|
|
| |
New page -- needs title & page settings.
|
|
| |
Calculating Energy Independence
Detailed calculation are available in this spreadsheet .
Data on corn acreage and yield
How to tell foreign fossil from domestic fossil
If we avoid using a gallon of gas, was that foreign gas, or domestic gas? Physically, it's about half and half, but that misses the point. When we don't use gas, what changes? American oil production stays the same, but we import less. So,
When we save 10 gallon of gas (e.g. with ethanol),
we reduce fossil imports by 10 gallons.
The same holds for using extra oil, gasoline, or natural gas.
When we use an extra 10 gallon of oil, gasoline or natural gas,
we increase fossil imports by 10 gallons.
But what about coal? Almost all our coal is produced here in the USA, and we can produce more. So,
When we use more coal, that does not increase fossil imports.
Any change in these assumptions would have to cut against ethanol. It cannot be that saving a gallon, that half comes from US oil wells, can save more than a gallon of imports. If saving comes 100% from imports, then so must extra use.
|
|
| |
How much of ethanol's fossil input is foreign?
Using the logic above, all of ethanol's natural gas and petroleum inputs should be counted as foreign, but none of it's coal input should be.
The Energy and Resources Group at UC Berkeley, compared about a dozen ethanol-energy models and made their own analysis using the best assumptions from the other models (data). They have adjusted for coproducts, and their energy input values are:
| Energy Input Type | Energy in MJ/L | Percent of Fossil |
| Coal | 8.78 | 56.3% |
| Natural Gas | 5.87 | 37.7% |
| Petroleum | 0.94 | 6.0% |
| Nuclear and Renewables | 0.89 | not fossil |
Combining Natural Gas and Petroleum shows that
Foreign Fossil inputs are 42.7% of all Fossil inputs.
The Argonne Lab value for total Fossil input to ethanol is 74%. In combination:
The Foreign Fossil Energy input to ethanol is 32.3%.
In energy units, 0.323 GGE of foreign fossil energy is needed to make ethanol with 1 GGE of energy. Nuclear and Renewables provide a small amount of non-fossil input that is not included in the Argonne-Lab/Wang estimate of "fossil energy input."
|
|
http://zfacts.com/p/782.html | 01/18/12 07:22 GMT
Modified: Fri, 20 Apr 2007 18:49:59 GMT
|
|
