Stories tagged geophysics
Minneapolis hosts 2011 GSA meeting: Six thousand geologists will descend upon Minnesota rocks this fallCourtesy Mark RyanNext week the Geological Society of America is convening in Minneapolis, Minnesota for the GSA's 2011 Annual Meeting and Exposition. That means something like 6000 geologist, paleontologist, hydrologists, and other ologists from around the world will be in our area to share new ideas and hobnob with their fellow earth scientists. The four-day event, which is hosted by the Minnesota Geological Survey, runs from Sunday, October 9 through Wednesday, October 12 at the Minneapolis Convention Center, and will include special lectures, award ceremonies, poster sessions, an exhibit hall, and several hundred technical talks covering a full range of geology-related subjects. There will also be a silent auction, a photo exhibition, short courses (available to non-registrants), and a screening of the locally produced documentary, “Troubled Waters: A Mississippi River Story”. Field trips happening before, during, and after the official meeting dates will give visiting geologists an opportunity to take in some of the spectacular and diverse geology that Minnesota and the Upper Midwest has to offer, not to mention the fall colors. This year’s meeting is titled “Archean to Anthropocene: The Past is the Key to the Future”, and even if you can’t make it to Minneapolis, you can download a cool poster of the event here.
Tags : What if I told you University of Minnesota geology and geophysics professor, Martin Saar, says geothermal energy can be made even greener through carbon sequestration?!
You’d probably say, “Huh?? Hold on, what is geothermal energy anyway, and how does it work?”
Geothermal is heat from deep inside the earth. Because heat is a form of energy, it can be captured and used to heat buildings or make electricity. There are three basic ways geothermal power plants work:
- Dry steam plants: Uses high-pressured hot steam to turn generator turbines. Think “steam to turbines.”
- Flash steam plants: Uses high-pressure hot water to create steam to turn generator turbines. Think “water to steam to turbines.”
- Binary cycle power plants: Uses high-pressure hot water to heat another liquid, which then turns to steam and turns the generator turbines. Think “water to other liquid to steam to turbines.”
(Click here for great diagrams of each of these geothermal energy production methods.)
“And what about carbon sequestration too? What’s that and how does it work?”
Carbon Sequestration: This nifty diagram illustrates both terrestrial and geologic carbon sequestration pathways. Bonus!Courtesy Department of Energy
Carbon sequestration includes carbon (usually in the form of carbon dioxide, CO2) capture, separation, transportation, and storage or reuse. Plants, which “breathe” CO2, naturally sequester carbon, but people have found ways to do it artificially too. When fossil fuels are burned to power your car or heat your home, they emit CO2, a greenhouse gas partially responsible for global climate change. It is possible to capture those emissions, separate the bad CO2, and transport it somewhere for storage or beneficial reuse. CO2 can be stored in under the Earth’s surface or, according to Martin Saar’s research, used in geothermal energy production.
Alright. We’re back to Professor Saar’s research. Ready to know just how he plans to sequester carbon in geothermal energy production?
It’s a simple idea, really, now that you know about geothermal energy and carbon sequestration. Prof. Saar says geothermal energy can be made even greener by replacing water with CO2 as the medium carrying heat from deep within the earth to the surface for electricity generation. In this way, waste CO2 can be sequestered and put to beneficial use! As a bonus, CO2 is even more efficient than water at transferring heat.
But don’t take my word for it. Come hear Professor Martin Saar’s lecture, CO2 – Use It Or Lose It!, yourself during the Institute on the Environment’s Frontiers on the Environment lecture series, Wednesday, October 27, 2010 from noon-1pm.
Frontiers in the Environment is free and open to the public with no registration required! The lectures are held in the Institute on the Environment’s Seminar Room (Rm. 380) of the Vocational-Technical Education Building on the St. Paul campus (map).
Boundary of North American and Eurasian plates seen along the Mid-Atlantic Ridge in Iceland: Westward view over the top of the east edge of the North American tectonic plate.Courtesy Joe HatfieldGeochemists at UCLA have determined plate tectonics – the theory involving the movement and collision of crustal plates – began much sooner after the Earth’s formation 4.5 billion years ago than thought previously.
Until now, plate tectonics were thought to have begun around 350 million years ago - or even later – but this new UCLA data points to much earlier beginnings.
"We are proposing that there was plate-tectonic activity in the first 500 million years of Earth's history," said professor Mark Harrison, director of UCLA's Institute of Geophysics and Planetary Physics and co-author of the paper. "We are reporting the first evidence of this phenomenon."
Their report appears in the science journal Nature.
The theory of moving crustal plates floating on molten rock was first championed in Alfred Wegener’s 1912 work, The Origins of Continents and Oceans. Wegener suggested all the continents existing today originated in a super-continent he called Pangaea that spread apart over time due to “continental drift”. Most scientists were skeptical of the theory until the 1960s when it was bolstered by the discovery of sea floor spreading.
Harrison and his colleagues analyzed zircon crystals found in 3 billion year old rocks from Western Australia. The rocks were formed from ancient magmas that had cooled and froze the mineral crystals in place. Using an ion microprobe, they bombarded the zircon with a beam of charged atoms (ions). The bombardment caused the zircon crystals to release their own ions and these were then analyzed using a mass spectrometer. The analysis showed the zircon crystals were more than 4 billion years old. It also showed the zircons had formed in an area where the heat flow was much lower than expected.
"The global average heat flow in the Earth's first 500 million years was thought to be about 200 to 300 milliwatts per meter squared," said Michelle Hopkins, a UCLA graduate student in Earth and space sciences, and the study's lead author. "Our zircons are indicating a heat flow of just 75 milliwatts per meter squared — the figure one would expect to find in subduction zones, where two plates converge, with one moving underneath the other."
The only places on Earth today where the average heat flow is one third that of the rest of the planet are in convergent plate-tectonic boundaries where magmas are forming.
Harrison published an earlier study in 2001 proving water was present early on the surface of the Earth during its formative years, and this current data strengthens his claim because plate tectonics can’t occur on a dry planet.
All this new information forces scientists to reevaluate their conception of how Earth appeared early in its formation.
"Unlike the longstanding myth of a hellish, dry, desolate early Earth with no continents, it looks like as soon as the Earth formed, it fell into the same dynamic regime that continues today," Harrison said. "Plate tectonics was inevitable, life was inevitable. In the early Earth, there appear to have been oceans; there could have been life — completely contradictory to the cartoonish story we had been telling ourselves."
LINKS
Story in Science Daily
What is a geochemist?
More about heat flow
More about plate tectonics
