical on a commercial basis unless you have very plentiful and cheap ethanol. In that case I would drink it and drive much less, thus solving the problem. :-)

As for the starting oil/grease, it must be dry (no water), low in FFAs (or cleaned up first which requires time/energy/money), and preferably have some large amount of unsaturation, so that the final biodiesel is not a solid at cool tempteratures. (Think of beef or pork fat at room temp. Do you think it will flow in a pump well?) But too much is bad, as it will polymerize or go rancid which is also bad. So the requirements for the input oil of biodiesel are also quite picky, which is why it is not yet as common as petrodiesel. But since the US uses huge amounts of diesel, and biodiesel is very compatible with it, it makes sense to find ways to make it.

So how to we solve the problems?

Genetic engineering of plants to make more oil is possible, as there are plants which produce huge amounts of oil in the tropic, we just need to tweak some plants to grow in the US or other similar climates which make a mono or diunsaturated oil in large quantities. Soybeans and rapeseed are already able to make oil at $4-5/gallon, and they only produce a small amount of oil per acre (~10-50 gallons/acre, I believe). Some plants can produce over 10 times that in the tropics. So if we could just make more oil/acre by 4 fold, the price of biodiesel would drop by $1-2 per gallon and already be cheaper than petrodiesel.

Better processes, catalysts, and equipment would drop the price of the biodiesel by small amounts, but incremental gains can still eventually bring the price down by about $0.50 / gal. Currently, the energy input for biodiesel (heating/cooling, pumping liquids, purification, etc) is also quite high, improvements to the process can make it much more energy positive (ie, generate more energy than it uses to make it). Even using solar power to warm the oil to filter it and transesterify it helps.

And if we can convince (engineer) plants, algae or bacteria to produce a simple fuel (ethanol, ethanol based biodiesel, or butanol) directly, that would allow a quick ramp up that might well produce gas or biodiesel at a very practical price.

Well, that my $0.02 worth. (OK, maybe a couple bucks worth.)

Bob

497 - 14-8-2011 at 11:52

Is there any actual reason to bother with plants when you could use algae? Especially with recent advances, algae cultivation makes so much more sense. The potential to utilize ocean water without desalinations seems like a vast advantage also.

The following process seems too elegant to ignore:
Grow your algae of choice in a container of your choice, while continously circulating the suspended algae through a nondestructive extractor. The extractor consists of a mixing section in which the stream of algae suspension is mixed with algae derived biodiesel by a mechanism of your choice (ultrasonic mixing is supposed to work well) then treansfered to a seperator section which somehow fully separates the mixture into two phases. It could be as simple as a settling tank or cyclonic separator. The algae suspension is returned unharmed to the main container and the biodiesel+triglyceride solution is transfered through a drier/filter to a transesterifier section where (m)ethanol is added and reacted with the triglycerides using a method of your choice. I like the looks of a MgO catalyst myself. The biodiesel+glycero mixture is then transfered to a washer where water is used to remove the glycerol and any unreacted alcohol. The biodiesel is the tranfered to a holding tank where the excess is periodically or continously removed for use as fuel or further processing, and the rest is reused to extract more algae.

Since the algae is not having to reproduce quickly to replenish it's population, it can devote a very large fraction of it's energy to the production of more lipids. Thus total yields per area or volume are increased substantially over the conventional destrucive extraction process.

biodiesel from algae

Gorbash101 - 3-12-2011 at 18:47

Hello.
I am new to this forum. I would just like to add that I have heard of using algae to produce oil as raw material for biodiesel. The advantage is that algae are easy to culture, it would not compete with cash crops and it does not need acres of agricultural lands. Do you have any idea if this is already being commercially done on a large scale application?

497 - 3-12-2011 at 21:32

Just Google it man. It is already being done. Not too much on a DIY scale though.

jayjay - 5-12-2011 at 23:13

I'll have a bushel or so of pecan shells after this year's harvest. Anyone have any suggestions...will it be worth the trouble, trying to extract the oils? (just tinkering with the idea)

497 - 1-2-2012 at 09:50

I found some more info on the system I refered to two posts ago.
https://docs.google.com/viewer?a=v&q=cache:vu5rLaUWbmkJ:...
They clearly show that the process of milking chlorella algae produces twice the total biomass/m2/d and 1.4 times more total oil. Another important benefit of the ultrasonic milking is the destruction of most algae predators. Other than euglenas, the algae competitors are all partially or fully eliminated after a single milking.

The company responsible for developing this system is Phycal Inc. They are not messing around here, in fact they were recently awarded the largest algae related contract from the DOE yet, $51 million.

[Edited on 1-2-2012 by 497]

Vitrian - 8-1-2014 at 18:55

Hey im new here but ive been an eager spectator of this forum for several years now. Decided it was time to join.

Anyway to my question: I was wondering what sort of pre-purification might be necessary when creating oil from beef fat? I work at a small butcher shop and see piles of the stuff everyday. I want to try to create biodiesel from the stuff in the future, mostly out of curiosity and to get a bit more hands-on chemist experience. Any other advice for this would be greatly appreciated. :D

hyfalcon - 9-1-2014 at 03:34

From Duda diesel:

Biodiesel is most commonly made from fats derived from vegetable oils. Its viscosity is similar to diesel and can run in any diesel vehicle without any modification of the engine, with the exception of old fuel lines and gaskets found in older diesels from the 1980's which may be corroded by biodiesel.

Most makers of biodiesel obtain their vegetable oil sources from restaurants. Restaurants will give away their used frying oil since it must be properly recycled and not thrown away. Aside from many other recycling methods, biodiesel is one of the best ways to recycle this used cooking oil since it helps aid an expensive fuel market and its by-products can be used for many other things.

http://www.dudadiesel.com/biodiesel.php

Dr.Bob - 27-3-2014 at 11:56

Quote: Originally posted by Vitrian  
Anyway to my question: I was wondering what sort of pre-purification might be necessary when creating oil from beef fat? I work at a small butcher shop and see piles of the stuff everyday. I want to try to create biodiesel from the stuff in the future, mostly out of curiosity and to get a bit more hands-on chemist experience. Any other advice for this would be greatly appreciated. :D


For beef fat, you would have to do a lot of prep work, as the fat/oil needs to be free of water to work well in the biodiesel production, so the best way would be to collect a good bit, heat it enough to melt it, filter it well to remove the solids, meat and some water, and then once it is more like lard/grease, it could be processed much like normally oils, only the temp would have to be higher for many operations. And the resulting fuel would work best in a warm climate or mixed with oil based biodiesel or regular diesel.

A number of meat producers like Smithfield are teaming up with biofuel companies to recycle their waste, which would otherwise require paying someone to haul off. The key is that they can mix the fuel to produce a final product that is not as likely to solidify at normal temps.

hyfalcon - 27-3-2014 at 14:43

The chicken fat biodiesel makes you smell like a Kentucky Fried Chicken going down the road.

draculic acid69 - 3-6-2019 at 19:15

Isn't propane from glycerol a possibility? HI and hypophosphorous reflux for example would have propane bubble out of the rxn off gasses condensed and purified.propanols and propane diols also being other useful products.

draculic acid69 - 4-6-2019 at 05:56

Has the possibility of making the alkanes from used cooking oils been looked into.i know that there chains are about two times as long as needed for diesel which means cracking would have to be used to break the chains but they should be fine for kerosene .once the methyl ester is formed the ester can be reduced w/sodium to the corresponding alcohols and then rediced to the alkene or alkane depending on the starting oil.

[Edited on 4-6-2019 by draculic acid69]
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