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Biofuels are probably the connecting thread between oil based vehicles and electric vehicles.

 

There's a large push for ethanol around here, largely because of the corn production.

 

Honestly, I feel cellulosic ethanol has the most potential, largely because it can be developed out of waste material. Making something out of nothing is generally a winning situation. However, it does require more initial prep before it can be turned into ethanol.

 

Corn is not as advantageous as sugar cane (which is what Brazil uses primarily) due to it's lower sugar content. We may see a dynamic shift from corn's use as a primarily food crop and develop into a fuel crop. Advances to increase sugar production in the corn at lower cost will have to happen it seems.

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Biofuels have great promise, but also they seem to be controversial. There are claims that their use is a choice between food (corn) and fuel (ethanol) although this isn't true for several reasons.

 

1) The ethanol produced from corn has, as a by product, "distillers grain" which retains most of the food value of the original corn (up to 91% dietary equivalent).

 

 

http://www.ddgs.umn.edu/overview.htm

 

from the article:

 

"yielding a DE [dietary equivalent] value that is approximately 91% of that found in corn. "

 

2) As noted by entropy, it can be produced from any cellulosic source, including garbage. As such, there is no food vs. fuel controversy here.

 

When these facilities start coming on-line at an industrial scale, its going to have a big impact on both our fuel (get ready for more E-85) and waste industries. :)

 

Theres been quite a bit of discussion on these and other controversies in previous threads such as:

 

http://www.scienceforums.net/forum/showthread.php?t=32479&highlight=ethanol&page=2

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Bio-ethanol in combination with bio-gas is the best, because you also utilize the waste. I'm sure many US corn ethanol producers are either considering bio-gas or already producing it. Or perhaps they make animal feed from the residues.

 

The cellulose feedstock for cellulosic ethanol is much cheaper. The existing bottlenecks are the pretreatment and enzyme costs:

 

Often the cellulose is not "available" for enzymes to break it down. In stead it is "locked" inside the plant, and protected by other polymers such as lignin.

That's where the pretreatment comes in. There exist lots of ways to destroy the plant. It sounds simple, but it is tricky because: you do not want to degrade the cellulose and sugars into something useless.

 

The second bottleneck is the price of enzymes. But these are getting cheaper all the time, and at some point this should not be a problem any more.

 

The main issue with any biofuels, and also solar and wind (and any form of energy that is not stored under ground) is that it needs SPACE. Something is there already, and it must move because we want solar panels, or a wind turbine, or corn fields. And bio fuels need the most space of them all.

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  • 3 months later...

This process increases the efficiency of biofuel by suppressing the formation of carbon dioxide. For this purpose, hydrogen from a carbon free source like nuclear or solar energy is added at the time of gasification.

 

In the traditional methods, the biomass is firstly converted into carbon dioxide, carbon monoxide and hydrogen in the gasification stage. These components are then separated and converted into liquid fuel.

 

The H2CAR methods provides greater efficiency as carbon atoms present in the starting materials are not lost in this process. In the conventional process, usually 60 to 70 percent of the carbon atoms in the starting materials are lost. So this process reduces the wastage. As the formation of carbon dioxide is also suppressed, it prevents the emission of a greenhouse gas into the atmosphere. The volume of biofuel produced is also three times that produced from the biomass using conventional methods.

 

Researchers are now trying to use these methods to produce fuel that can drive all the automobiles. In the new future, biofuel will be available for use not only in cars and buses, but also in trains and aeroplanes. In times when there is a great scarcity of conventional fuels, this can provide an added benefit by supplying an alternate and also a pollution free source of energy.

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Maybe we should start off with giving an overview what biofuels are instead of throwing in specific opinions to various sub-subjects of it? Just a thought.

 

AFAIK any fuel produced in relatively short term by organisms is considered biofuel. This is supposedly to contrast it from fossil fuels which are also the product of organism, but which took a long time to form.

To my knowledge there are basically four main directions:

-ethanol

-hydrogen

-biogas (methane)

-biodiesel (methyl esters)

 

I am no expert on any of these fields (though I do have close colleagues in the areas of biogas and biodiesel formation), so take my thoughts with a big chunk of salt. One of the main problems to date is that all processes depend on microorganisms and that at this time point the whole process is still too expensive. Moreover, no single approach is likely sufficient to cover the need of fuels we have got today.

At least not with further developments.

 

According to some calculations for example, more is lost than gained in terms of greenhouse gas reduction and fussil fuel dependency when land is switched to crop growth for ethanol production (see e.g. Hedegaard et al., Environ. Sci. Technol., 2008, 42 (21), pp 7992–7999).

 

Biogas is also now already used, especially in agricultural settings, but usually the output is just enough to power essential elements on the farm itself. However, they are usually truly powered by waste (in contrast to ethanol fermentation). A disadvantage is that methanogenesis is a somewhat complicated process that requires more than one species of bacteria to run efficiently. As such its productions is more difficult to control. Biodiesel is interesting as the one can engineer the organism simply to produce the required lipids and it does not require the rather inefficient means of fermentation for biomass increase. An interesting approach was to use either cyanobacteria or algae, which can directly produce the lipids required for biodiesel synthesis without the need to given them costly carbon sources (except CO2, of course). Still, this is to this date too expensive, though I expect much from this approach, as one is not dependent on growing other biomass first for fuel production.

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Another direction being considered is the production of bio-butanol :

 

http://en.wikipedia.org/wiki/Butanol

 

From the article: "Butanol is considered as a potential biofuel (butanol fuel). Butanol at 85 percent strength can be used in cars designed for gasoline (petrol) without any change to the engine (unlike 85% ethanol), and it contains more energy for a given volume than ethanol and almost as much as gasoline, so a vehicle using butanol would return fuel consumption more comparable to gasoline than ethanol. Butanol can also be used as a blended additive to diesel fuel to reduce soot emissions...Butanol can also be produced by fermentation of biomass by bacteria. Prior to the 1950s, Clostridium acetobutylicum was used in industrial fermentation processes producing butanol. Research in the past few decades showed results of other microorganisms that can produce butanol through fermentation."

 

I am beginning to think this will be an even better approach than ethanol.

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One of the main problems to date is that all processes depend on microorganisms and that at this time point the whole process is still too expensive.

 

And a big problem with that is that microorganisms are greedy bastards and use a bunch of that energy for themselves. And it gets worse when multiple microorganisms are required. Sometimes the enzymes can be extracted from the bacteria, but that tends to be an expensive process.

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To add one to Charon's list.

 

Anaerobic pyrolysis of organic waste, followed by reaction with hydrogen.

 

Start with something like wood waste from the forest industries - sawdust and so on. Heat it in the absense of oxygen to drive off volatile organic compounds. Mix those volatiles with hydrogen gas and pass the mixture over a heated catalyst, and hydrocarbon fuel forms.

 

Another by product is charcoal (carbon) which can be plowed into soils by the terra preta process to improve soil fertility and tilth. That carbon is thus sequestered and stored, potentially for thousands of years. This process provides biofuel, improves agriculture, and reduces CO2 in the atmosphere, storing it long term in the soil.

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