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U.S. Climate Report Predicts Growing Problems for Energy Sector

More frequent and intense weather events—from hurricanes to wildfires to sweltering summers—can be attributed to climate change and are affecting energy production and power delivery in the United States, according to a new government report.

The latest National Climate Assessment, prepared by the U.S. National Climate Assessment and Development Advisory Committee (NCADAC) and released yesterday, says that climate-related effects are not only already being felt but will likely get worse.

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Two Labs Get the Lead Out of Promising Perovskite Solar Cells

Photovoltaic cells made from perovskite materials have rapidly become one of the hottest areas in energy research over the past few years. But most of these materials have included the toxic metal lead, raising concerns about their environmental impact.

Now, two teams have independently developed perovskite cells that swap lead for tin, which could help to convince investors and regulators that the cells have a commercial future.

Perovskite materials are named after the common crystal structure they share with a naturally occurring mineral. Cells using the material made a modest debut in 2009, reaching energy conversion efficiencies of 3.8 percent.

But they were soon leaping ahead, rising to 10 percent efficiency in 2012, and 15 percent by 2013. The same year, Henry Snaith at the University of Oxford, UK, unveiled a perovskite cell that reached 15 percent efficiency, but with a much simpler design. His device relied on a thin film of methyl­ammonium lead iodide chloride to do double duty as both light absorber and charge carrier. Since then, photovoltaic cell efficiencies have ticked up further, to 17.9 percent—an advance achieved by Sang Il Seok at the Korean Research Institute of Chemical Technology in Daejeon.

This efficiency already rivals that of bulkier silicon cells, and is gaining fast on thin-film photovoltaic cells that use materials such as copper indium gallium selenide (CIGS). The unprecedented progress is made all the sweeter by the fact that these perovskites are extremely stable, use cheap and abundant materials, and are simple to incorporate into cells.

But using lead-based materials was obviously not ideal. There were only small amounts of lead in each cell, but enough to have a significant environmental impact if they were deployed widely around the world. Researchers worried that this might limit their use. “It’s a problem when it comes to convincing investors,” says Mercouri Kanatzidis, a chemist at Northwestern University, Evanston, Illinois.

Snaith has now reported in Energy and Environmental Science that a cell made from methyl­ammonium tin iodide, which is lead-free, is about 6 percent efficient. Just days later, Kanatzidis independently reported very similar results in Nature Photonics using methyl­ammonium tin iodide bromide.

One major drawback is that tin perovskites are unstable, and must be handled under an inert atmosphere. But Kanatzidis says that the necessary processing methods are already well-established in industry, and that the cells are fairly stable once sealed in an air-tight housing. He is also confident that tin perovskites can be pushed far above 6 percent efficiency. “There’s no showstopper,” he says.

Tin perovskites might offer an insurance policy if lead perovskites do turn out to be an environmental problem. But looking for alternative metals is also smart science, because they might actually improve the cells’ performance. The tin-based cells, for example, actually produce a higher voltage than the original lead perovskite cells. “It may well be that tin ends up being higher efficiency,” says Snaith.

The similarities between the results from the two labs highlights the frenzied pace of the field. “The competition is amazing,” says Snaith. “You can’t assume you’re doing anything unique.”

Snaith has cofounded a start up, Oxford Photovoltaics, to commercialize his perovskite cells, and Kanatzidis is talking to solar PV manufacturers about his tin tech. But both agree that the biggest hurdle for commercial deployment of the cells is their long-term stability. “The biggest question is whether we can make these things stable for 25 years,” says Snaith.

NASA Uses Transmission Lines For Geomagnetic Antenna Study

Not all threats to the electric grid originate here on Earth. To better understand large solar events, which can be dangerous to the transmission grid, a researcher at NASA’s Goddard Space Flight Center is using high-voltage transmission lines to map large-scale geomagnetically-induced currents (GICs).

GICs occur when the sun ejects huge bubbles of charged particles that can carry up to 10 billion tons of matter. When the bubbles strike the Earth’s atmosphere, the geomagnetic field that surrounds our planet fluctuates.

These fluctuations in the electrical current can then flow through any large conductive structure such as power lines, oil and gas pipelines, undersea cables, and railways, according to NASA. When excess current flows through the electric transmission system, it can overload transformers and collapse the system, leading to large-scale outages. From 1960 to 2000, the high voltage grid in the United States has grown nearly tenfold, according Oak Ridge National Laboratory [PDF], making it increasingly susceptible to GICs.

The concern that a large GIC could plunge part of the United States into a blackout is high on the list of issues faced by the Federal Energy Regulatory Commission (FERC), and is as much of a focus as physical or cyber security threats.

Last year, FERC ordered the North American Reliability Corporation to propose reliability standards for the grid that address the impact of geomagnetic disturbances; owners of the bulk-power grid will have to conduct assessments of the potential impact of GICs on their systems moving forward.

To better understand the effects of GICs, Antti Pulkkinen, a heliophysicst at Goddard, is installing three substations beneath high-voltage transmission lines to measure GICs.

“This is the first time we have used the U.S. high-voltage power transmission system as a science tool to map large-scale GICs,” Pulkkinen said in the NASA publication Cutting Edge [PDF]. “This application will allow unprecedented, game-changing data gathering over a wide range of spatial and temporal scales.”

Two of the three substations being built by Goddard engineers will be buried 1.2 meters below ground at a spot where Dominion Virginia Power’s high-voltage lines pass overhead. The lines will act as antennae for the electrical current. The substations will contain commercially available magnetometers that can make precise measurements of GICs. (The third substation will be located about three kilometers away to provide reference measurements.)

Pulkkinen’s team is using technology also developed at Goddard to command and control the magnetometers from an iPad. The application, which tags and geolocates data, will send it to a server once every second.

The pilot project is expected to last one to two years, but Pulkkinen hopes to eventually deploy hundreds of substations with long-term funding from multiple government agencies. The current project is funded by NASA’s Center Innovation Fund and Goddard International Research and Development program.

GE's Distributed Power Station Delivery Goes From Months to Weeks

When utilities needed new sources of power in the past, they planned for large, capital-intensive centralized generation that could take years to build and decades to pay off.

Big power plants are still being built, but many utilities are increasingly looking for smaller, more flexible solutions. In Libya, the General Electricity Company of Libya (GECOL), recently installed mobile backup power plants from General Electric (GE) in a matter of weeks, instead of the six-to-nine months usually required.

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U.S. Energy Department Offering $4 Billion for Renewable Energy Loans

Biofuels made from leftover corn may not be any better than conventional gasoline in terms of greenhouse gas emissions, according to a new study from Nature Climate Change that was paid for by the U.S. government.

In terms of life cycle analysis, fuels made from corn residue release 7 percent more greenhouse gases in a 10-year timeline compared to gasoline, even though they may be better than gas in the long run, according to a report in the Associated Press. The federal government has spent more than US $1 billion supporting cellulosic biofuel research.

Although the fuel stock may change, biofuels continue to be a big focus for the government. Biofuel-based drop-in replacements for gasoline are one of five technology areas that were identified as part of the U.S. Department of Energy’s (DOE) latest renewable energy and energy efficiency solicitation.

The DOE will offer up to $4 billion in loan guarantees to help commercialize technologies that may not be able to obtain full commercial financing, the agency said last week. The program falls under a different section of the law than the part than the one that funded Solyndra.That section,1705, has now expired but had a more than 90 percent success rate across the portfolio despite some significant failures. 

“Through our existing renewable energy loan guarantees, the Department’s Loan Programs Office helped launch the U.S. utility-scale solar industry and other clean energy technologies that are now contributing to our clean energy portfolio,” DOE Secretary Ernest Moniz said in a statement. “We want to replicate that success by focusing on technologies that are on the edge of commercial-scale deployment today.”

The DOE will take applications for any project that meets the eligibility requirements, but it is particularly interested in: 

  • Advanced grid integration and storage
  • Drop-in biofuels
  • Waste-to-energy
  • Enhancement of existing facilities
  • Efficiency improvements.

For biofuels, the DOE noted “qualifying projects may include, but are not limited to, the following: new bio-refineries that produce gasoline, diesel fuel, and/or jet fuel; bio-crude refining processes; and modifications to existing ethanol facilities to gasoline, diesel fuel, and/or jet fuel.”

The U.S. Department of Defense, in particular, is eager for drop-in biofuels to meet its goals. The Navy, for example, has a goal of 50 percent of its liquid fuels will come from alternative sources by 2020.

It is unclear if the findings from the Nature Climate Change study would be considered by the DOE for any applications that are related to corn residue biofuels. According to the AP, other research, including a study by the DOE’s Argonne National Laboratory, has found that corn-based biofuels were still better than gasoline in terms of greenhouse gas emissions.

There will be plenty of other technologies, both other feedstock for biofuels, and other areas of clean tech, that will be vying for the loans. In the first quarter of 2014, more than 90 percent of new power generation was renewable energy, according to the US Federal Energy Regulatory Commission [pdf].

In the area of advanced grid integration and storage projects would help mitigate grid issues caused by intermittent renewable energy. Along the same lines, the DOE's funding for “enhancement of existing facilities” will focus on incorporating renewables into existing generation facilities.

Waste-to-energy applications should focus on projects that turn landfill methane or segregated waste streams, such as forestry waste or crop waste, into energy. Energy efficiency is also a key area, and could fund efficiency in residential, commercia,l or industrial processes or ways that efficiency and demand response could help dispatch underutilized renewable energy.

The DOE is taking public comments until 16 May and the final solicitation will be issued in June.

White Light, Stored Heat

Researchers have developed a new material for solar thermal energy applications, a collector that can serve as its own heat battery. As a result, the technology could help smooth out the production of electricity from solar power over a day and night cycle, or during cloudy weather.

The essential idea, says MIT postdoctoral research associate Timothy Kucharski, involves a molecule containing a kind of spring-wound hinge. Exposing the molecule to a burst of sunlight latches the solar energy in place, like arming a mousetrap. The molecule can then be left idle until its energy is needed, at which point a simple chemical catalytic reaction springs the molecular hinge and releases the stored solar energy as heat.

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Supercapacitor-Enhanced Hybrid Storage to Earn Cash for Subways

A moving train represents a significant amount of energy, which is often lost as carriages slow to stop at a station. Trains in the Philadelphia subway are not only capturing that energy in banks of batteries but also selling it to the local grid operator. This fall, it’ll be capturing even more energy—maybe earning more money from grid operators—because it plans to upgrade the system with a hybrid of both lithium ion batteries and supercapacitors.

The Southeastern Pennsylvania Transit Authority (SEPTA) stores energy produced by braking railway cars, much the way a hybrid car juices its battery when slowing. The spinning wheels turn a motor-generator to charge a bank of batteries via a third rail system. The battery is located at the Lettery substation, which powers a portion of the Market-Frankford Line in Philadelphia, and the autumn upgrade will be installed on the same line about 5 kilometers away.

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Time to Rightsize the Grid?

Last week a team of systems scientists known for counter-intuitive insights on power grids delivered a fresh one that questions one of the tenets of grid design: bigger grids, they argue, may not make for better grids. Iowa State University electrical engineering professor Ian Dobson and physicists David Newman and Ben Carreras make the case for optimal sizing of power grids in last week's issue of the nonlinear sciences journal Chaos. 

In a nutshell, the systems scientists use grid modeling to show that grid benefits such as frequency stabilization and power trading can be outweighed by the debilitating impacts of big blackouts. As grids grow larger, they become enablers for ever larger cascading blackouts. The Northeast Blackout of 2003 was a classic case. From a tripped line in northern Ohio, the outage cascaded in all directions to unplug more than 50 million people from western Michigan and Toronto to New York City.

This week's findings are more conceptual, however, than some news outlets would have us believe. NBC News, in an online article entitled Researchers Suggest It's Time to Downsize Power Grid, misjudged the Chaos report as a call to break up the dual grids that interconnect most of eastern and western North America. "It’s not possible to really make that statement," says Carreras, who runs Oak Ridge, TN-based consulting firm BACV Solutions and is a visiting professor at Madrid's Universidad Carlos III.

B.A. Carreras/BACV Solutions

NBC misinterpreted Carreras et al's simulations showing that grids with just 700-1000 nodes (over 15 times smaller than North America's big grids) maximize interconnection benefits while minimizing blackout costs (see above chart). The researchers say this could indicate that some real grids are too large, but there are two big reasons to be cautious about drawing conclusions. 

Carreras stresses that the model nodes are not necessarily representative of those on a real grid. Many of the group's simulations, for example, use scale models of the Western grid in which each node in the model represents, on average, 10 nodes on the real grid. 

Newman, a physics professor at the University of Alaska in Fairbanks, notes that the specific models used in this Chaos study were idealized, homogeneous systems. As such, he says, they bear little resemblance to the heterogeneity of real grids with their diversity of voltage levels, branching patterns and other features. "700-1000 nodes was the optimal size for the artificial network we had constructed," says Newman.

Media hype is a problem that has dogged this team of system scientists since they gained notoriety over a decade ago by identifying cascading failures as an innate feature of power grids. Their simulations, which a Spectrum cover story profiled ten years ago, show that economic pressure to maximize return on investment loads power grids to levels that leave them at heightened risk of costly blackouts.

The researchers delivered a complex systems view of blackouts that they hoped would spur novel thinking about the costs and benefits in grid design, and novel approaches to blackout prevention. But their message was often misinterpreted as an attack on the quality of grid engineering, or an argument that trying to prevent blackouts was futile. 

Carreras et al argue that this week's report has important conceptual value, if one gets beyond the hype. For one thing, blackout risks should be factored into the cost-benefit calculation when grid planners consider expanded interconnection. This could be applicable in developing countries as well as in Europe, which recently expanded its grid to include Turkey's and is considering extensions to North Africa and Russia.  

It's also possible that grid design could be engineered to enable extended interconnection without expanding cascading blackout risk. Newman points to the possibility that weak links could be deliberately placed within grids to confine cascading blackouts to their region of origin. The team's next step, says Newman, is to study just that possibility by simulating and optimizing heterogeneous networks. 

A correction to this post was made on 23 April 2014: Ian Dobson is at Iowa State University, not the University of Iowa as originally reported.

Tequila Sunrise: Big Benefit from Co-Locating Agave Crops and Solar Power

Solar power in the desert has problems: big land use requirements, and the need for scarce water to clean the panels and suppress dust. In an unrelated story, biofuels production has problems: life cycle greenhouse gas emission issues, and land use questions again. How about solving both sets of problems at once? Stanford researchers have modeled the co-location of solar panels with agave plants used to make ethanol, and found it to be a winning combination.

The idea of "agrivoltaics", or combined solar power and agricultural production, has been floating around for a while now. It's an idea that springs at least partially from the modern distaste for "monoculture", or the growing of a single crop over huge swaths of land. The reasoning: Instead of "growing" only solar power on a plot of land, why not use the space between and underneath the photovoltaic panels to also grow crops? There are some projects in France that have tried this, and a post-Fukushima Renewable Energy Village in Japan also features crops underneath PV. There are also experiments at the University of Massachusetts, and some small-scale "solar farm" installations in Wisconsin.

It seemed unlikely, however, that the idea of studding the land around the solar plants that have started cropping up across the arid deserts of the American southwest would take root. But the Stanford folks, led by post-doctoral researcher Sujith Ravi, realized that the water required for a solar plant could actually make the desert more hospitable to agriculture as well. To test the idea, they chose agave plants, biofuel sources that are already quite hardy and require little water to survive.

They found that by combining a PV plant with agave production, a given area could yield more energy for the same amount of water than either PV or agave alone. The study, published in the journal Environmental Science & Technology, showed a "high-yield" scenario where only 0.42 liters of water would be needed to produce one mega-joule of energy.

"It could be a win-win situation," Ravi said in a press release. "Water is already limited in many areas and could be a major constraint in the future. This approach could allow us to produce energy and agriculture with the same water." This marriage of agave and solar panels is especially compelling for two reasons. First, because agave plants require roughly the same amount of water needed to keep solar panels clean and to suppress dust, it's possible to use the water dripping off a newly cleaned solar panel to nourish the plant. And a 2011 study found that the plants, also used to make tequila, perform just as well or better than corn, sugarcane, and switchgrass in terms of lifecycle greenhouse gas emissions and other parameters.

Aside from planting crops beneath existing solar panels, there are other ways to think about combining PV with plants. In a report on the topic, the National Renewable Energy Laboratory encouraged farmers to consider locating solar panels in the unused corners of their center-pivot farm plots. In Colorado alone, those currently underused spots could generate enough power to meet all of the state's electricity needs. Clearly, farming and solar power should become much better friends in the future.

Scientists Discover Efficient Way to Turn Carbon Monoxide Into Ethanol

Biofuels, once hailed as a planetary savior and alternative to oil and gas, have not quite fulfilled that destiny. Traditional, mass-produced biofuels from crops such as corn carry a litany of problems, including land use issues and questions of life cycle emissions. If we could generate usable fuels from more benign sources, it could go a long way toward solving a host of energy and environmental problems. A team at Stanford University reports today in Nature that they have a novel way to produce ethanol from carbon monoxide (CO) gas using a metal catalyst made of copper nanocrystals.

"We have discovered the first metal catalyst that can produce appreciable amounts of ethanol from carbon monoxide at room temperature and pressure—a notoriously difficult electrochemical reaction," said senior study author and Stanford chemistry professor Matthew Kanan in a press release.

Copper is the only material known to electroreduce CO down to generate fuels, but it does so at extremely low efficiencies. Kanan's group improved this with a nanocrystalline form of copper produced from copper oxide; this new material improves the efficiency of the reactions dramatically.

The researchers built a fuel cell, including a cathode made of the new copper nanocrystals, and suspended it in CO-saturated water; a small voltage applied across the fuel cell generates the resulting ethanol products. The Faraday efficiency using the oxide-derived material was 57 percent, meaning more than half of the current used went toward producing ethanol and acetate. Standard copper particles, meanwhile, produced hydrogen almost exclusively (Faraday efficiency of 96 percent) and very little ethanol.

In an e-mail, Kanan said a few years is probably enough to turn this basic work into prototype devices, outside of the lab, that can produce meaningful amounts of fuel. "Some of the technical issues include reformulating the catalyst such that it can be dispersed on high-surface area electrodes, and engineering an electrochemical cell that delivers CO to the catalyst at a high rate," he said. The long-term stability of the oxide-derived copper catalyst is still in question as well. Kanan declined to offer guesses on eventual costs of the device, given its still lab-bound status; copper, however, is not particularly expensive, as catalysts go.

If the details of this were actually to work out and at an acceptable cost, it could be enormous. Though there have been changes proposed recently in the biofuels mandate in the United States, we're still producing billions of gallons of the stuff each year, virtually all of it from corn. The big idea with the new catalyst would be to power the fuel cell using renewable energy rather than from fossil fuels; ideally, one would just grab carbon dioxide out of the atmosphere and turn it into CO.

"There is good technology for converting CO2 to CO using an electrical energy input, although it requires high temperatures," Kanan told me. "There has been much work by many groups including ours to develop a low temperature electrochemical process for converting CO2 to CO, and a number of good catalysts have been found recently. I don't think the CO2-to-CO would be a limiting factor."


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