Why Biochar Isn’t Green
by Ozzie Zehner
UTNE Reader | Ozzie Zehner
While burning biochar, a rebranded term for charcoal, is less harmful than burning firewood, the fuel source would have a negative impact if produced on a large scale. “Green Illusions,” by Ozzie Zehner, is a practical, environmentally informed and lucid book that persuasively argues for a change of perspective on dealing with climate change. When contemplating alternative energy sources, such as biochar, one must understand its advantages as well as its limitations. The following excerpt comes from chapter 3, “Biofuels and the Politics of Big Corn.”
Even as legislators flood cellulosic ethanol and other biofuel initiatives with funding, some biofuel opportunities go overlooked, mostly because they are boring in comparison. For instance, wastewater treatment facilities release methane, the main component of natural gas, but more than 90 percent of America’s six thousand wastewater treatment plants don’t capture it. As mentioned earlier, methane is a major greenhouse gas liability since its venom is more potent than that of carbon dioxide. The sludge output of the average American yields enough power to light a standard compact florescent light bulb without end. So skimming the methane from an entire city’s wastewater would not only prevent harmful emissions but also would produce enough power to run the entire wastewater operation, perhaps with energy to spare. Although not a large-scale solution, captured biogas is a reminder of the modest opportunities to draw upon biofuels without advanced technology.
Another biofuel product that is now starting to gain more attention is a convenient replacement for firewood. Burning firewood directly is a relatively dirty practice, emitting dangerous particulates, hydrocarbons, and dioxins. In poor countries, the soot from firewood, waste, and dung kills about 1.6 million people per year. It’s also a local climate changer; soot darkens air and darker air absorbs more solar radiation. But there’s another way to extract energy from wood besides burning it—one that was widely employed before the Industrial Revolution but has since fallen by the wayside—charcoal (recently rebranded as biochar). When processors heat wood above 300 [degrees celcius] with limited oxygen, in a process called pyrolysis, it spontaneously breaks into three useful fuels: biochar, heavy oil, and flammable gas. In addition to its use as a fuel, farmers can till their soil with biochar in order to reduce methane and nitrous oxide greenhouse-gas emissions. Archaeologists uncovered ancient South American settlements in which buried charcoal has been sequestered for thousands of years, lending interest to the concept of using biochar as long-term storage for excess carbon.
In all, there may be many benefits to implementing biochar techniques in place of burning wood and waste for fuel directly. But this doesn’t make biochar a global solution. Cornell researcher Kelli Roberts points out that large-scale biochar production, as envisioned by some eager biofuel productivists, could yield unintended consequences. As with other biofuel methods, if producers clear virgin land to grow biochar inputs such as trees and switch grass, the process could ultimately do more harm than good. Alternately, if producers grow biochar crops on existing farmland, farmers may be forced onto new land, yielding the same negative effects on virgin land plus the added risk of local food price instability. And then there is the hitch with any method for increasing available energy supply—it inevitability leads to growth, expansion, and increasing energy consumption—a reminder that smart upgrades in energy practices for local communities may not have the same positive effects if implemented on a larger scale.
Excerpted from Green Illusions: The Dirty Secrets of Clean Energy and the Future of Environmentalism by Ozzie Zehner, with permission of the University of Nebraska Press. © 2012 by Ozzie Zehner. Available wherever books are sold or from the Univ. of Nebraska Press (800) 848-6224.
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