The holy grail of energy storage may lie in chemical bonds, but a process for making this happen remains unknown. All of the Nobel Laureates who weighed in yesterday on a chemical energy conversion panel agreed on this much. “Replacement of liquid fossil fuels is still in far reach,” said moderator Wolfgang Lubitz, director of the Max Planck Institute for Chemical Energy and Conversion. From there, the men focused on the major questions relating to solar power, endothermic reactions, rare metals, the ever-controversial nuclear energy and another ice age. Solar energy Gerhard Ertl (Nobel Prize in Chemistry, 2007) told the audience that nuclear fusion stood as the en vogue future energy source when he was studying in graduate school. “We are still waiting for solutions,” he said. In a similar way, solar energy holds great promise, but the storage problem remains unsolved. Hartmut Michel (Nobel Prize in Chemistry, 1988), the photosynthesis expert of the group, reminded that even nature struggled to get the most out of photosynthesis. “In photosynthesis, only 40 percent of the sunlight — energy-wise — is absorbed by the plants,” he said. Therefore, the chemists onstage at the 63rd Lindau Nobel Laureate meeting exhorted young researchers to search for a brand-new catalytic conversion process that could solve the sunshine enigma. Producing energy requires energy Richard Schrock (Nobel Prize in Chemistry, 2005) reminded everyone that whatever the next energy source revolution is, it will most likely still rely on endothermic reactions. “Nearly all conversion processes require energy,” he said. Even with ideas such as carbon dioxide conversion, “it’s a zero-sum game to talk about converting [it] catalytically or storing it.” He apologized for sounding pessimistic, but wanted to be sure the researchers in the audience felt the gravity of the situation. Running out of rare metals A young researcher wanted the Nobel Laureates to answer this question: “What happens when we run out of a rare metal like lithium used in batteries?” Schrock was quick to point out that “we don’t run out of elements, but we run out of concentrated forms of them—they are neither created nor destroyed.” Robert Grubbs (Nobel Prize in Chemistry, 2005) pointed out that researchers have already begun looking at non-rare metals as potential energy sources, too. The consensus seemed to be that humans will use whatever source is most plentiful and easiest to extract before moving on to alternatives. “Fortunately, a lot of these problems have to do with inorganic chemistry,” said Schrock, looking out over the audience. “So, go to it!” Not another Fukushima No open discussion of energy sources can completely avoid the nuclear question. So eventually the question snuck into the dialogue. “The problem is with nuclear waste — not the energy,” Ertl injected. Schrock acknowledged that while nuclear energy is no longer an option due to political forces in Germany, “nearly 75 percent of France runs on nuclear energy, and I think that’s a little-known fact.” As the discussion focused more on politics, Astrid Gräslund, professor biophysics at Stockholm University and co-organizer of the Lindau meeting, picked up her microphone. “One has to consider that this is the situation now,” she said. She explained that politics and public opinion are constantly in flux and that these changes should not influence science per se. And what about 1,000 years from now? As the panel drew to a close, a young researcher in the first row stood up and gave a proposition. He offered: Won’t this discussion seem a bit strange, if we think 1,000 years into the future, when we will most likely be depending exclusively on renewable energy? The Laureates exchanged a few glances. Michel spoke first. He pointed out that some research has hinted that the next ice age on Earth may occur in the not-so-distant future. “So Berlin may be covered with ice and we won’t even be able to think about this because we’ll be under ice,” he said, with a half-smile. “How long will it last?” Schrock asked his colleague. “About 80 to 90,000 years, maybe,” Michel answered. “Oh, good, problem solved,” said Schrock.