Biofuels, the NON-renewable Resource

Where do little trees come from?

Whenever anyone drives a car, the car burns plant matter that was created by solar power and converted into petroleum a long time ago.  Nobody knows how much petroleum is in the ground but there's less every day.  As we've become more and more conscious of the possibility of catching all the fish in the sea or cutting all the trees in the forest, we've begun talking about sustainable yield.

Sustainable yield is the amount of something, be it fish, or trees, or whatever, that you can take from a given area without ever running out.  You have to leave enough fish or trees to breed more for you to catch next year.  If you take too many, you'll eventually take them all and there won't be any more.  If you don't take enough, the extra fish or trees will die and be wasted.

Although there are some who believe that oil is constantly formed deep in the earth, most oil scientists believe that oil isn't being formed any more.  On that basis, the "sustainable yield" of oil is zero.

Suppose that fish lived forever but that no fish were born.  If you took one fish per year, eventually they'd all be gone; the sustainable yield of any resource that doesn't reproduce is zero.  If no oil is being formed, the sustainable yield is zero.  Since we refuse to cut our petroleum use to zero, we're pumping oil above its sustainable yield and will eventually run out.

We're being urged to replace petroleum with "renewable resources."  A resource is renewable if it replenishes itself at the rate we consume it.  That is, a forest is claimed to be renewable if we harvest the trees at about the rate they grow.

Weeds always seem to grow back when we cut them; using biofuels to replace petroleum seems to have no cost.  The idea is to harvest plants and extract automobile fuel from them.  This shortcuts the natural processes by which long-ago plants were turned into petroleum.

Unfortunately, there's one teensy little problem: biofuels are no more sustainable than petroleum.

Where do little trees come from?

Jan Baptist van Helmont (1577-1644) got credit for performing the first experiment to determine where plant mass came from.  He carefully weighed the soil in a pot and planted a willow tree in it.  When the tree weighed about 170 pounds, he found that relatively little soil weight had been lost from the pot.

He concluded that the water he gave the tree had turned into plant matter.  Helmont ignored his own data that burning 62 pounds of oak charcoal produced 61 pounds of carbon dioxide and one pound of ash, some of the mass of the tree had come from gases in the air. He also ignored the ancient knowledge that crop yield declines when crops are grown repeatedly in the same field unless manure is added to the soil to put back what the plant takes out.

Helmont should have known better; we know that when a plant grows, the plant takes something out of the soil.  If the plant dies and rots in situ, whatever the plant took gets recycled, but if someone cuts the plant and takes it away, the soil loses something.  Eventually the soil runs out of whatever the plant takes and those plants won't grow there any more.

We know this from observing the ethanol boondoggle.  Corn makes heavy demands on soil.  The only way we can keep harvesting corn from the same farm year after year is to pour on fertilizer.

Corn fertilizer is made from guess what?  Petroleum!  As George Will put it:

In 2005, America used 15 percent of its corn crop to supplant less than 2 percent of its gasoline use.

Something is clearly wrong here.  As scientists who don't live in corn-growing states have looked into the facts behind making ethanol from corn, they've found that it takes so much petroleum to grow corn in the first place that we get very little more energy out of the ethanol than we put into the corn.

If we burn corn instead of eating it, food prices go up.  Ethanol use is based on politics, not on facts.

Eat corn or burn corn?

Using corn to make ethanol has pushed food prices up; people are talking about other plants such as sugar cane or switch grass.  George Will wrote:

In Indonesia alone, 44 million acres [of forest] have been razed to make way for production of palm oil.

Biofuels not only tempt investors to destroy forests, they can't work in the long run.  No matter what plant you use, every plant takes something from the soil.  Unless you put back whatever the plant takes from the soil, that plant won't grow there any more when it's gone.

We have a choice.  Continue powering our cars by taking petroleum out of the ground, or power our cars by taking whatever plants need to grow out of the ground.

The bottom line is, biofuels are not sustainable because they deplete the soil.  Crop rotation helps, but every plant that's hauled away takes something.

Biofuels are renewable only to the extent that we figure out what each plant takes from the soil and put it back.  Depending on the energy cost of making whatever it is we have to put back, we may or may not gain any energy in the process.

Ignore the hype.  Biofuels are neither sustainable nor renewable without a lot more work than anyone's talking about.

Kermit Frosch is a guest writer for  Read other articles by Kermit Frosch or other articles on Environment.
Reader Comments
I live in corn country and rather regularly drive past an ethanol plant. About six months ago there was a story about how the plant was in the negatives as far as energy in vs. energy out. The REPUBLICAN governor of our state is pushing for more of these things.

Sure, it makes the farmers happy, but food prices are going up, my car hates the stuff (mileage goes down and I need more of it).

But you're right... nobody follows through with their thinking to the conclusion. We live in a terribly shortsighted world.
February 6, 2008 11:20 PM
Don't they put ethanol in regular gasoline now? Everytime I go to the pump, I swear there's some sort of sticker that says "may contain xxx amount of e85".
February 7, 2008 9:34 AM
They do, and most cars are adjusted to work with it, OK. But E85 is much less "energy dense" than regular gasoline. You need to burn more of it and it takes more energy to make. Corn based ethanol is a complete joke as a fuel.
February 7, 2008 10:02 AM
So the libs expect to "grow energy" from corn, never once bothering to do the math. Like everything else on the left, it sounds like such a great, clean, wonderful thing. Until you poke your finger in.
February 7, 2008 10:25 AM
Rutledge also commented on this issue here:
February 11, 2008 2:52 PM
It would appear that the basic premise is that corn should not be grown to produce ethanol because doing so is not sustainable. It takes something from the soil.

But.... it's okay to produce corn in a nonsustainable way, if that way would produce cheap food.

It seems that the real issue here is cheap food, not sustainability.

February 12, 2008 2:03 PM
@garrison: Actually the libs want switchgrass rather than corn. Corn based ethanol is idiotic for many reasons.

Still, the alternative to not using biofuels is continuing to use oil... Biofuels are better than oil, but they are not perfect.

Solar/Wind/clean nukes are the way to go. however that requires the energy storage breakthroughs that we read about to be proven practical and marketable in the long run.
March 17, 2008 10:14 AM
For readers who think biofuels are useless, take a look at these stories (and then come back and commment). None of these biofuels are made from food:

Switchgrass Could Displace 30% of US Petroleum Usage With 94% GHG Reduction (

First Cellulosic Ethanol Plant Goes Online, Makes Fuel From Wood Waste (

BREAKING NEWS: First Cars Run on Algae Biodiesel; Breakthrough Production Possible (

GM Announces Biofuel Partnership: Cheap, Green Ethanol? (
March 20, 2008 11:52 AM
I don't think that the point of the article is that biofuels are useless, only that they are not renewable. Switch grass clearly takes a lot less petroleum input in the form of fertilizer than corn, but it still takes SOMETHING from the soil. When whatever that is is gone, switch grass won't grow there any more unless we put it back.

Making fuel from wood waste SOUNDS good, but what about the place where the wood grew? If we don't put the wood waste back in the forest, the soil in the forest will stop being able to grow trees that much faster.

Algae that make biodiesel have to eat SOMETHING. My problem with all the hype about biofuels is that nobody seems to want to close the circle and explain how we plan to renew the resource.

Farmers have known for centuries that every field has to be renewed somehow, either by crop rotation or by fertilizer. One Asian solution is to pump city sewage onto the fields, that closes the cycle and solves 2 problems at once.

But as the article asks, where do little trees come from? From the soil.
March 20, 2008 12:06 PM
Biofuels aren't "useless", no. But that wasn't the point of this article either. The problem is that they aren't renewable and, based on how they are processed, in some cases take MORE energy than they're worth. Burning cardboard boxes isn't "useless" for getting energy. They WILL burn and they WILL provide energy. But it's silly to use them after you consider the big picture of what energy they give, what it takes to make cardboard, what pollutants they give off, etc. This article on biofuels is about the big picture, which is exactly what a lot of environmentalists don't seem to be able to grasp.
March 20, 2008 12:12 PM
A small amount of ethanol can be used as an anti-knock additive. TAASTAAFL: There are no free lunches (solar panels increase environmental warming by definition; energy from the wind on a scale large enough to be useful must alter wind patterns). The point is well made. Ethanol in the present economy is more wasteful than oil fuels, and won't work without subsidy.
March 20, 2008 12:39 PM
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