Forum examines technologies aimed at reducing greenhouse gases
Scientists say advanced carbon capture, storage needed for coal
Lawrence Berkeley National Laboratory Director Steve Chu says both conservation and new energy sources are needed to address global climate change.
BY DAWN LEVY
In the coming century, climatologists predict a world that's 5 to 12 degrees Fahrenheit hotter. In America, that will likely mean a drier grain belt in the Midwest, endangered water supplies and forests in the West and stronger hurricanes in the Gulf Coast. Globally, sea levels are already at the upper limit of what the Intergovernmental Panel on Climate Change predicted a decade ago. Greenland is melting faster than scientists expected, and tropical corals struggle to survive as ocean chemistry changes. Increased damage from storms, floods and wildfires could lead to property loss and population displacement.
"Taking [climate change] seriously is really not a matter of personal virtue; it's hard economics," Steve Chu, director of the Lawrence Berkeley National Laboratory and 1997 winner of the Nobel Prize in physics, told an audience of 400 in the Frances C. Arrillaga Alumni Center Sept. 18 at the second annual research symposium hosted by the Global Climate and Energy Project (GCEP). "A dual strategy is needed, both conservation and developing new sources of energy."
Chu's keynote speech, titled "The Energy Problem, Our Current Choices and Future Prospects," set the stage for a three-day forum at which speakers from Stanford and elsewhere discussed diverse technologies aimed at reducing greenhouse gases.
Chu's talk explored technologies including nuclear, wind and solar. Nuclear fission supplies about 20 percent of U.S. electricity, and maintaining that level would require new, higher-energy plants to replace decommissioned ones and expanded solutions for dealing with waste. Technology to capture wind is well developed, he said, noting that the biggest turbines are able to extract 50 percent of the wind's kinetic energy, which is close to the theoretical upper limit of 59 percent. It's "not insurmountable" that solar power alone—captured in photovoltaic cells or biomass—could allow the entire world's population to rise to a European standard of living, he said. A giant weed called miscanthus could produce enough ethanol to eliminate our reliance on gasoline, he said, outlining a scenario in which one acre of the drought-resistant grass produced 3,000 gallons of ethanol.
While climate modelers disagree about the degree of climate-change effects, the press often misrepresents this debate among scientists, Chu said. "The press portrays it as, 'Well, we don't really know what's going to happen.' That part is true. But then the public automatically thinks, 'Well, maybe it's real, maybe it's not.' That part is not true. The spread is between bad and very, very bad."
Case in point: An optimistic model says the Sierra snowpack will decline by 30 to 70 percent, Chu said. A pessimistic model says it will decline by 73 to 90 percent. "If the Sierra snowpack declines by even 50 percent, this will have a profound impact on our water supply because the combination of dams and snowpack provides us with the water supply for the summer and late, early fall and even spring," he said.
Even in the face of uncertainty, climate change is affecting wallets. Chu cited a relationship between the temperature of water and the power of a hurricane: The warmer the water, the more ferocious the hurricane. Scientists say the relationship has a 90 percent chance of being correct. But with even a 50 percent chance of correctness, insurance companies adjust their rates.
"Changing the demand side of energy remains still the lowest-hanging fruit," said Chu, advocating conservation. "We use about 2 to 2.5 times more energy per person than Northern Europe."
On the supply side of energy, there's good news and bad news. "The good news is we won't run out of energy for the next 100 years or 300 or 500, probably 1,000 years—and that's [also] the bad news because that energy is in the form of fossil energy," Chu said. It exists as oil, natural gas and coal.
"The default source of energy in the United States is coal," Chu said. Natural gas prices have risen by a factor of four, driving Calpine, an energy-producing company, into bankruptcy because it can't run a cost-effective operation in the face of supply problems. "A number of natural gas power plants will be built in the coming 10 or 15 years, but unmistakably, coal plants will be increasing," he said, expressing optimism about the technical feasibility and safety of carbon capture and storage from coal plants.China's woes are our woes
"We cannot solve global warming without addressing China and India," said Doug Ogden, director of the China Sustainable Energy Program and another speaker at the symposium. Coal is "coming on strong" in these developing nations, he warned.
Four countries have most of the world's coal: the United States (27 percent), Russia (17 percent), China (13 percent) and India (10 percent). In 2002, coal accounted for 26 percent of world energy sources but a whopping 70 percent of China's energy—"the dirtiest energy mix on the planet," Ogden said. Coal is abundant and cheap—even free. Ogden mentioned a region where people just scoop up coal dirt from the hills and burn it for cooking.
Coal's convenience may contribute to the fact that 16 of the world's 20 most air-polluted cities are in China. Coal burning releases carbon dioxide and other greenhouse gases, sulfur oxides and other contributors to acid rain, and mercury and other health-harming contaminants. Each year, 400,000 Chinese die prematurely and 75 million suffer asthma attacks. And air pollution knows no borders. Ogden noted that 40 percent of U.S. mercury contaminants originate overseas.
Ogden presented an overview of governmental and grassroots efforts in China, which is ramping up its economy to achieve a Western standard of living while grappling with greenhouse gases produced through energy consumption. By 2020, as megacities rise, superfactories roil and automobiles rumble, China's gross domestic product is expected to quadruple and its energy consumption is expected to at least double.
Coal will continue to dominate China's future energy supply, Ogden said. For this reason, advanced coal technologies are essential. Carbon capture and sequestration may reduce emissions by 20 percent, he said.
China is likely to develop carbon-neutral coal, but only after the United States does, Ogden predicted. He said the Chinese tend to approach problems incrementally, "crossing the river by feeling the stones," rather than "leapfrogging across the United States."
Nonetheless, the Chinese have been champions of energy efficiency in some regards, Ogden said. Per capita, they consume about 10 times less energy than Americans. And the inefficient engines in typical sport utility vehicles will be illegal on Chinese streets starting in 2008.Other presentations
Scholars made two dozen other presentations at the symposium. Among them were Wes Hermann, a research and development engineer for GCEP, who gave an overview of the places where energy could be found and harnessed, such as ocean tides, and John Weyant, a Stanford professor (research) of management science and engineering, who explored the economic impacts of energy choices.
Christopher Edwards, an associate professor of mechanical engineering at Stanford, spoke about how to achieve ultra-high efficiency in engines by taking reactants to extreme states of energy density prior to conversion. His work may lay the foundation for engines that are 60 percent efficient. Compare that to today's engines, which are about 33 percent efficient.
Zhenan Bao, an associate professor of chemical engineering at Stanford, talked about solar cells made with carbon-based, or organic, materials. She spoke about improving the efficiency of organic solar cells both through development of new materials and understanding of the underlying physics governing device operation.
And geophysicist Mark Zoback, the Benjamin M. Page Professor of Earth Sciences at Stanford, spoke about sequestration of carbon dioxide in coal. Compared to sequestration in deep aquifers and depleted oil and gas reservoirs, sequestration in coal poses two major advantages, he said. Carbon dioxide stays in the coal because the gas sticks to the mineral surface, and injection of carbon dioxide may liberate coal-bed methane, offsetting the cost of sequestration and making available a relatively clean fossil fuel.