Free Energy

bhankiii,

Won't any form of ethanol production, regardless of the "feed material", require both fermentation (which generates CO₂ - "greenhouse gas"), as well as distillation (necessitating an input of heat, that must be generated by burning some sort of fuel), also generating geeenhouse gasses?

I was under the impression that (at least in the USA), much of the ethanol as an alternative fuel "hype" is just that, hype, to appease the "Agri-biz" giants like Archer-Daniels Midland & Cargill...

(Just my $0.02)

<Won't any form of ethanol production, regardless of the "feed material", require both fermentation (which generates CO₂ - "greenhouse gas"), >

While undoubtedly true the important thing is that it is short-cycle carbon dioxide that was captured recently by growing plants. The heat input could also come from this source, just like in a modern sugar processing factory - nothing is wasted; the good ones make their own fuel from their own feedstock.

"Everything is renewable. It's just a question of timescale. For bio-fuels it's a few tens of years. For fossil fuels it's a few tens of millions."

PWSlack,

I am familiar with sugar processing factories using bagasse as a form of fuel for their sugar cane boiling/reduction processes, however, that does not make these plants "carbon-neutral".

I believe that I have seen statistics somewhere that indicate roughly 1/4 of overall energy consumed at a modern sugar manufacturing plant can be supplanted by their use of bagasse for fuel (and cogeneration), but the remaining 3/4 of the total energy consumed in the sugar production (i.e., during the growing, harvesting and transportation of the sugar cane) comes from combustion of petroleum products.

I also recall reading that in order to produce 1 gallon of ethanol, more than 1 gallon of petroleum fuel (or the equivalent) must be consumed

According to this article (go to Setting the Record Straight on Ethanol) by the Rocky Mountain Institute,

for every one unit
of energy available at the fuel pump,
1.23 units of fossil energy are used to
produce gasoline, 0.74 of fossil energy
are used to produce corn-based ethanol,
and only 0.2 units of fossil energy are
used to produce cellulosic ethanol.

I also found this:

Corn ethanol is energy efficient, as
indicated by an energy ratio of 1.34; that is, for every
Btu dedicated to producing ethanol there is a 34 % energy gain.

from the latest USDA research:

http://www.usda.gov/oce/reports/energy/aer-814.pdf

And that's factoring in all the costs of growing the feedstock. Cellulosic ethanol is much more energy positive - since you don't count the energy of creating the feedstock - it's the waste from other processes that would normally go to the landfill. And the carbon that's released from the ethanol would be released anyway, either through decay or burning of the feedstock.

Corn ethanol is energy efficient, as
indicated by an energy ratio of 1.34; that is, for every
Btu dedicated to producing ethanol there is a 34 % energy gain

That might be true, however 1 US gallon of Ethanol only has about 67% of the BTU value of gasoline, meaning for every 10 gallons of gas you burn you're going to have to burn 15 gallons of pure Ethanol to produce the same amount of energy.

http://www.nafa.org/Content/NavigationMenu/Resource_Center/Alternative_Fuels/Energy_Equivalents/Energy_Equivalents.htm

As for the "cleaner burning" arguement, most of the numbers I see compare a gallon of gas to a gallon of ethanol without regard for the fact you will have to burn more ethanol to make power. I would like to see some statistics that compare real world data, especially for large vehicles where power is a must.

The energy numbers are calculated in terms of BTUs, not gallons.

Alcohol burns cooler, i.e. lower flash point

"sometimes its wiser to just look stupid, than opening your mouth and removing all doubt"

-Mark Twain, more or less

This process doesn't use fermentation. It's a two step process - first steam converts the waste into syngas (hydrogen and methane) and then a (non-biologic) catalytic process converts that into alcohol.

http://www.rangefuels.com/conversion_process

mouse over the pictures for words

Even turning oil to gas also requires distillation, right? (IDK)

I don't know the chemistry involved, but the chief issue with conventional ethanol is that you would have to use up all your food production capability to get enough ethanol to replace gas, but this process uses already available garbage, so no impact on food production.

PWSlack said it before I did

The method used for ethanol production is gasification of cellulosics followed by catalytic conversion to ethanol. I don't remember if the catalyst is chemical, or biological (fermentation). Think is was chemical.

Still a high energy cost for the gasification. I assume that the company in question is doing a final energy balance using the various possible feedstocks for the process.

Wood alcohol is a very old technology.

The hold up is the right strain of bacteria. If a fast multiplying bug is engineered will there be a wood frame house safe?

Anyone remember ice nine

long live the memory of Kurt

The catalyst is not a bacteria, not an enzyme, it's chemical rather than biological - that's the important feature of this process.

Here I'll be a bit more serious, link for FRontline energy

syngas has been around since the 30's. Syngas can be turned to diesel also, diesel ICE's are up to 30% more efficent than spark ICE's.

the enzymes are generally fungi derived [wood rotters]

ethanol has a lower vapor point [than gasoline] & will contribute to co2 emissions. this is why many states were using MTBE until the potential for ground water contamination became a problem!