Exploring Hydrocarbon Depletion
onlooker wrote:Just wondering if maybe we should have a methane levels thread similar to the Carbon thread we have. Especially of methane levels over the Arctic which is the place that has many spooked about a abrupt large release of methane that could really lead to spikes in temperatures? I am not aware of any real time tracker of methane levels site but maybe others know.
ROCKMAN wrote:Dohboi – Very interesting plot. Did you notice methane levels increased 26% from 1750 to 1900? That was before the industrial revolution (and the beginning of AGW) and during a period when there was almost no manmade methane extraction. You data seem to imply that at least initially the methane increase was a natural phenomenon unrelated to fossil fuel consumption. Granted the current NG extraction process might be adding to the natural release but how do you assign the split?
In tropical environments, hydropower methane emissions have been measured as high as double those of the greenhouse emissions of a coal-fired power plant that generates the same amount of electricity.
Further, although the Intergovernmental Panel on Climate Change (IPCC) has guidelines on calculating methane emissions from hydropower dams/reservoirs, there have been very few measurements of these methane emissions at the same time that large hydropower projects are being built by the thousands across the planet. One Brazilian scientist estimates that methane from hydropower currently accounts for 23 percent of all human-caused worldwide methane emissions. As hydropower plants proliferate, that number will only increase.
Hydropower is almost always greenwashed and sold to the public and policymakers as “clean energy” and “carbon-free.” Even though the IPCC lists hydropower’s methane emissions as a greenhouse gas source, and over a decade of science refutes the claim that hydropower is clean energy, the myth of carbon-free hydropower is embedded in the Kyoto Protocol’s “Clean Development Mechanism” to address planetary climate change and is increasingly being implemented by countries in attendance at COP 21 in Paris. Even worse, the World Bank still lists, promotes and funds hydropower as “clean energy,” and nearly every country in the world is building hydropower plants under the same auspices. Even the U.S. government still perpetuates the anti-science myth of clean hydropower.
Thus, countries that are completely destroying their rivers and their climate with hydropower including Malaysia, Brazil, Guatemala, Russia and even the U.S. don’t even list hydropower as a methane emissions source in their INDC, while including hydropower as a clean energy source, all under the auspices of likely misconstrued or purposely ignored IPCC guidelines.
A team of scientists from Norway, China and the Netherlands has now shown how the size of grains of the molecules that make up the natural structure of methane hydrates determines how they behave if they are loaded with weight or disturbed.
When methane hydrates "melt", they release the methane trapped inside the ice, but because the methane was first trapped under pressure when the hydrate was formed, one cubic metre of solid methane hydrate will release 160 cubic metres of methane gas. That makes them either a potent energy source, or if they melt as the permafrost melts, a potent source of methane, which will act as a greenhouse gas.
But mining methane hydrates as an energy source, an option that is being explored by Japan among others, is technically difficult. Their location on the soft, sediment-loaded edges of the continental shelves makes them difficult to mine, and when they are disturbed, their crystal structure may suddenly dissociate and release the methane trapped inside.
This mechanism has been suggested as one reason why the largest landslide known to humankind, the Storegga Slide, was so destructive. The Storegga Slide took place about 8000 years ago, from an underwater location off the west coast of southern Norway.
The slides - there were three in total - sent a wall of water roaring out across the North Sea and Norwegian Sea. The evidence of the passage of the tsunami wave in Scotland that shows the wave reached heights of 3-6 metres in that region. One hypothesis for the slide was that an earthquake caused the methane hydrates in the region to become unstable and to explosively release their gas.
The simulations showed that the size of the crystals—what researchers call the grain size—that made up the hydrate structure had a great deal to say in terms of how the structure reacted to both kinds of stresses.
In both tensile and compression stress simulations, the surprising finding was that as the grain size got smaller, the hydrates first got stronger, able to tolerate both compression and tensile stress—but only until they reached a certain grain size. If the researchers conducted simulations on grain sizes smaller than those identified as the turning point, the hydrate actually got weaker.
The maximum capacity of the hydrates appears when the grain size is around 15 to 20 nm. This resembles the behaviour of polycrystalline metals, such as copper. However, this is the first time that researchers have seen this type of behaviour in methane hydrates as a material. The grain size-dependent strength and maximum capacity that the researchers found can be used in predicting and preventing the failure of hydrates in the future.
This unexpected rapid weakening of the crystal structure as the grain size gets smaller has important implications for any work in areas where hydrates are found.
The researchers reported that the dissociation of methane hydrates can be triggered by the ground deformation caused by "earthquakes, storms, sea-level fluctuations or man-made disturbances (including well drilling and gas production from hydrate reservoirs)."
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