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Purdue Study Concludes Corn Stover Better Economically Than Switchgrass for Indiana Cellulosic Ethanol

Corn stover is a better feedstock economically than switchgrass for cellulosic ethanol produced in Indiana, according to a study by researchers at Purdue University.

Corn stover is plentiful in Indiana because of the state’s large corn acreage and could be harvested less expensively than switchgrass, said Wally Tyner, Purdue agricultural economist and the study’s lead researcher. Also, with high corn prices, corn stover would provide farmers extra profit without planting additional crops, he said. Switchgrass is a primary crop and must be planted separately.

For cellulosic ethanol in Indiana, corn stover is where it’s at. From a cost perspective, corn stover averages $40 per dry ton delivered to the ethanol plant while switchgrass averages $60 per dry ton. That’s a huge early advantage to corn stover. Then there’s the profit. Farmers would receive an average of $80 an acre extra profit for corn stover and $160 an acre average profit for switchgrass.

—Wally Tyner

The Purdue study compared the costs and returns of harvesting corn stover to the growing and harvesting of switchgrass for Indiana ethanol production. Tyner and his research assistants also examined the economic and environmental results of replacing some coal with the two types of biomass at electric power plants.

Using a corn stover yield of 4.25 dry tons per acre from a 160-bushel-per-acre corn crop and a switchgrass yield of 5 dry tons an acre, the study found that in the major corn-growing regions of northern and central Indiana, corn stover was the better cellulosic ethanol feedstock.

The economic numbers were better for switchgrass in portions of southern Indiana where soils are less conducive to growing corn, Tyner said.

I think it is likely that in the next few years cellulose-based ethanol is going to become viable. With $6 and higher per bushel corn it is already very close economically. And since the federal Renewable Fuels Standard calls for the production of 36 billion gallons of ethanol by 2022, of which 16 billion gallons have to be cellulose, cellulosic ethanol will advance.

—Wally Tyner

Before cellulosic ethanol can take off a number of issues must be resolved, however, Tyner said.

The biggest issue is going to be contracting. With a corn ethanol plant, if there’s not enough corn in one county you go to another county to get your corn, or get it from out of state. Corn moves cheaply and easily. Biomass, on the other hand, doesn’t. Cellulosic ethanol plants will need a local supply of corn stover and switchgrass. An investor isn’t going to sink $400 million into a cellulosic ethanol plant until they have a local supply of raw material locked up.

Conversely, farmers are going to need assurances that no matter what happens in the marketplace—fertilizer prices triple, natural gas and propane prices do this, diesel prices do that, corn prices go up or down—that growing biomass is viable for them. So we still need to develop risk-sharing, long-term contracting mechanisms that will be acceptable to both the supplier and the ethanol producer.

—Wally Tyner

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Comments

ejj

Duhhhh - this is a no-brainer, especially at today's corn prices. If the government was to eliminate the corn subsidies, and switchgrass or sweet sorghum became attractive in the midwest, it'd be a different story.

K

"Conversely, farmers are going to need assurances that no matter what happens in the marketplace—fertilizer prices triple, natural gas and propane prices do this, diesel prices do that, corn prices go up or down—that growing biomass is viable for them. So we still need to develop risk-sharing, long-term contracting mechanisms that will be acceptable to both the supplier and the ethanol producer."

They better go to another world. This one involves risk.

If they grow corn they are growing the stover anyway and it is worth something. So do they intend to grow nothing whatever?

Other than that the numbers work. They sell the corn and they sell the stover and they plant once and the profit beats growing switch grass.

They have a good point about the cost of transporting biomass. Perhaps better ways of compressing it before transport or partial reduction locally can be developed.

mark

If you gassify the biomass first then you can then pump the gas to a remote fuel plant via pipe.

Wetdog

-----"If they grow corn they are growing the stover anyway and it is worth something. So do they intend to grow nothing whatever?

Other than that the numbers work. They sell the corn and they sell the stover and they plant once and the profit beats growing switch grass.

They have a good point about the cost of transporting biomass. Perhaps better ways of compressing it before transport or partial reduction locally can be developed."---------

As usual, this type of article tells you nothing about farming or actual market conditions are misrepresented or glossed over. Either the research is flawed, or the reporter in order to cover a complex issue glosses over key important factors to save room and keep the article short, or does not understand the dynamics themselves.

First of all, corn subsidies are basement conditions, that kick in with certain conditions to prevent market collapse and loss of production capacity. This is not the case with corn selling for around $6 bushel---there is no subsidy.

Second, the article only refers to market price that is being paid at the door for raw materials. Since there is no cellulosic ethanol being produced or sold in Indianna currently, these are only estimates based on current conditions and uses. Switchgrass and stover are both fully interchangable as a raw material for ethanol produced by Fischer-Tropsch process. It won't matter which is fed into the hopper, or both. The corn crop is already grown, the grain is used to produce ethanol and high protien feed(DDG)---the use of stover adds pure profit on top of what has already been spent to grow the grains. Over time, this will lower the price of the grain.

The per ton market price of stover vs. grain stover does not exist in a vacuum. Switchgrass is a native grass and can be used as hay and is also an approved ground cover for wildlife habitat. It needs no cultivation or special treatment and will grow on marginal or depleted lands. It costs almost nothing to produce other than mowing and baling.

Ethanol made from grain with corn produces high protien, high quality animal feed that is more productive to produce and lower in price than the alternative soy beans. Using the stover to produce ethanol using F-T process(grain uses fermentation) only makes business sense,(pure profit--all production costs have already been included in growing the grain)---it is like finding trash cans full of $10 and $20 bills. Switchgrass would be a perfectly interchangable feed stock for the ethanol plant should for some reason corn stover availability should go down, drought for instance, leading to lower crop yeilds. Switchgrass could be a new crop that could help pay for lands that are not currently productive for other reasons---wildlife preserves for instance. With primarily switchgrass and blue stem stands, you would be able to have wildlife refuge in the spring when mating and brood rearing occur, and also harvest the grasses in the fall. And the harvested grasses could provide an income stream to help with other conservation projects. Harvesting the grasses in the fall would provide a back up feed stock for cellulosic ethanol production, additional income for conservation projects, and accomplish the same end (removal of dead plant material) that control burns accomplish. We are already producing switchgrass on wildlife preserves, management areas, and managed habitats. The only difference is, we would be burning the ethanol in vehicle engines instead of open fields. Economically much more efficient.

In other words, producing cellulosic ethanol is good deal for everyone all the way around, corn farmers, conservation managers, ethanol producers and ethanol consumers.

k

Wetdog: You begin with 3 quotes from my comment. But you do not say if you agree or disagree with them.

After my quotes you seem to blast the report itself about various points. Then proceed to say some nice things about switchgrass.

I think your point is that corn should not totally eclipse switchgrass. That grass should also be harvested from appropriate areas such as wildlife preserves.

Then your last paragraph is a firm endorsement of cellulosic ethanol.

I don't disagree with your comments. But why did you quote my three sentences?

Harvey D

Assuming that fuel can be economically mass produced with non-food plants or part of, does this mean that corn and other related food price would come down?

lensovet

wetdog: you're only partly correct. in the us, farmers get a combination of different subsidies. some of them are basement prices, as you say, but others simply pay farmers a flat fee over whatever market price they get per bushel.
for example, in the 2002 Farm Bill, for every bushel of wheat sold farmers were paid an extra 52 cents and guaranteed a price of 3.86 from 2002–03 and 3.92 from 2004–2007.

yep, that's how strong the farm lobby is.

gr

Those farm guarantees look an awful lot like collective bargaining contracts. Strong lobbies indeed.

Not to forget wetdog's caution that this article is estimating costs based on current market. Wally's statement:

"Farmers would receive an average of $80 an acre extra profit for corn stover and $160 an acre average profit for switchgrass."

So, due to low cost of growing switchgrass, under other circumstances, switchgrass will be an important profit center for farmers. Two ideas for stover transport:

Shred and bale in the field. Or design a new baler that can handle stover. It does look good all around.

Engineer-Poet

gr:  Note the word "extra profit for corn stover".  A farmer getting $5/bu over 150 bu/ac has a fair amount of profit right there, and doesn't have to wait for a switchgrass stand to establish itself either.

I would prefer to see corn stover be used in conjunction with CAES plants, not ethanol.  Using corn stover as the fuel for air reheat, huge amounts of electricity could be produced on demand with near-zero carbon emissions.

There is potential for a two-fer.  "Green diesel" made using F-T from gasified biomass produces a combustible tail gas in addition to the liquid fuel.  This gas could be used in the CAES system.  The result:  storable liquid transport fuel and stored energy for electricity.

More musings on the CAES part here.

jcwinnie

AFAICT, more "Syngas Spin", i.e., Wetdog, et al make Fischer-Tropsch synthesis a forgone conclusion. Unfortunately, it's a fine mess that Business As Usual and Above All Else has got us into now!

Syngas, by pipe or by wire, has an environmental consequence that is being ignored for the sake of profit, Mister Peabody. I am unsure whether anaerobic digestion of agricultural waste and /or ligno-cellulosic crops is a good idea, but, AFAIK, FT synthesis with or without burying the char is a very, very bad idea for life as we know it on the planet.

(sotto voce) "Follow the money."

sjc

If there are 600 acres in production per square mile and you can get 5 tons yielding 500 gallons per acre, you could get 300,000 gallons per square mile per year.

With an area 20 miles by 20 miles you would have 400 square miles yielding 120 million gallons of fuel from corn stalks every year.

So, just put a stover gasifier in the middle of a 20 by 20 mile area of corn fields and make money.

gr

EP: interesting application for conversion to electricity. Of course transport to the CAES plant costs something in C and efficiency and we are going to need liquid fuel for range extenders/hybrids until BEVs are fully evolved.

But it is a fascinating technology with good potential for buffering off-peak wind. I will be tracking this.

Engineer-Poet

Quoth sjc:

If there are 600 acres in production per square mile and you can get 5 tons yielding 500 gallons per acre, you could get 300,000 gallons per square mile per year.
The corn stover collection project found more like 2.5 tons/ac/yr.  That brings you down to 150,000 gal/mi²/yr, before system losses.

Overhead for transport is another issue.  If the average distance of transport is 14 miles (figuring roads laid on a grid) and trucks carrying 30 tons consume ethanol at 4 MPG average, each load of 30 tons requires 7 gallons of fuel (round trip) or about 1 quart per ton.  If the fuel yield is 100 gal/ton, this is barely significant.

More to the point is the small potential for replacing petroleum.  If 80 million acres of corn yield 2.5 tons/ac of stover, 200 million tons of stover will be produced.  At 100 gal/ton, the ethanol production would be 20 billion gallons.  This is barely 10% of US LDV energy requirements.

US LDVs cover roughly 3 trillion miles/year.  If that same corn stover (17.4 GJ/dry ton) were converted to electricity at 30% efficiency and used in electric vehicles at 0.25 kWh/mile, each ton would power 5800 vehicle-miles (contrast 2200 vehicle-miles for ethanol assuming per-gallon parity with gasoline).  If the same corn stover were burned to run a conventional CAES system at 80% fuel-to-electric efficiency, each ton would power more than 15,000 vehicle-miles; 200 million tons would suffice to power the annual LDV mileage of the US.  If burned in a regenerative CAES system at perhaps 120% fuel-to-electric efficiency (balance supplied by wind power), 200 million tons could power 3 trillion vehicle-miles at 0.25 kWh/mile (750 billion kWh) with roughly 10% of total US electric consumption left over.  (CAES would be ideal for displacing natural gas peaking plants, which allows gas to substitute for petroleum or simple conservation.)

This is the sort of goal we should be pursuing.

sjc

I see no reason why we can not go after several viable solutions. The discussion sometimes comes down to "I have the best way"...where this is seldom if ever the case in reality.

I favor gasifying corn stover and other biomass in local plants near the source and making methane to put in the pipes we have already. Now with T. Boone Pickens leading the charge, we may just see some action for once.

li-ion battery pack

ZAP Alias three- wheeled electric car can travel faster than a Porsche!

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