09/2007 Metrofarm - Gas from Grass: New Possibilities


Interview by Michael Olson 

Our daily bread travels an average of 2,000 miles on oil provided by those who simply do not like us. This leads us to ask, “can we turn our grass into gas?”

Metro Farn (MF) - Will it be possible to spin our grass into gas? Yes, the experts tell us. To help us with the answer is David Blume, author of Alcohol Can Be A Gas (www.permaculture.com). David, how did you come to write about alcohol and gas?

David - I discovered there was this history of running on alcohol long before gasoline existed. The Model A was a dual fuel vehicle. Once you left the city, there was no gasoline. You had to stop by a farm, and get alcohol made from apples. Apple moonshine is what got people around.

MF - Nathanael Greene, is a senior policy analyst from the Natural Resources Defense Council (www.nrdc.org). Nathanael, how did the NRDC become interested in ethanol?

Nathanael - As one of the energy experts at NRDC, I work primarily on renewable energy like wind and solar power. For a long time the enviro community has been talking about bio-energy, and biomass energy is an important renewable resource. About three years ago, I started focusing on making fuels out of biomass, or biofuels, and the role that can play in reducing greenhouse gasses, and our addiction to oil.

David - People have been making plant fiber cellulose into alcohol for more than 100 years. Henry Ford did on his research farm. We did it in WWII when we needed alcohol to make rubber and other products. Many Georgia Pacific paper mills where originally plants that turned wood into alcohol. Most of these used a weak acid hydrolysis technology that is very well proven. There are still plants operating that use this technology in Russia.

You take whatever the cellulosic matter is; sawdust, wood, waste paper, old blue-jeans. You put it under about 300 to 400 pounds per square inch of pressure at about 300-400 degrees, with a little bit of acid. The cellulose - which is really millions of sugar molecules all linked together - dissolves into two classes of sugar. Some sugars are easily fermented by average yeast, like bread yeast, and other yeasts can be fermented by a GMO yeast - which I am not so hot about - but can be used to produce butanol or methane. 

MF - What is the difference between that grain based ethanol and cellulosic ethanol?

David - There's really no difference in the alcohol. Starch is just an easier to break down material than cellulose, it's made with chains that are only 35 sugars long rather than tens of thousands. So we can use very common enzymes, like the kind in saliva or bread mold, which are industrially produced for less than a penny per gallon, for alcohol yield. When it comes to cellulose, the goal of trying to use enzymes to produce the alcohol is kind of a tail wagging the dog. The pre-treat that has to go on to expose the cellulose so the enzymes can get at it.  Other crops don’t even need enzymes at all. Sugar beets yield two to three times what corn does, and already have sugar in the form of yeast. The same is true with sugarcane and sorghum.

MF - I saw a piece that said you folks at the NRDC think ethanol is as viable as hydrogen.

Nathanael - We think it has just as good a chance of becoming the sustainable fuel of choice in the future. Of course, you can use it today, if you live near one of the 600 gas stations that sell ethanol.

David - Ethanol is actually much less expensive than gasoline. It can be produced for about 90 cents a gallon, which puts it down at about $30 a barrel. You can make alcohol on the individual scale for 40 or 50 cents a gallon moon-shining, and convert your car, or use a 50-50 mix without conversion.

Nathanael - Cellulosic technology has the potential to get below 50 cents a gallon. At one plant, there's a pilot project at farm-scale, making about 250 gallons a day, doing this very same thing. Now they're up at the 2500 gallons a day level, that is a de-bugging scale before they go to ten times that size. They're using a very simple variation on weak acid hydrolysis, no enzymes, no proprietary organisms, no GMO products. That's out of the fiber left over after they crushed the sugarcane, and gotten the juice out of it, to make alcohol. 

David - We use grass and Brazil, uses grass. Our corn is an annual grass that we turn into alcohol. In our case, a third of the energy in the plant is in the corn-cob and two-thirds is in the stalk. In Brazil where they use sugarcane that is perennial, two-thirds of the energy is in the alcohol produced from the thing. A third of it is from the fiber left over. They're both grasses, both carbohydrates. As soon as you bring cellulosic ethanol into the picture, the yields are similar. Right now the yields from sugarcane are double that of corn. But there are crops that we can grow in this country instead of corn that rival sugarcane. Sugar beets are a good one, fodder beets are even better. They can yield over 1000 gallons per acre.

There’s a lot of land that isn’t even considered farmland. All over the Southwest, we have taken prairies and made deserts. It takes 100 acres to raise one cow there. But there are crops we can grow in those arid areas without irrigation, like buffalo gourd, nopals - which is a kind of cactus-and mesquite; which all yield double what corn yields. This is in land that is not even considered farmland.

MF - Nathanael, can we grow enough to supply our needs?

Nathanael - We can grow a heck of a lot more than we grow now. We consume about 140 billion gallons of gas a year, and we're only producing four billion gallons of ethanol. We can produce more than ten times what we are currently. Between now and 2050, our demand for gasoline is expected to double. If we only try to solve this with a single technology like ethanol, bio-diesel, or vehicle efficiency, we can’t do it. We need to bring all of our resources to bear.

David - There's no point in trying to make more fuel without conservation. You brought up the gallons of gas we use a year. Another unit of energy is the 15 quadrillion BTU-s of energy we use yearly. The American Gas Association, not exactly tree-huggers or bio-fuel promoters, calculated that off the coast of California alone, we could produce 26 quads of kelp, which would provide all the fuel we need. The dead-zone of the Gulf, where the nitrogen fertilizer flows in from the Mississippi, poisons 20,000 square kilometers of ocean. This is prime growing space for kelp.

MF - What's the difference between plant carbohydrates and hydrocarbons?

David - Plants make carbohydrates, and hydrocarbons are what we're getting from oil. Plants take carbon dioxide from the air, water and sunlight and mix those into carbohydrates. We are capturing solar energy using carbon dioxide and water. Nothing from the soil ends up in a carbohydrate. When we make alcohol, nothing from the soil ends up in the fuel.

Where do those nutrients go if they’re not going into the alcohol? The by-product, if we return it to the soil, yields 10 percent more than we needed to produce the next crop, but it also suppressed all the weeds, when we use this with corn. We didn’t need chemical fertilizer, which is about half of what a farmer spends on an acre a year, and we didn’t need the $50 worth of Monsanto’s Roundup, because the weeds were suppressed. The ecological method of making fuel is also practically the organic method of growing corn. This basic idea works across many crops.

MF - Nathanael, do you see any environmental benefits to biomass fuel stocks as opposed to hydrocarbon?

Nathanael - Absolutely. There is tremendous potential moving forward to improve the environmental performance of the agriculture sector. There are crops we can use to make biofuels that are easier to grow in an environmentally gentle way. Just as we can grow corn in a very environmentally damaging or beneficial way, we can grow switchgrass either way, or any of the energy crops that people are talking about.

MF - We seem to get so little net energy gain from our corn ethanol in the Midwest. It seems like we're spending five dollars to get six, why bother?

David - It's always possible to do a good thing stupidly, as Barry Commoner used to say. If you take a look at the models where alcohol does return an enormous amount of energy for the amount put in - like in Brazil and India - there are a couple of things you notice right away. First of all, the nutrients left over in the liquid mash are returned to the soil. They're increasing soil biology, which is the source of all fertility.

The second thing in Brazil and India, is that they don’t use petroleum fuels to produce the alcohol. In Brazil, they take some of the fiber left over from crushing the cane, and use that in boilers to produce electricity and heat for the alcohol plant. They export two-thirds of the electricity back into the grid. In India, they take the liquid by-product, also from sugarcane, and put that in a methane digester, that produces methane gas that runs the alcohol plant, that produces a surplus of energy.

When you start thinking about things in a systems approach, you can start to do things like take the liquid that’s left over from making alcohol, use it to raise spirulina - a nitrogen fixing algae - you can feed talapia with it, which is a fish.  Take the talapia manure in the water and use it to fuel your next energy crop.

MF - Sounds like some kind of permaculture thing David.

David - Except Archer Daniel Midland already does it at a five-acre setup in Decatur, where they raise tilapia on the by-product from corn. They take three cent a pound by-product, and make three dollar a pound fish from it. They deliver the live fish to restaurants, in trucks running on bio-diesel. If corporations of that size can do it, we can do it on the small scale as well.

David - The largest crop in the U.S. by weight is grass clippings, which are cellulose. If every county had an alcohol plant turning green waste and cellulose into alcohol, we would be replacing a lot of our fuel. A recent study in Wisconsin showed that for every dollar spend on alcohol production in the state, 67 cents remained in the local economy, before it leeches out through a Wal-Mart for instance. With trans-national oil, over 85 cents leaves your county immediately.

MF - It would seem to me that a decentralized economy is a real threat to some interests.

Nathanael - It's funny David should mention Wal-Mart. They are one of the largest independent gas station owners in the country. Most consumers don't choose ethanol. The stations say no one's coming in and asking for this stuff. On the other side, auto manufacturers have been basically bribed to sell about five million vehicles that can use either ethanol or gasoline, without any perceptible difference to the driver. If Wal-Mart got involved, and put an ethanol pump at each of their gas stations, suddenly there would be three times as many pumps selling ethanol around the country. They are a big enough buyer, they could go out there and contract closer to the marginal costs of 90 cents a gallon and sell it for under $2 a gallon.'

Nathanael - A lot of people point to Brazil as a golden example. They switched back in the 70-s under a military dictatorship that said we-ll use ethanol. When the oil prices tanked in the 80-s, there was a shortage of ethanol, and people with dedicated ethanol vehicles where left with a bad taste in their mouth.

In just the last three years, they’ve seen the advent of the flexible fuel vehicles. Consumers in Brazil see this as a choice that they want to have. We have to get this to a point where consumers see this as a real choice. I think the next three years are going to be really exciting in terms domestic ethanol conversion.

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