What's the true story on ethanol?

Cecil's Columns/Staff Reports
1

Link to column #2481

I think Cecil missed a few points here.

He says Pimentel originally claimed that “making a gallon of ethanol takes 70 percent more energy than the finished product contains” and then revised his estimate to say “making a gallon of ethanol takes 29 percent more energy than it provides, not 70 percent”. So the original number was 1.70 and then he changed it to 1.29. This suggests to me that even Pimentel himself isn’t really sure what the precise number is and there’s a wide error bar surrounding this number (Let’s call it E). So, can we really say with confidence that E is definitely greater than 1.00?

Cecil also adds “And because that production energy comes mostly from fossil fuels, gasohol isn’t just wasting money but hastening the depletion of nonrenewable resources.” Most? How much is most? Certainly not all. Just for the sake of argument, let’s say “most” means 80%. Now we have to multiply E by 80% and we get 1.29x.8=1.032. Now can we still be confident that E is definitely greater than 1.00? Even if it is, all that means is that we should be using some other type of fuel to run the machinery. For example, we could run the tractors on biodiesel and run the refineries with electricity from hydroelectric dams. I don’t know about where you live, but here in the Pacific Northwest, 48% of our electricity comes from renewable sources like wind, solar, and hydro, and only 52% from fossil fuels like coal and natural gas.

Also, while it’s true that making ethanol from corn is rather energy intensive, that certainly doesn’t mean that the process wouldn’t get more efficient as we learn to iron out the bugs in the system. Maybe the value for E was 1.03 back in 2003 but what is it now in 2016?

And who said we have to keep using corn? Last I heard, they were looking into other plants like switch grass, which doesn’t take as much energy to process it into ethanol.

And what’s with this talk about thermodynamics? Bah. The corn itself is receiving energy from the sun and we are merely attempting to extract some of that energy in a concentrated form. Thermodynamics has nothing to do with it. Now, if this corn was grown indoors using sun lamps powered by fossil fuel generators, then yeah, the laws of thermodynamics would say you can’t get more energy out than what you put in. But planet Earth is not a closed system. I’m sure the physicists dopers here will back me up on this.

In conclusion, the most you could say is “According to data available in 2003, it’s PROBABLY true that making ethanol produces less energy than it consumes, IF you only use corn to make the ethanol, and IF you’re using machinery that runs on 80% fossil fuels (or more), and ASSUMING that the technology doesn’t become more efficient over time”. That’s an awful lot of qualifiers.

One more thing. The fact that it takes more gallons of ethanol to get the same energy as in one gallon of gasoline doesn’t imply that you’re better off without the ethanol. If you compare 10 gallons of gasoline compared to 10 gallons of gasahol, you’re missing the point. Remember that 10 gallons of gasahol contains 9 gallons of gasoline plus 1 gallons of ethanol. So ask yourself would you rather have 9 gallons of gasoline plus 1 gallon of ethanol or 9 gallons of gasoline period? Obviously, 9 gallons of gasoline plus 1 gallon of ethanol has more energy than 9 gallons of gasoline. Miles Per Gallon is a good way of comparing vehicle efficiency but only if everything else stays constant. If you’re comparing different types of fuel, it’s more fair to talk about MPGe, Miles Per Gallon-equivalent. One gallon of gasoline contains 33.7 kWh of energy. Ethanol has 22.3 kWh. To get 33.7 kWh of energy, you need 1.5 gallons of ethanol, which is one Gasoline-Gallon-Equivalent (GGE). If you fill up your tank with 15 gallons of gasoline, you’ll get the same number of kWh out of it as you would from filling up your tank with 14 gallons of gasoline plus 1 GGE of ethanol. Doing so does NOT rob your car of energy or make your car’s engine less efficient.

And BTW, gasoline isn’t immune to the effects of energy input either. It takes about 6 kWh of energy to drill, pump, ship, and refine oil into gasoline, then transport it the gas station.

But more importantly, Cecil mentioned carbon monoxide but didn’t mention the bigger problem of CO2. If we can get a more efficient system (using a source other than corn, or improving the process so it’s less energy-intensive), ethanol could help us reduce our carbon footprint because it’s renewable.

Just because ethanol made from corn using fossil fuel machinery was too energy-intensive is no reason to say that ethanol in general is a bad idea.

2

Wikipedia’s article “Ethanol fuel in Brazil” is a good place to start answering your questions … keep in mind:

  1. The tropical climate is suitable for sugar cane production,
  2. Brazil has an abundance of cheap hydro-power, and
  3. They are manufacturing internal combustion engines that run on straight ethanol.

Looks like they’re about ready for when the fossil fuels run out …

3

Sigh. Where does one begin with this dog’s breakfast.
Start with the silly concept of GGE. OK, so 1.5 gallons of Ethanol is the energy equivalent of 1 gallon of gasoline. The fuel tank in my car (and everybody else’s) has a certain specific volume. This is gallons, not GGEs. If my tank holds 15 gallons, I am always better off with 15 gallons of gasoline than with 14 gallons of gas and 1 gallon of ethanol. You say I should then get the same energy by using 1.5 gallons of ethanol. Where am I to put the extra 1/2 gallon of ethanol? My driving range is a function of the size of my tank and the energy density of the fuel I fill it with. I am thus always better with a maximum of the higher energy density fuel, which is gasoline. ANY amount of ethanol in my tank reduces the energy contained in the tank and thus reduces my driving range. It’s really simple.
To use your ten gallon example, I would rather have 10 gallons of gasoline than nine of gas and 1 of ethanol. To get the energy of ten gallons of gas in 10% ethanol mix, I need the extra two quarts of ethanol. Where do I put those two quarts? If I have room in the tank for those two quarts, I will opt for all gasoline. That will take me further than any combination of gas and ethanol.
It takes a certain amount of energy to move my car a certain distance. The more ethanol in my gas, the more of it I will need to go a certain distance. I can only carry on board what my fuel tank holds. If you say use a bigger tank (to hold the ethanol), I will use the bigger tank to hold more straight gasoline.

4

This assumes, of course, that one buys a car or fuel with the idea of maximizing the range from that purchase. Which, I submit, is not a generally common concept. I certainly don’t bother with that; one just fills up more often.

5

Not exactly. The point I was trying to make is that GGE isn’t a kludge to correct for the lower energy density of ethanol. It’s a way to compare cost between (among) various fuels, liquid or gaseous. He seems to be waving away the lower energy content by saying just use more. But I can’t, because I have nowhere to put more.
The choice is not 9 gallons gas plus a gallon of ethanol vs 9 gallons of gas. The choice is 9 of gas + one of ethanol vs 10 gallons of gas. As the concentration of ethanol increases it only gets worse.

6

Don’t forget to include price in your metric … if ethanol was half the price of gasoline for three quarters the energy … I’d happily fill up twice as often …

7

But that’s the whole point of the metric, to compare cost. It’s just a way of expressing $/btu in a more familiar fashion. I think it’s a bit off-point to try to use it to kludge for lower energy density, which is what the OP seems to be doing.

8

The part I dislike about the article is where he implies that the energy input being greater than the output is a consequence of the laws of thermodynamics. It’s true that the input is greater than the output, but it’s not because of thermodynamics, because there’s an extra energy source in the system, the sunlight used by the growing crops. Other biofuels, such as biodiesel, can and do produce more than what they take in (not counting the sunlight).

As to demonstrating the futility of ethanol, I have a simple criterion. Build me a facility (a combination of farms, refineries, and whatever else is needed) that doesn’t have any power lines going into it and doesn’t take in any fossil fuels, but puts out a nonzero amount of fuel. Run the tractors in the farm on ethanol. Haul the materials from place to place using ethanol. Use what you grow as the feedstock for your fertilizers. Heck, if you want, I’ll even let you put in windmills to run the refinery and miscellaneous electrical needs (backed up, of course, by ethanol-powered generators for when the wind’s not blowing). If, after all of that, you can still export ethanol to the outside world, then I’ll buy it. If not, then the system just plain does not work.

9

The windmills won’t do you any good if we can’t use any power lines … or do you mean having power lines is okay as long as they don’t connect to any fossil fuel electrical source?

If not, then we’d have to build great big fermentation vats and an elaborate system of evaporators using sunlight to purify the ethanol … the facility would have to be big, but I think it could be an net energy exporter … being we’re not counting sunlight …

10

But you seem to be arbitrarily limiting the “cost” comparison by the amount one tank of your car’s gas holds. But that’s silly; the tank is refillable. Therefore, the true metric isn’t how much the tank holds, but rather how much you’d use in a given time period.

11

My apologies … I’m only seeing distance traveled per tank of fuel in your comments … you haven’t touched upon the cost of that tank of fuel … if you’re assuming that gasoline and ethanol are the same price per gallon at the pump … then yes, the costs of a 10% ethanol blend will be about higher per mile traveled …

However, I think your assumption is wrong … maybe not today, maybe not next year … but someday we’ll start to run out of gasoline … and the price will increase dramatically … someday the price of a gallon of gasoline will be five times the price of ethanol … our 10% blend now is only four and a half times as expensive … so here we’ll have the ethanol blend being cheaper per mile even though you’ll still have to fill up a little more often … extending further by having an engine designed to run on straight ethanol and we’re looking at the costs being one fifth that of gasoline per mile … yet still only having to fill up a little more often …

Now, I understand that it will be a long time before we start running out of fossil fuels … however it will also take a long time to build all the facilities to make ethanol affordable at the pump … starting with a whole mess of nuclear power plants to generate the electricity to power our ethanol production … then the production facilities themselves … and all at the same time manufacturing engines that run on ethanol … so maybe, just maybe, starting right now is a very good idea …

All this while ignoring the costs of global warming …

12

I said no power lines going into the facility. Power lines within the facility are fine.

13

I think this misses the point of what Cecil was saying. If the point is that his lowest estimate that it takes 1.29 times more energy (type is not important) to produce ethanol that its resulting product, then the whole exercise is a net waste. The only type of ethanol production I’m away of that may produce more energy than it consumes on a scale to make a difference is algae based.

14

So if we built our facility to include Grand Coulee Dam, then we’d be allowed to use that 7 GW of power? … If we’re still ignoring sunlight, then this 7 GW is free … our only energy overhead is the farm tractor and transportation cost … this is an extreme example, but it would export energy even when the product is less energy dense … also keep in mind Grand Coulee Dam is already fully amortized … but that’s strictly a financial consideration … it does not address the energy efficiency …

I guess I’m wondering if the same constraint of no power lines coming in is put on a biodiesel facility if it would be an net energy exporter … and of course oil refineries just burn the incoming crude for power, no power lines needed; would you call this a net energy exporter? …

15

OK, I’m back. Early morning today.
Maybe I’m not as clear as might be. The metric of GGE is useful as a way to compare price. I make no assumptions about price here, I feel that the way the OP uses the GGE is to wave away the energy deficit of ethanol compared to gasoline by just saying, well buy more. That’s not the option. If gasoline is $2.00/gallon (typical around here right now) and ethanol is also $2.00/gallon that sounds like a wash. It isn’t. But if you have the price per GGE, then you can look and say which you would prefer. The same holds for any fuel, be it straight gasoline, E10, E15, E85 or whatever. What I don’t see is data (although it can be calculated) on the GGE equivalent of E10, E15, E85, etc. After all, around here that is how you buy it, as Exx. You normally don’t go to the station and buy gas and eth and mix them yourself. You buy what mix they have.
As far as range on a tank, I can easily exceed 450 highway miles on a tank. More fillups would not be a big deal. I was trying to say the OP seems to give two choices, 10 or 9+1.5. Those are not really practical choices. The choice at the pump is 10 gallons. Of whatever.

16

I guess that would be cheating, unless you also included the entire drainage basin of the Columbia river. Now that would be quite a facility; about the size of France…

17

Well … the parts we can grow crops on … my thought here is the processing plant could be located next to any of the hydroelectric dams in the area …

18

My point was that the energy your hydro plant exploits stems from the rainfall on a vast area, so it would be germane to include said area in your actual facility. After all, the people upstreams should be compensated somehow, right?