Tuesday, April 22, 2014 | By Great Energy Challenge | No Comments
The U.S. Department of Energy has been counting on leftover residue from corn cultivation—such as stalks and cobs—as an abundant future source of renewable clean energy, and touted it as a potential goldmine for farmers as well.
But University of Nebraska-Lincoln (UNL) researchers may throw a damper on those plans, with a newly published study in the scientific journal Nature Climate Change. They calculated that harvesting the corn residue may actually result in the release more climate-altering carbon dioxide into the atmosphere than federal environmental regulations allow. (See related coverage: “Biofuels at a Crossroads.”)
Those findings, however, were challenged by both a renewable energy trade group and a prominent biofuels researcher, who found fault with the study’s methodology.
The UNL team, led by agronomy and horticulture assistant professor Adam Liska, used a supercomputer simulation to estimate the effect of removing the corn residue (also called corn stover) from 128 million acres across 12 states in the Midwest’s Corn Belt.
If left undisturbed, most of the residue rots, releasing carbon dioxide into the atmosphere, but some of the material also becomes part of the soil, storing its carbon there. But when the corn residue is removed, converted to biofuel and burned in engines, it pumps out carbon dioxide more rapidly than a cornfield would release it, the researchers wrote. As a result, they calculated, biofuel made from corn residue would release so much carbon that it would probably exceed the limits set by federal regulations, which require biofuels to produce 60 percent fewer greenhouse gas emissions than gasoline. (Take the quiz: “What You Don’t Know About Biofuel.”)
The study’s lead author, UNL agronomy and horticulture assistant professor Adam Liska, declined to be interviewed by phone. In an email, he said that additional unpublished data shows that when both the actual corn and the corn residue are removed, “there is a net loss of soil carbon and there is also an absolute loss of soil carbon to the atmosphere.” In contrast, if only the corn itself was harvested for biofuel, on average the carbon going into the atmosphere would be canceled out by the amount going into the soil. (See related story: “Squeezing Gasoline from Plants.”)
The corn residue study, which was funded by a three-year, $500,000 grant from the U.S. Department of Energy, could signal a major problem for the nascent biofuels industry, which is heavily invested in using such waste material as a way to avoid competing for food supply with the use of actual corn.
Paul Winters, an official with the Biotechnology Industry Association, a biofuels trade group, said that corn residue is expected to provide three billion gallons of biofuel by 2022, or about 20 percent of the total production of cellulosic ethanol—that is, fuel produced from the inedible parts of plants. The study has no implications for materials such as switchgrass, a plant that is cultivated specifically for fuel. “You’re just harvesting the top, not disturbing the soil and the carbon in it,” Winters explained.
But Winters found fault with the UL study, saying that the computer model didn’t take into account the varying soil and other conditions in individual cornfields, or the careful efforts by biofuel producers to work with farmers to monitor how harvesting corn residue affected the carbon content of the soil. “The companies who are doing it now only take about 25 percent [of the corn residue],” he said. “They leave 75 percent on the ground.” (See related story: “U.S. Drought Fuels Debate on Ethanol.”)
John Sheehan, an engineer, biofuels entrepreneur and former researcher for the National Renewable Energy Laboratory who helped lead key research on the use of corn residue, said that he planned to contact Liska and raise questions about his methods. Sheehan said the study’s relatively short 10-year time scenario gave a misleading impression of the proportion of carbon that ended up in the atmosphere. The loss of soil carbon is highest in the first few years when corn residue is harvested, but it tends to decrease over a 20- to 30-year period, he said.
Liska “is using the most extreme response of the system as an indicator,” Sheehan said.
Sheehan also argued that the UNL researchers’ new model for calculating soil carbon loss failed to take into account variations in microbial activity and respiration rates in different corn fields, which are influenced by how farmers till the soil. “The respiration for aggressively tilling, versus conservation tillage, is very different,” he said. That, in turn, could produce big variations on how much carbon is stored or released. (Share your thoughts: “What Breakthroughs Do Biofuels Need Now?“)
In a second e-mail, Liska defended his team’s use of the shorter time frame. “Everyone really wants to know how these systems will perform in the first 10 years,” he said. He said that biofuels makers could switch to another source of material for fuel, or else plant cover crops in the fields to mitigate carbon loss. “The carbon lost in any residue that is removed must be either replaced or off-set somewhere else in the system,” he wrote.
Tuesday, April 22, 2014 | By Great Energy Challenge | No Comments
Forty-four years ago today, Denis Hayes convened the very first Earth Day, an event that drew millions to events across the United States and heralded a new global awareness of the need to preserve our natural resources.
Hayes is now at the vanguard of an effort to rethink our buildings and, by extension, our growing cities. More than two thirds of the world’s population is expected to live in urban areas by 2050. The planning decisions made in those cities will have a lasting impact on the well-being of people within them. (See related story: “IEA Report Offers Prescription to Ease Urban Transit Congestion.”)
Hayes is thinking about those planning challenges and how best to address them. As CEO and president of the Bullitt Foundation, which promotes sustainable communities in the U.S. Pacific Northwest, Hayes recently presided over the construction of what the foundation bills “the world’s greenest commercial building.” Indeed, the Bullitt Center in Seattle generates as much energy as it uses, thanks to a solar array on its roof and a staggering host of energy- and water-efficient design features. Per square foot, the Bullitt Center uses about one-fourth the energy of a building that is certified LEED Platinum, the highest level of the most commonly recognized building sustainability standard.
Completed last year, the Bullitt Center is now in the running to be the first commercial building to gain certification under the Living Building Challenge, a rigorous standard that has been fully attained by only five facilities worldwide to date. Hayes spoke with the Great Energy Challenge blog on the eve of Earth Day about the day’s significance and about his new efforts at Bullitt.
[This conversation has been condensed and edited.]
When you think about the first Earth Day in 1970, what memory comes to mind first?
The sheer scope. We knew we had a huge number of events that would be taking place, but until something happens, you never know how many people are going to show up. It’s not like a concert where there are tickets beforehand: People either come, or they don’t. Unlike [other marches in those activist years], this was something that wasn’t a focused event that would be drawing people from around the countryside, and even across the country, to a single location. We were having thousands of things taking place.
It could have been a million people and still we would have thought it was successful. When the wire services finally started toting it up and estimating it at 20 million, we were just blown away.
I think that’s the thing that impressed me most. The thing that maybe had the single greatest emotional impact—people say that fear of speaking in public is second to, or sometimes greater than, the fear of death. When I climbed up onto a platform that must have been 50 feet high in Central Park and looked out on a crowd that was stretching down into the streets—it was more than a million people concentrated—that was genuinely awesome. It was a powerful day.
Denis Hayes organized the first Earth Day. Now he is out to earn a landmark certification for his organization’s super-efficient office building in Seattle. (Photograph by Nic Lehoux)
When you think about the fact that this is now an institution, a day we mark every year that has evolved, what do you think of it now—what it means, and what it should mean?
It always had a multitude of things within it. Earth Day was about a value system and a vocabulary that allowed people to think about that value system that just didn’t exist before. It was changing air pollution from the smell of prosperity, the smell of progress, into a threat to human health that is an unnecessary aspect of the industrial production process. Different communities would choose different things that they focused on [lead paint, pesticides, endangered species].
All of that stuff came together around a unified value system. The event has certainly evolved as we’ve taken it international, and in some cases it’s undoubtedly been abused. One year the principal sponsor of Earth Day in Houston was Enron, which is not exactly a full buy-in to the value system we were trying to provoke [laughing]. But it is what it is around the world, and you learn to live with things that have a degree of cognitive dissonance to it.
As we move toward the 50th anniversary in 2020, I think we have a chance to once again to redefine it. You come in with a tailwind when you have the 50th anniversary of anything, and in this instance we hope to move it away from a day and into a full month of different kinds of things circling the world, everything from protecting big game on the Serengeti to talking about the impacts of poverty and war on the global environment to what have you. Just keeping this stuff in the public attention long enough in our increasingly attention-deficit-disordered digital world to have people think about it and ask what it means for them.
What was the thinking behind how you built the Bullitt Center?
The objective in this whole process of building a living building that responds to its environment [is] to design a building that is appropriate to Seattle and Vancouver and Portland but is not, if you will, a building that is the common building of the world: a glass sheath superstructure that pours a lot of energy into it in Phoenix to cool it and a lot of energy into it in Minneapolis to heat it. Rather, [it is] a building that, by being designed for the specific location that it’s in, can be much more adaptive to nature and working with nature instead of trying to fight it.
This is a big part of what the [Bullitt] foundation is about: How do you create model cities as the human population is on this vast migration to cities all over the planet. How do you create cities that work and are not so vastly resource-intensive. And another part was just walking that talk ourselves. We were in a wonderful old charming carriage house that had zero insulation . . . It was cold as hell in the winter despite the fact that we had electrical resistance heating, and breathtakingly hot in the summer. [Other green structures in Seattle] didn’t seem to us to be pushing the boundaries at all. So we said, instead of waiting for somebody to do it and just going and leasing it, why don’t we get out and push them ourselves.
Even though it has no air conditioning, Hayes says, the Center is the most comfortable office building in town during the summer. (Photograph by Nic Lehoux)
What did you learn from the process? I saw a talk of yours where you discussed challenges with the water system.
We’re using rainwater for potable drinking water, [putting] it through an activated charcoal filter to take out anything that might be dissolved in it. We then put it through increasingly fine ceramic filters that take out not just bacteria but that take out viruses. Then, in case we missed anything, we put it through ultraviolet radiation.
Then we’ve got this water that is pure, far purer than the driven snow, and we were required by the safe drinking water act to chlorinate it.
It had a degree of irony to it, but at the end, we appealed it [to various agencies] and as it turned out, there was a reason for the rule. There have been people [who have gotten sick from wells at individual houses] because microorganisms had gone up through the taps and down into the pipes from that direction . . .The odds of that happening are miniscule, but we’re a foundation. If it happened, we would be viewed as a deep pocket that people might sue, and besides that there’s no flexibility under the safe drinking water act . . . We just chlorinate it and then put charcoal filters on each of the taps, and take the chlorine back out before it comes out of the tap.
[The Center also used a window system designed in Germany by the company Schüco that was not available in the United States, so Bullitt licensed the design for local production.] I have to confess, I was worried about this. We’re moving from a gigantic multi-billion-dollar company sending its intellectual property to a good but small little enterprise up in Everett, Washington. If this didn’t work, then we were investing a whole lot of money in something that would dramatically undercut [the] energy statistics that allowed us to have no air conditioning and yet be the most comfortable office building in Seattle in the summer.
And it has worked perfectly. It’s just a tribute across the board to everybody who worked on the project, that they came to it with the sense that they were doing something that was new, original, important, and that they would bring a degree of craftsmanship to it and excellence in their work. That ability of people to become inspired by the vision—it was somehow really reassuring to know we still have that in the American character.
So now you have this amazing building, and the next step is to attain the Living Building Challenge certification. What remains to be done?
Mostly the passage of time. We needed to be 85 percent occupied [in order to qualify]. Commercial buildings often have floors or offices that are not occupied, so they couldn’t have a challenge that says you have to be 100 percent occupied 100 percent of the time. But we had to be above the 85 percent threshold which we achieved at the end of last year. Then we started monitoring ourselves [at that level of occupation] as of January 1.
In order to pass this “petal” [the Living Building Challenge term for a performance area], we need to use no more energy than is produced from sun beams that fall on the roof of this six-story building in the cloudiest major city in the contiguous 48 states. Going into this project, there were a great many people who thought that that was simply impossible.
We were required to get an EUI (energy use index measured in thousands of BTUs per square foot per year) of 16. The average office building in Seattle has an EUI of 95. It’s a pretty big leap. For the first year of operation, our EUI was 8.4. So we are very confident that we will be certified. We simply need to go through the process and keep ourselves on track.