Green Environment : Steps to Increase The Efficiency of Your Heating and Cooling System At Home

Heat & Cool Efficiently

As much as half of the energy used in your home goes to heating and cooling. So making smart decisions about your home's heating, ventilating, and air conditioning (HVAC) system can have a big effect on your utility bills — and your comfort. Take these steps to increase the efficiency of your heating and cooling system. For more information, see our Guide to Energy Efficient Heating & Cooling PDF (708KB).

Change your air filter regularly

Check your filter every month, especially during heavy use months (winter and summer). If the filter looks dirty after a month, change it. At a minimum, change the filter every 3 months. A dirty filter will slow down air flow and make the system work harder to keep you warm or cool — wasting energy. A clean filter will also prevent dust and dirt from building up in the system — leading to expensive maintenance and/or early system failure.

Tune up your HVAC equipment yearly

Just as a tune-up for your car can improve your gas mileage, a yearly tune-up of your heating and cooling system can improve efficiency and comfort. Learn more:

* Maintain your Equipment: A Checklist
* Finding the right contractor: 10 tips

Install a programmable thermostat

A programmable thermostat is ideal for people who are away from home during set periods of time throughout the week. Through proper use of pre-programmed settings, a programmable thermostat can save you about $180 every year in energy costs.
Seal your heating and cooling ducts

Ducts that move air to-and-from a forced air furnace, central air conditioner, or heat pump are often big energy wasters. Sealing and insulating ducts can improve the efficiency of your heating and cooling system by as much as 20 percent — and sometimes much more.

Focus first on sealing ducts that run through the attic, crawlspace, unheated basement, or garage. Use duct sealant (mastic) or metal-backed (foil) tape to seal the seams and connections of ducts. After sealing the ducts in those spaces, wrap them in insulation to keep them from getting hot in the summer or cold in the winter. Next, look to seal any other ducts that you can access in the heated or cooled part of the house. See our See our Duct Sealing brochure PDF (1.13MB) for more information. for more information.

Consider installing ENERGY STAR qualified heating and cooling equipment

If your HVAC equipment is more than 10 years old or not keeping your house comfortable, have it evaluated by a professional HVAC contractor. If it is not performing efficiently or needs upgrading, consider replacing it with a unit that has earned the ENERGY STAR. Depending on where you live, replacing your old heating and cooling equipment with ENERGY STAR qualified equipment can cut your annual energy bill by nearly $200. But before you invest in a new HVAC system, make sure that you have addressed the big air leaks in your house and the duct system. Sometimes, these are the real sources of problems rather than your HVAC equipment.

Ask about Proper Installation of your new equipment

Replacing your old heating and cooling equipment with new, energy-efficient models is a great start. But to make sure that you get the best performance, the new equipment must be properly installed. In fact, improper installation can reduce system efficiency by up to 30 percent — costing you more on your utility bills and possibly shortening the equipment's life.

Department of Energy Announces Winners of Federal Energy and Water Management Awards

The U.S. Department of Energy today announced that more than 30 individuals, teams, and organizations across the federal government were selected to receive Federal Energy and Water Management Awards for outstanding and innovative efforts to implement sustainable strategies that improve energy, water, and vehicle fleet efficiency. These awards demonstrate the commitment by federal agencies to invest in efficiency measures that save money for taxpayers, reduce carbon pollution, and create a stronger economy for the American people. The 31 initiatives receiving awards today saved taxpayers almost $42 million in energy and water costs in fiscal year 2009 and kept the equivalent of about 190,000 metric tons of carbon dioxide from being released into the atmosphere. These efforts are also helping to move cutting-edge clean energy technologies into the marketplace, create new American jobs, and strengthen our national security.

"As the single largest consumer of energy in the country, the federal government has a responsibility and an opportunity to lead by example in implementing clean energy projects that save taxpayers money, create new jobs, and reduce carbon pollution," said Secretary of Energy Steven Chu. "Today's award winners show what is possible when it comes to implementing energy efficiency and renewable energy projects in the federal government and beyond."

The 2010 Federal Energy and Water Management Awards winners were selected from nominations submitted by 17 federal agencies. Included among the award winners are employees from the U.S. Air Force, Army, Marine Corps, and Navy; the Departments of Defense, Energy, Homeland Security, Interior, Transportation, and Veterans Affairs; the Environmental Protection Agency; General Services Administration; and National Aeronautics and Space Administration.

Last year, President Obama signed Executive Order 13514 on Leadership in Environmental, Energy, and Economic Performance, which called on the federal government to dramatically reduce its greenhouse gas emissions and implement aggressive energy and water efficiency programs. As part of their commitment to meet the president's goals to "green the government," agencies are undertaking projects to increase their use of renewable energy, make their buildings and vehicles more efficient, and limit their use of fossil fuels.

The federal government has already achieved substantive results towards cleaner energy and improved energy efficiency. Data for fiscal year 2009 shows that the federal government has decreased energy consumption per square foot of building space by approximately 13.1% compared with fiscal year 2003, surpassing the goal of 12% for the year. The federal government also reported purchasing or producing 2,331 Gigawatt-hours of electricity from renewable sources, equivalent to 4.2% of their electricity use, surpassing the goal of 3% for fiscal year 2009.

The combined accomplishments of this year's winners include:

* Saving 38 billion Btu through the installation of renewable energy systems, including solar thermal and photovoltaic systems, wind turbines, and methane gas generated by landfills.
* Implementing facility-wide comprehensive changes to operations and maintenance practices, saving 1.7 trillion Btu by upgrading heating, ventilation, and air conditioning equipment, and by installing high efficiency lighting and energy management control systems.
* Installing significant water efficiency improvements, saving 3.2 billion gallons of water through high efficiency plumbing fixtures, upgrades to irrigation systems, use of native landscaping, discovery and repair of major leaks, and reuse of reclaimed and recovered ground water.
* Building Leadership in Energy and Environmental Design (LEED) facilities with state-of-the-art technologies and environmentally friendly workspaces.
* Implementing energy savings performance contracts, in which a federal agency partners with an energy service company, who designs and constructs a project, arranges the necessary financing, and guarantees that the improvements will generate energy cost savings sufficient to pay for the project over the term of the contract.
* Implementing utility energy services contracts, where a utility arranges financing to cover the capital costs of the project, which are repaid over the contract term from cost savings generated by the energy efficiency measures.

This awards program is one of several held each year in October in conjunction with Energy Awareness Month to highlight the critical importance of energy efficiency and renewable resources and federal efforts to lead by example in energy management. To see the complete list of this year's winners visit the 2010 Federal Energy and Water Management Award Winners Web page.

Few Trees and Insects Are Made for Each Other

Coevolution--mutual adaptation of two or more species to one another--shapes much of the natural world and produces some of the most remarkable biological phenomena, from the exceptional speed of cheetahs and gazelles, to the virulence of the HIV and swine flu viruses.

The interaction between plants and insects is another prime example. These range from pollination relationships where both species benefit to insect outbreaks that kill entire forests. Plants and insects are also amazingly diverse, with more than 300,000 described species of insects and at least 200,000 species of flowering plants. Many scientists, starting with Charles Darwin, have suggested that coevolution might be responsible for the enormous diversity of these two groups of organisms. However, why mutual adaptation would lead to species diversity is not clear. New research is shedding light on this century-old question.

"The most repulsive tree"

Joshua trees are probably some of the strangest plants in the world. Relatives of agaves, they look like an aloe on steroids, with short, spiny leaves, and long spindly branches that form twisted candelabra.

Their bizarre appearance inspires the imagination of anyone who sees them. Early American explorer John C. Fremont described them as, "The most repulsive tree in the Vegetable Kingdom." Mormon settlers saw in their silhouette the figure of the prophet Joshua. More recent visitors to Joshua Tree National Park have called Joshua trees, "The Dr. Seuss Tree."

"The most remarkable fertilization system"

The strangest thing about Joshua trees may be the way that they are pollinated. These desert plants produce no nectar. So, in order to reproduce, the Joshua tree relies on small, inconspicuous grey moths. The moths have tentacle-like appendages that grow out of their jaws, which they use to collect pollen from Joshua tree flowers. The moths then crawl from flower to flower, deliberately spreading pollen onto the female part of each flower.

Why would a simple moth go to so much trouble to help a tree? The answer is that the moth needs the Joshua tree for her own reproduction. Before she pollinates each flower, the moth lays her eggs on the immature seeds of the Joshua tree, cutting into the flower with a thin, blade-like organ called an ovipositor. Her eggs will eventually hatch into caterpillars that will eat some of the seeds before crawling to the ground to form a cocoon. So, for her babies to eat, the moth needs to ensure that there will be Joshua tree seeds, and for there to be seeds, the moth must pollinate the flower.

Needless to say, the relationship between the Joshua tree and its pollinators is fascinating. In fact, Charles Darwin considered it "the most remarkable fertilization system ever described."

Seven years in the desert

In 2003, much of what we thought we knew about Joshua trees and their pollination changed. That year, biologist Olle Pellmyr of the University of Idaho discovered that Joshua trees were actually pollinated by two similar-looking-but-genetically-distinct species of moth.

Olle, his graduate students and I have spent the last seven springs living in the Mojave Desert seeking to understand how this difference affects the relationship between the Joshua tree and its pollinators. The results show that coevolution between plants and insects may indeed be the reason both groups are so startlingly diverse.

One of the first discoveries that we made was that the two moth species occur in different parts of the desert. The slightly larger of the two species exists in California and central Nevada. The second, smaller species is distributed throughout southern Nevada and Arizona.

Second, it seems that the trees pollinated by each moth species are not exactly the same. When we looked at the flowers of different trees, we found the covering that protects the immature seeds was much thicker on plants that were pollinated by the larger moth.

Finally, we noticed that the ovipositors--the organ that they use to lay their eggs on the seeds--of the two moth species matched the thickness of the wall surrounding the seeds. Each moth has an ovipositor that is just the right length to reach the seeds of the flower it pollinates, almost as if the moth and the tree were made for each other.

This view of life

The implications of these findings were tantalizing. First, the match between the Joshua tree flowers and the moths' ovipositors suggested that coevolution might have molded the relationship between the plant and the pollinator. Second, because the plants are completely dependent on the moths for reproduction, the differences in the flowers might have caused Joshua trees to split into two different species.

This might provide an explanation for how interactions between species have generated the diversity of plants and insects. I am working to further test that hypothesis by measuring natural selection acting on the moths and the trees.

Though the two moth species occur mostly in different parts of the desert, they live side-by-side in a small stretch of desert in Nevada. At that site, both moths visit trees with both flower types, but when moths lay eggs on a tree that is normally pollinated by the other species, the moths produce fewer caterpillars. That is, moths that lay eggs on the 'wrong' tree have lower fitness.

I'm currently conducting experiments that will address why this happens, and whether the trees also pay a cost when pollinated by the wrong species of moth.

The most exciting part of this research is the prospect that a single natural process--natural selection--has produced both the spectacular diversity of plants and insects and the remarkable fit between insects and the flowers they pollinate.

Toxic Grass Puts Animals to Sleep

Legend has it that five railroad surveyors killed by Indians in 1854 in New Mexico lost their lives because they unwittingly allowed their horses to graze on "sleepy grass" the night before. The next morning, under attack, the surveyors jumped on their horses to escape--but the animals were frozen in place. Without the means for a quick getaway, the workers were doomed.

Whether true or apocryphal--the story is unverified--it could have happened, considering the toxic effects of sleepy grass, also known as robust needle grass, which commonly grows in many western states and causes animals that eat it to turn into living statues--or, if they consume too much of it, even die.

"Native Americans are said to have fed a single seed to colicky babies to quiet them, and they--and ranchers--have fed small amounts to cattle to make them more sedate and easily managed when moving them from summer to winter ranges in the mountains," said Stan Faeth, professor of biology and head of the biology department at the University of North Carolina, Greensboro.

Moreover, in a book called "Horse Tradin," by Ben K. Green, the author recounts "how he bought a horse from the Mescalero Apaches in the 1920s which seemed tame and broken, but later found it was unbroken and wild--but had been fed a small amount of sleepy grass," Faeth added.

Sleepy grass has this effect because, like all plant species, it harbors microbial "partners," that is, microbes such as bacteria or fungi that "infect" the plant and live within plant tissues. The microbes can dramatically change plant growth and performance, frequently to the plant's benefit. Also, like plant and animal species, microbes also can hybridize and create new genetic species and variants.

Fungal endophytes, which are found in many types of grasses, make alkaloids which fight against drought and insects. But, as is the case with sleepy grass, these alkaloids also can be poisonous to animals--including humans.

"If ingested, infected sleepy grass--but only from a few selected populations--has the same effects on humans as in livestock," Faeth said. "One main alkaloid is lysergic acid amide--very closely related to LSD, but apparently without the hallucinogenic effects."

Faeth and his colleagues, who include Nadja Cech, associate professor in the university's department of chemistry and biochemistry, are trying to better understand the workings of fungal endophytes. Because their research could have broad implications for the multi-billion dollar livestock industry, as well as for the restoration of native grasslands and the management of forage grasses, the National Science Foundation (NSF) is funding the program as part of the American Recovery and Reinvestment Act of 2009.

In replenishing native grasses, for example, it would help to know whether seeds were infected before planting them. The knowledge also could help the turf grass industry in the planning and maintenance of recreation areas.

"You can plant grass with high endophytes in places where nothing is grazing--golf courses, for example," Faeth said. "The grass uses less water and resists insects. It's good for golf courses, but you don't want to plant it in pastures where it will make livestock sick."

Faeth's team has been conducting field experiments in Arizona on two native grasses--"sleepy grass," and Arizona fescue. The endophytes within Arizona fescue also make alkaloids but they are harmless to livestock.

The research team has created "common garden experiments" to understand how the endophytes work within the plant, and whether changing certain conditions can increase the grass's ability to survive and compete better in harsh environmental conditions.

"We take plants with different strains of endophytes and grow them," he said. "Then we alter the factors that can change the endophyte effect on the host--such as water, nutrients and competition. The alkaloid production stays the same. We are looking at the plant's response in terms of growth and reproduction--how does the plant respond to these variants? We want to better understand how [endophytes] work."

Endophytes sometimes are not beneficial to the plants, depending on the strain. "We are studying this, as well," Faeth said. Although generally thought to be positive to plants, "most of our research is showing you can get highly variable effects," he said. Also, one section of land can have mixed strains containing areas with toxic-producing endophytes--or not. There's no way to tell without testing--although livestock, once sickened, will not eat there again.

Faeth and his colleagues also have been collecting native grasses in very remote mountainous areas of New Mexico--Lincoln National Forest, near Cloudcroft, for example--as well as insects from the plants. They want to test the effects of endophytes and their alkaloids on herbivores. "Just like livestock, endophytes may protect grasses from insect consumers," he said.

The researchers gather the bugs using a machine, called a Burkhard Vortis Insect Sampling device, that suctions them out of the plant. "It makes a lot of noise--it runs on a gas leaf blower engine--and looks like some type of weapon," Faeth said.

These field trips may seem relatively benign, but sometimes, the unexpected happens. "On more than one occasion, we've had the local ranchers approach us, gun-in-hand, wondering 'what the hell are you doing out here?'" he said.

Another time, a rancher and his wife--who happily gave permission for the researchers to work on his land--often enjoyed chatting with the three young undergraduate and graduate students Faeth brought along--all of them women, and all raised in the city.

Bone-crushing Experiments possibly will Yield Better Protective Gear

No sample is safe in Nikhil Gupta's Composite Materials and Mechanics Lab at the Polytechnic Institute of New York University.

Whether it's a small nugget of rabbit bone or a piece of industrial protective foam, all are bound for a custom-built compression machine designed to study how materials split and shatter.

Gupta, a materials scientist and mechanical engineer, and his team capture each compression with a high-speed camera that records over 10,000 frames per second to study every crack and splinter. The results are critical--they may ultimately help physicians better diagnose and treat injuries and aid engineers as they improve protection for military and civilian armor, including helmets.

Along with collaborator Paulo Coelho, a New York University College of Dentistry materials scientist (and a dentist who specializes in surgical research well beyond the jaw bones), Gupta has pioneered research that reveals surprising insights about the effect of compression on bones, and about the limitations of the foams used to protect bones in helmets and armor.

Gupta and Coelho found that bone injuries differ dramatically depending on the speed at which the bone is compressed. At high compression rates--like a shock wave from a bomb blast or a hard hit in a football scrimmage--bones show widespread micro-cracks so small they can only be detected by a scanning electron microscope.

When bones are compressed slowly, as when jogging or falling, fewer cracks occur, but they tend to be larger and easily spotted. The experiments were conducted on rabbit femur bones, though the scientists believe similar findings would apply to a range of human bones.

"We were surprised to find that not only did the nature of the bone fractures change depending on the speed of compression, but that bones crack in different directions based on speed," Coelho said. Learning that bones need to be reinforced from multiple angles to prevent injury brought Gupta back to the initial impetus for his research--improving the foams used in protective military gear.

Two years ago, Gupta attended a conference at which veterans from Iraq and Afghanistan were discussing injuries related to Improvised Explosive Devices (IEDs). At that time, more than one-third of all war casualties were due to IEDs, which cause a unique type of brain injury that is difficult to diagnose. Those "closed" brain injuries result not from a direct impact or penetration of the skull, but from the force of the compression. Similar damage may be happening to other organs and bones, as well.

Damage from blast injuries is often not visible with today's diagnostic equipment, and soldiers may be pronounced healthy enough to return to the field. In many cases, the extent of the injury only becomes evident over time.

"I was already studying foams and body armor and developing new protective materials, but my approach changed when I learned about the nature and prevalence of IED injuries," Gupta said. "I realized it was critical to understand how the bones themselves behaved in these circumstances in order to devise the next-generation of protection."

Gupta set out in search of a collaborator who could bring essential medical expertise to the investigations. When colleagues introduced him to Coelho, the connection was immediate. "I had discussed the project with several physicians, but we spoke completely different languages," Gupta said. "But because Coelho's previous research has focused on bone surgery and we have a common background in materials science, we were able to start working very quickly."

In addition to researching bone injuries, Coelho and Gupta also exposed protective foams to their compression machine, called a "Kolsky Bar" system. They found that much like bone, foam materials behave differently as the rate of compression changes. Foams that seem soft when slowly compressed can become much stiffer under higher compression speeds. The team plans to investigate whether this change can actually increase, instead of reduce, the risk of injuries.

The next step for these two scientists is to combine the findings of the foam and bone studies by testing human bones and soft tissues with new formulations of protective foam. The ultimate goal is to enable manufacturers to create customized foams tailored to specific activities or environments. The implications are wide-reaching and may help designers create safer military armor, sports equipment and even automobiles and boats.

Since Gupta and Coelho showed widespread microscopic damage occurs in bones subjected to high compression rates, their findings also point to the need for improvements in medical diagnostic equipment that can one day detect injuries on a scale much smaller than current CT scanners.

According to Coelho, "now that we've seen how much bone damage happens at the extreme microscopic level, it's an opportunity to develop more sensitive devices that can diagnose such injuries and allow physicians to better treat that damage quickly."

Good Bacteria can solve world's most complex problems

Good Bacteria Eat Bad Greenhouse Gas

A small rectangular window on the front of the fermenter shows bubbling liquid inside. If it is clear, then that means it is only solution. If it is foggy, then bacteria have been added. Today, the liquid looks milky grey. It fizzes and froths as the correct amounts of air and methane are added, growing and feeding the bacteria inside.

This solution is more than just bacterial soup; it could hold the answers to some of the world's most complex problems, including how to mitigate global warming and how to clean up toxic waste in the environment.

At first, that doesn't seem possible. How could a simple, one-celled organism do something that advanced technology struggles to do?

Amy Rosenzweig, a professor of biochemistry, molecular biology, cell biology and chemistry at Northwestern University, explains that this type of bacteria uses copper from the environment to metabolize methane, turning it into methanol for food.

Not only does this mean the bacteria leech heavy metals from the soil, but they also consume a potent greenhouse gas--solving two environmental issues in one molecular gulp.

"The process is very basic science," said Rosenzweig, whose work is funded by a National Science Foundation (NSF) grant from the American Reinvestment and Recovery Act (ARRA) (MCB-0842366). "But it has potential for a lot of real-life applications."

Some people suggest venting methane emissions through filters of these bacteria to scrub the methane out of the atmosphere. Others suggest feeding leftover methane from natural gas reserves to the bacteria so they can convert the gas into methanol--instead of exercising the typical solution of burning it. Then, the methanol could be stored and later used for fuel. The bacteria could also be used to dispose of copper and other heavy metals where levels are unnaturally high, preventing illness in humans.

But, before these real-world applications are explored, it's important to understand the physiological processes of how the bacterial cells work.

"There are always problems with stability," explained Rama Balasubramanian, a postdoctoral fellow in Rosenzweig's lab. "Any biological molecule is going to die over time. If we understand how it works, then we can design something more stable that will last for years."

For Rosenzweig's group, this involves better understanding how these bacteria are able to acquire copper from environmental mineral resources. Previous work suggests that the bacteria secrete a molecule called methanobactin, which binds tightly to copper ions to deliver them back to the cell.

"Something outside the cell would have to recognize the molecule, grab it, and push it back inside," she said. "We're trying to discover what cellular machinery makes this happen."

The process is explored by closely watching the bacteria in action. Members of Rosenzweig's lab spend their days growing bacteria in a 15-liter fermenter that's calibrated with an optimal flow of air and methane. The bacteria are starved of copper to force them to secrete methanobactin into the extracellular solution.

The researchers place the medium into a centrifuge and spin it at 7,000 times the force of gravity until the cells fall to the bottom, allowing methanobactin in the solution to be isolated. After a couple of purification steps, the molecule is ready to be studied.

"We don't know if all methane-consuming bacteria make methanobactins and secrete them to get copper," Rosenzweig said. "And if they do, is the process different in different species? You could imagine that every type of bacteria might make something slightly different to help them compete for copper."

The particular strain of bacteria that Rosenzweig studies was originally isolated in the hot baths in Bath, England, so the bacteria prefer high temperatures. But she emphasizes that methane-metabolizing bacteria, known as methanotrophs, are found everywhere.

Although Rosenzweig's grant covers three more years of research, Balasubramanian feels optimistic that a breakthrough will happen sooner.

"If our experiments continue to run correctly, then we may be just a year or two away from understanding how this molecule works," he said. "It will take much longer for the applications, but knowing how the molecule enters the cell is step number one."

3-D Images Disclose New Composition of the Sun

Improved 3-D simulations carried out at the NSF-supported Texas Advanced Computing Center are leading scientists to reevaluate the sun's composition and theories about the structure and evolution of stars

What would happen if the yardstick that astronomers used to measure the universe was too long?

This is what Carlos Allende Prieto, a researcher at the Institute of Astrophysics of the Canary Islands (IAC), and his colleagues, David Lambert of the University of Texas at Austin and Martin Asplund of the Max Planck Institute for Astrophysics, proposed in their 2001 paper, "The Forbidden Abundance of Oxygen in the Sun," stirring up controversy in the world of astronomy.

The team's investigation of the chemical abundance of the sun suggested that the amount of carbon and oxygen in our star is 30 to 40 percent lower than previously believed. Since the chemical make-up of the sun is a reference point for the composition of other objects in the universe, many models that relied on the higher abundances were also put into question by Allende Prieto's assertion. A dozen rebuttals appeared in scientific journals.

In 2009, more comprehensive simulations computed at the National Science Foundation (NSF)-supported Texas Advanced Computing Center (TACC) proved that Allende Prieto's measurements were accurate. This discovery has led to new notions about our cosmic evolution, as well as a reevaluation of the distinctiveness of the sun.

"Everything we know from objects in the universe comes from the analysis of light," said Lars Koesterke, Allende Prieto's collaborator and a research associate at TACC. "We analyze the light of stars to figure out what they're made of, what their temperature is and how much energy they emit."

Certain characteristics, like an object's color or intensity, give us clues about the source of the light. Astronomers developed a method called "spectral analysis," where they refract and analyze light to determine the amount of a given chemical species in a star or planet.

By breaking light down into optical bands signifying different chemical elements and comparing this spectrum with models of the sun, astronomers can accurately determine the solar abundance.

Or so they believed.

For decades, scientists had been using one-dimensional models of the solar surface to perform these analyses.

"In a one-dimensional model of a star, we assume that everything is static, frozen," Allende Prieto said. "In reality, everything is moving and you have this boiling at the surface. That changes the dynamics, the energy balance and the appearance of the spectrum."

Using a new three-dimensional model of the solar surface and updated atomic data, Allende Prieto obtained a spectrum that indicated significantly lower amounts of carbon and oxygen than those determined by earlier studies.

This huge change in chemical abundance alters prevailing theories about the structure and evolution of stars. For instance, the sun's chemical composition is a primary piece of evidence used in telling the story of our galaxy's evolution: the cycle of birth and destruction that led to the creation of Earth and its heavy elements.

"If you believe that there's now less carbon and oxygen, then our view of the chemical evolution of the galaxy has to be changed," Koesterke said.

Originally, critics claimed that Allende Prieto's conclusion was based on a small fraction of the spectrum and used unproven models and codes. Allende Prieto would have liked to present more proof, but the simulations required all of the computer processing power available to produce just a few lines of the spectrum.

A full spectrum analysis, using 3-D models, required computers a million times more powerful than what was available. Which is to say: impossible.

It was at this time, in 2004, that the McDonald Observatory hired Lars Koesterke to assist with Allende Prieto's problem. Working over a period of four years, Koesterke created a tool that simulates in 3-D the light emerging from the solar atmosphere much more efficiently. Simultaneously, computers grew dramatically more powerful.

"Suddenly, we're able to compute the whole spectrum, something that seemed utterly impossible five years ago," Koesterke said.

In 2008, as a consequence of this speed-up, Koesterke and Allende Prieto proved definitively that the initial assessment of chemical abundances was no fluke. The pair published a paper describing their work, and increasingly, the new abundances are being accepted and integrated into solar models. Furthermore, work done in parallel by the German group led by Martin Asplund has also independently confirmed their results.

"A good fraction of astrophysics relies on getting the chemical composition of the stars right," Allende Prieto said. "If the huge revisions to carbon and oxygen abundances we've seen with the sun are waiting for us with other stars, then there will be exciting surprises."