Subsidized production of ethanol generates strong opinions. Either it is saving the world from greenhouse gas emissions or endangering our food and water. This blog has a few unbiased statistics to guide your opinion.

This blog only has space to consider ethanol impacts on food; water and greenhouse gas emissions will have to wait.

Ethanol production requires a huge share of the U.S. corn production: In 2012 U.S. farmers produced 10.8 billion bushels of corn (down from 12.4 billion bushels in 2011), and 4.6 billion bushels were used for ethanol production. Using these numbers, ethanol consumed 42 percent of all our corn. But, before you start hoarding tortilla chips, we need to note that 1.3 billion bushels of the corn sent to ethanol plants becomes livestock feed and corn oil. That makes the net corn use for ethanol about 30 percent.

For those who like statistics or are watching their diet, high fructose corn syrup uses about 0.5 billion bushels or 4 percent of corn production. The major non-ethanol uses of corn are: Animal feed: 49 percent; food and beverages: 12 percent; and exports: 8 percent. These statistics are from the National Corn Growers Association.

Does ethanol production impact global food prices? The answer is yes, but the correlation is complicated. Between 2000 and 2012, the World Bank global food price index increased 104.5 percent. Over the same period global biofuels production increased over 5 fold. Rather than only blaming biofuels, the World Bank observes that the recent upward trend in food prices and volatility can be traced to multiple factors including climate change, policies promoting the use of biofuels, rising energy and fertilizer prices, poor harvests, national export restrictions, rising global food demand, and low food stocks.

The Energy Information Administration reports that in 2012, about 134 billion gallons of gasoline (3.19 billion barrels) were consumed in the United States, which contained about 13 billion gallons of ethanol, accounting for 10 percent of the volume of gasoline consumed. The percent of ethanol in gasoline varies by region, but the US is close to maximum ethanol use because many cars cannot use gasoline with more than 10 percent ethanol.

A future blog and AAPG Explorer article will discuss the Reformulated Fuel Standard, one of the major forces driving the recent increase in ethanol production.