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Mariner
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Not sure if anyone cares about this idea anymore, or even if they do would care about bioenergy. But hey, why not ask? The topic is obviously in the news quite a bit (usually with the typically mainstream media quality of accuracy and unbiasedness...), and it's come up here a few times. And it's one of the few topics I feel qualified to talk about. So feed my fragile ego, Ornery members! [Smile]

Topics I would be willing to discuss include, but are not limited to:

Corn-based ethanol
Sugarcane based ethanol
Cellulosic ethanol
Soy-based biodiesel
Palm-based biodiesel
Algae biodiesel
Biogasoline, bioalkanes, biobutanol, etc.
Bioelectricity
Bioplastics

Feel free to ask any questions on the technical, scientific, economic, environmental, political, commercial, or whatever side of the issue you'd like. And feel free to ask about the tangential issues, such as farming, final use of the fuel, etc. I can't claim to be an expert on all of this, but I try to keep my own interests in the area as broad as possible, so I've at least thought about all of these aspects.

Also, since the merging of science and politics/advocacy is one of my pet peeves, I will do my best to remain as unbiased and objective as possible, and will clearly mark what is my own opinion vs otherwise.

I do NOT want to go into the relative merits of biofuels vs hydrogen, electric, etc., since that will undoubtedly move into politics and advocacy real quick, and I don't know enough about the other options to give an accurate, unbiased opinion. Suffice to say that if we want energy stored in carbon, than biomass is the only non-fossil fuel source of that carbon (to say nothing of bioplastics). And that's all I'll say on the matter.

And if anyone's wondering about my qualifications, I've been doing research in this field since early 2005. Which puts me as more experienced than the majority of biofuel researchers these days... Or to put it in terms that indie music lovers would understand, I was into it before it was cool [Smile]

Ask away!

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philnotfil
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My biggest question is why are we pushing corn-based ethanol so hard over cellulosic ethanol. My understanding is that cellulosic ethanol uses all of the parts that we don't use as food. Wouldn't that be what we want to use?
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Paladine
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Awesome, Mariner!

First maybe you could start by explaining exactly what biofuels are and how they're produced. How much energy can we produce with these different biofuels relative to their production costs?

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DonaldD
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Also, an analysis (in an open market) of what effects we could expect - as well as the effects we have already seen - on land usage as fuel acreage begins to provide a better profit margin than food acreage.

As an example, how it makes economic sense to clear peat-land and swamps to produce food and fuel in today's market, but that it makes zero ecological sense since the CO2 released by clearing the land far outweighs any possible bio-fuel replacement value. Since the cost of releasing all the CO2 pent up in the peat is not borne by the producer and not factored into the cost of the product, it pays in this case to increase the CO2 load in the atmosphere.

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Paladine
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Donald-

As I understand it, it isn't necessarily an either-or proposition viz a viz food or fuel. Isn't it possible to produce biofuels using only the parts of crops we don't use for food? (The husks of corn, etc.)

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DonaldD
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Yes, but there are (I believe) different technologies and different costs associated with using different types of biomass as the feedstock for biofuel.

Regardless, if it becomes profitable to deforest an area or replace millenium-old peat with a corn plantation or some other biomass source (as is currently the case) it becomes economically profitable to do so regardless of the CO2 effect.

CO2 'reduction' is only one reason for using biofuel, though...

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Lyrhawn
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Some of these are simple answers. Corn ethanol is used for one reason and one reason only: Iowa's position in the presidential primaries. You can't win Iowa without promising to support and then actually support their corn farmers, of which a large majority receive vast sums of our tax dollars for use in fuel production. There's some sort of joke that goes "If you want to be president, you don't vote in Congress against ethanol, and everyone in Congress wants to be president someday." If Iowa were last in line to vote, ethanol wouldn't be alive today. It's a wasteful process that from "well to wheel," to use an oil industry term, costs more and uses more energy than is gotten out of it. Lately it has also been spiking the price of food across wildly because we use corn in America for EVERYTHING. We feed it to livestock, we make fake sugar out of it, we make thousands of different kinds of foods, etc. etc. Corn is king. Remove Iowa's political power and you remove corn's prominance in biofuels.

But even with that in place and unlikely to change, corn is still only a gateway fuel source to the good stuff, like cellulosic, which can come from dozens of different sources. There are a lot of different sources under study right now, but in the end I don't think there will be any silver bullet fuel source, it'll come from a variety of waste products that'll be turned into fuel. Algae based fuel is going, I think, to be cost competitive in some ways because CO2 producing coal fired plants out west, especially in the desert areas will have a lot of space and sunlight for algae growth, (it's more an issue of space than sunlight, as it takes a lot of space to set up the algae growers, but they can make it work even in Canada). But the CO2 is free, hell, when we get CO2 capping legislation in America, it might even be a boon to sell your CO2 to algae growers who'll pipe it right into tubes to grow the stuff by leaps and bounds, and then it'll be turned right into fuel. Tests are underway right now on B100 algae biofuel, which is 100% synthetic biofuel, not a mixture like E80 which is corn ethanol and regular gas mixed on an 80/20 ratio. One question that remains unanswered is the long term effects of biofuel on your engine, but we do know that corn ethanol has a lot of harmful effects long term based on the way it burns, which is also why it has less output, and actually reduces your MPG when you use it.

The problem with cellulosic is really just a matter of time. We need to find better enzymes that will break down the materials in question, be they switchgrass or sorgrum or wood pulp and leftovers or whatever. I'm not as well versed on the specific of the process, but I know they need an efficient process to break it down to I think sugars, so it can then be turned into biofuel via a refinery. Cellulosic test refineries are being built in several locations currently, where they hope to some day soon achieve some sort of parity with the cost of regular fuel, which is being made easier by the high cost of gas.

Some plants like sorgrum can be grown in really adverse conditions, like the depleted tobacco fields of Virginia, where most other crops can't really survive, and it has a very high energy per acre yield, which would essentially have zero CO2 problems, as little grows there currently, it'd be a local boon to the economy, and it wouldn't impinge on food crop production at all.

I think in the end we're going to see the use of a lot of hardier plants that can grow in places food crops can't be grown, that get high energy yields per acre, and a lot of waste products like from wood pulping and from farming, such as corn stalks and husks that right now are thrown away. With the coming drought due to climate change in many ares of the US, we'll have to make sure we have many different sources for our fuel, and that crop failures won't imperil the transportation sector. I think electric cars will really take over the personal transportation sector in 50 years anyway, but from a purely national defense and economic standpoint, there is a lot to be said about biofuels.

Feel free to correct anything I may have gotten wrong, expand upon what I got right, and fill in the gaps there Mariner. I'm just a treehugger with a lot of time to read on my hands.

I'm most interested in hearing about bioplastics. I know Ford is working on some plant based foams and has recently licensed the technology out to John Deere, but how close are we to a mass market bioplastic that will replace oil based plastics?

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Mariner
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Because Iowa's the first caucus state and a swing state, phil [Smile]

A more serious answer is that, if you're only looking to make a small amount of EtOH (ethanol, for those not used to chemistry abbreviations), cellulosics make almost no sense. Corn is superior to cellulosic in many, many ways:

- Starch (like corn) is MUCH easier to turn into EtOH than cellulosics. It's not even close. Not only does it require far less enzymes (both in quantity and # of types), but it does not require a (possibly) expensive pretreatment to make the sugars more accessible.

- We have far more experience in making EtOH from starch than cellulosics. After all, we've been doing the former since ancient history (although for a rather different form of consumption...). Cellulosics have only moved out of the lab intermittently in the past decade or so, and only on pilot plant or demonstration plant scale. Corn has had time to come down in price and compete with gasoline, cellulosics haven't.

- We have far more experience farming and collecting corn than agricultural residue. The infrastructure just isn't there, or isn't as complete, for cellulosics. We can collect corn stover (ie, all the parts of the corn that's not the grain). We can transport it. But farmers tend to be conservative (in the classic sense rather than political), and thus aren't going to do it unless they're guaranteed to get money.

- Corn is likely to be more energy dense (ie, more gal EtOH per ton material) than cellulosics, or at least cellulosics from biochemical conversion at this point in time.

- Corn is more area dense (more gal EtOH per acre farmland) than agricultural waste and possibly much of perennial grasses.

- Corn is physically more dense (mass per volume) than cellulosics. These last two points are especially important when taking into account costs of transporting the material to the ethanol refinery.

- Corn ethanol has about 33-50% of the capital investment of cellulosics, and does not require large economies of scale to be profitable. One can make a 40million gallon EtOH per year corn plant economical, but a 40million gpy cellulosic plant might be more difficult.

So it's very, very simple. Corn ethanol is cheaper than cellulosics. As long as one doesn't want to make more than a little bit of it.

When you need more than just a few billion gallons however, cellulosics become more attractive.

- Fiber is cheaper, much cheaper, than starch. At worst, it's about 50% as expensive as starch, and could conceivably be much less. As land use becomes more constrained, corn prices will rise faster than cellulosics.

- Fiber can be grown on less fertile grounds than corn, opening up different types of land to energy production.

- Fiber can potentially be more area dense than corn when grown as a perennial grass.

- Most of the advantages of corn can be diminished or reversed with increased technology.

Really, that's why we've been doing corn ethanol for all this time, and why cellulosic ethanol is just now starting to become popular. The first few refineries will undoubtedly struggle to make a profit, but with rising corn prices they should become competitive fairly quickly. It's also why research in cellulosic ethanol has increased dramatically over the past 2 years.

Does that help?

Paladine

Good call. I'll do biodiesel later, and can do other biofuels if anyone wants me to later as well. But now, I'll focus solely on biochemical conversion to ethanol.

If you all go back to your high school biology, think about how glucose (sugar) got converted to energy. There were two steps; anaerobic (no oxygen) was the first step, which released very little energy, and aerobic (with oxygen) was the second step, which converted it completely to CO2 and released a frickload of energy. Yeast, when there's no oxygen present, can only do the first part. To get rid of the half-broken glucose that happens in that step, it converts it to ethanol. About half the weight is converted to CO2, although almost no energy is lost (so beware, all ye alcoholic dieters. Alcohol is twice as fattening as sugar! [Razz] ) Hence, the conversion of glucose to ethanol, called fermentation, is a very efficient process.

But where does the sugar come from? Monomers (one glucose molecule unlinked to any other) of glucose are not all that common in nature. If you're in Brazil, however, you can use sugarcane, which is made of the dimer (two sugar molecules connected) sucrose. Thus, all you need to do is separate the sugar from the cane (called bagasse), and you're good to go.

But we're not in Brazil, and we can't grow sugarcane. Thus, we need a polymer (many sugar molecules linked). Starch is nice and easy to break down; anyone (well, except cats) can do it. The enzymes (proteins that assist chemical reactions) to break them down are everywhere, and you only need a small amount of them to do the job. Starch is made to be broken down, so it's easy to do. This process is called hydrolysis, or enzymatic hydrolysis. Most refineries cook the corn a bit first, although it's not necessary anymore. Once the enzymes turn the starch to glucose monomers, you can ferment them.

What about fiber? Well, we all know that we can digest fiber. Even cows take a long time to break hay down, and it's hardly as effective as starch. See, fiber is cell walls, which Mother Nature made to keep the plant protected. It's not as simple as just cellulose (which, like starch, is a glucose polymer, but one that is much more ordered and constricted). It also contains hemicellulose (polymers of multiple types of sugar), lignin (large phenolic indigestible compounds), and pectin (a little glue), all wrapped together in a tight little bundle. If you just dumped some enzymes on the fiber, you'll get out a little sugar, but not much. Evolution is just too strong.

Thus, you need to outsmart evolution. Thus, before hydrolysis, you need to perform an initial step called pretreatment. There are numerous types of pretreatment which I can lay out if you'd like, but they're all based on the idea that you need to break up the tight little package that is a cell wall. Once you do this, then you can add the enzymes, and you can get out far more sugar without too much of a problem.

So, to recap:

Sugarcane ethanol steps:
1) Cane + sugar separation
2) Fermentation
3) Distillation (separating the ethanol from water)

Corn ethanol steps:
1) Steeping (cooking) the corn
2) Starch hydrolysis
3) Fermentation
4) Distillation
5) Residue drying

Basically, after you get the ethanol, you still have a lot of gunk left over. All the protein, fat, and fiber in the corn (along with any unfermented starch and all the yeast residue) still has value, so it is dried and sold as an animal feed called distiller's dry grain and solubles (DDGS).

Cellulosic ethanol steps:
1) Pretreatment
2a) Enzyme production
2b) Hydrolysis
3) Fermentation
4) Distillation
5) Power Generation

Because you need far more enzymes for cellulosics than starch, it may not be economical to buy them from an outside source, but rather produce them on-site. Like with corn, there's still other residue left over, but it's predominantly lignin, which has little value for anything other than energy. Thus, it will likely simply be burnt for all the heat and power required in the refinery.

There's variations, of course, and some steps can be combined (which I'll likely discuss later). But that's the gist of it.

Energy requirements?
Sugarcane: 8:1 (8 units of energy outputted for every unit of fossil energy input, if I recall correctly)
Corn: 1.5:1 (NOT less than 1:1, as one person claims)
Cellulosics: no one knows for sure, but ~6:1 isn't a bad estimate.

However, that's only important if you cared about how much fossil fuel is used. Quite frankly, no one really cares. This means nothing about the global warming issues, and it means nothing about the other issue: oil mitigation. In all cases, it's about 15-20:1 (20 barrels of oil saved vs barrel invested). That's because the only oil inputs is the transportation and the requirements at the farm.

Donald, I'll get to you later [Smile] I'll just say that it's possible to produce ethanol economically and not environmentally. It's also possible to produce ethanol economically AND environmentally. But that's lengthy and I don't have time to do it at the moment...

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Mariner
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Lyrhawn, while there's nothing wrong with the general gist of what you said, a lot of the "facts" in the media aren't as factual as one might think. So no offense as I go through a quick fisking...

You can't win Iowa without promising to support and then actually support their corn farmers, of which a large majority receive vast sums of our tax dollars for use in fuel production.
The ethanol subsidy go to the blenders, not the farmers or the ethanol plants. Not that this doesn't mean the farmers don't get an indirect break from the government, they obviously do. And then there's the rest of farm subsidies... But just trying to be clear. Oh, and McCain's been adament about NOT giving federal subsidies for Iowa. Sure, he didn't win the caucus, but he still has a chance at the presidency!

It's a wasteful process that from "well to wheel," to use an oil industry term, costs more and uses more energy than is gotten out of it.
Nope and nope. Well, we'll ignore the cost, since that's so dependent upon corn prices that the current ethanol boom may be a bubble. But the whole "uses more energy" bit is a myth perpetuated by one person. Every other person who investigated it has concluded the opposite. Besides, the net energy concept is stupid. For oil displacement, it's irrelevent, as my previous post showed. For GHG emissions, it's irrelevent, as my next post will show. So who cares?

Lately it has also been spiking the price of food across wildly because we use corn in America for EVERYTHING.
I'll get to this later even if no one asks about it. Not that what you said is wrong, but you insinuate that this is a terrible calamity. I'd like to put more background into the issue.

Remove Iowa's political power and you remove corn's prominance in biofuels.
Enh. It would most likely still be the most common biofuel in the US. It also would not be likely to be anywhere near the amount used today. As my post above indicates, corn makes sense for small amounts of biofuel (other than GHG emissions, but whatever).

Tests are underway right now on B100 algae biofuel
A) Algae research died until very recently, and I doubt anyone cares about proving it will work in cars at the moment (there's a 99% chance it will, so why bother?). B) We already know B100 in general works. Heck, Mr. Diesel knew it when he built his motor [Smile]

One question that remains unanswered is the long term effects of biofuel on your engine, but we do know that corn ethanol has a lot of harmful effects long term based on the way it burns
Cite please? I have heard nothing to that effect.

which is also why it has less output, and actually reduces your MPG when you use it.
Actually, it's simpler than that. EtOH has less mileage because it's less energy dense than gasoline. It has nothing to do with the way it's burned (actually, theoretically EtOH is more energy efficient than gas, so the way it's burned is actually better than gas)

With the coming drought due to climate change in many ares of the US
I'm not touching that one. Just don't let G2 or Daruma see it!

So no problems with the thesis (for the record, I'm all about killing corn ethanol too, even if I seemed pro-corn in my post above. The whole "being objective" thing and all.), just with some of the specifics [Smile] I'll write something about bioplastics soon.

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Mariner
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The environmental impact of biofuels
(just for you, Donald)

When it comes to the global warming side of the biofuel debate, we need to be clear that there are multiple aspects of it. It is impossible to say that biofuels are better or worse for CO2 than oil, since that's far too general. So first, let's get the sources of GHG emissions clear.

1) Land use change: This seems to be what Donald is referencing, and is what caused a major stir last month with a couple articles in Science. The gist is simple: for a true comparison between oil and biofuels, one would need to take into account what would happen on the land. Most people think biofuels automatically have the upper edge since they're sucking CO2 out of the air, but the land will still be there if you don't grow anything on it. Thus, if you have a plot of fallow land that sucks more CO2 out than your biofuel crop, then that should count as a credit for oil.

Which means the first step to figuring out the environmental impact is deciding what you're going to grow and where you're going to grow it. To take an extreme example, cutting down the rainforest in Malaysia to grow palm oil is probably not as good an idea as building an algae pond in the middle of the Sahara.

Of course, you still have other issues. With ethanol increasing, food prices are going up, and you're going to remap the face of worldwide agriculture. This is very dicey to model, and any results are going to depend on your assumptions, assumptions which may or may not be reality.

2) Emissions due to agriculture: This goes beyond the emissions from tractors and the like. In fact, the biggest issue is nitrous oxide, which has somewhere around 300 times the global warming potential of CO2. According to the EIA , 73% of N2O emissions in 2003 came from agriculture, with 74% of that coming from nitrogen fertilizer. So if your crop is something that requires you to dump tons of fertilizer on it due to its poor ability to take it up (*cough* corn *cough*), you're looking at something a lot worse than a plant (like, say, a perrenial grass) that sucks up its fertilizer quickly.

But you can't just pick a crop and know the emissions. Corn grown in Iowa will be different than Indiana which will be different than South Dakota, etc. And farming practices vary from farm to farm. The decision to use tilling vs no till, planting cover crops for winter/spring, how much stover is left on the farm, etc ALL have impacts on the environmental and ecological impact of the farm.

3) Emissions due to production: This is what happens at the actual refinery. And they'll be different depending upon what type of material you're using and how your refining it. Corn ethanol uses a lot of natural gas; cellulosics likely won't. And biodiesel has a very simple process that requires little energy.

4) Tailpipe emissions: What comes out of your car. There's been some debate over this, which I won't get into now. Suffice to say that all ethanol will act the same regardless of its source, and all biodiesel will generally (but not completely) be the same. And despite the debate, we'll just say that it's not likely there's a huge difference between biofuels and oil per mile driven. This isn't as big of a part of the overall issue, but it's still important for city air quality, etc.


So, the million dollar question: does *insert type here* biofuel reduce GHG?

Corn: Unlikely, but don't take the Science article as an article of faith. The NCGA (surprise, surprise, right?) gave a reasonable rebuttle questioning many of the assumptions here . And yes, some of those rebuttles are valid. Note, however, that they say nothing about whether that will completely change the result. That should tell you something [Smile] Furthermore, because the energy costs in ethanol refineries (#3 above) and the N2O emissions are so bad for corn (#2 above), I'm betting that these changes in assumptions won't matter. I've seen a few different LCAs for corn ethanol (I don't have them handy at the moment unfortunately), and the end results were never as promising as one might expect for a "green" industry.

Sugarcane: I haven't a clue. That really depends on Brazil's agricultural policies, and I don't know enough to separate the fact from the fiction here. My gut instinct, however, is that it does reduce GHG. I personally haven't seen any complete studies on it, at least none that I've delved into enough to check their assumptions.

Agricultural waste residue: Probably. There will still be some land use change, and some concerns regarding how the removal will affect everything, but the fact that it's a byproduct (and thus avoiding most of the issues with #1 and #2) will help tremendously.

Perennial Grasses: It's impossible to tell at the moment, but very likely. The good news is that #2 and #3 are favorable for grasses. However, since we don't grow grasses commercially on this scale, it's hard to tell what the direct and indirect land use change will be like. But there's reason to hope. These things can grow all over the place, so we don't necessarily have to open up otherwise fertile land. The other article in that Science journal showed the "payback" time for land use change to be virtually nonexistent for converting abandoned cropland to grasses. And while the article focusing on indirect land use changes is less optimistic, I have reason to believe that they're wrong. This would take too much time to explain now, and I probably can't talk about all of it (it's my own research and not all of it is published yet), but my goal is to have the change in land use be all about reducing corn acreage (which, as implied above, sucks horribly in environmental and ecological ways) rather than peat bogs like Donald feared.

Biodiesel: I haven't seen any specific studies on these, since it's not my area. But algae would almost certainly be good, and soy oil most likely is as well (since it's a byproduct rather than the primary benefit). But canola or palm? There may be a reason to doubt. However, there may be a reason to not doubt. I'll look it up later.

So in conclusion, Lyrhawn can still claim that corn is the devil. At least environmentally (*grumble* durned hippies... [Razz] )

Is that what you were looking for?

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IrishTD
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quote:
And despite the debate, we'll just say that it's not likely there's a huge difference between biofuels and oil per mile driven.
You're going to have to expand on this one, esp. for ethanol. When the ethanol cheerleaders (ethanol.org) admit that there is an MPG loss and car folks (cartalk.com) agree (E85 blend being nearly 2/3 the MPG of gas/E10), I'm not sure this is a reasonable statement. Just for a point of reference (and I'm only looking up the one for now) the 2008 Chevy Impala gets about 2/3 the MPG running on E85 that it does from unleaded (chevy.com).
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Mariner
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The debate I referred to is two-fold. The first is about the other tailpipe emissions, such as carbon monoxide and NOx and particulates and the like. The second is over the actual performance of EtOH in engines, whether it actually gets a boost in energy efficiency and how cars handle different blends and the like. Because of that, I didn't want to talk too much about the specifics. But if we're focusing just on CO2, then what I said was true. Mostly. Actually, ethanol is better.

EtOH energy density: 23.5 MJ/L
EtOH carbon density: 411.7 gC/L
EtOH emissions: 17.5 gC/MJ

gasoline energy density: 34.8 MJ/L
gasoline carbon density: 639.6 gC/L
gasoline emissions: 18.4 gC/MJ

You can see that the 23.5/34.8 numbers is where the 2/3 gas mileage number comes from. However, ethanol also has 2/3 the carbon as gasoline. Hence, the CO2 emissions are not much different.

[ March 20, 2008, 06:03 PM: Message edited by: Mariner ]

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Jesse
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Mariner, way less tailpipe NOx and Sulfides with ethanol, neh?

Lyrhawn -

With hardend valves and seats, Ethanol is less damaging to an engine than gasoline. It leaves behind far less in the way of residue, so much less in fact that even if you leave the tank full for six months and don't operate the vehicles, you can just drain the tank, refill, and not worry about varnish in your fuel lines and injectors.

I know an old crank that converted a 1964 bug to ethanol almost 40 years ago. Running it on stuff he distills himself, he's put almost 400k on it, and it still runs like a champ.

He claims he's only changed the fuel filter once, and has never had to rebuild the carbs or replace fuel lines in all those years.

I've gotten to know several old cranks of his type over the last couple years, including one that started doing to recycled cooking oil bio-deisel thing almost 20 years ago.

A simple, unsafe, and unrecommended couple of ways to demonstrate this is to pour some rubbing alchohol on the ground and a similar ammount of gasoline, and see what's left when they both evaporate completely, or to torch off a small puddle of each a foot beneath a piece of white paper.

[ March 21, 2008, 05:24 AM: Message edited by: Jesse ]

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scifibum
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Bump.

I saw an article about plant-based gasoline (linked from the Dilbert Blog). here it is.

Mariner, any comment? The article is pretty sparse on details and I haven't heard about this direction for plant based fuels before.

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Mariner
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I talked to someone at UW-Madison a few months ago about their work with this (it might be someone from the group mentioned in that article, I don't really know). It's not my field of expertise, so I can't really comment on the science of it. It's a catalytic process, so it's basically a chemical conversion of sugars into various alkanes. If I remember correctly, they were also looking at doing it on cellulose (fiber, or long chained glucose), which would cut out a costly hydrolysis step and possibly a pretreatment step as well. And that article says the UMass group did do it with cellulose, so the technology is there. So it's definitely quite promising.

However, I do remember asking them if they've tried it on actual biomass, and the answer was no. Now, they might have done it by now, I honestly don't know. But there's a lot of other junk in plants besides fiber, including lignin, phenolics, protein, lipids, minerals, acids, etc. These have a tendency to screw up catalysts. Will it screw up these catalysts? Not a clue. But it's definitely a concern. The article mentioned it was done on "plant cellulose", but that may very well be purified cellulose. MSM articles always miss the important details [Smile]

I've also never seen anything on the economics. It should have a "head start" over ethanol, since downstream costs will be much lower than in biochemical ethanol conversion (it's a lot easier to separate gasoline from water than ethanol from water...). And the basics of catalytic conversion should be cheaper than SSCF (combined breakdown of fiber to glucose and fermentation of glucose to ethanol). But I have no idea about the rate and extent of conversion, the cost of the catalysts, or any cost associated with recycling the catalyst. My guess is the research is just too early for that yet.

But yes, it is an option, and a good one. But I think there's still a few questions left that I haven't heard answered, although I'm not exactly up to date on the issue.

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Lyrhawn
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Have you read the cover article that TIME put out two weeks ago about Corn ethanol Mariner?
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