Monday, January 24, 2011

SQUEEZING SUSTAINABLE ENERGY FROM THIN AIR

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Energy from compressed air stored underground is cheap, clean and renewable, and could even save lives. Researchers at the UA's School of Sustainable Engineered Systems are designing systems that will run fridges, buildings or power plants.

Solar collectors and wind generators hold so much promise for clean energy, but they have a major flaw – they produce no power when the sun doesn't shine or the wind doesn't blow.

"If all we had to do was to generate power when the sun is shining, we would actually be in good shape right now," said Ben Sternberg, a researcher in the University of Arizona's Compressed Air Energy Storage, or CAES, program. "The crucial issue now is finding economical ways to store energy for large-scale use, either home-by-home over the entire country, or utility scale."

Batteries have traditionally been used to store energy, but they're expensive, have a limited number of charge-discharge cycles, and pose resource and disposal problems.

The CAES group is developing cost-competitive energy-storage systems based on compressing air and storing it in man-made containers or below ground in natural reservoirs.

When solar panels shut down and wind generators stop spinning, the compressed air is heated slightly and released to drive turbines that generate electricity. The compressed air also can be released directly to drive mechanical systems without being converted to electricity.

Although CAES researchers are putting a high-tech spin on compressed air storage and its modern materials, sophisticated remote sensing gear, and computer analysis, it's a simple, well-tested and mature technology. Urban systems were built in European cities as early as 1870, and by the 1890s were storing and delivering power to factories and homes.

The UA's CAES research team is working on three projects that range from systems that might power a single air conditioner or refrigerator to building-wide systems, as well as massive storage sites that could store utility-scale energy.

In this system, a low-speed motor uses some or all of the power from a solar panel or wind generator to pump air into a tank similar to those used for propane or oxygen. The energy is later used to power an appliance, such as a refrigerator. Several of these units could be linked together to power a home.

"We hope to develop a single-appliance system that could be built for less than $1,000," said Dominique Villela, a doctoral student in materials science and engineering. "We've had visitors from Alaska, whose villages depend on energy generated from propane. This is very expensive. Systems like ours could save them a lot of money by using solar or wind power for refrigerators or lights, for instance."

These systems could also save lives and taxpayer dollars in combat zones by producing energy on site. A recent segment on NPR's Science Friday program featured military efforts to conserve energy and switch to renewable energy fuels. Program guests noted that a gallon of gas that cost $2.35 in the U.S. could cost between $200 and $400 by the time it reaches outposts in Afghanistan. They also noted that more than 1,000 Americans have been killed moving fuel since that war began.

Villela said the group's research is now focusing on reliability issues, scaling the system to provide more energy storage, and adapting the system to less expensive materials and components.

UA civil engineers are designing hollow structural members that could be used to store compressed air in load-bearing components, such as foundation piles or the frames of buildings and houses.

"The key to our system is that the loads on structural components coming from compressed air are small compared to building loads, such as the weight of the building and wind loads," said George Frantziskonis, a professor of civil engineering and engineering mechanics. "This makes CAES storage in buildings economically and aesthetically feasible."

The larger the building, the more economical the CAES system and the greater the energy cost savings both in the short and long term, Frantziskonis said.

Researchers in the UA's Laboratory for Advanced Subsurface Imaging, or LASI, are developing high-resolution underground imaging systems that can be used to find salt deposits, porous rocks and other natural underground storage reservoirs. These sites could be used to hold large amounts of compressed air to drive utility-scale turbines.

While salt deposits have traditionally been associated with CAES technology, "you don't need a large cavern," said Sternberg, a professor of mining and geological engineering and director of the LASI program. "Rocks that have lots of pores also can provide energy storage. A third option is alluvium in basins, such as those found throughout the Southwest."

All of these possibilities require mapping the Earth's subsurface in high resolution with ground-penetrating electromagnetic waves. "That's where our work comes in because accurate imaging is needed to determine if there are discontinuities in these underground storage areas that will allow too much air to escape," he said.

Sternberg said porosity within the Earth, either from caverns or lots of interconnected pore space, has tremendous potential for low-cost storage that would make renewables cost competitive with fossil fuels.

Recent breakthroughs in the LASI program could help drive exploration and development of these resources. "We're getting data that's an order of magnitude more sensitive than conventional measurements," Sternberg said. "It's a combination of a new approach to collecting data, a new type of antenna array and a very different way of analyzing the data."

Sternberg is anxious to rapidly expand this technology to utility-size exploration. "Right now, so much of our energy is coming from volatile areas of the world, and we've got to overcome that," he said. "Energy security is our biggest risk. That's why this is so pressing. We cannot afford to drag this out and sit on the new developments in energy independence that are being created here in the LASI and CAES programs, as well as in other programs at universities across the country."

(Photo: U. Arizona)

University of Arizona

UF STUDY OF LICE DNA SHOWS HUMANS FIRST WORE CLOTHES 170,000 YEARS AGO

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A new University of Florida study following the evolution of lice shows modern humans started wearing clothes about 170,000 years ago, a technology which enabled them to successfully migrate out of Africa.

Principal investigator David Reed, associate curator of mammals at the Florida Museum of Natural History on the UF campus, studies lice in modern humans to better understand human evolution and migration patterns. His latest five-year study used DNA sequencing to calculate when clothing lice first began to diverge genetically from human head lice.

Funded by the National Science Foundation, the study is available online and appears in this month’s print edition of Molecular Biology and Evolution.

“We wanted to find another method for pinpointing when humans might have first started wearing clothing,” Reed said. “Because they are so well adapted to clothing, we know that body lice or clothing lice almost certainly didn’t exist until clothing came about in humans.”

The data shows modern humans started wearing clothes about 70,000 years before migrating into colder climates and higher latitudes, which began about 100,000 years ago. This date would be virtually impossible to determine using archaeological data because early clothing would not survive in archaeological sites.

The study also shows humans started wearing clothes well after they lost body hair, which genetic skin-coloration research pinpoints at about 1 million years ago, meaning humans spent a considerable amount of time without body hair and without clothing, Reed said.

“It’s interesting to think humans were able to survive in Africa for hundreds of thousands of years without clothing and without body hair, and that it wasn’t until they had clothing that modern humans were then moving out of Africa into other parts of the world,” Reed said.

Lice are studied because unlike most other parasites, they are stranded on lineages of hosts over long periods of evolutionary time. The relationship allows scientists to learn about evolutionary changes in the host based on changes in the parasite.

Applying unique data sets from lice to human evolution has only developed within the last 20 years, and provides information that could be used in medicine, evolutionary biology, ecology or any number of fields, Reed said.

“It gives the opportunity to study host-switching and invading new hosts — behaviors seen in emerging infectious diseases that affect humans,” Reed said.

A study of clothing lice in 2003 led by Mark Stoneking, a geneticist at the Max Planck Institute in Leipzig, Germany, estimated humans first began wearing clothes about 107,000 years ago. But the UF research includes new data and calculation methods better suited for the question.

“The new result from this lice study is an unexpectedly early date for clothing, much older than the earliest solid archaeological evidence, but it makes sense,” said Ian Gilligan, lecturer in the School of Archaeology and Anthropology at The Australian National University. “It means modern humans probably started wearing clothes on a regular basis to keep warm when they were first exposed to Ice Age conditions.”

The last Ice Age occurred about 120,000 years ago, but the study’s date suggests humans started wearing clothes in the preceding Ice Age 180,000 years ago, according to temperature estimates from ice core studies, Gilligan said. Modern humans first appeared about 200,000 years ago.

Because archaic hominins did not leave descendants of clothing lice for sampling, the study does not explore the possibility archaic hominins outside of Africa were clothed in some fashion 800,000 years ago. But while archaic humans were able to survive for many generations outside Africa, only modern humans persisted there until the present.

“The things that may have made us much more successful in that endeavor hundreds of thousands of years later were technologies like the controlled use of fire, the ability to use clothing, new hunting strategies and new stone tools,” Reed said.

(Photo: Jeff Gage, Florida Museum of Natural History)

University of Florida

ATTENTION LADIES AND GENTLEMEN: COURTSHIP AFFECTS GENE EXPRESSION

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Scientists from Texas have made an important step toward understanding human mating behavior by showing that certain genes become activated in fruit flies when they interact with the opposite sex.

This research, published in the January 2011 issue of the journal GENETICS (http://www.genetics.org), shows that courtship behaviors may be far more influenced by genetics than previously thought. In addition, understanding why and how these genes become activated within social contexts may also lead to insight into disorders such as autism.

"Be careful who you interact with," said Ginger E. Carney, PhD, co-author of the research study from the Department of Biology at Texas A&M University in College Station. "The choice may affect your physiology, behavior and health in unexpected ways."

To make this discovery, the scientists compared gene expression profiles in males that courted females, males that interacted with other males, and males that did not interact with other flies. The investigators identified a common set of genes that respond to the presence of either sex. They also discovered that there are other genes that are only affected by being placed with members of a particular sex, either male or female. Researchers then tested mutant flies that are missing some of these socially responsive genes and confirmed that these particular genes are important for behavior. The scientists predict that analyzing additional similar genes will give further insight into genes and neural signaling pathways that influence reproductive and other behavioral interactions.

"This study shows that we're closing in on the complex genetic machinery that affects social interactions," said Mark Johnston, Editor-in-Chief of the journal GENETICS. "Once similar genes are identified in humans, the implications will be enormous, as it could bring new understanding of, and perhaps even treatments for, a vast range of disorders related to social behavior."

Genetics

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