A friend recently sent me a one-page press release from an ethanol lobby group that purported to debunk "myths" of biofuels. Our ensuing discussion helped me clarify why even people who once were excited and optimistic about biofuels (like me) are now so opposed to production subsidies (as opposed to R&D).

My friend asked (paraphrasing), "If not biofuels, then what?" and noted that what we’re doing now — "squeezing oil out of rocks" — is not exactly good for the planet.

For me, the bottom line is simply this:

Ethanol is no more a renewable fuel than hydrogen is.

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Rather, ethanol is a way for us to consume natural gas, diesel oil, and coal (not to mention a huge volume of water and vast acreage of cropland) to make motor fuels. All this is on top of serious problems raised by studies about land diversion for carbon emissions and food availability.

It’s important to remember that fossil fuels are biofuels (fuels made from once-living matter), so using that term alone isn’t helpful.

Rather, we have to distinguish between fossil fuels, which we could call "ancient biofuels," and crops grown today, which we could call agrofuels or "current biofuels."

The primary difference is that nature made the fossil biofuels over eons, and stored them away below the earth in natural reaction chambers, tremendously intensifying their energy density and putting them into materially dense forms by removing everything but the fundamental hydrocarbons — everything but the constituent molecules and the embedded energy is gone.

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Fuels from current plant matter — today’s fresh biofuels — capture around about 1 percent of incoming solar energy and lock it up as forms of matter most suitable for their own purposes (roots, stems, leaves, fruit/seeds, etc.). Corn ethanol starts with the plant’s energy packet, the seed grain. Cellulosic attempts to use the other parts of the maize, which are much less energy dense. All of that structure must be broken down to access the hydrocarbon energy.

When we try to use current rather than fossil biofuels, we start out way, way down the energy density curve, because we lose the advantage of the eons and eons of free processing and concentrating.

To use corn ethanol, for example, we have to expend a lot of energy to grow it, then bring vast masses of crop together in one place, break it down so that yeast can process it, and apply a huge amount of energy to boil (distill) the resulting beer (ethanol/water mixture) to concentrate it enough to use. With cellulosic and biodiesels, we have to physically concentrate the energy from the bulky, low-energy parts of the plants and put even more into breaking those down.

So it will always be difficult to make "fresh" biofuels pay off, even putting aside the opportunity costs of using land and water this way. (What those could have been used for were they not growing fuel crops — food crops, carbon storage in the soil, natural reserves for biodiversity, etc.).

And for what? So that we can forestall the switch off ancient biofuels (fossil fuels). But delaying this switch causes a net increase in carbon released to the atmosphere (without even accounting for the carbon cost of land use).

Thus the issue is clear:

  • If we are to have any hope of a stable climate, we have to dramatically reduce the use of ancient biofuels.
  • Current biofuels are designed to allow us to use more of those ancient biofuels.
  • We do not currently know how to make fresh biofuels without using significant quantities of ancient biofuels.

On that last point:

When when we make current biofuels, what we really do is launder the energy from the ancient biofuels by passing it through a crop so we can call the product "green." But it’s not green in any sense of sustainable. Most of the energy content in current biofuels is provided by an ancient biofuel, hidden upstream in the process.

Most of the biofuels industry has implicitly (and often explicitly) conceded the point by agreeing that corn ethanol is unsustainable while trying to shift the discussion over to "next generation ethanol." (Talking about the ethanol we don’t have rather than the ethanol we do have.)

However, a lot of folks haven’t conceded the point and respond hostilely to anyone who claims it’s true. Here’s a proposal for reducing the conflict and getting to the bottom of the issue:

The Experiment

Let’s find a county or at least a large set of biofuels growers and refiners and get them to agree to demonstrate their ability to make fresh biofuels sustainably by agreeing to discontinue all fossil fuel inputs to their operations after the first year (which lets them get a first crop). They can make any fresh biofuels they want, using any method they like.

That is, for three years, the biofuels growers and processors participating in the study have to run all the machines that they use to plant, tend, harvest, transport, dry, and otherwise process their fresh biofuels using nothing but the energy from their own products.

At the end of three years, we measure the resulting fresh biofuel energy stocks. We subtract the energy of the ancient biofuels embedded in the fertilizers and by the first year’s ancient biofuels inputs and by the fraction of electricity used that was generated from ancient biofuels (mostly coal).

If we can subtract the ancient biofuel energy inputs and there is enough fresh biofuel energy left over to continue the experiment for another year, and to provide a contribution toward the energy required to remake or replace the farm and processing machinery (elevators, tractors, trucks, combines, crushers, refineries, etc.) used, then we can look at whether there is any left over for non-farm use for motor fuels and how much revenue it can provide to the participants.

If it’s a lot, then maybe we’ve found a renewable fuel and we’ve learned how much net energy there actually is in practice.

Note that this is the most optimistic scenario possible because on-farm use of biofuels is most likely to be sustainable; you don’t have an energy loss in transportation or distribution to distant markets.

I suspect the tiny residue of energy left over (if any) would, when you look at the size of the assets tied up in the experiment, produce a rate of return on investment that you would need a 100 power telescope to see. But heck, I could be wrong. But if fresh biofuels are as sustainable as the biofuels lobby says, then they should be able to show it.