Commencement Speaker Daniel Yergin Visits Caltech

This year's commencement speaker, Pulitzer Prize-winning energy expert Daniel Yergin, came to campus a day early to get better acquainted with Caltech's faculty and students, and in particular to learn more about Caltech's energy initiatives.

Yergin spent the morning touring JPL. "I was especially excited to see the Curiosity Rover," says Yergin. "Also, it was remarkable to actually be in the space flight operations center, having seen it in the news so often before."

In the afternoon at Caltech, Yergin specifically asked to spend most of his time meeting with people to learn more about their work. "Caltech is such a preeminent institution," says Yergin, "and I thought that coming for commencement provided a wonderful opportunity to get a sense of the culture here. Caltech has such a large impact for such a small place, and I wanted to experience more of it."

Of course, high on Yergin's agenda was the opportunity to meet with those engaged in research on sustainable energy. A mid-afternoon meeting at the Resnick Sustainability Institute yielded a lively exchange between Yergin, graduate students, and postdoctoral fellows about the future of energy research and the geopolitics of energy policy. Asked what he had learned from writing The Prize and The Quest, his two bestselling volumes on the history of oil, gas, and energy policy, Yergin replied that the main takeaway was that throughout the history of the industry, "everybody will feel they know where everything related to energy is going to go, and then in four or five years, something comes along to completely change it."

Stressing the increasingly important role of innovation in energy technology and geopolitics, especially as global markets continue to grow, Yergin says, "The challenge is that energy is a long-range investment and a long-range research project. It's very hard to say what is actually going to make a difference, but the cumulative impact of what you and people like you are doing is absolutely necessary. It's these kind of centers that will map the future of energy policy. The innovation is not going to come from big companies; it's going to come from universities and research institutes.  So keep doing what you're doing."

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JCAP Stabilizes Common Semiconductors For Solar Fuels Generation

Caltech researchers devise a method to protect the materials in a solar-fuel generator

Researchers around the world are trying to develop solar-driven generators that can split water, yielding hydrogen gas that could be used as clean fuel. Such a device requires efficient light-absorbing materials that attract and hold sunlight to drive the chemical reactions involved in water splitting. Semiconductors like silicon and gallium arsenide are excellent light absorbers—as is clear from their widespread use in solar panels. However, these materials rust when submerged in the type of water solutions found in such systems.

Now Caltech researchers at the Joint Center for Artificial Photosynthesis (JCAP) have devised a method for protecting these common semiconductors from corrosion even as the materials continue to absorb light efficiently. The finding paves the way for the use of these materials in solar-fuel generators.

"For the better part of a half century, these materials have been considered off the table for this kind of use," says Nate Lewis, the George L. Argyros Professor and professor of chemistry at Caltech, and the principal investigator on the paper. "But we didn't give up on developing schemes by which we could protect them, and now these technologically important semiconductors are back on the table."

The research, led by Shu Hu, a postdoctoral scholar in chemistry at Caltech, appears in the May 30 issue of the journal Science.

In the type of integrated solar-fuel generator that JCAP is striving to produce, two half-reactions must take place—one involving the oxidation of water to produce oxygen gas; the other involving the reduction of water, yielding hydrogen gas. Each half-reaction requires both a light-absorbing material to serve as the photoelectrode and a catalyst to drive the chemistry. In addition, the two reactions must be physically separated by a barrier to avoid producing an explosive mixture of their products.

Historically, it has been particularly difficult to come up with a light-absorbing material that will robustly carry out the oxidation half-reaction. Researchers have tried, without much success, a variety of materials and numerous techniques for coating the common light-absorbing semiconductors. The problem has been that if the protective layer is too thin, the aqueous solution penetrates through and corrodes the semiconductor. If, on the other hand, the layer is too thick, it prevents corrosion but also blocks the semiconductor from absorbing light and keeps electrons from passing through to reach the catalyst that drives the reaction.

At Caltech, the researchers used a process called atomic layer deposition to form a layer of titanium dioxide (TiO2)—a material found in white paint and many toothpastes and sunscreens—on single crystals of silicon, gallium arsenide, or gallium phosphide. The key was that they used a form of TiO2 known as "leaky TiO2"—because it leaks electricity. First made in the 1990s as a material that might be useful for building computer chips, leaky oxides were rejected as undesirable because of their charge-leaking behavior. However, leaky TiO2 seems to be just what was needed for this solar-fuel generator application. Deposited as a film, ranging in thickness between 4 and 143 nanometers, the TiO2 remained optically transparent on the semiconductor crystals—allowing them to absorb light—and protected them from corrosion but allowed electrons to pass through with minimal resistance.

On top of the TiO2, the researchers deposited 100-nanometer-thick "islands" of an abundant, inexpensive nickel oxide material that successfully catalyzed the oxidation of water to form molecular oxygen.

The work appears to now make a slew of choices available as possible light-absorbing materials for the oxidation side of the water-splitting equation. However, the researchers emphasize, it is not yet known whether the protective coating would work as well if applied using an inexpensive, less-controlled application technique, such as painting or spraying the TiO2 onto a semiconductor. Also, thus far, the Caltech team has only tested the coated semiconductors for a few hundred hours of continuous illumination.

"This is already a record in terms of both efficiency and stability for this field, but we don't yet know whether the system fails over the long term and are trying to ensure that we make something that will last for years over large areas, as opposed to weeks," says Lewis. "That's the next step."

The work, titled "Amorphous TiO2 Coatings Stabilize Si, GaAs, and GaP Photoanodes for Efficient Water Oxidation," was supported by the Office of Science of the U.S. Department of Energy through an award to JCAP, a DOE Energy Innovation Hub. Some of the work was also supported by the Resnick Sustainability Institute and the Beckman Institute at Caltech. Additional coauthors on the paper are graduate students Matthew Shaner, Joseph Beardslee, and Michael Lichterman, as well as Bruce S. Brunschwig, director of the Molecular Materials Resource Center at Caltech.

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Stabilizing Semiconductors for Solar Fuels Generation
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Resonate Awards Honor Global Champions of Sustainability

New awards granted by the Resnick Sustainability Institute recognize emerging global innovators in energy science and environmental policy.

On May 19, the Resnick Sustainability Institute at Caltech announced five innovators in the fields of energy science and sustainability as the inaugural winners of the Resonate Awards.

As part of the Resnick Sustainability Institute's mission to advance research in renewable energy and sustainability science, the new award is meant to draw attention to important work in green innovation, which is often overlooked among other advances in technology. The Resonate Award recognizes early career researchers and emerging leaders in sustainability who have the potential to make a significant global impact but have not yet received widespread recognition.

With the award, the Resnick Sustainability Institute will honor those who have contributed to green solutions in a variety of fields including science, technology, economics, and public policy.

"We are committed to finding scalable long-term solutions to some of the biggest energy and environmental problems facing the world today," says Harry Atwater, the Howard Hughes Professor of Applied Physics and Materials Science and director of the Resnick Sustainability Institute. "We started the Resonate Awards because we realized that there is an urgent need to recognize and promote the advances of sustainability innovators."

After receiving more than 50 candidate nominations last fall, an internal review panel narrowed the field to 12 finalists, from which the five 2014 Resonate Award winners were selected by a panel of judges from industry, academia, international governments, and journalism:

  • Thomas Francisco Jaramillo, an assistant professor in the Department of Chemical Engineering at Stanford University, received the Resonate Award "for catalyzing chemical reactions for renewable energy production and storage." Jaramillo's work has led to the discovery of stable earth-abundant catalysts that drive chemical reactions for renewable hydrogen production from water and the sustainable conversion of carbon dioxide into fuels and chemicals.
  • Sarah Kearney, the founder and executive director of PRIME Coalition, was honored "for designing flexible impact-focused investment models to fund innovative ventures offering scalable solutions to global social problems." At PRIME Coalition, a membership-based nonprofit, Kearney's work links philanthropists and investors to high-risk, high-reward startups addressing global environmental and social problems.
  • Shinichi Komaba, a professor of applied chemistry at Tokyo University of Science and project professor at Kyoto University, was selected "for developing materials for safe, efficient battery storage for electric vehicles and the grid." Komaba's research in the field of energy storage is aimed at making batteries safer and more efficient—an important step in the design of zero-emission vehicles.
  • Javad Lavaei (PhD '11), an assistant professor in the Department of Electrical Engineering at Columbia University, was chosen "for building a computational backbone to transform the power grid into one that is flexible, smart and dynamic." Lavaei's interdisciplinary work in math, control and optimization theory, economics, and computer science provides a computational framework for incorporating renewable energy into the electricity grid in an efficient and cost-effective manner.
  • Jay Whitacre, an associate professor at Carnegie Mellon University and founder and chief technology officer of Aquion Energy was awarded "for research and development of scalable, environmentally benign, low-cost grid-scale energy storage." Whitacre's contributions to finding safe, reliable, cost-effective, and sustainable energy storage solutions resulted in the development of a sodium-based electrolyte battery technology that can be made with low-cost materials.

"Each of these extraordinary sustainability champions has combined academic and professional excellence with imagination and boldness to not only envision but create solutions to the pressing challenges that face us today and tomorrow," Atwater says.

The awards will be presented at the Fortune magazine Brainstorm GREEN conference this week in Laguna Niguel, California. In addition to receiving their honors, the awardees will also give presentations at the conference.

For more information about the awards, please see the Resonate Awards webpage.

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Awards Honor Global Champions of Sustainability
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New Gift Helps Caltech Address Global Challenges in Clean Energy and Sustainability

A new $15 million gift by Lynda and Stewart Resnick in support of the Resnick Sustainability Institute at Caltech will help scientists and engineers advance research aimed at helping humanity sustainably meet its needs for energy, food, clean water, and a healthy environment. This brings total funding of the Resnick Sustainability Institute to nearly $60 million, beginning with a foundational $21 million gift from the Resnicks in 2009.

Since its founding, the Resnick Sustainability Institute's researchers have pursued wide-ranging investigations in energy science and technology. Support from the Resnick Sustainability Institute has enabled advances in distributed wind-energy systems, batteries and fuel cells, smart grid systems, record-breaking solar photovoltaics, pioneering technologies for deriving fuels from sunlight, and chemical catalysts that convert waste materials to biofuels.

"Securing a sustainable source of energy for future generations is the most fundamental issue facing mankind," says Stewart Resnick, Caltech senior trustee and the chairman and co-owner, along with his wife, Lynda, of Roll Global, a private holding company with interests in fresh fruit and tree nuts, premium beverages, and floral delivery. "It is at the heart of all of the other long-term sustainability challenges such as feeding the world's population and providing people with access to clean water and health care. We see funding Caltech's efforts as an investment in our future, not just as philanthropy." Caltech, he adds, is uniquely qualified to address the problems that challenge our world: "The intimacy of its campus allows many diverse scientific disciplines to easily and regularly come together for a kind of innovative thinking that is hard to achieve elsewhere."

Inspired by the success of the first generation of research at the Resnick Sustainability Institute, $3 million of the Resnicks' new gift establishes the Resnick Institute Innovation Fund, which will support new ideas in clean-energy and sustainability science that have the potential for rapid impact. The fund will initially focus on two programs. The first is the Resnick Sustainability Institute's newly launched Resonate Awards program, which will honor creative breakthroughs in energy and sustainability science made by early-career scholars worldwide. The second, a postdoctoral scholar program offering distinguished fellowships, will help bring particularly outstanding young leaders in energy and sustainability research to Caltech to create a corps of top innovators who will have the freedom to focus exclusively on research.

In keeping with the Resnick Sustainability Institute's innovative programming, a major portion of the gift—$12 million—establishes the Lynda and Stewart Resnick Matching Program. This program will provide a one-to-one match for contributions that create new, endowed funds within the Resnick Sustainability Institute, and thus will represent a potential $24 million in long-term funding. Through the Resnick match, a new donation that would have supported one graduate or postdoctoral fellowship, for example, will now provide for two. Because each endowed fund will be managed to work in perpetuity, each will support energy and sustainability research, education, and outreach over decades.

"The toughest issues in sustainability are not short-term, two- or three-year problems," says Harry A. Atwater, Howard Hughes Professor of Applied Physics and Materials Science and director of the Resnick Sustainability Institute. "They require a 50-year view and need to be approached with creativity and a transformative perspective. Lynda and Stewart Resnick's generosity and vision are critical to the future."

"The Resnick Sustainability Institute has helped to transform the landscape for energy research and education at Caltech," says Edward Stolper, interim president, and provost. "Creating a central hub to connect all our faculty who work on energy has accelerated the pace of discovery." Stolper continues, "We are grateful to Stewart and Lynda for their longstanding and generous support of Caltech. The Resnicks' new gift continues their tradition of strong support for faculty research and provides for new outreach programs so that the results of energy research can be shared with audiences worldwide."

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On the Front Lines of Sustainability

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On the Front Lines of Sustainability
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The chemical processes used to make products ranging from pharmaceuticals to perfumes can have a harmful impact on the environment. However, Caltech chemist and Nobel laureate Robert Grubbs has spent several decades developing catalysts—compounds that speed up a chemical reaction—that can make the synthesis of these products more efficient and ecologically friendly, ultimately reducing their environmental footprint. Similarly, chemist Brian Stoltz is developing new strategies for the synthesis of compounds needed in the chemical, polymer, and pharmaceutical industries. His new processes rely upon oxygen and organometallic catalysts—greener alternatives to the toxic metals that are normally used to drive such reactions.

Switching from paper files to cloud-based data storage might seem like an obvious choice for sustainability, but can we further reduce the environmental impact of storing data? The theoretical work of engineer and computer scientist Adam Wierman suggests that with the right algorithms, we can. Today, data centers—the physical storage facilities Wierman calls the "SUVs of the Internet"—account for more than 1.5 percent of U.S. electricity usage. And as more data goes online, that number is expected to grow. Wierman's work helps engineers design algorithms that will reroute data, with preference to centers that use renewable energy sources like wind and solar.

Energy from the sun—although free and abundant—cannot easily be stored for use on dreary days or transported to cloudy regions. Caltech engineer and materials scientist Sossina Haile hopes to remove that barrier with a specific type of solar reactor she has developed. The reactor is lined with ceramic cerium oxide; when this lining is heated with concentrated sunlight it releases oxygen, priming it to remove oxygen from water molecules or carbon dioxide on cooling, thus creating hydrogen fuel or "syngas"—a precursor to liquid hydrocarbon fuels. This conversion of the sun's light into storable fuel could allow solar-derived power to be available day and night.

Caltech student participants in the Department of Energy's biennial Solar Decathlon competition set out to prove that keeping a house lit up, cooled down, and comfortable for living is possible—even while off the grid. The Techers teamed up with students at the Southern California Institute of Architecture to create CHIP and DALE, their entries in the 2011 and 2013 competitions, respectively. These functional and stylish homes, powered solely by the sun, were engineered with innovative components including a rainwater collection system and moving room modules that optimize heating and cooling efficiency. 

Although many of us take the nearest bathroom for granted, working toilets require resources and infrastructure that may not be available in many parts of the world. Inspired by the "Reinventing the Toilet Challenge" issued by the Bill and Melinda Gates Foundation, environmental scientist and engineer Michael Hoffmann and his team applied his research in hydrogen evolution and water treatment to reengineer the toilet. The Caltech team's design—which won the challenge in 2012—can serve hundreds of people each day, treat its own wastewater, and generate electricity, providing a sustainable and low-cost solution to sanitation and hygiene challenges in the developing world. Prototypes are being tested in India and China for use in urban and remote environments in the developing world.  

Geophysicist Mark Simons studies the mechanics of the Earth—furthering our understanding of what causes our planet to deform over time. His research often involves using satellite data to observe the movement associated with seismic and volcanic activity, but Simons is also interested in changes going on in the icy parts of Earth's surface, especially the dynamics of glaciers. By flying high above Iceland's ice caps, Simons and his colleagues can track the glaciers' melt-and-freeze response in relation to seasonal and long-term variations in temperature—and their potential response to climate change.

The production of industrial nitrogen fertilizer results in 130 million tons of ammonia annually—while also requiring high heat, high pressure, and lots of energy. However, in a process called nitrogen fixation, soil microorganisms that live near the roots of certain plants can produce a similar amount of ammonia each year. The bugs use catalysts called nitrogenases to convert nitrogen from the air into ammonia at room temperature and atmospheric pressure. By mimicking the behavior of these microorganisms, Jonas Peters and his colleagues synthesized an iron-based catalyst that allows for nitrogen fixation under much milder conditions. The catalyst could one day lead to more environmentally friendly methods of ammonia production.

Traditionally, the photovoltaic cells in solar panels have been expensive and have had limited efficiency—making them a hard sell in the consumer market. Engineer and applied physicist Harry Atwater's work suggests that there is a thinner and more efficient alternative. Atwater, who is also the director of the Resnick Sustainability Institute, uses thin layers of semiconductors to create photovoltaics that absorb sunlight as efficiently as thick solar cells but can be produced with higher efficiency than conventional cells.

The generation of chemical fuels from sunlight could completely change the way we power the planet. Researchers in the laboratory of Caltech chemist Nate Lewis are working to develop different components of a fuel-producing device that could do just that called a photoelectrochemical cell. The cell would consist of an upper layer that could absorb sunlight, carbon dioxide, and water vapor, a middle layer consisting of light absorbers and catalysts that can produce fuels, which are then released through the device's bottom layer. When such a device is created, the Joint Center for Artificial Photosynthesis, of which Lewis is the scientific director, aims to ease the transfer of these technologies to the private sector. 

Clean energy from the wind is a promising alternative to fossil fuels, but giant pinwheel-like wind turbines that are common on many wind farms can create dangerous obstacles for birds as well as being an unpleasant addition to a landscape's aesthetic. To combat this problem, Caltech engineer and fluid-mechanics expert John Dabiri is testing a new design for wind turbines, which looks a bit like a spinning eggbeater emerging from the ground. By placing these columnar vertical wind turbines in a careful arrangement—an arrangement inspired by the vortex of water created behind a swimming fish—his smaller vertical turbines create just as much energy as the "pinwheels" and on a much smaller land footprint.

In the early 1990s, Caltech bioengineer Frances Arnold pioneered "directed evolution"—a new method of engineering custom-built enzymes, or activity-boosting proteins. The technique allows mutations to develop in the enzyme's genetic code; these mutations can give the enzyme properties that don't occur in nature but are beneficial for human applications. The selectively enhanced enzymes help microbes turn plant waste and fast-growing grasses into fuels like isobutanol, which could sustainably replace more than half of U.S. oil imports, Arnold says. She's also exploring ways the technique could help factories to make pharmaceuticals and other products in much cleaner and safer ways.

The combined research efforts of Richard Flagan, John Seinfeld, Mitchio Okumura, and Paul Wennberg aim to improve our understanding of various aspects of climate change. Chemical engineer Flagan is pioneering ways to measure the number and sizes of particles in the air down to that of large molecules. Seinfeld studies where particles in the air come from, how they are produced by airborne chemical reactions, and the effect they have on the world's climate. Chemical physicist Okumura studies the chemical reactions that occur when sunlight encounters air pollution and results in smog. Wennberg, an atmospheric chemist, studies the natural and human processes that affect smog formation, the health of the ozone layer, as well as the lifetime of greenhouse gases. Wennberg and his colleagues join a legacy of Caltech researchers who have improved air quality through key discoveries about pollution.

In the past, researchers have discovered materials that can act as reaction catalysts, driving sunlight to split water into hydrogen fuel and an oxygen byproduct. However, these wonder materials are often expensive and in short supply. The research of chemist Harry Gray, who leads the National Science Foundation-funded Center for Chemical Innovation in Solar Fuels program, tests combinations of Earth-abundant metals to search for an inexpensive catalyst that boosts the water-splitting reaction with the sun. Gray also coleads an outreach project in which students in the classroom can participate in the race for solar fuels by testing thousands of materials and reporting their results to Caltech researchers.

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Although Earth Week has officially come to a close, Caltech's commitment to sustainability continues. In this feature, you will meet some of the researchers at Caltech whose work is contributing to a greener planet and to the long-term improvement of our global environment.

Research for a Greener Future

Today's Earth Week feature highlights three cross-disciplinary research centers where Caltech scientists and engineers collaborate on projects that will have a positive impact on energy, the environment, and Earth's sustainable future.

The Ronald and Maxine Linde Center for Global Environmental Science

The Ronald and Maxine Linde Center for Global Environmental Science brings together researchers from chemistry, engineering, geology, environmental science, and other disciplines, with the goal of understanding the global environment and developing solutions to complex environmental problems. Linde Center scientists investigate how Earth's climate and its atmosphere, oceans, and biosphere have varied in the past and how they may change in the future. They are working on solutions to vexing challenges in climate change prognosis and mitigation, and to improve air and water quality.

The Linde Center was established thanks to support from Caltech alumnus and trustee Ronald Linde and his wife, Maxine. Led by acting director Paul Wennberg, Caltech's R. Stanton Avery Professor of Atmospheric Chemistry and Environmental Science and Engineering, the center is housed in the Linde + Robinson Laboratory, which was constructed in 1932 as an astronomy lab. The building recently underwent extensive renovations, to become one of the nation's most energy-efficient laboratories and the first existing historic building to earn the LEED Platinum rating. In 2012, Linde + Robinson was honored with a 2012 Los Angeles Conservancy Preservation Award for the "exceptionally creative and sensitive approach" of the renovation. The project, the conservancy noted, "not only preserved the building's unique historic features, it found brilliant new uses for them—particularly the solar telescope, built as the centerpiece of the original building but functionally obsolete. Now it tracks the sun and uses the light it captures for both illumination and exploration."

Resnick Sustainability Institute

Caltech's Resnick Sustainability Institute was created to fund and foster innovative Caltech-based sustainability and energy-science research collaborations with the potential to develop renewable-energy technologies that may one day help solve our global energy and climate challenges. The mission of the institute, which was founded with a generous gift from Stewart and Lynda Resnick, spans research, education, and communications. Current projects include research into energy generation, such as advanced photovoltaics, photoelectrochemical solar fuels, cellulosic biofuels, and wind-energy system design; energy conversion work on batteries and fuel cells; and research into technologies for energy efficiency and management, such as fuel-efficient vehicles, green chemical synthesis, and thermoelectric materials, as well as advanced research on electrical grid control and distribution.

This year the Resnick Sustainability Institute debuted two new initiatives: the Resonate Awards, which honor breakthrough achievements in energy science and sustainability, and a prize postdoctoral fellowship program. The Resonate Award winners will be announced at the Fortune Brainstorm GREEN conference in May 2014, and the inaugural class of postdoctoral fellows will be announced this fall.

Led by Harry Atwater, Caltech's Howard Hughes Professor and professor of applied physics and materials science, the institute is collocated with the Joint Center for Artificial Photosynthesis (JCAP) in the recently renovated Jorgensen Laboratory, which has been awarded LEED Platinum certification. In the renovation, Caltech and its partners were able to reuse or recycle over 90 percent of the materials removed from the original facility, a computer science building. Jorgensen has high-efficiency lighting and HVAC systems, a "living roof" composed of evergreen and drought-tolerant grasses, and water-saving plumbing and landscaping, among other green features.

The Joint Center for Artificial Photosynthesis (JCAP)

JCAP, established in 2010 as a U.S. Department of Energy (DOE) Energy Innovation Hub, is the nation's largest research effort focused on artificial photosynthesis. Led by researchers from Caltech (JCAP South, housed at the Jorgensen Laboratory) and partner Lawrence Berkeley National Laboratory (JCAP North), the center aims to create a low-cost artificial generator that uses sunlight, carbon dioxide, and water to make fuel from the sun 10 times more efficiently than current living crops. Once a prototype generator is developed, it will be handed off to private-sector companies to launch a new solar-fuels industry. Such a transformative breakthrough would reduce our country's dependence on oil and enhance energy security.

JCAP researchers include Scientific Director Nathan S. Lewis, Caltech's George L. Argyros Professor and professor of chemistry; Jonas Peters, the Bren Professor of Chemistry; William A. Goddard, Charles and Mary Ferkel Professor of Chemistry, Materials Science, and Applied Physics; and Harry Atwater.

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Caltech and JPL Experts Discuss Climate Change

In today's installment of our Earth Week 2014 features, Caltech experts share their knowledge about climate change.

 

Caltech professor Jess Adkins, a geochemist and paleoclimatologist, offers insight into global warming in the video "Is There Hope for Planet Earth?" produced by Green Wish, a nonprofit organization that funds green initiatives at the local level. In the video, Adkins talks about the history of climate change, where we are today, and what we can do to mitigate its impact in the future.

 

On April 22—Earth Day—the Caltech Center for Teaching, Learning, & Outreach sponsored an "Ask A Scientist" panel on the Caltech campus to answer questions about climate change and earth sciences. Panel members included David Crisp, JPL senior research scientist and principal investigator of the NASA Earth System Science Pathfinder Orbiting Carbon Observatory mission; Joshua Fisher, JPL research scientist, Water and Carbon Cycles Group; science communicator and education specialist Laura Tenenbaum; and Caltech alumnus Julius Su (BS '98 and '99, PhD '07), cofounder of Su-Kam Intelligent Education Systems (SKIES). Su used the SKIES iPad app, an online learning and information crowdsourcing tool, to relay online and audience questions to the panelists. The video is a recording of the live event.

 

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Caltech Celebrates Earth Week

Events and online features honor Caltech's commitment to sustainability

Caltech joins the world in celebrating Earth Week, April 21–25, 2014, with events, news, and features highlighting our past, present, and future contributions to a healthier, cleaner, and greener planet.

Check out our homepage and Facebook, Twitter, and YouTube pages for daily Earth Week coverage, including features on Caltech's "Sustainability Heroes" and the centers where Caltech researchers are advancing sustainability, energy, and environmental science as well as highlights of our pioneering work to green the Caltech campus.

Through research and application, Caltech faculty, students, staff, and supporters/partners are actively engaged in protecting our earth and ensuring a sustainable future, not just on Earth Day but throughout the year.

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Airborne Over Iceland: Charting Glacier Dynamics

Mark Simons, professor of geophysics at Caltech, along with graduate student Brent Minchew, recently logged over 40 hours of flight time mapping the surface of Iceland's glaciers. Flying over two comparatively small ice caps, Hofsjökull and Langjökull, they traveled with NASA pilots and engineers in a retrofitted Gulfstream III business jet, crisscrossing the glaciers numerous times. Using a radar instrument designed at the Jet Propulsion Laboratory (JPL) and mounted on the underbelly of the plane, they imaged the surface of the glaciers, obtaining precise data on the velocity at which these rivers of ice flow downstream.

Following a set of test flights in Iceland in 2009, Simons and Minchew went to Iceland in June 2012 to systematically image the two ice caps at the beginning of the summer melt season. They have just returned from a February 2014 expedition aimed at setting a baseline for glacier velocity—during the winter freeze, meltwater should not play as significant a role in glacier dynamics. They sat down recently to discuss the science and the adventure of monitoring Iceland's glaciers.

Why go to Iceland to study glaciers?

Mark Simons: Iceland is an ideal natural laboratory. The glaciers there are small enough that you can do detailed measurements of them, and afterward you can process the data and analyze each ice cap in its entirety without needing overwhelming computer resources. This manageable scale lets us explore a wide range of models. Glaciers in Greenland or Antarctica are far too big for that. Logistics are also a lot easier in Iceland. We can drive up to the glaciers in just a few hours from downtown Reykjavik.

Most importantly, the Icelanders have a long history of studying these ice caps. In particular, they have nearly complete maps of the ice-bedrock interface. We can complement this information with continuous maps of the daily movement or strain of the glacier surface as well as maps of the topography of the glacier surface. These data are then combined to constrain models of glacier dynamics.

How can you map bedrock that is under hundreds of feet of ice?

Brent Minchew: Our collaborators at the University of Iceland have been doing this work for decades. Helgi Björnsson and Finnur Pálsson mapped the subglacial bedrock by dragging long radar antennas behind snowmobiles driven over the glaciers. They use long-wavelength radar that penetrates through the ice to the underlying bedrock. By looking at the reflection of the radar signals, they can estimate where the interface is between ice and bedrock. They are expert at studying the cryosphere—the earth's frozen regions, including ice caps, glaciers, and sea ice—as you might expect given their location so far north of the equator.

Is this similar to the radar you use in your airplane flights over Iceland's glaciers?

Simons: It's a similar principle. Radar is an active imaging system, so unlike optical observations, where you're just looking at the reflected light from the sun, we're actually illuminating the surface like a flashlight, but using radar instead.

Was this radar technology developed specifically for imaging glaciers?

Minchew: No. The technique we use, InSAR [Interferometric Synthetic Aperture Radar], has been available since the mid-1990s. It has revolutionized a number of disciplines in the earth sciences, including glaciology. The system we are using in Iceland is truly state-of-the-art. It enables complete control over where and when we collect data, and it returns images with millions of independent pixels. It's a very rich data source.

Simons: Actually, the exact same airplane we use in Iceland to study glaciers is also used to measure motion above restless volcanoes due to changes in magma pressure or along major seismically active faults such as the San Andreas fault. Repeated radar imaging can show us the parts of the fault that are stuck—those are the places that will generate earthquakes every so often—and the other parts that are steadily creeping year after year. Basically, we're bringing our experience from earthquake physics, both in terms of observation and modeling, to see if it can help us address important problems in glaciology.

Are there other methods besides radar for studying glacier dynamics?

Minchew: We can drill to the bed and take direct measurements, but a lot of effort is involved in this. Compared to Greenland, where the ice is close to a mile thick, or Antarctica, where it is even thicker, Iceland's glaciers are relatively thin. But they're still on average 300 meters thick. That's a long way to drill down for one data point.

Simons: Traditionally people measured velocities of glaciers by putting stakes in the glacier, and then returning to see how far downstream those stakes had moved by the end of the melting season. This approach can give an average velocity over the season. We still utilize this principle by installing GPS units at various spots on the glacier. These GPS units also help us calibrate our radar-based measurements and confirm that our velocity estimates are accurate.

What advantages does radar have over these other methods?

Simons: One of the wonderful things about radar imaging, unlike optical imaging, is that we can "see" the glacier whether it's day or night, whether it's cloudy or clear.

Minchew: Right. Another major advantage of radar technology is that we don't just see the average velocity for the season; we can detect short-term dynamics and variability over the entire glacier if the imaging is done sufficiently often.

How exactly does radar work to image the ice cap?

Simons: Radar images are usually taken at oblique angles to the surface of the earth, not straight down in a perpendicular line. Given two radar images taken from nearly identical positions but at different times, we can combine them in such a way as to measure changes in ground position that occurred in the intervening period along the oblique direction of the transmitted energy. We quantify these displacements in terms of fractions of a radar wavelength. This process is called repeat pass interferometry. We design the plane's flight path to make several interferometric measurements from different viewing angles, in order that the surface of the glacier is imaged at least three times and often as many as six times. We then combine these different perspectives to create accurate 3-D maps of the surface velocity of the glaciers, detecting its underlying east, north, and up components.

How can you be so precise in your measurements from that high up in the air?

Simons: The altitude itself isn't a problem. The trick is making certain the plane is at the same absolute position over consecutive flights. We owe this precision to engineers at NASA/JPL; it has nothing to do with us down here at Caltech. They have developed the technology to fly this plane at 40,000 feet, at 450 miles per hour, and then to come back an hour later, a day later, or a year later, and fly that exact same path in coordinates relative to the ground. Essentially they are flying in a "virtual tube" in the air that's less than 10 meters in diameter. That's how accurate it is.

Minchew: Of course even within this virtual tube, the plane moves around; that's what aircraft do. But aircraft motion has a characteristic appearance in the data, and it's possible for us to remove this effect. It never ceases to amaze me that we can get centimeter-scale, even millimeter-scale accuracy from an airplane. But we can do it, and it works beautifully.

What was the motivation for JPL and NASA to develop this radar technology in the first place?

Simons: Part of what NASA has been doing with airborne radar technology is prototyping what they want to do with radar from satellites, and to understand the characteristics of this kind of measurement for different scientific targets. The instrument is called UAVSAR, for Uninhabited Aerial Vehicle Synthetic Aperture Radar. Right now it's clearly not uninhabited because the radar is on a plane with pilots and engineers on board. But the idea is that eventually we could do these radar measurements from a drone that would stay aloft making observations for a day or a day and a half at a stretch. We can also use satellites to make the same type of measurements.

Minchew: In ways, satellites are an easier platform for radar measurements. In space, there aren't a whole lot of dramatic perturbations to their motions; they fly a very steady path. But one advantage of an airborne platform is that we can collect data more frequently. We can sample the glacier surface every 24 hours if we wish. Satellites typically sample on the order of once a week to every several weeks.

What do you hope to learn from observing glacier dynamics in Iceland?

Simons: We want to use measurements of the ice cap to explore what is happening at the bottom of the glacier. We already know from the previous campaign in 2012 that over half of the movement measured in the early summer is associated with sliding at the bed rather than deformation of the ice. In the early part of the melt season, water gets down to the bottom of the glacier and doesn't have anywhere to go, so it increases the pressure at the bottom. It ends up reducing the friction so the glacier can flow faster over the bedrock. At some point there's so much water flow that it starts to make tunnels in the ice, and then the glacier drains more efficiently. But then the tunnels will collapse on themselves, and the whole glacier settles back down, compacting on itself. The glacier actually slides faster in the early part of the melt season than later in the melt season.

Minchew: The thing that propels glaciers is simply gravity. Ice is a viscous fluid, like honey. Very cold honey. Once it warms up and begins to melt slightly, the dynamics change tremendously. That's something we can observe in Iceland—unlike in Antarctica—where temperatures regularly go above the freezing point in summer. In Iceland, we think almost all the meltwater at the bed comes from surface melting. Geothermal heating from the earth and frictional heating from the sliding itself can also contribute to melting in Iceland's glaciers. These are the main sources of melting in Antarctica. But geothermal and frictional heating don't have anything to do with climate change nor should they vary with the seasons in the way that meltwater does.

Is climate change the major reason why you're studying glaciers?

Minchew: No, I just like cold and inhospitable places. Seriously, I was drawn to the field work aspect of geophysics, the opportunity to go to places in the world that are for the most part the way nature intends them to be. I'm also drawn to glaciers because they are fascinating and surprisingly complex physical systems. A number of fundamental problems in glaciology remain unsolved, so there is tremendous potential for discovery in this field. But helping to understand the potential effects of climate change is an obvious application of our work. People are much more interested in glaciers now as a result of climate change. One of the glaciologists at the University of Iceland likes to say, "We've turned a very cold subject into a hot one."

Simons: Iceland is actually a very good place to learn about how glaciers will react to climate change. We can watch these glaciers on a seasonal basis and see how they respond to temperature variation rather than trying to compare the behavior of those glaciers in Antarctica that have yet to experience surface melting to what we think their behavior might be 50 years from now. But for me, glaciology has always been interesting in itself. My job is to study the mechanics of the earth and how it deforms. And the cryosphere is just as much a part of that as the crust.

 

Simons's initial exploratory campaign on Iceland's glaciers was partially supported by the Terrestrial Hazard Observation and Reporting (THOR) Center at Caltech, funded by an endowed gift from Foster and Coco Stanback. Current efforts are supported by NASA.

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Cynthia Eller
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Is Natural Gas a Solution to Mitigating Climate Change?

Methane, a key greenhouse gas, has more than doubled in volume in Earth's atmosphere since 1750. Its increase is believed to be a leading contributor to climate change. But where is the methane coming from? Research by atmospheric chemist Paul Wennberg of the California Institute of Technology (Caltech) suggests that losses of natural gas—our "cleanest" fossil fuel—into the atmosphere may be a larger source than previously recognized.

Radiation from the sun warms Earth's surface, which then radiates heat back into the atmosphere. Greenhouse gases trap some of this heat. It is this process that makes life on Earth possible for beings such as ourselves, who could not tolerate the lower temperatures Earth would have if not for its "blanket" of greenhouse gases. However, as Goldilocks would tell you, there is "too hot" as well as "too cold," and the precipitous increase in greenhouse gases since the beginning of the Industrial Revolution induces climate change, alters weather patterns, and has increased sea level. Carbon dioxide is the most prevalent greenhouse gas in Earth's atmosphere, but there are others as well, among them methane.

Those who are concerned about greenhouse gases have a very special enemy to fear in atmospheric methane. Methane has a trifecta of effects on the atmosphere. First, like other greenhouse gases, methane works directly to trap Earth's radiation in the atmosphere. Second, when methane oxidizes in Earth's atmosphere, it is broken into components that are also greenhouse gases: carbon dioxide and ozone. Third, the breakdown of methane in the atmosphere produces water vapor, which also functions as a greenhouse gas. Increased humidity, especially in the otherwise arid stratosphere where approximately 10 percent of methane is oxidized, further increases greenhouse-gas induced climate change.

Fully one-third of the increase in radiative forcing (the ability of the atmosphere to retain radiation from the sun) since 1750 is estimated to be due to the presence and effects of methane. Because of the many potential sources of atmospheric methane, from landfills to wetlands to petroleum processing, it can be difficult to quantify which sources are making the greatest contribution. But according to Paul Wennberg, Caltech's R. Stanton Avery Professor of Atmospheric Chemistry and Environmental Science and Engineering, and his colleagues, it is possible that a significant source of methane, at least in the Los Angeles basin, is fugitive emissions—leaks—from the natural-gas supply line.

"This was a surprise," Wennberg explains of the results of his research on methane in the Los Angeles atmosphere. In an initial study conducted in 2008, Wennberg's team analyzed measurements from the troposphere, the lowest portion of Earth's atmosphere, via an airplane flying less than a mile above the ground over the Los Angeles basin.

In analyzing chemical signatures of the preliminary samples, Wennberg's team made an intriguing discovery: the signatures bore a striking similarity to the chemical profile of natural gas. Normally, the methane from fossil fuel sources is accompanied by ethane gas—which is the second most common component of natural gas—while biogenic sources of methane (such as livestock and wastewater) are not. Indeed, the researchers found that the ratio of methane and ethane in the L.A. air samples was characteristic of the samples of natural gas provided by the Southern California Gas Company, which is the leading supplier of natural gas to the region.

Wennberg hesitates to pinpoint natural-gas leaks as the sole source of the L.A. methane, however. "Even though it looks like the methane/ethane could come from fugitive natural-gas emissions, it's certainly not all coming from this source," he says. "We're still drilling for oil in L.A., and that yields natural gas that includes ethane too."

The Southern California Gas Company reports very low losses in the delivery of natural gas (approximately 0.1 percent), and yet atmospheric data suggest that the source of methane from either the natural-gas infrastructure or petroleum production is closer to 2 percent of the total gas delivered to the basin. One possible way to reconcile these vastly different estimates is that significant losses of natural gas may occur after consumer metering in the homes, offices, and industrial plants that purchase natural gas. This loss of fuel is small enough to have no immediate negative impact on household users, but cumulatively it could be a major player in the concentration of methane in the atmosphere.

The findings of Wennberg and his colleagues have led to a more comprehensive study of greenhouse gases in urban settings, the Megacities Carbon Project, based at JPL. The goal of the project, which is focusing initially on ground-based measurements in Los Angeles and Paris, is to quantify greenhouse gases in the megacities of the world. Such cities—places like Hong Kong, Berlin, Jakarta, Johannesburg, Seoul, São Paulo, and Tokyo—are responsible for up to 75 percent of global carbon emissions, despite representing only 3 percent of the world's landmass. Documenting the types and sources of greenhouse gases in megacities will provide valuable baseline measurements that can be used in efforts to reduce greenhouse gas emissions.

If the findings of the Megacities Carbon Project are consistent with Wennberg's study of methane in Los Angeles, natural gas may be less of a panacea in the search for a "green" fuel. Natural gas has a cleaner emissions profile and a higher efficiency than coal (that is, it produces more power per molecule of carbon dioxide), but, as far as climate change goes, methods of extraction and distribution are key. "You have to dig it up, put it in the pipe, and burn it without losing more than a few percent," Wennberg says. "Otherwise, it's not nearly as helpful as you would think."

Wennberg's research was published in an article titled "On the Sources of Methane to the Los Angeles Atmosphere" in Environmental Science & Technology. Data for this study were provided by the Southern California Gas Company, NASA, NOAA, and the California Air Resources Board. The research was funded by NASA, the California Energy Commission's Public Interest Environmental Research program, the California Air Resources Board, and the U.S. Department of Energy.

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Cynthia Eller
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