***Assuming one planting/harvesting cycle per year***

146,000,000,000 / 90(gallons) = 1,622,222,222 tons required / 8(ton/acre) = 202,777,777 acres = 316,840 square miles required producing 100% ethanol to fuel the US year round for gasoline alone (not including diesel and other products).

Texas = 268,820 sq miles.

There ya go.

edit:
And I couldnt find how much total landmass is used for Corn, but Iowa produces Corn on 13,000,000 acres - 8% of the total landmass needed for switchgrass. Its not 3%, but its still just drops in the bucket.

 

Thanks. You missed one factor, though -- a gallon of ethanol doesn't completely replace a gallon of gasoline. You need to increase the number of gallons by about 34%.

BTW, I'm all for replacing everything in Texas with one giant switchgrass field.

 

This is an important piece of the puzzle, but the overall answer will have to include a variety of sources. The GM/Coskata venture is extremely efficient and can use garbage and old tires as well as other feedstock for ethanol production. A great many side benefits would also be realized from that process. We can do this (and really must do it), it will just require a sustained drive toward getting the job done.

 

From Wikipedia's article on Ethanol Fuel:

"Engines using fuel with from 30% to 100% ethanol also need a cold-starting system. For E85 fuel at temperatures below 11 °C (52 °F) a cold-starting system is required for reliable starting and to meet EPA emissions standards."

I didn't realize this. 52 °F for E85? That's crazy.

 

Wikipedia is NOT a good source. I could go on there and say that Ethanol causes herpes and somebody would believe it...

 

Fine, but there's lots of good information on Wikipedia. I know it's questionable; that's why I specified the source. Can you prove/disprove the figures, or are you just assuming that they're wrong because it's on Wikipedia?

EDIT: Nevermind, I did it myself. Wikipedia provides this PDF of a study done by the State of Michigan as the source for those figures. Within the PDF itself, it appears that the actual figure is 32F, not 52F.

Still, that's not good enough.

 

I was under the impression that one of the advantages of switchgrass was that it grows very fast and would basically be mowed and collected... Not harvested like corn... The benefit would be MANY times the gross output per acre...

 

 

Would be interesting to see how many times a year you could harvest switchgrass. That could take the number of acres required down significantly.

Besides, what will happen with this and other technologies is that it will only need to lessen and not replace our dependence on foreign oil. When we start using significantly less oil, the price will drop. E85 can be part of the solution, but hybrids (especially plug in), fuel cell cars, natural gas cars, and others will make this work. Good thing about E85 is that there are many cars out there today that can run it.

 

Thats the impression I was given too - but after some searching I couldnt find the length of time taken to grow and regrow. Even two cycles a growing season would cut the amount of land required in half - which is HUGE.

I knew I was forgetting something

Either way the fact remains that its a *lot* of land thats needed.

Not to go and say "Mr Fusion!" a thousand times, but there was also the work done by Startech Environmental in regards to using plasma to recycle trash. Either solution is something we really really need to look into, as the footprint of such a facility wouldnt be too incredibly large and it would (obviously) reduce landfill and garbage dump requirements.

As the saying goes, we're not out of the woods yet - but I swear there's daylight out there.

 

A gallon of E100 replaces a gallon of gasoline. Guess who has showed off a number of E100 concepts? GM's SAAB division w/ the AeroX concept using a TT E100 V6 producing like 400 hp.

 

This is important to keep in mind. There will not be just one single source or method by which we replace gasoline. And who knows, gasoline may never be completely phased out as an energy source. But I could see a combination of ethanols derived from different sources and hybrid technologies putting a big enough dent in oil.

Not in terms of energy output, which is what I think he was getting at. A car gets worse fuel mileage running on current E85 than it does on gasoline. So, we'd need to grow even more switchgrass and make more ethanol than gasoline we currently demand to make up the difference.

 

The current E85 vehicles aren't optimized for E85, make some changes to timing and compression and then you will get closer to the same output.

 

The grass is a perennial, so it gets planted once and harvested many times over the years from that single planting. Far more sustainable than an annual crop such as corn. Add to that, the reduced need to cultivate the soil and fertilize and you have additional environmental benefits on the supply side. Fertilizer runoff and soil erosion have been major concerns for a very long time.

The trash to fuel approach is great for similar reasons. But one added benefit I see to it is the ability for such production to be handled locally. The side benefits to this are huge. Elimination of much of the need for landfill space, a major reduction in the cost of disposal, hopefully the elimination of the need to ship waste long distances, elimination of the need for centralized refineries, no need for pipelines or shipping the fuel over long distances...

The list goes on.

 

You'll still need to fertilize over the long run, since you'll still be depleting soil nutrients by harvesting the entire plant.

Trash-to-fuel is nearly worthless in the long run. Assume that you get efficiencies in the 80-90 gallon/ton range. Well, my wife and I throw out maybe a hundred pounds of trash each week - that's enough to get ~5 gallons of fuel. And as oil gets more expensive, we'll throw out even less stuff. Sure, we can mine the landfills and get a short-term surge of available fuel, but it's not sustainable.