Self-Cleaning Atmosphere

Anyone who's ever used a public restroom appreciates regular and dependable air freshener.

Earth's atmosphere has just that, thankfully, and it's operating better than expected. A critical part of the self-cleaning system is hydroxl, and the chemical maintains a more stable level of activity than previously thought, according to research by the National Oceanic and Atmospheric Administration (NOAA). Considering that recent models indicate greenhouse gasses are going to be a long-term atmospheric issue to clean up after, this news comes as a bresh of fresh air.

“Now we know that the atmosphere’s ability to rid itself of many pollutants is generally well buffered or stable,” said lead author, Stephen Montzka of the National Oceanic and Atmospheric Administration (NOAA).

“This fundamental property of the atmosphere was one we hadn’t been able to confirm before,” said Montzka in a NOAA press release.

The amount of hydroxyl in the atmosphere rises and falls by only a few percentage points a year, according to the results published recently in Science. Earlier studies had suggested it might fluctuate by as much as 25 percent.

Hydroxyl helps break down pollutants like sulfur dioxide, carbon monoxide, hydrocarbons and even the powerful greenhouse gas, methane. Methane is over 20 times more effective than carbon dioxide at trapping heat. However hydroxyl has no effect on carbon dioxide.

“Say we wanted to know how much we’d need to reduce human-derived emissions of methane to cut its climate influence by half,” Montzka said. “That would require an understanding of hydroxyl and its variability. Since the new results suggest that large hydroxyl radical changes are unlikely, such projections become more reliable.”

Previous studies inferred the levels of hydroxyl being produced in the atmosphere by measuring the concentration of methyl chloroform, a long lived pollutant partly responsible for ripping a hole in the ozone layer. But the results varied widely, possibly because of inaccurate estimates of methyl chloroform released by human activities. The gas was banned by the Montreal Protocol, so now, no new methyl chloroform is fouling the data.

Now that the gas is no longer being produced, scientists can more accurately gauge the action of hydroxyl upon methyl chloroform's atmospheric concentration. They took measurements over time of methyl chloride concentrations. By measuring its decay, they could calculate the amount of hydroxyl acting upon it.

With a better understanding of the mechanisms that clean the atmosphere, scientists can better forecast the future.

by "environment clean generations"

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Posted in: atmosphere,carbon dioxide,clean,hydroxyl

Fuel Cells

 

According to many experts, we may soon find ourselves using fuel cells to generate electrical power for all sorts of devices we use every day. A fuel cell is a device that uses a source of fuel, such as hydrogen, and an oxidant to create electricity from an electrochemical process.

               Much like the batteries that are found under the hoods of automobiles or in flashlights, a fuel cell converts chemical energy to electrical energy.

All fuel cells have the same basic configuration; an electrolyte and two electrodes. But there are different types of fuel cells, based mainly on what kind of electrolyte they use.

              Many combinations of fuel and oxidant are also possible. The fuel could be diesel or methanol, while air, chlorine, or chlorine dioxide may serve as oxidants. Most fuel cells in use today, however, use hydrogen and oxygen as the chemicals.

             Fuel cells have three main applications: transportation, portable uses, and stationary installations.

In the future, fuel cells could power our cars, with hydrogen replacing the petroleum fuel that is used in most vehicles today. Many vehicle manufacturers are actively researching and developing transportation fuel cell technologies.

             Stationary fuel cells are the largest, most powerful fuel cells. They are designed to provide a clean, reliable source of on-site power to hospitals, banks, airports, military bases, schools, and homes.

             Fuel cells can power almost any portable device or machine that uses batteries. Unlike a typical battery, which eventually goes dead, a fuel cell continues to produce energy as long as fuel and oxidant are supplied. Laptop computers, cellular phones, video recorders, and hearing aids could be powered by portable fuel cells.

             Fuel cells have strong benefits over conventional combustion-based technologies currently used in many power plants and cars. They produce much smaller quantities of greenhouse gases and none of the air pollutants that create smog and cause health problems. If pure hydrogen is used as a fuel, fuel cells emit only heat and water as a byproduct. Hydrogen-powered fuel cells are also far more energy efficient than traditional combustion technologies.

            The biggest hurdle for fuel cells today is cost. Fuel cells cannot yet compete economically with more traditional energy technologies, though rapid technical advances are being made. Although hydrogen is the most abundant element in the universe, it is difficult to store and distribute. Canisters of pure hydrogen are readily available from hydrogen producers, but as of now, you can't just fill up with hydrogen at a local gas station.

             Many people do have access to natural gas or propane tanks at their houses, however, so it is likely that these fuels will be used to power future home fuel cells. Methanol, a liquid fuel, is easily transportable, like gasoline, and could be used in automobile fuel cells. However, also like gasoline, methanol produces polluting carbon dioxide.

by "environment clean generations"

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Posted in: clean,fuel cells,hydrogen