Posts tagged energy
CU: Gas-fired plants help clean the air
Jan 10th
Power plants that use natural gas and a new technology to squeeze more energy from the fuel release far less of the greenhouse gas carbon dioxide than coal-fired power plants do, according to a new analysis accepted for publication Jan. 8 in Earth’s Future, a journal of the American Geophysical Union. The so-called “combined cycle” natural gas power plants also release significantly less nitrogen oxides and sulfur dioxide, which can worsen air quality.
“Since more and more of our electricity is coming from these cleaner power plants, emissions from the power sector are lower by 20, 30 even 40 percent for some gases since 1997,” said lead author Joost de Gouw, an atmospheric scientist with NOAA’s Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder. NOAA is the National Oceanic and Atmospheric Administration.
De Gouw, who works at NOAA’s Earth System Research Laboratory (ESRL), and his NOAA and CIRES colleagues analyzed data from systems that continuously monitor emissions at power plant stacks around the country. Previous aircraft-based studies have shown these stack measurements are accurate for carbon dioxide (CO2) and for nitrogen oxides and sulfur dioxide. Nitrogen oxides and sulfur dioxide can react in the atmosphere to form tiny particles and ozone, which can cause respiratory disease.
To compare pollutant emissions from different types of power plants, the scientists calculated emissions per unit of energy produced, for all data available between 1997 and 2012. During that period of time, on average:
- Coal-based power plants emitted 915 grams (32 ounces) of CO2 per kilowatt hour of energy produced;
- Natural gas power plants emitted 549 grams (19 ounces) CO2 per kilowatt hour; and
- Combined cycle natural gas plants emitted 436 grams (15 ounces) CO2 per kilowatt hour.
In combined cycle natural gas plants, operators use two heat engines in tandem to convert a higher fraction of heat into electrical energy. For context, U.S. households consumed 11,280 kilowatt hours of energy, on average, in 2011, according to the U.S. Energy Information Agency. This amounts to 11.4 metric tons per year of CO2 per household, if all of that electricity were generated by a coal power plant, or 5.4 metric tons if it all came from a natural gas power plant with combined cycle technology.
The researchers reported that between 1997 and 2012, the fraction of electric energy in the United States produced from coal gradually decreased from 83 percent to 59, and the fraction of energy from combined cycle natural gas plants rose from none to 34 percent.
That shift in the energy industry meant that power plants, overall, sent 23 percent less CO2 into the atmosphere last year than they would have, had coal been providing about the same fraction of electric power as in 1997, de Gouw said. The switch led to even greater reductions in the power sector’s emissions of nitrogen oxides and sulfur dioxide, which dropped by 40 percent and 44 percent, respectively.
The new findings are consistent with recent reports from the Energy Information Agency that substituting natural gas for coal in power generation helped lower power-related carbon dioxide emissions in 2012.
The authors noted that the new analysis is limited to pollutants emitted during energy production and measured at stacks. The paper did not address levels of greenhouse gases and other pollutants that leak into the atmosphere during fuel extraction, for example. To investigate the total atmospheric consequences of shifting energy use, scientists need to continue collecting data from all aspects of energy exploration, production and use, the authors concluded.
Authors of the new paper, “Reduced Emissions of CO2, NOx and SO2 from U.S. Power Plants Due to the Switch from Coal to Natural Gas with Combined Cycle Technology,” are de Gouw (CIRES), David Parrish (NOAA ESRL), Greg Frost (CIRES) and Michael Trainer (NOAA).
CIRES is a joint institute of NOAA and CU-Boulder.
-CU-
Ma Nature’s sky light show on the way
Jan 9th
University of Colorado Boulder space weather experts say a powerful solar storm may cause the aurora borealis to light up as far south as Colorado and New Mexico in the coming nights.
http://youtu.be/Ip2ZGND1I9Q
Aurora borealis may dip into state
tonight, say CU-Boulder experts
Daniel Baker, director of CU-Boulder’s Laboratory for Atmospheric and Space Physics, said space weather forecasts indicate there is a good chance a coronal mass ejection tied to a large solar flare from the sun Tuesday may impact Earth today, hitting the planet’s outer magnetic shield and causing spectacular light displays tonight and perhaps tomorrow night. National Oceanic and Atmospheric Administration experts have estimated there is a 90 percent chance a coronal mass ejection will hit Earth today.
“The aurora borealis, or ‘false dawn of the north,’ are brilliant dancing lights in the night sky caused by intense interactions of energetic electrons with the thin gases in Earth’s upper atmosphere,” said Baker. “The aurora are most commonly seen in Alaska, northern Canada and Scandinavia when the sun sends out powerful bursts of energy that can strike Earth’s protective outer magnetic shield called the magnetosphere,” he said.
“The strong solar winds associated with the storm events generate strong electric currents when they blow by the Earth’s magnetosphere,” said LASP Research Associate Bill Peterson. “These currents become unstable and drive processes in the magnetosphere that accelerate electrons down magnetic field lines where they hit the atmosphere over the poles.”
“One can think of aurora in some ways as if the Earth’s atmosphere is a giant TV screen and the magnetosphere generates intense beams of electrons that blast down along magnetic field lines to produce the red and green light picture show,” said Baker. “If the sun produces extremely powerful energy outbursts, the aurora can move to much lower latitudes than normal and then one can see the fantastic light displays in the lower 48 states, even as low in latitude as Colorado and New Mexico.”
According to Peterson, geophysicists have been measuring magnetic activity – essentially “wiggles” on instruments measuring Earth’s magnetic field – for over a century. The scientists have come up with a planetary magnetic index known as KP, ranging from 0 (quiet) to 9 (very active).
“The aurora is typically seen in Canada for KP less than 4,” Peterson said. “When the KP is 9, auroras can sometimes be seen as far south as Mexico City. Auroras are seen in Colorado when the KP is about 7.”
Peterson suggested those interested in seeing the northern lights or want to report sightings visithttp://www.aurorasaurus.org, a website called “Aurorasaurus” and led by the Los Alamos National Laboratory in New Mexico. The site is designed as a real-time map of confirmed aurora sightings and includes a place for citizen-scientists who want to participate to report aurora sightings in their own neighborhoods.
For additional information visit NOAA’s Space Weather Prediction Center at http://www.swpc.noaa.gov. For more information on LASP visit http://lasp.colorado.edu/home/.
-CU-
Roberson’s late scoring frenzy puts close game away
Dec 29th
But putting into practice what they had emphasized recently in practice, the Buffaloes showed if they continue to grind they can succeed. Applying the brakes to stubborn Southern Utah Sunday in the last 8 minutes, the Buffs finally put away the Thunderbirds 75-59 and now can turn their full attention to the Pac-12.
CU opens conference play on Friday at Southern California, then plays at UCLA next Sunday. The Buffs’ Pac-12 home opener is Friday, Jan. 10 against No. 23 Cal, with No. 4 Stanford visiting on Sunday, Jan. 12. The Pac-12 features four ranked (AP) teams, with Arizona State at No. 25.
Although CU did enough against Southern Utah to claim its 10th non-conference win (10-1), the Buffs often had difficulty getting in synch offensively and let a 14-point second half lead dwindle to two with 8:09 to play.
But that was as close as the Thunderbirds (7-3) would get. After Carli Moreland hit a pair of free throws to bring Southern Utah to 54-52, the Buffs launched a 19-2 run to take a 19-point lead (73-54) with 1:24 remaining.
Outscored 21-7 over the final 8:09, the T-Birds were toast.
“Overall, I liked how we responded to the last three days of practice,” CU coach Linda Lappe said, noting the Buffs had focused on rebounding, tighter defense and setting screens. “I saw all three things improve.”
Most apparent, according to guard Jasmine Sborov, was the defensive factor: “To be honest, it didn’t really feel like the score was that close leading up to the two-point deficit . . . we looked at scoreboard and we were like, ‘All right, we need to get down, get some stops and just extend our lead.’ I think that’s one negative thing with this game – we were up and then we were down and we were up and we let them get closer. We didn’t step on their throats and just keep going.”
Not until they needed to, anyway. During the decisive 8-minute surge, Arielle Roberson scored seven of her team-best 18 points while Ashley Wilson, who finished with career highs in points (14) and assists (5), contributed four points. Roberson added 12 rebounds for her fourth double-double in five games and seventh of her career.
Wilson’s performance came in 21 minutes off the bench. “That’s kind of my role – to provide energy off of the bench,” she said. “It just happened; it’s a credit to my teammates, they gave me energy.”
Down by 12 points at halftime, the Thunderbirds crept to within four before the Buffs answered with a 12-2 run to take what appeared to be a comfortable 50-36 lead. Not so. The visitors kept competing, climbing back to within 54-52 before CU delivered its final answer.
“We relaxed instead of keeping our foot on the gas,” Wilson said. “They play hard (but) we responded every single time; it shows what kind of team we have.”
Lappe agreed: “They’re a feisty group, well-coached and have lot of energy . . . at times we didn’t look very good, didn’t get stops and our offensive sputtered. Southern Utah made us play a half-court game, made us become stagnant (offensively) at times.”
But, noted Lappe, compensating with solid defense down the stretch was good for the Buffs with the Pac-12 schedule looming: “In terms of playing defense and unleashing our aggressiveness, we needed to do that against an opponent.”
CU also got double-figure scoring from Jen Reese (11) and Jasmine Sborov (12), who also recorded her first career double-double with a career-high 10 rebounds.
Desiree Jackson led Southern Utah with 21 points and was her team’s only player in double figures.
“Slow start” doesn’t come close to describing what the Buffs overcame to eventually pull away and take a 36-24 halftime lead. Just under 9 minutes into the first half, CU had one more turnover (five) than baskets (four) but still led 10-7.
But after Moreland, a 6-1 senior forward from Broomfield, tied the score at 13-13 on a 3-pointer, CU made its move. Over the next 6 minutes, the Buffs outscored the Thunderbirds 17-6 to take their first double-digit advantage (30-19) on a basket by Ashley Wilson.
Southern Utah rallied briefly, closing to within six points (30-24) before CU used a 6-0 run – four free throws by Roberson, a layup by Jamee Swan, who made her second career start – to establish its 12-point halftime advantage. But the T-Birds quickly cut into that, forced the Buffs to make a run, then the whole process was repeated.
Neither team shot impressively from the field – CU checked in at 37.9 percent, Southern Utah at 34.0 – and between them the Buffs and Thunderbirds committed 45 turnovers (CU 21, Southern Utah 24). And long-range accuracy was lacking: the teams were a combined 2-of-26 from beyond the arc, with each getting one trey in 13 attempts. The Buffs also clanked 12 free throws, giving them 25 misses in their last two games – which Lappe conceded concerns her.
Still, noted Wilson, “We’re happy with this win. There were a lot of different things we worked on the last three practices that definitely showed up in the game. We wanted to ramp up our defense a whole lot more going into Pac-12 because we know there are a lot of good teams that are going to come after us . . . so, it was a great win.”
CU redshirt freshman Lauren Huggins did not dress; she is recuperating from a lower leg injury and is hopeful of returning for the Pac-12 opener. In Huggins’ absence, freshman Desiree Harris saw her first playing time of the season, getting 5 minutes.
Contact: BG.Brooks@Colorado.EDU
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