Newest Material for More Ecological, Efficient and Economic Refrigeration Systems

An Extract from ScienceDaily dated Apr. 21, 2010 — Two teams based at the Barcelona Knowledge Campus, one from the University of Barcelona and one from the Universitat Politècnica de Catalunya, have worked with a group from the University of Duisburg-Essen to develop a new solid material that produces a caloric effect under hydrostatic pressure (solid-state barocaloric effect). The work was carried out using a high-pressure system developed by the UPC, which is the only one of its type in Spain.




This research was described in an article published in the scientific journal Nature Materials and was inspired by guidelines in the Kyoto protocol on renewing current refrigeration systems based on the compression of harmful gases.
Research into materials showing large caloric effects close to room temperature is 1 of the areas currently being explored to develop new refrigeration systems. Until recently, the most promising materials for applications in this field were giant magnetocaloric materials, which change temperature under the influence of an external magnetic field. The authors of this new study show that application of a moderate hydrostatic pressure to a nickel-manganese-indium alloy (Ni-Mn-In) produces results comparable to those achieved with the most effective magnetocaloric materials.
According to Mañosa, a professor with the Department of Structure and Constituents of Matter at the UB and principal investigator of the study, "the aim of this field of research is to identify materials that are efficient, economic and environmentally respectful, and the advantages of the alloy used in this study is that all of the component materials meet these requirements."
In addition, Antoni Planes, a professor with the same UN department, explains that, "this type of material can produce much greater caloric effects with only slight variations in pressure, which makes it ideal for domestic refrigeration systems (refrigerators, air conditioning and other cooling systems)." When these alloys are submitted to an external field, either magnetic or pressure, the material undergoes a solid-state phase transition, and Mañosa explains that, "this phase change generates a considerable latent heat exchange." The physical principle involved is the same as the effect observed when an ice cube is placed into a glass of water: the ice absorbs heat from the water, lowering its temperature.
The experiments were carried out using a unique high-pressure system developed by the Materials Characterization Group at UPC, directed by Josep Lluís Tamarit, a professor with the Department of Nuclear Physics and Engineering. The system was designed to measure the temperatures during state changes according to the pressure and heat exchanged in the process.
According to the researcher Maria Barrio, who works for the same UPC department and co-authored the study, "studying the behaviour of materials under different pressures has a wide range of uses in many fields," and applications include various types of refrigeration systems, such as domestic refrigerators and air-conditioning systems, food storage facilities, industrial machinery and supercomputers. Scientists have understood the magnetocaloric effect for some time, and it has been used extensively in work requiring extremely low temperature, but it was not until the 1990s that experts discovered materials capable of producing a large magnetocaloric effect close to room temperature, or giant magnetocaloric effect.
In 2005, an article in Nature Materials presented the inverse magnetocaloric effect, under which the temperature of a material submitted to an external magnetic field decreases instead of increasing, which is the standard response of most magnetic materials.
The study, carried out as preparation for the doctoral thesis of Xavier Moya, under the direction of Lluís Mañosa (UB), was awarded the 2009 Ramon Margalef Prize by the UB Board of Trustees.
In addition to the barocaloric effect described above, the Ni-Mn-In alloy also exhibits the inverse magnetocaloric effect. As such, the magnetic field can be combined with exertion of hydrostatic pressure to produce the caloric effect, which can be modulated with a series of parameters to control the temperature. With this new material it is possible to observe the pressure and the magnetic field to control the state change at a desired temperature.

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Adapted from materials provided by Universidad de Barcelona, via AlphaGalileo.
Journal Reference:
1.Lluís Mañosa, David González-Alonso, Antoni Planes, Erell Bonnot, Maria Barrio, Josep-Lluís Tamarit, Seda Aksoy, Mehmet Acet. Giant solid-state barocaloric effect in the Ni-Mn-In magnetic shape-memory alloy. Nature Materials, 2010; DOI: 10.1038/nmat2731

Carbon, Nitrogen Link May Provide New Ways to Mitigate Pollution Problems

Carbon, Nitrogen Link May Provide New Ways to Mitigate Pollution Problems

(Apr. 21, 2010) — A new study exploring the growing worldwide problem of nitrogen pollution from soils to the sea shows that global ratios of nitrogen and carbon in the environment are inexorably linked, a finding that may lead to new strategies to help mitigate regional problems ranging from contaminated waterways to human health.



A new CU-Boulder study shows that ratios of nitrogen and carbon in soils, rivers and oceans are closely linked, a finding with potential implications for mitigating pollution and health problems. (Credit: Casey A. Cass, University of Colorado)

The University of Colorado at Boulder study found the ratio between nitrates -- a naturally occurring form of nitrogen found in soils, streams, lakes and oceans -- and organic carbon is closely governed by ongoing microbial processes that occur in virtually all ecosystems. The team combed exhaustive databases containing millions of sample points from tropical, temperate, boreal and polar sites, including well-known, nitrogen-polluted areas like Chesapeake Bay, the Baltic Sea and the Gulf of Mexico.

"We have developed a new framework to explain how and why carbon and nitrogen appear to be so tightly linked," said CU-Boulder doctoral student Philip Taylor, lead author on the new study. "The findings are helping us to explain why nitrate can become so high in some water bodies but remain low in others."

A paper by Taylor and CU-Boulder ecology and evolutionary biology Professor Alan Townsend is being published in the April 22 issue of Nature. The study was funded in part by the National Science Foundation. Both Taylor and Townsend also are affiliated with CU-Boulder's Institute of Arctic and Alpine Research.

While the vast majority of nitrogen gas is abundant in the atmosphere, it is nonreactive and unavailable to most life, said Townsend. But in 1909 a process was developed to transform the nonreactive gas into ammonia, the active ingredient of synthetic fertilizer. Humans now manufacture more than 400 billion pounds of fertilizer each year -- much of which migrates from croplands into the atmosphere, waterways and oceans -- creating a suite of environmental problems ranging from coastal "dead zones" and toxic algal blooms to ozone pollution and human health issues.

Taylor said the new study indicates that in virtually every area of Earth's environment where there is substantially more dissolved organic carbon than nitrates, the nitrogen is sucked up by microbial communities. "But most of these nitrates are probably not locked away forever," said Taylor. "Instead, they are passed on to other ecosystems, essentially just moving pollution problems elsewhere in the environment."

The consistent relationship between nitrogen and carbon detected in the study was surprising, said Taylor, a doctoral student in CU-Boulder's ecology and evolutionary biology department. "The microbial communities that are controlling this link are found across the globe, whether in pristine environments or in areas of heavy pollution."

Taylor said the CU-Boulder team looked at available data from virtually every ecosystem type, ranging from high-altitude tundra and tropical forests to riparian areas and estuaries. "We looked at a large number of data sets, from sites as small as an office table to as large as entire oceans," said Taylor. "We saw the same correlation between nitrogen and carbon wherever we looked."

"The bottom line is that if there is sufficient organic carbon present, it keeps the nitrates at a low level," said Townsend. "By using available data, we can now make more accurate evaluations of when and where nitrate pollution may pop up." In the February 2010 issue of Scientific American, Townsend and co-author Robert Howarth of Cornell University wrote that "a single new atom of reactive nitrogen can bounce its way around these widespread environments, like a felon on a crime spree."

Nitrogen pollution is increasing globally in part because of fertilizer-intensive activities like biofuel synthesis and meat production that relies on the growth and cultivation of grains used to feed animals. In addition, the burning of fossil fuels -- which releases nitric oxide and nitrogen dioxide -- causes ground-level ozone pollution. Some scientists have ranked nitrogen pollution as one of the top threats to global biodiversity, Townsend said.

High nitrate concentrations in drinking water also is a potential hazard to human health and may cause several types of cancer and elevate risks for Alzheimer's disease and diabetes, while atmospheric nitrogen pollution can elevate cardiopulmonary ailments, said Townsend. In addition, studies also have shown elevated nitrogen concentrations may increase the risks of several other human and wildlife diseases.

Taylor said the new study showed that "downscaling" from a global analysis of the carbon-nitrogen link to system-specific scenarios indicates the relationship between the elements typically becomes even stronger. "Analyzing the problem using these methods at smaller scales could allow ecosystem management teams to better predict and influence the fate of nitrates in the environment," Taylor said.

Story Source:

Adapted from materials provided by University of Colorado at Boulder.

Journal Reference:

1. Philip G. Taylor, Alan R. Townsend. Stoichiometric control of organic carbon%u2013nitrate relationships from soils to the sea. Nature, 2010; 464 (7292): 1178 DOI: 10.1038/nature08985

Solutions to Climate Change: Using Trees and Grasses to Capture Carbon and Produce Energy

(Jan. 29, 2010) — A unique £1.1 million research project is investigating how coppiced trees and grass crops can be used both to generate renewable energy and to trap carbon in the soil over the long term.

Led by Professor Gail Taylor, an expert on plants and the environment at the University of Southampton, a team of scientists across the UK will track the path of carbon, captured by plants and grasses through the process of photosynthesis, as it flows through the plant to the soil, which is inhabited by micro-organisms, before becoming locked into organic matter in the soil in which the plant is growing.

The team will also compare the process with that of arable food crops, such as wheat, and will test the idea that the 'bioenergy' crops are better at stimulating long-term retention of soil carbon.

Unlike existing food crops that are harvested after just a few months, trees and grasses can spend decades growing before they are harvested and release their trapped CO2, making the process more effective.

"Scientists now believe that CO2 is an important greenhouse gas and a major cause of climate change, so it's vital we develop ways of removing it from the atmosphere," comments Professor Gail Taylor, of the University's School of Biological Sciences.

"Using trees and grasses is an efficient and cost-effective way of doing this, whilst providing a source of energy and off-setting CO2 emissions from equivalent fossil fuels. Our research has already shown that bioenergy crops could potentially reduce carbon emissions by several million tonnes in the UK over the next decade."

'Carbon opportunity' maps will be developed to identify the optimum areas of the countryside in which bioenergy crops could most effectively be grown. The crops could then be combusted alongside coal in power stations to produce electricity, producing fewer CO2 emissions than fossil fuels, or used in heating systems.

"In the future, bioenergy crops could be turned into liquid fuels such as bioethanol, avoiding the conflict between food and fuel when grain crops are used for these purposes," adds Professor Taylor.


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Adapted from materials provided by University of Southampton.

Scientists are reporting that "biochar" -- a material that the Amazonian Indians used to enhance soil fertility centuries ago -- has potential in the modern world to help slow global climate change. Mass production of biochar could capture and sock away carbon that otherwise would wind up in the atmosphere as carbon dioxide, the main greenhouse gas.


Their report appears in ACS' Environmental Science & Technology, a bi-weekly journal.

Kelli Roberts and colleagues note that biochar is charcoal produced by heating wood, grass, cornstalks or other organic matter in the absence of oxygen. The heat drives off gases that can be collected and burned to produce energy. It leaves behind charcoal rich in carbon.

Amazonian Indians mixed a combination of charcoal and organic matter into the soil to improve soil fertility, a fact that got the scientists interested in studying biochar's modern potential.

The study involved a "life-cycle analysis" of biochar production, a comprehensive cradle-to-grave look at its potential in fighting global climate change and all the possible consequences of using the material. It concludes that several biochar production systems have the potential for being an economically viable way of sequestering carbon -- permanently storing it -- while producing renewable energy and enhancing soil fertility.
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Story Source:

Adapted from materials provided by American Chemical Society, via EurekAlert!, a service of AAAS.

Journal Reference:

1. Roberts et al. Life Cycle Assessment of Biochar Systems: Estimating the Energetic, Economic, and Climate Change Potential. Environmental Science & Technology, 2010; 44 (2): 827 DOI: 10.1021/es902266r

Saving Marshes - Saving The Planet Soil Scientists Restore Marshes To Protect Coastal Ecology

Soil scientists spread material dredged from shipping channels over shore areas to help rebuild marsh areas. Wetlands along the shore protect the land from storm surges, create habitat for wildlife, and the plants that grow in them could sequester three to eight tons of carbon dioxide per acre every year.

Our nations wetlands are disappearing at an alarming rate. But now, marshes are being restored to help save the planet.

Bill Giese has lived near wetlands his whole life, and year after year he's watched a once thriving marsh disappear. "We've lost over 8,000 acres of wetland vegetation," said Giese.

Increasing atmospheric carbon dioxide causes global warming, which causes rising sea levels that are then washing away wetlands. But tidal marshes are excellent at capturing carbon dioxide.

"Now, the beauty of a tidal marsh the decomposition is very slow, so most of the carbon that's fixed, or sequestered, stays. It doesn't get returned back to the atmosphere," Brian Needelman, Ph.D., soil scientist at the University of Maryland, told Ivanhoe.

Now, soil scientists are wading through soggy, murky marshes in a new project to help restore wetlands and help reduce carbon dioxide in the atmosphere. Dirt and sediment from the bottom of rivers and bays are pumped into washed-out marshes. New marsh grasses are planted, die and decompose in the water -- taking carbon dioxide down with them. A healthy marsh can collect three to eight tons of carbon dioxide per acre a year.

"What we do is take a soil sample each year and we try to tell how much more carbon is in the soil after each year, and it increases slowly from year to year," Dr. Needelman said.

Marshes are a vital habitat for wildlife; they improve water quality and prevent shoreline erosion. Restoring wetlands is essential for a healthy earth.

"If we want marshes as part of our ecosystem and part of our lives, then we need to restore them and we need to build new ones," said Dr. Needelman.

Helping to save the planet one marsh at a time.

THE CARBON CYCLE: The carbon cycle describes the movement of carbon, in its many forms, between the earth, atmosphere, oceans, and the animals, plants and bacteria that live there. For example, much of the carbon stored in trees and soils is released into the atmosphere when forests are cleared and cultivated. Sometimes this release happens very quickly, like when a forest fire burns. Sometimes it happens slowly, as dead plants decompose. When forests regrow on cleared land, trees draw carbon from the atmosphere and store it again in the plants and soil. If the global totals for photosynthesis (plants taking CO2 from the air and using it for energy, giving off oxygen) and respiration (animals taking in oxygen and using it to make energy, giving off CO2) are not equal, carbon accumulates, either on land or in the atmosphere. The rates of photosynthesis and respiration are not known, and they're not measured well enough, but there does appear to be an imbalance, known as the "missing sink" of carbon. Yet the carbon cycle must be a closed system, which means there is a fixed amount of carbon; we just don't know where the missing carbon is yet. Understanding why there is an imbalance, and where it occurs, is critical to combating the threat of global warming.

ABOUT GLOBAL WARMING: Global warming refers to an increase in the earth's average temperature -- which has risen about 1 degree F over the past 100 years. A warmer earth may lead to changes in rainfall patterns, and a rise in sea level, for example, as polar glaciers melt. Some of this rise is due to the greenhouse effect: certain gases in the atmosphere trap energy from the sun so that heat can't escape back into space. Without the greenhouse effect, the earth would be too cold for humans to survive, but if it becomes too strong, the earth could become much warmer than usual, causing problems for humans, plants and animals.

The American Geophysical Union and the American Waterworks Association contributed to the information contained in the TV portion of this report.