Paul Alivisatos Keynote:
“At a certain point, the risk becomes so high we have to act,” said Paul Alivisatos, referring to the risk of advanced climate change and geopolitical conflict as a result of the way humans are currently using energy.
In his talk at the Grand Challenges Summit, Alivisatos focused on energy efficiency and solar energy technology as two strategies for reducing our dependence on fossil fuels, which emit carbon dioxide—a greenhouse gas—when burned.
“We have a tremendous opportunity in the area of energy efficiency,” he said. As an example, he pointed to electricity use in California. From 1973 to 2008, electricity use grew steadily in the U.S.—except for California. Electricity use per person there held steady, even though the gross domestic product per person doubled. The reason? Refrigerators. California instituted standards for new refrigerators and offered rebates for discarding old inefficient ones. The rebates encouraged people not just to buy better refrigerators but also to actually unplug and get rid of the old ones. Over the years, the size of efficient refrigerators has grown and the price has fallen, all while using less energy per month than the inefficient variety. Alivisatos estimated that California’s refrigerator standards have prevented the need to build 40 power plants (1-gigawatt each).
Alivisatos also pointed out another area that’s ripe for an efficiency overhaul: buildings. Almost 40 percent of the energy used in the U.S. is used in residential, commercial and government buildings, and this energy use accounts for almost half (48 percent) of the country’s carbon emissions. With good planning and technology, new buildings can get by on just 10 to 20 percent of the energy used in traditional buildings, he said.
But energy efficiency alone cannot solve energy problems. On the supply side, renewable energy will play a role. Much of Alivisatos’s research is related to improving solar energy technology.
He said that it’s a myth that the technology is all ready and just waiting to be implemented. “We don’t have all the knowledge that we need,” he said. “New energy technologies are possible and necessary.”
Currently, renewable energy accounts for only 7 percent of the energy consumed in the U.S., and solar accounts for only 1 percent of that. Engineers have many problems to solve before that number can be ramped up. Solar cells need to be cheaper to produce and install. They need to be durable and easy to maintain. They need to wring more usable energy out of each photon of sunlight. They need to be made of materials that are available in mass quantities. Alivisatos said that in the 1960s, engineers were exploring many different compounds for use in photovoltaic solar cells, but that after the oil shock of the early 1970s, engineers began to focus solely on the handful of elements and compounds that were already showing promise. Alivisatos said scientists need to go back and look at some of the other alternatives because there aren’t enough of the workable compounds available worldwide to make widespread solar applications practical. “We need transformative solutions,” he said.
Alivisatos and his colleagues are looking into making solar cells using nanocrystals. “The smaller the crystal, the less total energy to make a perfect crystal,” he said. A question with nanocrystal solar cells is whether the electric charges generated would be trapped in the gaps between the tiny crystals.
Alivisatos hopes to solve this problem by using a material whose electron wavelength is larger than any of the “traps” between the nanocrystals. He made an analogy to potholes on a highway: “Your car will drive right over a pothole that is 1 millimeter wide.”
Another intriguing possibility Alivisatos is investigating is artificial photosynthesis. Plants produce fuel for themselves by using water, carbon dioxide and energy from the sun to produce hydrocarbons. Engineers are trying to figure out how to do the same thing. One advantage would be that the resulting hydrocarbon fuel could be used when needed, in contrast to current solar technology, which produces electricity that must be used right away or stored in expensive and unwieldy batteries.
Alivisatos said it’s an exciting time in energy research because environmental awareness is attracting people to science and engineering. “We have a generation of young students who are energized,” he said.
Robert Socolow Keynote:
“If you had to make a list of the grand challenges of the 21st century, how would you do it?” asked Robert Socolow.
In fact, Socolow was on the National Academy of Engineering committee that was asked to do just that a couple of years ago. He and his engineering colleagues came up with four broad categories—sustainability (or energy and the environment), health, vulnerability to human and natural disasters, and joy of living. Within these categories they came up with several specific challenges, such as “provide energy from fusion” and “make solar energy economical.”
In his talk at the Grand Challenges Summit, Socolow spoke primarily about the challenges related to energy and the environment.
“Achievement in one area brings challenge in that same area,” he began, giving electrification as an example. Providing electrical service to all Americans was a great engineering achievement of the last century, he said. Today, the United States uses 4 million kilowatt hours of electricity a year, or 4,000 terawatt-hours.
“We’re using fossil fuels as if there’s no tomorrow,” but there is a tomorrow,” he warned. “We’re dependent on an environmental system and we better admit it. We could screw it up.”
Like Paul Alivisatos, interim director of the Lawrence Berkeley National Laboratory, Socolow stressed the importance of energy efficiency. “With efficiency, it’s really quite credible that we will need no more than 4,000 terawatt-hours indefinitely. No one needs to build more [power plants] if efficiency is a serious proposition.”
One important and often overlooked aspect of energy efficiency is cogeneration—using the waste heat produced during electric generation to run industrial processes. “If engineers ran the world, we’d see a lot more cogeneration than we do now,” Socolow said.
Socolow said energy efficiency should be the first step for reducing carbon dioxide emissions. After that, he said, “It’s a free-for-all with nuclear, [carbon] capture and storage, and renewables.”
Carbon sequestration, or capture and storage, is a topic of particular interest to Socolow. “Can we have our cake and eat it too?” he asked. “When you burn fossil fuel, you produce carbon dioxide. There is no law that says carbon dioxide has to go to the atmosphere. It’s the lazy way.”
Instead, electric plants could capture the carbon dioxide and pump it into an underground layer of sediment and brine that’s overlain by an impermeable rock layer, he said.
When an audience member asked about the safety of carbon sequestration, Socolow replied that carbon dioxide leaking slowly to the surface would not be a hazard, but that a sudden loss of a lot of carbon dioxide could kill people. Because of this, he said, “There will be a strong bias toward the safest possible places for storage.”
Carbon sequestration is taking place on a small scale in several places already, he pointed out, including Norway, where a million tons of carbon dioxide a year have been buried in a briny sandstone layer undersea since 1996.
But what about the carbon dioxide emissions produced on the run, when fuel is burned by cars, trains and airplanes? One way to deal with this, according to Socolow, is to drastically reduce business travel and commuting.
“What if no one ever takes a trip they don’t want to?” he asked. Employees can telecommute to work and replace out-of-town meetings with teleconferencing. Engineers provided connectivity to the world in the last century, and people can now choose to be connected by teleconferencing rather than traveling. That connectivity has given people a planetary identity that Socolow said will help solve planetary problems.
“Meeting the grand challenges is going to be a lot easier now that large numbers of us feel we are citizens of the Earth,” he said.
In the panel discussion following Socolow’s talk, one theme was that energy challenges will require a multi-pronged approach. Emil Jacobs, vice president of research and development at ExxonMobil Research and Engineering Company, said, “There’s not a silver bullet here. We’re going to need a set of integrated solutions.”
Panelists seemed to agree that coal cannot be kept out of the mix, especially considering China’s vast reserves and growing economy. “We’re going to end up using coal,” Alivisatos said. “I’m concerned we’re not doing as much as we could to figure out the sequestration of carbon dioxide.”
Lincoln Pratson, associate professor of sedimentary geology at the Nicholas School for the Earth and the Environment at Duke, added, “Human ingenuity is the silver bullet to our grand challenges. Engineers are well positioned to lead the energy revolution. We’re not only going to meet those challenges, but exceed them. When you have such collective will power, I don’t see how you can fail.”