August 03, 2008
Miscanthus Seen As Superior To Corn For Ethanol

My fear with biomass energy is that we will find plants that can convert sunlight to usable energy so efficiently that biomass energy can compete on cost but not efficiently enough to limit use of land for energy to a very small area. Well, miscanthus looks like it will help make the nightmare scenario cost effective. Miscanthus beats corn and switchgrass for biomass production.

CHAMPAIGN, Ill. — In the largest field trial of its kind in the United States, researchers have determined that the giant perennial grass Miscanthus x giganteus outperforms current biofuels sources – by a lot. Using Miscanthus as a feedstock for ethanol production in the U.S. could significantly reduce the acreage dedicated to biofuels while meeting government biofuels production goals, the researchers report.

The new findings, from researchers at the University of Illinois, appear this month in the journal Global Change Biology.

If these researchers are correct then half of US agricultural acreage could supply all current US liquid fuels needs.

Using corn or switchgrass to produce enough ethanol to offset 20 percent of gasoline use – a current White House goal – would take 25 percent of current U.S. cropland out of food production, the researchers report. Getting the same amount of ethanol from Miscanthus would require only 9.3 percent of current agricultural acreage. (View a narrated slideshow about Miscanthus research.)

That is bad news. Why? Because there is the rest of the world with Asian demand on a course that will send it far past current US liquid fuel demand. A way to make cost competitive liquid fuel from agriculture will pull much more land around the world into biomass energy production. That cuts into land available for all the other species of critters on this planet.

Miscanthus might displace corn for use in ethanol production.

“What we’ve found with Miscanthus is that the amount of biomass generated each year would allow us to produce about 2 1/2 times the amount of ethanol we can produce per acre of corn,” said crop sciences professor Stephen P. Long, who led the study. Long is the deputy director of the BP-sponsored Energy Biosciences Institute, a multi-year, multi-institutional initiative aimed at finding low-carbon or carbon-neutral alternatives to petroleum-based fuels. Long is an affiliate of the U. of I.’s Institute for Genomic Biology. He also is the editor of Global Change Biology.

In trials across Illinois, switchgrass, a perennial grass which, like Miscanthus, requires fewer chemical and mechanical inputs than corn, produced only about as much ethanol feedstock per acre as corn, Long said.

“It wasn’t that we didn’t know how to grow switchgrass because the yields we obtained were actually equal to the best yields that had been obtained elsewhere with switchgrass,” he said. Corn yields in Illinois are also among the best in the nation.

The world's population is around 6.7 billion today and headed for 9.3 billion or maybe 9.1 billion by 2050. Crop demand will grow for a few reasons:

  • Population growth.
  • Buying power growth for meat due to Asian industrialization.
  • Demand for biomass energy crops.

Advances in agricultural biotechnology will boost yields. But dwindling supplies of oil and natural gas will drive up input costs. Also, population growth will reduce land available for farming as more land gets converted into residential and commercial building usage. A big global push for population control would help reduce the severity of this problem.

Share |      Randall Parker, 2008 August 03 06:42 PM  Energy Biomass

Wolf-Dog said at August 3, 2008 10:11 PM:

Here is a biotechnology company that is focusing on genetically engineered crops optimized for cellulosic ethanol production:

So far, the biotechnology companies were trying to improve the yield of grains per plant, not the carbon content, etc, but this seems to be a very promising direction.

This company claims that: "growing energy crops that can deliver 20t/acre on 60 million acres of non-crop or idle farmland could yield 120 billion gallons of ethanol (60M acres X 20t/ac X 100g/t = 120B gallons or 85% of current US gasoline demand—i.e., E85."

And this was only for small plants that grow in idle land. But there are already hybrid versions of poplar trees that grow an astounding 10 feet per year. Ultimately there will be genetically engineered trees that can grow in deserts. Imagine fast growing high carbon cactus plants in deserts. Of course, the danger is that some of these genetically engineered trees will develop cannibalistic man-eating properties, and they will start walking in the streets.

Larry said at August 4, 2008 6:38 AM:

I look to algae rather than grasses for biofuels. The output per acre is dramatically larger. Costs are too high at the moment, but once you have the right genome, the rest is an engineering problem that will yield to scale efficiencies. Rather than 2.5x corn, you get 100x. And you don't have to use arable land. The only threat to biofuel is solar. If prices crash as they might (because of innovation and scale), we could go to full-on electrics and leave the internal combustion engine out of the picture entirely.

pond said at August 4, 2008 7:25 AM:

One problem with land-based crops for ethanol (and maybe algae too, I don't know about that) is the loss of topsoil.

Everything that makes a plant comes from air (CO2) water and soil. When you harvest wheat and return the straw to the soil, you are losing only the amount of soil that went into the grains. When you harvest miscanthus and turn it all into ethanol (and cattle feed) you are losing ALL the soil that went into the above-ground stalks and seeds (soil that went into the roots remains). This means the dung from the cattle must be returned to the fields to minimize topsoil loss.

Plants add to topsoil, but modern agricultural methods, including plowing the ground for every crop, takes topsoil away. The US is losing topsoil at frightening rates. And once the topsoil is gone, how will we grow? How will we grow anything at all? We can't do it all with 1,000-sq.-km hydroponics plants, especially with fossil-water also running low.

Switch-grass and miscanthus grass, if we can just plow and seed once, then manure the fields every year, look to be the least-harmful land-based crops for ethanol out there -- IF we only do a little. But dreaming of supplying billions of barrels a year of the stuff is really a dangerous pipe dream.

Dave M said at August 4, 2008 8:15 AM:

There are several problems with any biomass crop that would need to address.
1. A huge one, as mentioned above would be the need for very large applications of fertilizers to replace the nutrients removed from the soil by harvesting the entire plant needed to prevent soil degradation.

2. A second major stumbling block revolves around all the logistical issues around transportation and storage of large quantities of bulky materials to ethanol plants.

3. Competition for land from the food and feed industries will limit the amount of acres available for fuel production. Farmers will always plant crops they will make the most profit from growing.

4. Switch grass and miscanthus are wild grasses. People have been growing domesticated crops like wheat, barley, rye, oats and more recently corn for thousands of years and researchers still struggle with ways to breed in disease resistance, drought tolerance, insect tolerance while increasing yield. It would take decades of fairly intensive research to learn how to prevent major losses from all these issues with a never before domesticated grass.

5. Corn yields have been steadily increasing by 3% a year for decades. Assuming all the new traits like lower water use varieties, multiple disease resistant traits and lower fertilizer requirements, don't dramatically spike global corn production, it is safe to assume that corn yield will continually to steadily increase by at least the 3% indefinitely. With corn ethanol effectively capped under the current biofuels policy, and corn yields slated to rise by nearly 20% in the next decade, by 2012 you will once again see the price of corn collapse to under $2.00/bushel. Since no one is predicting that oil will drop to the $30-$40/barrel range it was in when corn was last at these prices, corn ethanol will remain wildly profitable which reduces the need for biomass solutions.

I firmly believe that biomass ethanol will only be produced on a large scale from forestry waste and I agree with Larry that algae likelys offers the best long term alternative to corn/grain

Muggins said at August 4, 2008 11:03 AM:

Population growth makes cities grow, primarily, although the suburbs of these cities will reduce farmland.
But the economics of biofuels is that it requires a refinery reasonably close by. The 3rd world will not lose
farmland to bio-fuel production because the further a farmer has to transport his crop, the less profit in it.
Another thing to consider is that these fuel stock grasses can grow on marginal and depleted soils ill-suited
for grain.

Zack said at August 4, 2008 11:06 AM:

"A big global push for population control would help reduce the severity of this problem."

Let's take a page out of China's book. Great idea. Which population would you like to control? Inevitably, those who couldn't defend themselves would be the controlled populations.

TallDave said at August 4, 2008 11:11 AM:

"That cuts into land available for all the other species of critters on this planet."

I doubt it matters much. We're not talking about tearing down forests in national parks, and anyways these are fairly friendly to local wildlife.

"A huge one, as mentioned above would be the need for very large applications of fertilizers to replace the nutrients removed from the soil by harvesting the entire plant needed to prevent soil degradation."

Did you RTFA? They don't require much, because they're perennials.

"Competition for land from the food and feed industries will limit the amount of acres available for fuel production. Farmers will always plant crops they will make the most profit from growing."

They can be grown in soil that is poorly suited for ag crops.

"Switch grass and miscanthus are wild grasses. People have been growing domesticated crops like wheat, barley, rye, oats and more recently corn for thousands of years and researchers still struggle with ways to breed in disease resistance, drought tolerance, insect tolerance while increasing yield. "

That's the upside, not a problem. We're already seeing twice the corn yield despite barely any work to improve miscanthus yields. It's likely miscanthus yields could be improved faster than corn yields because we're starting from a lower baseline, much as China's GDP grows faster than ours because they're so much poorer.

People generally don't realize that ag crops like corn are very difficult to grow partly because they're highly specialized: they produce human-edible biomass. Wild corn produces tiny, thumb-sized cobs and it took the South Americans millennia to breed what we now eat and convert to ethanol. With Miscanthus, we're starting with something that hasn't already been bred to a point where it requires lots of ag inputs to survive.

RKV said at August 4, 2008 11:14 AM:

There is a logical fallacy at work here. Not all arable land is in production in the US or anywhere else for that matter. The Malthusian proposition has been proved wrong before and will be again. Politics (and by association economics) will be the key factors, not technology or sheer space. Then of course, I'm old enough to remember when anthropogenic global cooling was supposed to be the bugbear, so I have a bit longer view than some. The market will work it out if we let it and we'll get a mix of fuels to meet our needs.

Brian Wang said at August 4, 2008 11:14 AM:

This is just one intermediate result. Well before there is a scale up to 9.3% or 45% of cropland there will be far more improvements to biomass.

Genetic modifications to this current grass.
The Algae systems that have been mentioned.

The fact that there is already an option that will substitute for oil with less than half of existing croplands just shows that the eventual solution will be far superior. We can take the corn/switchgrass option as the massive scaleup out of the future discussion. Now there is only Iowa political lobbies that will be pushing funding for those options.

So instead of the discussion: "But using all the cropland still will not replace the oil we use" can give way to "but the new grass still uses too much land" which will gave way to "you have new variety or genetic modification of Miscanthus or algae system" that shows that technology will crush the pathetic worries about peak oil. Fine you techno bastards fixed that one but now we can worry about ..... Because if technology did not improve that would doom us.

Peak oil is weak threat. Electric airplanes for hyperefficient transport and faster than current cars. Electric bikes/trikes that go up to 60mph safely can be used for local movement. Efficient biofuels for when we need something like oil.

paul abarge said at August 4, 2008 11:24 AM:

"That cuts into land available for all the other species of critters on this planet"

Why don't you have the common courtesy to just come right out and say that you want us all to be driven back to hunting and gathering with a life expectancy of 42?

AC said at August 4, 2008 11:25 AM:

"But dwindling supplies of oil and natural gas will drive up input costs."

Sigh. We have an infinite amount of coal in the US and Australia is practically made of coal. Probably ditto for oil, though at some point (hunnert years?) it'll be darn hard to get.

Having said that, it'll obviously be easier to find spare land to grow the stuff than to have to wade though fields of verklmept so-called environmentalists to drill for the stuff.


JohnMc said at August 4, 2008 11:32 AM:

Want to reduce population? Foster the expansion of wealth. The wealthier a society becomes the fewer children they foster in future generations.

thedoctor said at August 4, 2008 12:00 PM:

Absolute nonsense. "Bio"-fuel. In 20 years it will as dead as "The Coming Ice-Age" of the 70's is now. Oil is being naturally produced continually. Let's have the maraccas to go down and get it.

deoxy said at August 4, 2008 12:05 PM:
Also, population growth will reduce land available for farming as more land gets converted into residential and commercial building usage.

Do you realize how much land we actually have?

OK, just picking a large, central US state, Texas has 268,820 square miles of land. Converting, we get 172044800 acres - 172 million acres. Most homes in the US southwest sit on, what 1/8 acre, give or take? I know if CA, it's smaller than that. Anyway, let's assume households of 4 on 1/8 acrea each - that's 32 people/acre. So, Texas could hold 5.5 BILLION people EXCEEDINGLY comfortably.

10 billion people leaves a ridiculous amount of space left. We are not going to run out of space any time soon, not from PEOPLE usage. You could make that case for agricultural usage, but people have been doom-saying on that topic since at least the 70s, and they've been so wrong it's funny.

But feel free to join them... I'm sure YOU'll be right, when they were all wrong, eh?

Tim Stegner said at August 4, 2008 1:36 PM:

Don't all US interstate highways have a grassy sward between the two lanes? Doesn't grass grow there anyway? Switch the weed grass over to this stuff. Already got highways there to transport it...

David said at August 4, 2008 2:02 PM:

Make ethanol fuel ONLY available to plug-in hybrid drivers, and make it practically free (through subsidies at first).

If we did that, we'd displace a bunch more gas and wouldn't need to divert nearly as much land from food to fuel. If the plug-ins got 1500 miles/tank or more (which they should with normal driving patterns), 9-10% of our crop land would supply our entire gasoline need.

Mark B. said at August 4, 2008 2:14 PM:

"4. Switch grass and miscanthus are wild grasses. People have been growing domesticated crops like wheat, barley, rye, oats and more recently corn for thousands of years and researchers still struggle with ways to breed in disease resistance, drought tolerance, insect tolerance while increasing yield."

A feature, not a bug. Over the millenia, nature's done what agronomists continually work to do with food crops, namely increase those tolerances. The locally-native strains have evolved to optimize for survival in their respective microclimates and to resist local plant and animal pests.

As "pond" notes above, the much larger issue is replacing soil nutrients and replenishing topsoil mass when, as should be self-evident, most of the biomass would be removed in repeatedly harvesting what normally gets returned to the soil.


m00tpoint said at August 4, 2008 2:56 PM:

Ummm, did everyone miss this from the actual article? Once established, Miscanthus returns annually without need for replanting. If harvested in December or January, after nutrients have returned to the soil, it requires little fertilizer.

Worrying about inputs is kind of silly. Since the goal is making hydrocarbons (ethanol), leaving the grass in the field for a couple of months after frost will not reduce fuel production. But it will give time for the trace minerals etc. to leach out of the leaves into the soil. The carbon comes from the air. The hydrogen comes from water, which falls as rain. Most of the other trace nutrients are recycled if you harvest intelligently. So there is very little input needed for this crop.


VanillaThunder said at August 4, 2008 3:31 PM:

"Absolute nonsense. "Bio"-fuel. In 20 years it will as dead as "The Coming Ice-Age" of the 70's is now. Oil is being naturally produced continually. Let's have the maraccas to go down and get it."

Fan of the biogenic theory of petroleum production are ye?

M. Simon said at August 4, 2008 4:15 PM:

We should consult the Germans. I'm told they are experts in industrial population control.

Bill said at August 4, 2008 5:50 PM:

Populations in the developed world are shrinking, not growing.
A huge amount of undeveloped land and marginal lands are available for biomass and biofuels crops.
Biomass can be compacted, torrefied, pelletized, cubed, in any number of ways, for more efficient transport and use.
Biomass can be co-fired with coal in conventional power plants, to reduce pollution and emissions.
Biomass can be gasified and converted into liquid fuels, gaseous fuels including hydrogen and a natural gas equivalent, or turned directly into electricity.
The biomass you are reading about like miscanthus and switchgrass are about 10 years behind the state of the art in thinking about biofuels. That puts corn about 20 or 30 years behind, for all the improvements made every year in the efficiency of corn biofuels.
The speed of change in bio-power is impressive.
This posting is far too conservative and pessimistic.

Randall Parker said at August 4, 2008 9:14 PM:


The shrinking of populations in Japan, Russia, and some European countries is not making much difference to the total world population because of rapidly growing populations in the Indian subcontinent, Africa, and some other places. Again, world population is headed toward 9 billion people.

Look at the data:

World population growth will continue. World population is 6.6 billion in 2007, up from 6.1 billion in 2000. It is projected to rise to 9.3 billion by 2050, with nearly all of that increase in developing countries. By 2008, half of all people will live in urban areas.

Fertility rates may be rising again in some European countries. After years of low but stable rates, the number of children women are having is increasing in Italy, Spain, and Sweden, among others.

Fertility rates are holding steady at high levels in some developing nations after years of decline. In Afghanistan, the rate is nearly seven children per woman; in Nigeria, it is nearly six.

We will hit 7 billion in 2013 and 8 billion in 2028.

Fat Man said at August 4, 2008 11:16 PM:

Let us just start with current consumption. According to the EIA the US used approximately 13,825,000 barrels a day of petroleum based fuels in 2005.

There are 42 gallons in a petroleum barrel (approximately 159 l). So in 365 days the US used about 800 Billion l of petroleum.

Taking gasoline (~725g/l) as about 3/5 of the total and diesel as 2/5 (~850 g/l), I get about 620 Billion Kg or 620 Million Tonnes of fuel.

Diesel is on the average C12H26 and Gas is ~C8H18. Averaged as C9H20 it would have a molecular weight of 9*12 + 20 = 128, so it would be 84% Carbon, and the 620 Million Tonnes of fuel would be ~525 MT of Carbon.

Now to get that much carbon from biological sources, most of it will be in the form of carbohydrates, which have molecular formula of HCOH. The oxygen atom is heavier (16) than the Carbon and Hydrogen (12+2) so carbohydrates (and most plant matter) are 40% Carbon.

To get 525 MT of Carbon in the form of carbohydrates requires 1.3 GT of plant matter.

Could it be done? ORNL published a report "Biomass as Feedstock for a Bioenergy and Bioproducts Industry: The Technical Feasibility of a Billion-Ton Annual Supply, April 2005" [PDF 8.5 MB]

From the "Executive Summary" of the report:

Looking at just forestland and agricultural land, the two largest potential biomass sources, this study found over 1.3 billion dry tons per year of biomass potential

Forestlands in the contiguous United States can produce 368 million dry tons annually. This projection includes 52 million dry tons of fuelwood harvested from forests, 145 million dry tons of residues from wood processing mills and pulp and paper mills, 47 million dry tons of urban wood residues including construction and demolition debris, 64 million dry tons of residues from logging and site clearing operations, and 60 million dry tons of biomass from fuel treatment operations to reduce fire hazards. All of these forest resources are sustainably available on an annual basis. For estimating the residue tonnage from logging and site clearing operations and fuel treatment thinnings, a number of important assumptions were made:

* all forestland areas not currently accessible by roads were excluded;
* all environmentally sensitive areas were excluded;
* equipment recovery limitations were considered; ...

From agricultural lands, the United States can produce nearly 1 billion dry tons of biomass annually and still continue to meet food, feed, and export demands. This projection includes 428 million dry tons of annual crop residues, 377 million dry tons of perennial crops, 87 million dry tons of grains used for biofuels, and 106 million dry tons of animal manures, process residues, and other miscellaneous feedstocks. Important assumptions that were made include the following:

* yields of corn, wheat, and other small grains were increased by 50 percent;
* the residue-to-grain ratio for soybeans was increased to 2:1;
* harvest technology was capable of recovering 75 percent of annual crop residues (when removal is sustainable);
* all cropland was managed with no-till methods;
* 55 million acres of cropland, idle cropland, and cropland pasture were dedicated to the production of perennial bioenergy crops;
* all manure in excess of that which can applied on-farm for soil improvement under anticipated EPA restrictions was used for biofuel; and
* all other available residues were utilized.


However the assumptions for bio-fuel production from agriculture make me very nervous. Do they represent soil mining that will leave us with depleted and unproductive land? Will increasing crop yields require additional applications of fertilizer and pesticide that could create their own problems? Would converting that much cropland into fuel production adversely affect food prices and harm people in poor countries?

Further, It would require an enormous input of energy to turn carbohydrates into alkane fuels. to make C12H24O12 into C12H26 requires the addition of 13 H2. The source of that H2 and the process heat required to drive the process, if it is not more bio-fuel or fossil fuel must be wind, solar or nuclear, and in large quantities. This is not to say that it is impossible -- just that it would be an enormous task.

Bill said at August 5, 2008 9:12 AM:

Fat Man: Nice analysis. But isn't it a bit ridiculous to demand that biofuels replace all petroleum? Is it not indeed a bit odd to make that demand? Let biofuels be one piece of the solution. Over time perhaps it will become a major liquid, gaseous, and solid fuel source, as well as a major source for electric power.

The production of biofuels does not make all coal, oil sands, shale oil, gas, heavy petroleum, conventional petroleum, and other energy sources disappear.

As you illustrate so well, replacing the infrastructure of petroleum is going to take a lot of ingenuity. It will require many approaches simultaneously. Let's use our brains and use the time we have. Let's not whine that it can't be done, and end up getting stuck on stupid.

Fat Man said at August 5, 2008 9:54 PM:

I was not demanding that all hydrocarbon fuels come from biological sources, I was illustrating the scope of the issue. Personally, I am very concerned that using land to produce fuel will lead to soil depletion and to food shortages in the poorer countries. It is a bad, perhaps even immoral trade-off.

The only biological sources of carbon that I would consider using for the production of fuel are garbage dumps and sewerage systems.

Bob in NM said at August 6, 2008 8:21 PM:

In the narrated slideshow above, it was noted that miscanthus produces about twice the biomass tons per acre as switchgrass. One reason is that miscanthus uses the C4 (modified Calvin cycle) photosynthesis (like sugarcane), while switchgrass uses the normal C3 Calvin cycle photosynthesis (rice, wheat). The C4 cycle is expected to be better than the C3 cycle because of lower photorespiration (reverse photosynthesis) at higher temperatures, and also because of a lower requirement for water. The C4 cycle is about twice as efficient as C3 for converting sunlight to biomass.

Randall Parker said at August 7, 2008 5:52 PM:


The amount of land is far larger than the amount of usable land. Water and other inputs prevent large areas from being used.


We are going to hit limits on phosphorus and potassium availability fertilizer. We will need to do more recycling since the mining industry is extracting faster than they are finding new replacement sources.


Populations in the less developed world are growing, not shrinking. Some countries have total fertility rates of 5, 6, 7+ babies per woman. Some countries even have rising fertility, not declining fertility.


Biomass energy reduces species diversity. said at August 7, 2008 9:20 PM:

Genetically engineered sea based algae, perhaps? You could have an algae farm the size of Texas in the sea or the ocean, to be harvested then converted to biomass fuel. The kind of biomass fuel version of "soylent green" (at least as it was understood in the movie until the main character clued into the big secret).

Any idea as to the feasibility of that?

Randall Parker said at August 7, 2008 9:29 PM:


A lot of money is getting thrown at algae biodiesel. I wish those efforts the best of luck. But so far algae biodiesel isn't near cost competitive.

I think genetic engineering will do the trick eventually. But that sort of genetic engineering will take many years to bring to fruition.

Craig Patterson said at January 22, 2010 2:01 PM:

Great article. Here’s an update. Several firms have begun to commercialize giant miscanthus in the US. This after all the news out of Illinois about it. This should allow easier, more cost-effective, and quality controlled growing. The notable one I’ve run across is SunBelt Biofuels ( They’ve branded a high-yielding cultivar from Mississippi State University. 25 tons per acre is the claimed yield, but all yield numbers I've seen for miscanthus blow corn and even switchgrass out of the water.

Post a comment
Name (not anon or anonymous):
Email Address:
Remember info?

Go Read More Posts On FuturePundit
Site Traffic Info
The contents of this site are copyright ©