Scientists identify new implications of perennial bioenergy crops

March 1, 2011

Research shows a conversion from annual to perennial bioenergy crops has broader implications beyond just the impacts on carbon

A team of researchers from Arizona State University, Stanford University and Carnegie Institution for Science has found that converting large swaths of land to bioenergy crops could have a wide range of effects on regional climate. Download Full Image

In an effort to help wean itself off fossil fuels, the United States has mandated significant increases in renewable fuels, with more than one-third of the domestic corn harvest to be used for conversion to ethanol by 2018. But concerns about effects of corn ethanol on food prices and deforestation had led to research suggesting that ethanol be derived from perennial crops, such as the giant grasses Miscanthus and switchgrass. Nearly all of this research, though, has focused on the effects of ethanol on carbon dioxide emissions, which drive global warming.

“Almost all of the work performed to date has focused on the carbon effects,” said Matei Georgescu, a climate modeler working in ASU’s Center for Environmental Fluid Dynamics. “We’ve tried to expand our perspective to look at a more complete picture. What we’ve shown is that it’s not all about greenhouse gases, and that modifying the landscape can be just as important.”

Georgescu and his colleagues report their findings in the early online Feb. 28 edition of the Proceedings of the National Academy of Sciences. Co-authors are David Lobell of Stanford University and Christopher Field of the Carnegie Institution for Science, both located in Stanford, Calif.

In their study, the researchers simulated an entire growing season with a state-of-the-art regional climate model. They ran two sets of experiments – one with an annual crop representation over the central United States and one with an extended growing season to represent perennial grasses. In the model, the perennial plants pumped more water from the soil to the atmosphere, leading to large local cooling. 

“We’ve shown that planting perennial bioenergy crops can lower surface temperatures by about a degree Celsius locally, averaged over the entire growing season," Lobell said. "That’s a pretty big effect, enough to dominate any effects of carbon savings on the regional climate.” 

The primary physical process at work is based on greater evapotranspiration (combination of evaporated water from the soil surface and plant canopy and transpired water from within the soil) for perennial crops compared to annual crops. 

“More study is needed to understand the long-term implication for regional water balance," Georgescu said. "This study focused on temperature, but the more general point is that simply assessing the impacts on carbon and greenhouse gases overlooks important features that we cannot ignore if we want a bioenergy path that is sustainable over the long haul.”

Matei Georgescu, (480) 965-3770; Matei.Georgescu">">
David Lobell, (650) 721-6207; dlobell">">
Chris Field (650) 223-690, cfield">">

Media contact:
Skip Derra, Skip.Derra">">
(480) 965-4823

Director, Media Relations and Strategic Communications


Work of Regents' Professor Tom Moore is energy-focused

March 1, 2011

This article is part of a" target="_blank">series that looks at ASU's 2010 Regents' Professors and President's Professors.

Tom Moore is a rock star among scientists. One of the most highly cited international chemists, Moore’s 2001 paper, “Mimicking Photosynthetic Solar Energy Transduction,” co-authored with fellow professors Ana Moore and Devens Gust, helped set the stage for today’s research seeking innovative approaches to alternative energy. Download Full Image

While his colleagues describe him as “pioneering” and “legendary,” when you meet Moore his soft-spoken nature belies a man with little ego. He talks about his career as a series of unfolding events ignited by his own innate curiosity.

Moore came to ASU in 1976 from the University of Washington with his wife Ana, who he met in graduate school. Trained as a photobiologist – he focuses on the scientific study of the interactions of light and living organisms – Moore’s work dovetailed nicely with his wife’s, whose specialty is organic chemistry.

“Photosynthesis, the process that converts energy in sunlight to chemical forms of energy that can be used by biological organisms, powers the biosphere,” Moore says. “How do we take what nature does and improve upon it to meet human energy demands? The need for an alternative to fossil fuel as our primary source of energy is paramount. Reserves are limited, perhaps more than we realize, and they are polluting our planet and contributing to global warming.”

Shortly after arriving at ASU, the two Moores met Devens Gust and the three established a successful research partnership that focuses on biomimetic photosynthesis – best explained as the chemical mimicry of biological photosynthesis. By the mid-80s, their work was attracting millions in grant support and attention among international scientists seeking to develop alternative fuel sources derived from the sun.

Over the years, Moore, a fellow of the prestigious American Association for the Advancement of Science, and his colleagues have published more than 230 papers that have been cited more than 10,000 times by other scientists – an important indicator, says William Petuskey, professor and chair of the Department of Chemistry and Biochemistry, “of the strong influence of his work.”

When not in the lab, Moore is a dedicated teacher and mentor of both undergraduate and graduate students, having guided 20 doctoral students in chemistry over his career. It’s a role he takes great pride in.

Interest in alternative energy is at an all-time high among his graduate students, he says. While most undergraduates may be more focused on the present and their more immediate future, Moore relishes the challenge of helping them to become more critical thinkers. It’s imperative, he says, in a democracy.

“Policy is determined by the democratic process, which needs good information. It’s the university’s job to get that information out there,” Moore says. “The Internet has changed the ballgame in that information is everywhere. When I went to school, you learned things from a textbook or from peer-reviewed articles – sources that in most cases you could at least start by assuming were not going to be misleading. Today, it’s a big job to know whether information taken from the net is even right, not to mention whether stuff is important and what it means. Critical thinking was always a key to good science; today it is the crucial skill in processing information.”

Moore says, for example, he gets frustrated over the debate about whether burning fossil fuels is actually contributing to the warming of the planet.

“There is no doubt in the science. CO2 levels are going up and it is very straightforward – the increase is related to the burning of fossil fuels,” he says. “CO2 is a greenhouse gas, the Earth will warm, and it is warming. The questions are, ‘how much?’ and ‘what will it mean?’ The impact will be different in different areas and certainly developing countries will be most negatively affected.”

Moore, who says he “thinks about energy all the time,” says the drive to find a clean, renewable energy source should not be based solely on economics – although he’s a realist and knows that the cost-effectiveness of energy to power gross domestic product growth drives many decisions.

“Coal, oil and natural gas grow the GDP – let’s face it, the growth in our pension funds relies on a profitable Exxon Mobile,” he says. “We can minimize our dependence on foreign oil, but we have fossil fuel reserves right here in North America, including the very profitable but environmentally disastrous syncrude from Canada. If we don’t care about CO2, climate change or the consequences on the developing world, then finding an alternative energy solution in our lifetime may be unlikely.”

Yet Moore prefers to be optimistic, and that’s why he keeps working tirelessly to unlock the key to the sun’s energy creating power.

“When fluorocarbons were banned, it was not a huge change for people because there were alternatives,” he says. “If we do our job right, our research will have provided an alternative. Whatever causes us to wake up, we will be ready.”