Study casts doubt on climate benefit of biofuels from corn residue

Apr 20, 2014
Corn residue is being baled on a University of Nebraska-Lincoln field experiment site in Saunders County, Neb. Credit: University of Nebraska-Lincoln

Using corn crop residue to make ethanol and other biofuels reduces soil carbon and can generate more greenhouse gases than gasoline, according to a study published today in the journal Nature Climate Change.

The findings by a University of Nebraska-Lincoln team of researchers cast doubt on whether corn residue can be used to meet federal mandates to ramp up ethanol production and reduce .

Corn stover—the stalks, leaves and cobs in cornfields after harvest—has been considered a ready resource for production. The U.S. Department of Energy has provided more than $1 billion in federal funds to support research to develop cellulosic biofuels, including ethanol made from corn stover. While the cellulosic biofuel production process has yet to be extensively commercialized, several private companies are developing specialized biorefineries capable of converting tough corn fibers into fuel.

The researchers, led by assistant professor Adam Liska, used a supercomputer model at UNL's Holland Computing Center to estimate the effect of residue removal on 128 million acres across 12 Corn Belt states. The team found that removing crop residue from cornfields generates an additional 50 to 70 grams of per megajoule of biofuel energy produced (a joule is a measure of energy and is roughly equivalent to 1 BTU). Total annual production emissions, averaged over five years, would equal about 100 grams of carbon dioxide per megajoule—which is 7 percent greater than gasoline emissions and 62 grams above the 60 percent reduction in greenhouse gas emissions as required by the 2007 Energy Independence and Security Act.

Importantly, they found the rate of carbon emissions is constant whether a small amount of stover is removed or nearly all of it is stripped.

"If less residue is removed, there is less decrease in , but it results in a smaller biofuel energy yield," Liska said.

To mitigate increased carbon and reduced soil carbon, the study suggests planting cover crops to fix more carbon in the soil. Cellulosic ethanol producers also could turn to alternative feedstocks, such as perennial grasses or wood residue, or export electricity from biofuel production facilities to offset emissions from coal-fueled power plants. Another possible alternative is to develop more fuel-efficient automobiles and significantly reduce the nation's demand for fuel, as required by the 2012 CAFE standards.

Liska said his team tried, without success, to poke holes in the study.

"If this research is accurate, and nearly all evidence suggests so, then it should be known sooner rather than later, as it will be shown by others to be true regardless," he said. "Many others have come close recently to accurately quantifying this emission."

The study's findings likely will not surprise farmers, who have long recognized the importance of retaining crop residue on their fields to protect against erosion and preserve soil quality.

Until now, scientists have not been able to fully quantify how much soil carbon is lost to carbon dioxide emissions after removing . They've been hampered by limited carbon dioxide measurements in cornfields, by the fact that annual carbon losses are comparatively small and difficult to measure, and the lack of a proven model to estimate carbon dioxide emissions that could be coupled with a geospatial analysis.

Liska's study, which was funded through a three-year, $500,000 grant from the U.S. Department of Energy, used carbon dioxide measurements taken from 2001 to 2010 to validate a soil carbon model that was built using data from 36 field studies across North America, Europe, Africa and Asia.

Using USDA soil maps and crop yields, they extrapolated potential carbon dioxide emissions across 580 million 30-meter by 30-meter "geospatial cells" in Corn Belt states. It showed that the states of Minnesota, Iowa and Wisconsin had the highest net loss of carbon from residue removal because they have cooler temperatures and more carbon in the soil.

The research has been in progress since 2007, involving the coordinated effort of faculty, staff and students from four academic departments at UNL. Liska is an assistant professor of biological systems engineering and agronomy and horticulture. He worked with Haishun Yang, an associate professor of agronomy and horticulture, to adapt Yang's soil carbon model, and with Andrew Suyker, an associate professor in the School of Natural Resources, to validate the model findings with field research. Liska also drew upon research conducted by former graduate students Matthew Pelton and Xiao Xue Fang. Pelton's master's degree thesis reprogrammed the soil carbon model, while Fang developed a method to incorporate into life cycle assessments of cellulosic ethanol.

Liska also worked with Maribeth Milner, a GIS specialist with the Department of Agronomy and Horticulture, Steve Goddard, professor of computer science and engineering and interim dean of the College of Arts and Sciences, and graduate student Haitao Zhu to design the computational experiment at the core of the paper. Humberto Blanco-Canqui, assistant professor of agronomy and horticulture, also helped to address previous studies on the topic.

Explore further: Carbon sequestration not so simple in biomass crop production

More information: Biofuels from crop residue can reduce soil carbon and increase CO2 emissions, dx.doi.org/10.1038/nclimate2187

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Ronan
4.3 / 5 (7) Apr 20, 2014
As a chemist working at a plant run by one of the "several private companies" mentioned in the article, this is rather worrisome to me. I'll need to see if I can track down a .pdf of the original paper and take a gander at it.
Returners
4.4 / 5 (7) Apr 20, 2014
Solar cells are more efficient at converting sunlight to useful energy than is Ethanol from corn. Additionally electric motors are 80% efficient instead of the net operating average of 20% for automobile combustion engines.

An acre of solar panels can produce as much energy in 3 days as an acre of corn field could produce in an entire growing season, and it leaves soil composition in tact.

In principle, you could even grow some crops on the same land as the panels, though those crops would be less efficient than in an open field, it would nevertheless give you double use of the land. A good candidate might be grasses for hay or other biofuels, it would just grow slower I guess due to reduced sunlight, but would be a way of capturing whatever light energy misses the panels.

The point here is solar-electric is a better use of the land given the energy density you can harvest with solar...and you don't need water or phosphorous to do it, saving resources for food crops...
Foundation
3.6 / 5 (5) Apr 20, 2014
I agree with your points, Returners. But how about the energy density, cost and weight of the batteries? I think we still need serious improvements in that area before solar-electric will be a truly superior alternative.
Feldagast
5 / 5 (1) Apr 20, 2014
Go to a system that uses solar electric during the day and super compressed air at night?
Whydening Gyre
5 / 5 (2) Apr 20, 2014
Go to a system that uses solar electric during the day and super compressed air at night?

you could also just heat water with passive solar, store it in underground tanks and use Sterling engine for heat gen at nite, too...
betterexists
1 / 5 (5) Apr 20, 2014
This clearly proves that ALL carnivores should be IMMEDIATELY & COMPLETELY removed from earth & let herbivores grow up in both numbers & age. Once, they grow up to the correct size, humans can hunt & eat them plus make biofuel out of their carcasses.
Humans cannot go hungry.
So, We thus get FREE HERBIVORE MEAT plus We get Vegetables from Fenced Farmlands. All the Flour fed to animals in the animal farms can be saved & used for biofuel or bread making!
Thus we retain Carbon in the soil & limit Co2 Release into the air diminished as much as possible.
What is the use of still continuing to live together with the Cruel Carnivores in this Internet Age?
WE HAVE ROBOTS, DRONES, TRUCKS, CCTV CAMERAS & SCIENCE to Control population levels of herbivores. Hitherto we had no use for too much meat from all kinds of herbivores. But now excessive meat can be used to convert to Ethanol. Ethanol can be exclusively used in Automobiles as they are doing now in Brazil.
betterexists
1 / 5 (5) Apr 20, 2014
Dunk Heat energy trapping devices into Lava Domes & Lift them up! OR Drag Chains of such devices from 1 end to the other!
Let Robots work for us in this context.
Drones too can help us.
betterexists
1 / 5 (5) Apr 20, 2014
Google's Bull shaped Robots can Pull those chains while running. Drones can help attaching the chains to Robots initially. Once Energized Devices are removed from the Robots, Another Robot on the other side can pull the chain again with fresh devices. Drones can help in attaching each time.
Dunk Heat energy trapping devices into Lava Domes & Lift them up! OR Drag Chains of such devices from 1 end to the other!
Let Robots work for us in this context.
Drones too can help us.

betterexists
2 / 5 (4) Apr 20, 2014
Actually, Lands used by Solar Panels & Wind Turbines can be filled with water & used to grow algae for ethanol production.
Algenol, industrial biotechnology company can produce ethanol and other fuels i.e 4 most important fuels (ethanol, gasoline, jet, and diesel fuel) using proprietary algae, sunlight, carbon dioxide and salt water.
Area between Wind Turbines can filled with branches of mini wind turbines like tree branches.
Solar panels can be multi-storeyed ...stacked up like various storeys of skyscrapers. Sky is the Limit.
Boats, Drones, Robots & Planes can help in the entire process!
betterexists
1.3 / 5 (4) Apr 20, 2014
All the HEAT Collected can be used to produce steam by dropping those devices into water tanks.. Then, we can produce some goods with all that steam! We cannot keep on losing heat energy of lavas into the atmosphere. It is high time to create big cities full of factories near lavas...of course, residences of workers at a safe distance. Just like Ants around a SUGAR CUBE!
Google's Bull shaped Robots can Pull those chains while running. Drones can help attaching the chains to Robots initially. Once Energized Devices are removed from the Robots, Another Robot on the other side can pull the chain again with fresh devices. Drones can help in attaching each time.
Dunk Heat energy trapping devices into Lava Domes & Lift them up! OR Drag Chains of such devices from 1 end to the other!
Let Robots work for us in this context.
Drones too can help us.


alfie_null
5 / 5 (1) Apr 21, 2014
deleted
betterexists
1 / 5 (2) Apr 21, 2014
Google's Bull shaped Robots can Pull those chains while running. Drones can help attaching the chains to Robots initially. Once Energized Devices are removed from the Robots, Another Robot on the other side can pull the chain again with fresh devices. Drones can help in attaching each time.
Dunk Heat energy trapping devices into Lava Domes & Lift them up! OR Drag Chains of such devices from 1 end to the other!
Let Robots work for us in this context.
Drones too can help us.


The faster those Robots Run (Max ~30mph), more heat plucked from Lava can be transferred to the water tanks into which they can be dropped! Steam Steam Everywhere...No limit to production of goods anymore!
Surly
5 / 5 (1) Apr 21, 2014
@betterxists: Trying to extract waste heat often consumes more energy than it produces. For example, if you strapped a steam engine to your car's engine, the energy wasted by the extra gasoline you'd need to move its weight would exceed the energy you'd get by having waste heat power the steam engine.
Shakescene21
3 / 5 (2) Apr 21, 2014
I tried to read the full report and it is PAY-WALLED. If the taxpayers spent $500,000 supporting this study, why do we have to pay $32 for a copy of the full report?

(There is a $5.00 option to "rent" the report for 48 hours without printing, but I need a hard copy to carefully read and mark a complex report.)
GraemeMcRae
5 / 5 (1) Apr 22, 2014
"(a joule is a measure of energy and is roughly equivalent to 1 BTU)"...

No. A joule is about 0.000948 BTU
antialias_physorg
4 / 5 (4) Apr 22, 2014
I tried to read the full report and it is PAY-WALLED. If the taxpayers spent $500,000 supporting this study, why do we have to pay $32 for a copy of the full report?

You don't pay for the study. You pay the people who print the journal (Elsevier, Springer, etc.).
The author of the study does not get one cent for having their stuff published. (The authors have to PAY THE PUBLISHERS extra for some newfangled features, like color graphs).

The publishers make the authors sign a contract that they will not give out the study/make it available in other media.
In effect the paper you write is no longer your own after you hand it over to them.

So while I can understand your criticism it's directed at the wrong people. (If you really want the study just go ask the authors, nicely. Even though they aren't allowed to send you the file I have yet to meet one who didn't)
betterexists
not rated yet Apr 22, 2014
Imagine a Rocket being launched...It needs so much Pressure...Heat energy ...So much wasted too!
Drop that same Rocket down while still in the atmosphere from a height. You do NOT expend any energy at all to fall down. GRAVITY takes care of it.
Apply the Same Principle to LAVA DOME area. You drop an object into it. It falls because of gravity WITHOUT using any energy. Once that object acquires energy, no problem at all to fly out of it!
So, what we need is INTELLIGENCE put into the object. A Sensor Plus Drone Combo!
It should fly out & fall into water tank located at the intended place producing the DESIRED Steam! That object should get out of the lava dome BEFORE it is damaged.
Work is going on groups of Robots working just like Termites OR Ants at an Ant-hill!
So, All these Scientists & Technicians should take their Robots & Computer Systems over there...AROUND THE LAVA DOMES!
I envisage 2 to 3 unit systems...one of that fall into the water after snapping out of the whole unit.
betterexists
not rated yet Apr 22, 2014
I could not correct the grammar in the last sentence of my last comment above;
I also wanted to add there about an oblong 'O' shaped Belt-like object over the lava dome on which objects would move through...Various ups & down like in the game parks too. The objects should know to snap from & fly out of the composite after acquiring enough energy. They must be Super-Light! They should actually think of Wireless transfer of energy directly from lava domes to desired places.
I was reading about Transfer of Moon light or whatever a year back!
betterexists
not rated yet Apr 22, 2014
Plan Well with a Miniature Lava & Miniature Robots in a Lab before going to repeat it at the Lavas of Nature;
Otherwise, you will burn your fingers Financially & will have to put it off for future generations;
It is a Crime to Leave it All to the Future Gen, particularly when so much Profit can be made.
When Termites & Ants Can, so also humans...that too those belonging to Icy, Freezing Weather!
rockwolf1000
5 / 5 (1) Apr 22, 2014
Plan Well with a Miniature Lava & Miniature Robots in a Lab before going to repeat it at the Lavas of Nature;
Otherwise, you will burn your fingers Financially & will have to put it off for future generations;
It is a Crime to Leave it All to the Future Gen, particularly when so much Profit can be made.
When Termites & Ants Can, so also humans...that too those belonging to Icy, Freezing Weather!

It's a good idea to get heat energy from geologic sources though I'm not sure your ideas would work too well. "Objects" dunked into molten lava will probably emerge from it covered in the same. A fairly significant issue. Would it not be more feasible to run molten salts thru hi temp piping in the same manner glycol/water is used to extract geothermal energy from ground heat far removed from magmatic sources? No robots or drones or magical flying "objects" required.
Can you give me an idea of how an "object" submerged in lava would generate thrust to "fly" out of the lava pool?
betterexists
not rated yet Apr 22, 2014
@rockwolf1000 Computerization!
Once The Combo senses that the attached heat-capturing device has reached the desired Temperature (I do not mean total dunking, though), the computer system will tell the attached Drone to leave the place IMMEDIATELY along with it so as not to lose any heat ....Once it reaches the water tank, Drone gets rid of the hot device to go back to its original location to snap on to one of the Non-hot devices there all over again.
Some one/A Robot can collect all the devices from the water tank & truck them back en mass to the original starting point.
All of this should be done as much as possible by Robots....Even Truck driving....Google has Self-driving vehicles since a few years, as all of us know !
Minimum human intervention will provide greater profits.
They should do that 24X7X365 i.e Day & Night!
betterexists
not rated yet Apr 22, 2014
@rockwolf1000
Look at this also: "Descending Into an Active Volcano" at discoverydotcom/tv-shows/curiosity/topics/yellowstone-super-eruptionsdothtm Website
Recently we had Volcanic Eruption in Ecuador. To REPEAT....No dunking of devices into Lava itself; Only inside the Lava Dome only!
It's a good idea to get heat energy from geologic sources though I'm not sure your ideas would work too well. "Objects" dunked into molten lava will probably emerge from it covered in the same. A fairly significant issue. Would it not be more feasible to run molten salts thru hi temp piping in the same manner glycol/water is used to extract geothermal energy from ground heat far removed from magmatic sources? No robots or drones or magical flying "objects" required.
Can you give me an idea of how an "object" submerged in lava would generate thrust to "fly" out of the lava pool?

rockwolf1000
5 / 5 (1) Apr 22, 2014
@betterexists
Please explain how robotic trucks, drones and a fleet of magic devices would be more economical than a pipeline of molten salt circulating to and from the heat source. The very same molten salts proposed for heat transfer in newer nuclear reactors.
betterexists
not rated yet Apr 22, 2014
I will be the happiest person to see the Entire Lava losing all its heat energy for the sake of mankind in our present generation itself...
It will not happen because we do NOT need so much energy for just 1 generation!
I wish to see Planes, Trains & Buses charging just less than $10/Ticket & carrying ship loads of goods from country to country for just $10,000!
If extinguishing by using up all the heat energy helps in reducing earthquakes...that will be great too!
betterexists
not rated yet Apr 22, 2014
@rockwolf1000
Please explain how robotic trucks, drones and a fleet of magic devices would be more economical than a pipeline of molten salt circulating to and from the heat source. The very same molten salts proposed for heat transfer in newer nuclear reactors.


How can you get the Super-hot molten salts into the pipes in the first place? That is why I suggested that the Drones should leave the scene IMMEDIATELY on sensing the heat going above the limits of their tolerance!
rockwolf1000
5 / 5 (1) Apr 22, 2014
@rockwolf1000
Please explain how robotic trucks, drones and a fleet of magic devices would be more economical than a pipeline of molten salt circulating to and from the heat source. The very same molten salts proposed for heat transfer in newer nuclear reactors.


How can you get the Super-hot molten salts into the pipes in the first place? That is why I suggested that the Drones should leave the scene IMMEDIATELY on sensing the heat going above the limits of their tolerance!

The same way they get liquid metal or glass into injection molds. Where there is a will there is a way. Especially if it's cheaper than building and maintaining a fleet of robotic machines, trucks and drones that will be fly in and out of volcanoes.
Shakescene21
1 / 5 (1) Apr 26, 2014

"The publishers make the authors sign a contract that they will not give out the study/make it available in other media.
In effect the paper you write is no longer your own after you hand it over to them.

So while I can understand your criticism it's directed at the wrong people"

@Antialias -- If the taxpayers spent $500,000 supporting this study, why isn't it simply posted for free on the internet? You are being an apologist for scientists who are boosting their careers by publishing their work in a prestigeous journal that will charge the public for access. This is a controversal report that seems to be based on numerous assumptions that are not detailed in the abstract.
But you are right that I am complaining to the wrong people. I will write to my Congressman about this, and I will probably discover that his full report is probably on a government website somewhere.

Read more at: http://phys.org/n...html#jCp