Home

Ethanol.. Lets look at some numbers.

Tue, 02/07/2006 - 00:44 — kebernet

I did some poking about on Google tonight, because I was curious..

Let us go with the better case numbers for ethanol. Assuming:

1.35:1 net energy gain from ethanol production. (USDA via the National Corn Growers Association -- The DOE numbers don't seem so good and a couple of studies range from bleak to wasteful)

140 bushels of corn per acre (USDA via Wikipedia, March 2000 numbers)

2.6 Gallons of Ethanol per Bushel (USDA via Governors' Ethanol Coalition)

320,500,000 Gallons of Gasoline per day (Gibson Consulting. How Stuff Works says the DOE puts that at 400,000,000 but I am using the low number.

140 * (2.6 g/b * .7407 production) = 269 gallons/acre/year

(320,500,000 * 365) / 2 / 269 = 217,439,591.08 acres per year to offset one half of our current gasoline consumption, not counting growth in that number .

2,263,960,480 total acres in the US. 19.13% is arable according to the CIA World Factbook

That means 217,439,591.08/433,095,548, or 50.2% of all available farmland in the US.

Does this really seem practical?

(In the interest of being completely honest here, this doesn't take into account the gasoline consumed in gasoline production, or that ethanol has about 85% the number of BTUs per gallon of gasoline. The former I simply couldn't find a number for, the second I will ignore in order to "help" the case for ethanol.)

Also, w/r/t Kevin Drum's mentioning:

Jaffe thinks ethanol could be used to directly power hydrogen fuel cells, for example

I would note this:

In early 2004, researchers at the University of Minnesota announced that they had invented a simple ethanol reactor that would take ethanol, feed it through a stack of catalysts, and output hydrogen suitable for a fuel cell. The device uses a rhodium-cerium catalyst for the initial reaction, which occurs at a temperature of about 700 °C. This initial reaction mixes ethanol, water vapor, and oxygen and produces good quantities of hydrogen. Unfortunately, it also results in the formation of carbon monoxide, a substance that "chokes" most fuel cells and must be passed through another catalyst to be converted into carbon dioxide. (The odorless, colorless, and tasteless carbon monoxide is also a significant toxic hazard if it escapes through the fuel cell into the exhaust, or if the conduits between the catalytic sections leak.)

At best, this is a significant engineering hurdle.

Comments

Tue, 02/07/2006 - 10:06 — Shmooze (not verified)

RE: Ethanol.. Lets look at some numbers.

However if (no research done here - just pulling numbers out of my ass) today's average MPG is 20 and you increase the average MPG to 100 then that would be a much better way to significantly reduce the amount of gasoline consumed. I cannot believe that we could not attain a number like that fairly quickly if we really wanted to. My diesel rabbit from the 80's was half way there.

Tue, 02/07/2006 - 10:33 — cooper (not verified)

RE: Ethanol.. Lets look at some numbers.

True, however, if we could reduce our consumption by 80%, we wouldn't even really have a crisis :P

Tue, 02/07/2006 - 10:50 — atrox (not verified)

RE: Ethanol.. Lets look at some numbers.

I have been wanting to post this same story. The whole ethanol thing is a joke. Even if we switched to something other than corn, in order to actually get a decent amount of cellulose from the plant (like sugarcane) its still barely net positive. Its not the answer. (Dont take my word, Tad. W Patzek, Berkeley professor is a skeptic as well).

There are thousands of ways we could improve efficiency and reduce dependence on fossil fuels altogether (foreign or not). We cant even pass higher CAFE standards with our current "leadership" (yeah "leadership" should now officially be in quotes to sardonically note how great a job our "leaders" are doing).

Wind, Solar, or more efficient fossil fuels would all help. Bicycles, walking, light rail that is actually useful (not just in inner cities and operating at a loss) and so on as well.

And I think diesel is a viable approach too - however it does have issues with emissions (especially in the states).

Tue, 02/07/2006 - 13:46 — Shmooze (not verified)

RE: Ethanol.. Lets look at some numbers.

You know I think the worst part of this whole thing is that really it's all just bogus. Make a speech mentioning all this stuff without having any plans at all to actually do something. Amazingly that seems to work out pretty well for this administration. It seems like once a week I hear some story on NPR about states unable to get EPA backing to force power companies to build new technology plants. At the end of the day it really is just one speech a year in an enviornment where the big mega companies are effectively running the bureaucracies that are supposed to be regulating them. That's why you don't see a huge outcry from the companies - they know this is all bogus.

Tue, 02/07/2006 - 16:12 — jheimann (not verified)

RE: Ethanol.. Lets look at some numbers.

I think the trick is that there isn't going to be just one 'magic bullet' for energy. The key will be to get away from a near 100% dependency on fossil fuel and diversify our energy base. Hydrogen? Sure that will work, but you have to make the hydrogen first. That'w where nuclear, solar, wind, tidal energy comes in to convert water into hydrogen. Ethanol as the only solution? Please! My family has had a farm for 100 years and they laugh about this one. First, corn is very intensive to farm and very hard on the land. You have to rotate other crops in to replenish it. But, you could use it as an additive to help stretch fossil fuel supplies for things that can't be so easily converted over to other sources. Biodiesel would be another great way to go. Also, I would like to see homeowners get off the grid. The fact is that most people who own homes could easily live almost completely independent of the public utilities by installing solar electric and solar water heating solutions. Add to that fuel cell generators for folks who live in cloudier climates and who needs the big utility companies? Fossil fuels will always be important for some applications. For other applications other sources are even better. I know when I build a house the next time I'm going to use a superefficient wood stove or a corn stove (look it up, very cool stuff) to heat seldom used parts of the house, like a basement.

Wed, 02/08/2006 - 05:16 — anonymous (not verified)

RE: Ethanol.. Lets look at some numbers.

All told, a gallon of ethanol costs $2.24 to produce, compared to $0.63 for a gallon of gasoline.

Converting corn to ethanol requires about 99,119 BTUs to make one gallon, which has 77,000 BTUs of available energy. So about 29 percent more energy is required to produce a gallon of ethanol than is stored in that gallon in the first place. That\'s why fossil fuels are used to produce ethanol.

So, if we were to switch entirely to ethanol use, we\'d run out of petroleum four times as fast.

Wed, 08/02/2006 - 09:53 — anonymous (not verified)

RE: Ethanol.. Lets look at some numbers.

I feel this is an excellent opportunity for genetic engineering; produce a plant that wouldnt necessarily be viable for human consumption but that will produce an abundance of sugar. If we can make more 'efficent' plants (to serve the purpose of converting solar energy into chemical energy) we can easily supply our energy demands. The best solar cells are 10% efficent; in one day the solar energy that hits the earth could provide us the power humans use in a year. What if with genetically modified plants we could achieve a 20-50% efficency? There would be no manufacturing costs because the plants would GROW :)

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.