Caltech scientists, inspired by a chemical process found in leaves, have developed an electrically conductive film that could help pave the way for devices capable of harnessing sunlight to split water into hydrogen fuel.
When applied to semiconducting materials such as silicon, the nickel oxide film prevents rust buildup and facilitates an important chemical process in the solar-driven production of fuels such as methane or hydrogen.
“We have developed a new type of protective coating that enables a key process in the solar-driven production of fuels to be performed with record efficiency, stability, and effectiveness, and in a system that is intrinsically safe and does not produce explosive mixtures of hydrogen and oxygen,” says Nate Lewis, the George L. Argyros Professor and professor of chemistry at Caltech and a coauthor of a new study, published the week of March 9 in the online issue of the journal the Proceedings of the National Academy of Sciences, that describes the film.
The development could help lead to safe, efficient artificial photosynthetic systems—also called solar-fuel generators or “artificial leaves”—that replicate the natural process of photosynthesis that plants use to convert sunlight, water, and carbon dioxide into oxygen and fuel in the form of carbohydrates, or sugars.
The artificial leaf that Lewis’ team is developing in part at Caltech’s Joint Center for Artificial Photosynthesis (JCAP) consists of three main components: two electrodes—a photoanode and a photocathode—and a membrane. The photoanode uses sunlight to oxidize water molecules to generate oxygen gas, protons, and electrons, while the photocathode recombines the protons and electrons to form hydrogen gas. The membrane, which is typically made of plastic, keeps the two gases separate in order to eliminate any possibility of an explosion, and lets the gas be collected under pressure to safely push it into a pipeline.
Scientists have tried building the electrodes out of common semiconductors such as silicon or gallium arsenide—which absorb light and are also used in solar panels—but a major problem is that these materials develop an oxide layer (that is, rust) when exposed to water.
Lewis and other scientists have experimented with creating protective coatings for the electrodes, but all previous attempts have failed for various reasons. “You want the coating to be many things: chemically compatible with the semiconductor it’s trying to protect, impermeable to water, electrically conductive, highly transparent to incoming light, and highly catalytic for the reaction to make oxygen and fuels,” says Lewis, who is also JCAP’s scientific director. “Creating a protective layer that displayed any one of these attributes would be a significant leap forward, but what we’ve now discovered is a material that can do all of these things at once.”
The team has shown that its nickel oxide film is compatible with many different kinds of semiconductor materials, including silicon, indium phosphide, and cadmium telluride. When applied to photoanodes, the nickel oxide film far exceeded the performance of other similar films—including one that Lewis’s group created just last year. That film was more complicated—it consisted of two layers versus one and used as its main ingredient titanium dioxide (TiO2, also known as titania), a naturally occurring compound that is also used to make sunscreens, toothpastes, and white paint.
“After watching the photoanodes run at record performance without any noticeable degradation for 24 hours, and then 100 hours, and then 500 hours, I knew we had done what scientists had failed to do before,” says Ke Sun, a postdoc in Lewis’s lab and the first author of the new study.
Lewis’s team developed a technique for creating the nickel oxide film that involves smashing atoms of argon into a pellet of nickel atoms at high speeds, in an oxygen-rich environment. “The nickel fragments that sputter off of the pellet react with the oxygen atoms to produce an oxidized form of nickel that gets deposited onto the semiconductor,” Lewis says.
Crucially, the team’s nickel oxide film works well in conjunction with the membrane that separates the photoanode from the photocathode and staggers the production of hydrogen and oxygen gases.
“Without a membrane, the photoanode and photocathode are close enough to each other to conduct electricity, and if you also have bubbles of highly reactive hydrogen and oxygen gases being produced in the same place at the same time, that is a recipe for disaster,” Lewis says. “With our film, you can build a safe device that will not explode, and that lasts and is efficient, all at once.”
Lewis cautions that scientists are still a long way off from developing a commercial product that can convert sunlight into fuel. Other components of the system, such as the photocathode, will also need to be perfected.
“Our team is also working on a photocathode,” Lewis says. “What we have to do is combine both of these elements together and show that the entire system works. That will not be easy, but we now have one of the missing key pieces that has eluded the field for the past half-century.”
Along with Lewis and Sun, additional authors on the paper, “Stable solar-driven oxidation of water by semiconducting photoanodes protected by transparent catalytic nickel oxide films,” include Caltech graduate students Fadl Saadi, Michael Lichterman, Xinghao Zhou, Noah Plymale, and Stefan Omelchenko; William Hale, from the University of Southampton; Hsin-Ping Wang and Jr-Hau He, from King Abdullah University in Saudi Arabia; Kimberly Papadantonakis, a scientific research manager at Caltech; and Bruce Brunschwig, the director of the Molecular Materials Research Center at Caltech. Funding was provided by the U.S. Department of Energy, the National Science Foundation, the Beckman Institute, and the Gordon and Betty Moore Foundation.
Solar Energy is the Future and the Time Has Come
The world is going solar everywhere you look. Google is investing $300 million in SolarCity. Apple is building a massive $850 million solar farm in California. Utilities and small businesses are placing solar panels on rooftops, homeowners are finding out that they can save money on home installations, and even Pakistani farmers are finding out there are benefits in switching from diesel to solar.
The world is transitioning from fossil fuels to solar power, and it’s a change that is setting humanity on a new course for the future.
The newly released book Power Shift: From Fossil Energy to Dynamic Solar Power, by Robert A. Stayton, explores this fundamental change in the human relationship with energy.
“Solar energy is the clear economic and environmental choice,” says Stayton. “The advantages over oil, gas, coal, nuclear, wind, and hydro make it the best choice hands down. Its time has come.”
“We are at the beginning of a new epoch in history,” Stayton says. “If you live a modern energy-enabled lifestyle, then you’re a player in this drama, and you have choices to make. The energy decisions you make today will decide the fate of many generations to come.”
What People Are Saying …
“Solar is surging all of a sudden, and if you read this comprehensive book you’ll understand why!”
—Bill McKibben, author of Earth
“California has ambitious goals for moving from fossil fuels to renewable energy, goals that can only be met by understanding our relationship to the energy we use and the steps we must take to get to live by renewable energy. Robert Stayton’s book lays this out in an understandable framework – and points the way to a clean energy future.”
—John Laird: California Secretary for Natural Resources
“Power Shift is a bright light that will expand your view on the energy journey we are all on. Written in an easily comprehensible way Stayton takes us from our quest for fire to understanding each form of energy with predictability and accountability. In the process he dispels nuclear myth with nuclear truth and offers a bold vision for harnessing the energy that has always been in the sky above us. Laying out a map with the steps we need to make the transition from renewable to permanent, he presents solar energy in a new way. One is not surprised our sun is key, only grateful.”
—John Francis, PhD, Environmentalist, author of Planet Walker
“Finally, a crystal-clear, colorful, and inviting guide to everything you need to know for understanding and helping civilization to progress along our inevitable path of running on the Sun. This new book is visionary and brilliant (while also very fun and interesting)—introducing a whole new way of thinking, doing, and being. If you are looking for some reality that’s encouraging and enlightening, here it is.”
—Joe Jordan, NASA Researcher and Solar Educator
For more information visit www.sandstonepublishing.com
IHS Technology analysts top 10 predictions for the 2015 global photovoltaic (PV) market
EL SEGUNDO, CALIF. (January 8, 2014) – While 2014 remained a challenging time for the solar photovoltaic (PV) industry, it marked an inflection point in the market’s development. According to a new white paper issued by the IHS Solar service at information and analytics provider IHS (NYSE: IHS), solar PV demand grew at a double-digit pace, largely due to policies in China and Japan; yet conditions remained extremely tough for suppliers.
“Through mergers, acquisitions and bankruptcies, the supplier base consolidated further, as companies struggled with debt-laden balance sheets and a rapid shift in their customer base away from their traditional markets,” said Ash Sharma, senior research director for solar at IHS. “All signs point to a strengthening recovery of the solar industry in 2015, even if the recovery itself remains incredibly fragile.”
Following are the top 10 predictions for 2015, from the IHS solar research team:
1. Global solar PV demand is forecast to grow by up to 25 percent in 2015. Due to the ongoing cost reductions for solar PV, IHS forecasts that installation demand will grow at a double-digit rate of 16 to 25 percent and installations in the range of 53 to 57 gigawatts (GW). Geographically, the largest markets again will be China, Japan and the United States, while the largest contributors in terms of absolute growth will be China, the United States and India.
2. Concentrated Photovoltaic Solar (CPV) to experience accelerated growth. Starting in 2015, IHS forecasts an accelerated CPV market expansion of 37 percent, to reach approximately 250 megawatts (MW) of new installations. Installations of both high-concentration photovoltaic (HCPV) and low-concentration photovoltaic (LCPV) systems will expand at double-digit percentages every year through 2020.
3. Distributed PV (DPV) in China to fall behind expectations, but continues to grow. With challenges ahead for China’s ambitious plans for DPV, IHS forecasts the country will struggle to achieve it aggressive targets. Even so, the market is clearly beginning to build momentum, and policies and business models are helping to accelerate growth. IHS forecasts that DPV installations in China will reach 4.7 GW in 2015, an increase of nearly 20 percent from 2014.
4. Grid-connected PV energy storage installations to triple. The PV power system is evolving away from the traditional and relatively simple system of one-directional flow—from large-scale conventional generators through transmission and distribution lines to consumers, to an increasingly complex mix of small, distributed generators and consumers at all points in the electricity grid. Annual installations of grid-connected PV systems, paired with energy storage, will grow more than threefold, to reach 775 MW in 2015.
5. Emerging markets mature – Chile will follow South Africa to reach 1 GW of installed PV capacity. IHS forecasts that Chile will be the next emerging market, after South Africa, to reach the milestone of 1 GW in installed PV solar capacity. Aside from Chile, other new emerging markets poised for rapid growth in 2015 are Jordan, the Philippines and Honduras. Conversely, great uncertainty still surrounds Mexico, Brazil and Turkey.
6. Monocrystalline technology to increase market share. Although monocrystalline technology will not threaten multicrystalline domination in the near future, IHS expects it will steadily gain share, benefiting from growth on rooftop installations, as well as increasing demand for higher-efficiency products. IHS forecasts the monocrystalline share of global cell production will increase to 27 percent in 2015, up from 24 percent in 2014.
7. Systems up to 100 kilowatts to account for 30 percent of global installations. There is potential in store for DPV in both established and emerging markets around the world. IHS forecasts distributed photovoltaic (DPV) systems—i.e., those sized 100 kilowatts (kW) or smaller—to account for 30 percent of global installations in 2015, with 15.7 GW projected, up from 13.2 GW in 2014. The largest market for these installations in 2015 will be Japan, with DPV accounting for nearly 70 percent of installations. The U.S. is also expected to install more than 2.2 GW of DPV in 2015, as net-metering and third-party ownership models continue to drive this market.
8. Second quarter (Q2) halt to U.K. utility-scale PV to trigger new wave of consolidation among European Engineering, Procurement and Construction (EPC) contractors. The clock is running down for integrators of large-sized solar systems in Europe, with the expiration of a U.K. incentive program bringing an end to a boom in utility-scale installations and triggering a flurry of consolidation. The U.K. in 2015 will dominate the utility-scale PV landscape in Europe by installing 1.4 GW of ground-mount systems, primarily under the renewable obligation certificates (ROC) scheme.
9. Three-phase string inverters to account for one-third of global solar inverter revenue. Driven by attractive prices in key PV markets, global revenue for three-phase string inverters is forecast in 2015, to reach more than $2.2 billion, equivalent to one-third of worldwide revenue for the overall market for inverters. Estimated shipments next year of three-phase string inverters will exceed 15 GW, up 31 percent from 2014. A surge is expected in important markets like China and Japan, whose combined shipments will account for 7.6 GW of the total.
10. California in 2015 will become global leader in solar power penetration. IHS expects that by the end of 2015, California—the largest renewable power market in the United States—will attain worldwide leadership in market share of annual power generation received from solar PV. Following another year of strong utility-scale and DPV additions, solar power is expected to provide more than 10 percent of California’s annual power generation in 2015. This penetration level would push California above other leading global solar markets, such as Germany and Italy, in terms of the share of total power generation sourced from solar PV.
December 22, 2014 – Kyocera Corporation (President: Goro Yamaguchi; herein “Kyocera”) and Century Tokyo Leasing Corporation (President: Shunichi Asada; herein “Century Tokyo Leasing”) announced today that Kyocera TCL Solar LLC, a joint venture established by the two companies, will develop and operate a 13.4-megawatt (MW) floating solar power plant on the Yamakura Dam reservoir, managed by the Public Enterprises Agency of Chiba Prefecture in Japan for industrial water services. The plant will become the largest floating solar installation in the world*1.
Aiming to reduce its burden on the environment, the Public Enterprises Agency of Chiba Prefecture had been publicly seeking companies to construct and operate a floating solar power plant at the Yamakura Dam. Kyocera TCL Solar was selected to undertake this project in part due to its experience and expertise in developing utility-scale solar power plants in Japan. The company aims to begin operations in March 2016 after negotiating with related parties including Tokyo Electric Power Company.
“When we first started R&D for solar energy in the mid 1970’s, the technology was only viable for small applications such as street lamps, traffic signs and telecommunication stations in mountainous areas,” stated Nobuo Kitamura, senior executive officer and general manager of the Corporate Solar Energy Group at Kyocera. “Since then, we have been working to make solar energy use more ubiquitous in society, and have expanded our business to residential, commercial and utility-scale solar applications. We are excited to work with our partners on this project, taking another step forward by utilizing untapped bodies of water as solar power generation sites.”
The project will be comprised of approximately 50,000 Kyocera modules installed over a water surface area of 180,000m2. The plant will generate an estimated 15,635 megawatt hours (MWh) per year — enough electricity to power approximately 4,700 typical households*2 — while offsetting about 7,800 tons*3 of CO2 emissions annually.
Under the plan, Kyocera TCL Solar will build and operate the installation, and Century Tokyo Leasing will provide project financing. The Kyocera Group will be responsible for the supply of solar modules and related equipment in addition to construction, operation and maintenance. The modules will be installed on floating platforms manufactured by Ciel et Terre (headquarters: France), which is also supplying the platforms for a floating solar power plant project in Hyogo Prefecture currently being constructed by Kyocera TCL Solar.
By cooperating with local companies on construction and operation, and establishing an environmental education facility adjacent to the plant to provide environmental classes for local elementary school students, Kyocera and Century Tokyo Leasing hope that the project will play a role in the development of the local community. The companies are committed to promoting solar energy as a means to attain a low-carbon society.
*1 World’s largest floating solar power plant in terms of output (as of December 22, 2014)
*2 Based on an average annual use of 3,313kWh per household. Source: Federation of Electric Power Companies of Japan (2012)
*3 Based on calculations derived from JPEA standards
By 2018, a large solar power plant in the Tunisian part of the Sahara desert may start sending power to energy-hungry Western Europe. The company running the plant says once it is fully operational it will generate almost twice as much electricity as an average nuclear plant and supply two million homes in Europe.
Solar Power Rocks, the nation’s leading source for clear and detailed information about U.S. residential solar energy policy, has just released its 2015 State Solar Power Rankings report.
The report contains ratings of all 50 states and the District of Columbia based on twelve key criteria leading to strong financial results for homeowners interested in installing solar panels. State summaries include links to pages with detailed discussions of policy, incentives and rules that affect each state’s residential solar power prospects.
Solar Power Rocks is committed to giving homeowners a clear picture of the policy, incentives, and investment returns on local solar panel installations. The organization also seeks to recognize the best states for solar and clearly illustrate how all state legislatures can encourage residential solar energy growth based on the best practices in the most successful states.
WASHINGTON, DC – The Solar Energy Industries Association (SEIA) and the Solar Electric Power Association (SEPA) today announced that U.S. Secretary of Energy Ernest Moniz will keynote the general session at Solar Power International (SPI) in Las Vegas, Nevada, on Wednesday, Oct. 22. In his cabinet role, Dr. Moniz implements critical Department of Energy missions in support of President Obama’s goals of growing the economy, enhancing security and protecting the environment.
“Since Secretary Moniz took office, he has been a strong supporter of the solar industry and the 143,000 Americans who work in solar energy,” said Rhone Resch, SEIA president and CEO. “From the new pilot job training program for veterans to the continuation of the hugely successful SunShot Initiative and the important research at its national laboratories, the Energy Department under Secretary Moniz has helped reduce red tape and facilitated the development of clean, renewable solar energy. This Administration’s forward-looking public policies – which allow emerging technologies to compete with entrenched energy sources – are helping to ensure a clean, prosperous future for our nation.”
”Under the leadership of Secretary Moniz, the Department of Energy recognizes the important role of collaboration between the solar and utility industries to successfully advance our nation towards a cleaner energy future,” said Julia Hamm, SEPA president and CEO. “Through funding of partnerships on smart grid deployment, solar research, and soft cost reduction, Secretary Moniz and the Energy Department are helping parties with often disparate interests to collaborate on areas of common interest. His participation in SPI 2014 is a demonstration of his commitment to further those positive efforts.”
Today, solar is the fastest-growing source of renewable energy in the United States, pumping $15 billion a year into the U.S. economy and helping to reduce pollution.