There’s a lot of talk today about the size of one’s so-called “carbon footprint” as a measure of alleged greenness. Perhaps a better measure might be the size of one’s corn footprint. That’s because our current rush towards ethanol – that greenest of green fuels – has, in just a few years, reached major geographic proportions.

This year, over 25 percent of America’s corn crop will be burned as transportation fuel after being converted into ethanol (at great cost in government subsidies). This is an unbelievable feat, given that America is by far the world’s largest corn producer (China is a distant second) and that U.S. farmers have planted the most extensive corn crop in modern history – nearly 94 million acres.

This means that 24 million acres of the most productive land on Earth have, with the stroke of a few pork-laden Congressional acts, been taken out of food production. That’s nearly equal to all the arable land in Kansas.

For around 500,000 barrels of oil equivalent per day, an area the size of Virginia has had nearly every wild organism on it killed off and replaced with a single monoculture crop, one that requires massive amounts of diesel fuel, pesticides, and fertilizers to be expended upon it every season. As a result, world food prices have soared, while high oil prices remain unmoved thanks to corn ethanol’s meager net energy production.

The increased prices of grain, milk, and meat have led to a global rush to put marginal acreage into production. Listen closely and you can hear the buzz of the chainsaws as the production of “green” biofuels in the U.S. causes whole swaths of rainforest to be clear-cut to make room for increased agricultural production. After all, the world will not eat less just because America has decided to burn one-fourth of all its corn.

Now, 24,000,000 arable temperate acres (37,500 square miles) is quite a footprint by any standard, but to truly appreciate what we are doing to the environment with biofuels production, let’s compare that to the footprint required to produce an equivalent amount of fuel via environmentally unfriendly oil.

In a convenient coincidence, the Prudhoe Bay field of Alaska produces about the same gross amount of energy (about 475,000 barrels per day) as total U.S. ethanol production. In terms of net energy, of course, Prudhoe Bay is much more productive than U.S. ethanol production, since it doesn’t require any fertilizer (and only minimal tillage). But let’s be generous and say that ethanol and Prudhoe Bay productions are equal.

The entire Prudhoe Bay oilfield covers just 213,543 acres. Were the oil industry to poison the entire field with herbicides and plow under the dying residue, it would still have affected less than 1 percent of the land we are currently plowing under for ethanol production. But of course, most of Prudhoe Bay is not developed – only around 5,000 acres are paved for roads and oil pads. Prudhoe Bay has cleared less than three-hundredths of 1 percent of the land that has been cleared to produce ethanol. Put another way, ethanol’s footprint is 5,000 times larger than oil’s.

And this comparison is not merely hypothetical, since just east of Prudhoe Bay we have a potential oilfield that may be twice as productive as Prudhoe – the coastal plain of the Arctic National Wildlife Refuge. For those worried about development’s impact on A.N.W.R., consider that the coastal plain covers 1.5 million acres – larger than Delaware, but still less than 7 percent of the territory we are now sacrificing to corn ethanol production. We could plow the whole place under and do less damage than ethanol (assuming one could somehow plow permafrost).

Assuming only 5,000 acres were developed for drilling, we would do far less damage in A.N.W.R. than ethanol does in the lower 48, for twice the fuel and more than twice the return in terms of net energy and net economic good. No one has ever had to argue that oil is a source of net energy or that it can pay for itself – unlike ethanol.

If you worry about your energy’s development footprint, clearly oil is preferable to ethanol – unless you believe that an acre of land in Alaska is 5,000 times more precious than an acre in Iowa.