First, let me say that I am all for the goals of reducing our dependence on foreign oil and increasing vehicle mileage. Doing so disengages us from foreign entanglements that do not serve us well. I also recognize that the era of “cheap oil” may have passed. If this is true, then the era of relying on a single major source of energy may also be over because nothing else seems to be a direct replacement. If this is also true, then we should use an integrated approach that meshes multiple sources of energy so that we may begin an orderly transition away from oil as our major source of energy.
Make no mistake. A world without a single cheap source of energy will probably look and operate very much differently from the world we presently live in. I expect much disruption as we transition from where we are to where we will be. However, what that world will look like is not the focus of this post.
At the same time, whatever we do must be balanced against how effectively it helps us to reach our goals. To do this, we must at least test whether the benefits exceed the costs. I suggest that any alternative that doesn’t meet that test should not be implemented.
Consumer Reports (CR) recently did
a test of a 2007 Chevrolet Tahoe sport utility vehicle. This particular Tahoe is designed to run on 85 percent ethanol and 15 percent gasoline. Noting that this is only one vehicle, and a large and heavy one at that, one must be cautioned about how widely the results can be generalized.
That said, CR reports of a Harris study that found buyers of such alternative energy vehicles do so for two main reasons: reducing our dependence on foreign oil and increased fuel economy.
Although CR did not directly examine whether the claim of reducing foreign oil dependence is possible with such a vehicle, they did test to see how mileage is affected.
As readers of this site already know, ethanol has a lower energy content than gasoline. What this means is that you get fewer miles per gallon with any ethanol mix versus 100 percent gasoline. How much less? CR reported “In highway driving, gas mileage decreased from 21 to 15 mpg; in city driving, it dropped from 9 to 7 mpg.” Hence, due to its specific physical/chemical properties, properties that are not easily changed without expending more energy, ethanol will always give you less mileage when compared to gasoline.
Overall, CR found the following:
The fuel economy of the Tahoe dropped 27 percent when running on E85 compared with gasoline,
from an already low 14 mpg overall to 10 mpg (rounded to the nearest mpg). This is the lowest fuel mileage
we’ve gotten from any vehicle in recent years.
With the retail pump price of E85 averaging $2.91 per gallon in August, according to the Oil
Price Information Service, which tracks petroleum and other fuel prices, a 27 percent fuel-economy
penalty means drivers would have paid an average of $3.99 for the energy equivalent of a gallon of gasoline.
When we calculated the Tahoe’s driving range, we found that it decreased to about
300 miles on a full tank of E85 compared with about 440 on gasoline. So you have to fill up more often with E85.
The majority of FFVs are large vehicles like the Tahoe that get relatively poor fuel economy
even on gasoline. So they will cost you a lot at the pump, no matter which fuel you use.
Clearly, switching to ethanol does not increase mileage. In fact, it substantially decreases it (the higher the percentage of ethanol, the lower the resulting mileage relative to gasoline). But were there no advantages to burning ethanol? Well, yes. Sort of. You get decreased smog producing emissions. This is a GoodThing. On the other hand, is this benefit worth the cost or are there other cheaper methods of reducing emissions?
In addition, whether a switch to ethanol will decrease our dependence on oil is, in my opinion, also questionable. In order to grow the plants that are then processed/refined into ethanol requires the expending of energy. A big chunk of that energy is in the form of petroleum based fertilizers used to grow the plants in the first place. Although there may be alternatives to such fertilizers, it is not clear any of them would be lower in cost or practical to produce in the quantities needed to grow the untold acres of plants needed for fuel. The more plants grown, the more fertilizer needed. The more fertilizer needed, the more oil you use.
But, even if you assume fertilizer is not a problem, how much ethanol can the US produce? As a practical matter, only so many acres are available for production of any crop. Secondly, only so much water is available to grow the crops on these acres. Not all of these acres are spread evenly across the country so you have the problem of how to transport the ethanol since there are no major ethanol pipelines and you can’t use the ones for oil/gasoline due to water contamination (water present in oil/gasoline pipelines easily mixes with ethanol, causing engines to run roughly or not at all).
With these limitations, the article quoted “Eric Washburn of Windward Consulting, an energy and environmental consulting firm that specializes in renewable energy, says, ‘Anyone who has followed this knows that corn will top out at 11, 12, or 15 billion gallons a year’ in terms of ethanol production. That’s still a fraction of the 140 billion gallons of gasoline the U.S. consumes each year.” In other words, if we were to try to replace all 140 billion gallons of gasoline with 100 percent ethanol, all else being equal, we would need in excess of 200 billion gallons of ethanol (before you say it, yes, there are some people who say we should convert to 100 percent ethanol). Clearly, at least with the present technologies, we cannot depend only on ethanol to replace oil.
The bottom line is the goals of reducing foreign oil dependence and higher mileage are important and worthwhile. The problem is, in my opinion, switching to only ethanol may not be the most cost effective way to do it. Rather, it seems to me that we need an integrated approach that may also include wind, solar, wave, and various other alternative fuels. But whatever path we choose, we need to keep testing how cost effective is this path. YMMV. Insert disclaimer here.