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Ethanol Weighs More Than Gas

I’ve seen comments about an inverse relationship between gas mileage and gas prices – as the price goes up, folks comment that mileage is dropping.  It is political – someone pushed the idea that alcohol was a renewable resource, Congress voted, and now nearly all of our regular gasoline has ethanol added.

Like most things in life, mathematics explains what’s going on, how to figure out how much ethanol is in your gas, how far gasoline will put you down the road, and what ethanol will do to your gas mileage.  You don’t need to fasten your seatbelt – the research is complete and available online.  So, let’s look at the two substances.  My little chart is in gallons – though we could change to liters as we cross the 49th parallel, and I’m just pencil-whipping regular.  (everything is standardized at 68 degrees Fahrenheit.)

                                    Weight                        Energy

Gasoline (regular)        6.1 lbs                          114,100 BTUs

Ethanol (E100)            6.58 lbs                          76,100 BTUs

Methanol (M100)        6.60 lbs                          56,800 BTUs

Obviously, with a quality scale, I can weigh a gallon and figure out how much is gas and how much is alcohol.  It’s going to be harder to figure out whether the alcohol is ethanol or methanol – the weight of each is fairly similar.  It gets a bit more complex when we notice that different grades of gas can vary from 5.9 lbs per gallon to a high of 6.5 lbs per gallon.  We’ll use the normal 6.1 for our calculations.

Still, we can figure out that 9 gallons of gas will weigh 61 lbs, and when we add a gallon of ethanol, the total weight will be 67.58 lbs . . . or 6.758 lbs per gallon of E10 blend.  Still, in order to keep gas prices down, our President has ordered that the 10% alcohol can be raised to 15%. 

Now here are the critical calculations:

9 gallons of gasoline provide 1,026,900 BTUs.  A gallon of ethanol provides 76,100 . . . so a gallon that is 10% ethanol yields 110,300 BTUs – which is 3.33% less energy than the 114,100 BTUs that a gallon of pure gas produces.  We’d expect that reduced energy to yield an equivalent drop in gas mileage.

If we go to 15% ethanol – which Joe Biden has approved (to end the high prices I guess) the math works easily – 8.5 gallons of gasoline provide 969,850 BTUs, 1.5 gallons of ethanol provide 114,150, for a total of 1,084,000 BTUs.  Divide that by 10, and we’re looking at 108,400 BTUs – a full 5% drop in energy potential, and probably a similar result on gas mileage.

You can work the values of ethanol blend gasoline prices at the pump when you know what the blend is – my old Talon likes premium . . . $5.52 today and 93 octane.  Octane measures how stable the fuel is as it burns – I pay more, but I don’t really get any BTU increase.  But the ethanol blend just doesn’t let the high compression engine run well.  E15 fits in at 88 octane, so I won’t be using it if I can help it.

A Science for Everyone, Community

Energy’s Unyielding Numbers

I’m a positivist – which basically says my science is confined to numbers.  Since I’m also a stats guy, it means my numbers aren’t always precise – the world is usually plus or minus.  That’s OK.  Then there is the problem of units of measurement.  They need to be consistent.

So here’s a local set of numbers – Eureka is about 50 miles of deadhead run from highway 2.   A gallon of gas provides enough energy to move a ton of material about 50 miles by truck, or about 200 miles by rail.  Folks fortunate enough to use barges and water can move that same ton about 500 miles – but Koocanusa just isn’t set up for commercial traffic.  A century ago Fortine Creek was commercial navigation – logs moved downstream to the mill in Eureka – but we don’t have commercial waterways like the Great Lakes, the Mississippi, Ohio, lower Missouri, etc.

Basically the economics of energy mean that our retail prices have to be higher than Kalispell.  As fuel prices increase, that 50 miles of deadhead run costs twice – once to get the munchies to the grocery store in Eureka, and once to get the empty truck back.  That same economics of energy isolates us further from the county seat in Libby – 37 is a deadhead route either way, while Libby and Troy are on Highway 2.

At Trego, I’m 50 miles from Walmart.  Eureka is 30% further.  Stryker is 10% closer in terms of energy.  The equations don’t change.  They affect our shopping patterns.  They affect our ability to market local products.  This chart  shows the energy equivalents in terms of gallons of gas:

Gasoline Gallon Equivalents

Fuel TypeUnit of MeasureBTUs/UnitGallon Equivalent
Gasoline (regular)gallon114,1001.00 gallon
Diesel #2gallon129,5000.88 gallons
Biodiesel (B100)gallon118,3000.96 gallons
Biodiesel (B20)gallon127,2500.90 gallons
Compressed Natural Gas (CNG)cubic foot900126.67 cu. ft.
Liquid Natural Gas (LNG)gallon75,0001.52 gallons
Propane (LPG)gallon84,3001.35 gallons
Ethanol (E100)gallon76,1001.50 gallons
Ethanol (E85)gallon81,8001.39 gallons
Methanol (M100)gallon56,8002.01 gallons
Methanol (M85)gallon65,4001.74 gallons
Electricitykilowatt hour (Kwh)3,40033.56 Kwhs

I’d make a wild guess that it takes somewhere around 100 gallons of gasoline equivalent to run a logging operation for a day.  The cost of fuel for a truck was a management decision when that log truck could run to American Timber (Olney), Ksanka (Fortine) or Owens & Hurst (Eureka).  With fewer mills, more distant, energy costs reduce the value of our main product.  Increased energy costs effectively reduce the value of labor as they increase the cost of living.

Electric vehicles for transportation?  We’ll know when the cost of fuel has begun to match the cost of electric vehicles when we see Lincoln Electric linemen driving electric trucks.  As long as our electric co-op finds it cost-effective to use gasoline and diesel, they operate as an indicator – heck, they buy fossil fuels at retail or close to it, and buy electricity wholesale.  The numbers may not be precise when I type at my kitchen table – but they are good enough for the calculations I need.

The cost of housing increased dramatically with inmigration – unlike our boomtown days with the highway and railroad relocation and the tunnel, private investment isn’t moving in to supply more housing quickly.  I see what may be the beginning of a trend – long-time residents selling and moving away.  I’ve looked at what happens when an area moves into the recreation dependent and retirement destination classifications.  The first noticeable step is long-time locals moving into jobs that serve the new landowners in new houses – the folks who are replacing them.