The Ergosphere
Sunday, September 04, 2005

The ethanol mirage

Over on Winds of Change (and probably many other places besides), some people are promoting increased ethanol production as a response to refinery outages on the Gulf coast.

This is not merely a false solution; it would be one of the worst things we could do.  We can conserve gasoline and import more, but we cannot replace the fuels which would go to the distilleries.  Following the mirage of ethanol will just lead us further into the desert, where we shall die of thirst.

Ethanol is no solution

If corn equal to 20% of the 2004 harvest cannot be shipped because the Mississippi ports are closed, the surplus would be 2.36 billion bushels.  At a conversion rate of 2.66 gal/bu, the total ethanol production would be 6.28 billion gallons, with energy equivalent to about 3.77 billion gallons of gasoline.  The US burns about 134 billion gallons of gasoline per year; that extra ethanol would amount to a mere 2.8%, when our shortage is 10%.  That is assuming the ethanol could be produced, which it probably cannot.

We could save 10% or more by slowing down to 60 MPH on the freeways and removing gas-guzzling vehicles from the roads.  (The people who own Hummers and Navigators can afford to rent something for the duration.)  We can import gasoline from Europe, and we are doing so.

Ethanol is a problem

What we cannot do is replace the fuel needed to distill more ethanol.  (We may not even be able to afford the fuel to distill what we're using.)

It takes around 33,000 BTU of fuel to distill a gallon of ethanol (which yields a mere 84,200 BTU/gallon [1]).  Each gallon of ethanol requires about 33 cubic feet of natural gas (or the equivalent in LPG) to distill it.  This is fuel which becomes unavailable to heat homes.  The hypothetical 6.28 billion gallons of ethanol would require 207 trillion BTU of natural gas.  The average home which heats with natural gas uses ~50 million BTU per season; the extra gas usage would otherwise be able to heat 4.14 million homes.

At last count, Katrina damaged wells and production platforms in the Gulf and "shut in" gas production of 7.2 billion cubic feet per day.  Running 20% of the US corn crop through distilleries would consume gas equivalent to another 30 days of this missing production.  Using ethanol just makes a bad situation worse.

Natural gas prices have shot up to $15 per million BTU; home-heating costs are going to run to record highs this winter.  The tax subsidy of ethanol distilleries uses the taxpayer's own money to increase the cost of keeping themselves warm.  The public interest would be best served by cutting off natural gas and LPG supplies to all distilleries immediately.  Let them burn straw or stalks.

It's time to see the ethanol lobby for what it is:  leeches sucking the life's blood from the nation's taxpayers, waving flags while selling the public down the river.  If we need to dispose of 2 billion bushels of corn, let's take a hint from the corn stove sellers and use it for heat straight out of the sacks.  The people who demand we use precious heating fuel to help line their pockets should be seen for what they are:  traitors.

Thaw a family, shoot a distiller.

[1]  The heat of combustion of ethanol is 12,780 BTU/lbm, and 6.588 pounds of ethanol per gallon; the heat value is thus 84,200 BTU/gallon. (back)

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I also did some work on the ethanol debate from an Australian perspective. Our yields per hectare are lower than yours and it makes it even harder. My post is

If you get to read it I limited ethanol fuelled PHEV vehicles to 10% of the fleet and still got an answer of 14 Million hectares of land required. That is a lot of land, water and fertilizer.

I totally agree with you that ethanol is pretty much a fools gold of a solution. The only time that you would consider it if there was the choice of ethanol or absolutely nothing. It could be used to keep some essential services going if/when oil becomes scarce.

I think your zinc solution and the reflecting solar thermal plant that makes it is the best idea. That plant can also produce electricity in a Brayton cycle gas turbine that can also use this new experimental steam electolysis unit
to produce hydrogen. This can be use to make methanol, methane, ammonia etc as well as zinc to be stored.
The throughput efficiency of a zinc-air cell appears to be about 50% (irreversibilities at the oxygen electrode are said to be the major factor).  This does affect the economics, though the cost of Zn-air is far less than hydrogen PEM fuel cells.

Sometime I hope to get back to zinc-air and various methods of regenerating metal to see how the energetics work.
I agree completely with your argument. I just started my own blog, and my first entry is about grain-derived ethanol.

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