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Grass Power

miscanthus.jpgWhen talking about biomass-based fuels, a few plant names keep popping up -- soy, jatropha and (to a lesser extent) corn. But what about Maiden Grass?

Professor Steve Long, at the University of Illinois, argues that Maiden Grass, the common name for the various species of Miscanthus, has some pretty attractive qualities as a feedstock for bio-energy. Also called "elephant grass" (as it can reach four meters in height), It can be grown in a wide variety of soil types, requiring little or no fertilizer. It can be harvested off-season, so farmers can grow it along with food crops. Each ton of dried Miscanthus yields energy equivalent to three barrels of oil, and a single hectare can produce from 12 to 60 metric tons of dried plant. (The lower number is a typical current yield; the higher is from an experimental stand at U of I.)

The grass appears to be hardy, but as it's not a native species, Long is taking no chances:

The scientists used a sterile hybrid of the plant, which comes from high altitude areas in Japan and produces a silver, feather-like foliage, in the trials so it would not become invasive.

"Currently, in those trials that have been carried out, there appears to be no real problem with pests or diseases," according to [Long's partner Dr. Mike] Jones.

Long claims that converting about eight percent of the land area of Illinois to growing Miscanthus would produce sufficient fuel to generate the entire electricity load of the entire state, including Chicago. Eight percent is roughly equivalent to the entire developed area of Illinois, and about 1/8 of the current farmland. Such estimates are a bit silly, of course; real conversion of electricity production to renewable sources will need a mix of types, including wind and solar.

(Thanks, Eric Townsend)

Comments (14)


I keep wondering why they dont try kudzo as that stuff grows so fast even if its not great per ton your gona harvest alot of tons of the stuff.

Maiden Grass Flower:

German inventor turns dead cats into diesel


Hundreds of European citizens protest against Europe's largest miscanthus biomass generating plant:


Quite a few grass-plants are already operating here, but it's best to keep them small.

Jamais Cascio:

Thanks, Lorenzo. I agree -- this would likely be best received if the generation facilities were small.

I'm totally down with a renewable source of fuel, if soil erosion and elimination of petroleum inputs (fertilizer etc) can be achieved. Grass in its many forms seems like a good candidate for meeting these goals. (Still waiting for a cellulose ethanol production facility to actually be built; that is another story.)

But, a minor rant, already addressed in the post:

For a scientist to whip out his sliderule and say that all we need to do is convert 8% of Illinois to a grass farm is flatly misleading.

Sure, and if I can travel at 70 percent of the speed of light, I can travel to Alpha Centauri and back in 13 years.

It is within the realm of physical possibility but it ain't ever going to happen.

Maiden Grass Flower:

george monbiot, as usual, wrote a great piece on biofuels: "Feeding cars not people"

even with higher yields, the ramifications of teh monbiot article are likely to hold true, esp if govt all assume that infinite ec growth is still achievable & worthwhile

It's increasingly apparent that the energy solution will be a mixed bag of efforts, ie no one grand-scale alternative can meet our needs without serious drawbacks. Instead it will need to be a dispersed effort using several different technologies.

What do you make of http://ergosphere.blogspot.com/2005/09/scribblings-for-september-2005.html
which does some back of the envelope calculations which suggest that a lot more than 8% of Illinois would be needed. And how does this compare to covering 8% of the state with photovoltaic cells?

Daniel Haran:

Peter: the linked article assumes a yield of 10 tons/acre/year. The original poster used hectares, so I'm a bit confused here. Not only that, the original figures were 12-60 tons/acre... with the higher levels for experimental yields. I love skepticism, although I prefer it when people are remotely talking about the same thing.

As for 8% of a state's surface being covered with solar cells, that seems high to me. Keep in mind as well that much of the solar cells would likely be "solar shingles" or similar technologies.

Maiden Grass Flower: as Jamais noted, we'll need a mix of different technologies. First and foremost of course will always be conservation. What bugs me about Monbiot's article is how one sided he is. If Euro farmers grow fuel instead of crops, might the EU finally stop dumping food to developing markets? He further assumes that the entire fleet would be converted to bio-fuels --- while staying at the same fuel efficiency. Pessimism and absolutism are poor attitudes when dealing with new technologies.


Maiden Grass Flower, what Daniel Haran says. But I wanted to add that Monbiot is important as someone who signals potential exaggerations and aberrations. When tomorrow we read about a biofuels project in say Africa or Brazil, which cuts rainforests to plant palm trees which have to be harvested by slave labor, and then exports the product to wealthy markets - then we remember what Monbiot said. That's his function, to be a warning sign.

He does make the mistake though of assuming that we need to replace all petroleum right now, while what we need to do is to diversify the energy portfolio, increase efficiencies (biggest gains to be won here), and invest in top science and technology research.

Maiden Grass Flower:

Monbiot is not himself assuming a particular pathway at all. Instead he is pointing out the logical extension of recent policies proposals + the potential pitfalls of assuming that an activity that works at a smaller scale can function the same at a larger scale. Ie the broader system.

He reports proposals to turn africa into a biofuel zone, and an ambitious govt plan to ramp up biofuels backed by a review that ignored the impact on food production.

Daniel: he's not binning the technology outright, he's urging a thoughtful approach, eg he says that using stubble (byproducts) for biofuels sounds great, but think twice before food-producing land is replaced with biofuel plantations. His position (v important one) is to point out important issues that have been overlooked.

In other works he dumps on food dumping as well. (He has actually declared that he sees no reason to have a particular allegience to his own country's interests over others & asked if that makes him a terrorist, so he can't be accused of being euro-arrogant).

Maiden Grass Flower:

oh I'd better correct myself before I get slammed on a subpoint: monbiot doesn't actually declare that using stubble is great as it gives less energy than growing crops specifically for biofuels so perhaps the fuel energy isn't greater than the costs of transport & processing. Phew, now back to the big issues... let's engage in open consideration:

What do you think would happen **if** biomass became a signficant source of vehicle fuel? Industrial monocrop farming? Would biomass crops earn more per land area than food crops? (And v's the earnings on food crops in developing nations?) Which countries of the world wouldl hav the greatest competitive adv in growing biomass crops & what would the opportunity cost be?


On a solar-powered Illinois . . .

Here's my back of the envelope calculation: If you assume that the average solar insolation per day is about 4 kWh per sqaure meter, and you can capture about 10 percent of that, then the amount of solar power you can collect is 400 Wh per square meter a day, or about a million kWh per square mile per day.

Taking the Engineer-Poet's figure of 92,358 million kWh for the annual electricity consumption in Illinois and dividing by 365, you get something like 250 square miles of flat surface covered with PV to power Illinois.

Compare that to the 4,680 square miles necessary for grass cultivation under optimistic assumptions.

Of course, because grass is a fuel, it's easier to use, easier to store, easier to increase demand in peaky situations. Before we can even think about building PV by the square mile, we need to perfect industrial-scale batteries (or other form of energy storage) that can take all this solar goodness and sock it away for the dark nights and dreary days when we crave it. And we need to get the price of PV down under a $1,000 a square meter. (Though a look at the Con Ed bill and its 18 cents a kWh may change that price point.)

But at the end of the day, harvesting solar energy directly (along with its primary manifestations of wind and waves) is the way to go.

The scribblings at The Ergosphere were partially based on a mis-reading of the article, which I have yet to correct.  On the other hand, the 12 tonnes/ha yield figure is well within the range of what's available with switchgrass (a native grass), and the 60 T/ha figure might not be sustainable without special conditions of growing season, rainfall and absence of pests (either imported or locally evolved).  For the record, a hectare (10,000 square meters) is 2.47 acres (an acre is 43,560 square feet or 1/640 square mile).

jlw is right about the relative area required for PV vs. biomass; higher plants are not very good at converting sunlight to fixed energy.  Dependence on harvests of tallgrass would also subject the energy economy to vagaries of harvest and even grass fires; not very appealing!  The way to go is to grab a whole bunch of different things, and if Miscanthus or switchgrass winds up being planted in fallow fields, buffers next to creeks and highway medians, that's just fine.

The real issue is getting energy to the point of use without big expenses or losses.  The best scheme I've seen thus far is a zinc-electric system, because zinc works very well as energy storage and it can be produced either chemically (reduced with carbon from biomass or coal) or electrically (electrolytically recovered from a solution of zinc salt).  This allows one to put solar energy, biomass or wind in and get metallic zinc out:  a three-fer.


Does anyone know if this Miscanthus can be used in, or produced through, something like John Todd's so-called "living machines?


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