The contending needs for energy, food, sustainability and carbon reduction is an intensifying worldwide dilemma. The world’s population is growing and arable land is not, Tilman said. “Our population is at 6.3 billion people and heading toward 9 to 9.5 billion people,” he said. “We’re on a steep population growth curve. People around the world are consuming more of everything—not just food—and in the next 50 years the population will grow by another 3 billion more people.”
Rising incomes in developing parts of the world are allowing millions of people to transition from subsistence diets consisting of mainly grains to those including beef. This dietary shift is accelerating the demand for grain around the world at a rate that is “much greater than the world’s farms can produce,” and that is contributing to higher grain, land and food prices. Similar forces are driving energy prices higher. “Global energy consumption has doubled in the past 50 years, paralleling demand for food,” Tilman said, explaining that it will double again in the next 40 years.
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As this global competition for land materializes, there is a growing belief that producing fuel from traditional food crops is leading to corn, soybean oil and wheat being priced at the “energy equivalent” of $100-per-barrel oil. “There’s a fear that the food and energy sectors are becoming less independent and more joined,” the ecologist said.
In spite of these new pressures, Tilman said there is still enormous potential for next-generation biofuels if they can attain irrefutable low-carbon status. In addition to sharply cutting the fossil energy used to make biofuels—a would-be boon to biomass power—future producers must look to waste, agricultural residues and perennial energy crops grown on marginal, degraded or abandoned land to achieve conclusive low-carbon status, he said.
Tilman’s critics say those constrictions greatly diminish the role of biofuels in an increasingly carbon constrained world. In fact, Tilman admits that only 15 percent of the world’s current petroleum use could be offset by biofuels made from the environmentally friendly feedstocks he endorses.
Tilman is best known in the biofuels industry for his groundbreaking work with mixed prairie grasses for ethanol production. The Cedar Creek Biodiversity Experiment in Minnesota showed that the best yields of biomass energy per acre came from planting a combination of six perennial grass species together on unproductive land. Biofuels made from such high-diversity prairie grasses are carbon negative, in theory yielding 140 percent less greenhouse gases than gasoline, he said.
In the near future, Tilman said, it’s likely that the high price of food and food crops will make it increasingly less likely that farmers will dedicate grain to biofuels. “Economics and ethics will likely mean that our best land will go to food production with ag residue and dedicated energy crops like mixed prairie grasses grown on degraded land going to biofuels,” he said.
The Emergence of ‘New Agriculture’
Lynd, a leading biomass expert and co-founder of Mascoma Corp., asserted that land conversion theory is new, fragmented and still not wholly accepted by the scientific community. He said it’s decidedly premature to conclude that biofuels have no potential because of their superficially inherent connection to land-use change. “The space has been so incompletely explored,” he said, adding that the hope of “new agriculture” will provide previously unforeseen pathways around the land conversion dilemma.
New uses and new combinations for existing crops, as well as new crops and new crop systems will lead to exponential gains in productivity and biomass yields, Lynd said. “This new agriculture has only scant investigation worldwide.”
Looking at the broad issue of land use and resource consumption, Lynd said the world will not be able to produce its way out of the dilemma it now faces. He said it will require systemic redesign and radical changes in the way we use and produce energy. Ultimately, Lynd said, the continued investigation and development of biomass-based fuels, coupled with the limitless potential of new agriculture, hold great potential for dramatic land-use reductions while increasing the amount of land used for food, feed and fuel globally. “Even the most challenging cellulosic ethanol land conversion scenarios can achieve large carbon reductions given the motivation to achieve [that] outcome.”
Lynd said theories put forth by scientists such as Princeton’s Tim Searchinger do not embody the multiple systemic changes that are characteristic of sustainable transition paths. Translation: They lack hope and underestimate human ingenuity.
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