The closer you get to this hole in the landscape, the more burnt it smells. The hissing of flames can be heard, and it is getting hotter and hotter. In some places you can't even reach the rim of the crater because of the infernal heat. Where it succeeds, however, an unparalleled spectacle opens up – as can be read in travel reports and guessed on aerial photographs. Countless flames flicker on the ground and on the steep walls of the crater of Derweze. Especially at night, this burning hole of about 70 meters in diameter looks spooky.
The locals in the Karakum desert in Turkmenistan call it "gateway to hell". It has been burning for decades. Now it is to be deleted at the instruction of President Gurbanguly Berdimuhamedow. The BBC reports that the environment and health of people - and to increase natural gas export. Because the flames are nourished by excellent methane.
Unlike other natural gas fires in the area, the desert wind did not stop the fire in the crater. The expert commission, which is now to develop a deletion strategy, is likely to have a hard time, as a survey of experts showed. When the Hell's Gate caught fire is not clear. The common story is that Soviet engineers suspected an oil deposit here near the village of Derveze and wanted to learn more about the deposit in 1971 with a borehole.
Who started it all is debatable.
However, they came across a near-surface "bag" full of natural gas, soon after the ground collapsed and the equipment crashed into the crater. The reconnaissance team saved itself and lit the escaping gas so as not to endanger the health of the population. After a few weeks, so the experience and assumption, the gas would be flared off and the fire would go out. Some locals also say that the crater was formed in the 1960s, the escaping gas was not lit until the 1980s.
Regardless of when the ground collapsed, the geological background is relatively clear. There are several round holes in the area that geoscientists call "sinkholes," explains Hobart King, editor of "Geology.com " in a background article worth reading. They are formed when water creates cavities under the surface – for example, by dissolving limestone and flushing it away – and the ever-thinning ceiling collapses.
In the crater of Derweze, natural gas also flows out of the depths: by tens of small columns and porous material, such as in a deposit that is exploited via a hole. Air oxygen is added to the countless resignations and thus ensures a flame spectacle. In order to end it, experts say that two things have to be done: firstly, the fire extinguish the fire, secondly prevent gas replenishment. It is difficult to assess which method is most suitable because there is little information, says Guillermo Rein, Professor of Fire Science at Imperial College London.
Explosives and foam
"In order to suffocate the flames, you can basically use water, but that will hardly be available in the necessary amount in the desert," says the researcher. It is better to be extinguishing foam: a mixture of water, air and a foam that generates countless bubbles. The foam separates the burner of the fire from the oxygen and suffocates the fire. "The entire crater would have to be filled with foam," says Rein.
Another option is reminiscent of legendary firefighter Paul Neal "Red" Adair, who extinguished burning natural gas wells with explosives. This could also work in the crater of Derweze, says Rein: "At the bottom of the ground, explosives are detonated, causing there to be no oxygen for a few seconds – and the flames go out."
The problem: to bring the explosives to the center of the burning hole. It is possible to reach the bottom of the crater at a depth of 30 meters. This was shown by adventurer George Kourounis, who roped in a heat protection suit in 2013 and collected rehearsals from there. But to deposit explosives below, requires considerably better preparation and technical skills.
Another issue is the hot floor.
It is also important that the soil must not be too hot to prevent the methane's ignition. "You could also fight the fire with liquid nitrogen," says Roland Goertz, head of the Chair of Chemical Security and Defensive Fire Protection at the University of Wuppertal. The -196 degrees Celsius cold fabric suffocates the fire on the one hand and on the other hand cools the layers of earth. Because of this double effect, nitrogen is often used in silo fires, he says. "With the crater in Turkmenistan there is no single huge flame, but many small ones, it could work."
This method is also dangerous, adds Goertz. Nitrogen dilutes the air, the oxygen content decreases and must therefore be well monitored to protect the firefighters. It is crucial to extinguish everything at the same time so that the fire does not spread again. This can happen quickly if methane continues to outgas at the surface. "At a concentration of between five and 17 percent by volume of methane in the air, the mixture is flammable," says Ulrich Krause, head of the Institute for Apparatus and Environmental Technology at Otto von Guericke University Magdeburg. "All it takes is a single source of ignition, a flame or a spark, and it starts again."
Therefore, the gas intake should be stopped from the depth. "Geologists have to explore exactly where the deposit is located and the way the methane comes up," says Krause. He has researched carbon inflow for many years and knows that the real situation in nature is always a bit more complicated than a simple diagram in the textbook. If the location is not to be confused, it could be possible with the appropriate technology to "capture" the gas flow in the depth, to bring it to the surface via a borehole and use it there or at least dagger.
Just let it burn, perhaps?
Guillermo cleans up two other options. On the one hand, a blast at a large depth near the deposit by bringing the load down over a hole. "This creates a small earthquake that moves everything down there and hopefully closes the gas paths." That is certainly not. The gas may be looking for new ways and is coming to light elsewhere, the scientist warns.
The other option would be to put a lid on the crater, a solid structure that envelops the entire hole and allows the natural gas to be used. "But that will be very time-consuming," says Rein, and concludes: "Personally, I wouldn't do anything about it and just keep the Derweze crater burning." No one is endangered by the fire, and there are no problems for flora and fauna. The flames are even useful, because the methane that is already escaping is many times more harmful to the climate than carbon dioxide, which is produced during combustion.
Burning carbon wages and bogs are an much larger environmental and climate problem. In the case of the latter, experts expect such fires to increase as a result of climate change, says Rein. "In both cases, large amounts of carbon dioxide are released." However, attention to this topic is low, he says. Here more has to be researched to get the problem under control. It himself should also benefit from it, like the Magdeburg researcher Ulrich Krause, who worked a lot about it in China. "There are more than 200 seam fires there alone," says Krause, confirming that they are still a problem, but have now come out of view.
The bigger problem is coal.
It is difficult to estimate how much coal burns and what quantities of pollutants are released. Accordingly, figures should be treated with caution, such as an analysis of satellite data, according to which 20 million tons of coal are burned annually in China. The seam fires can occur naturally if the coal layers reach to the surface of the earth and are ignited by lightning or forest fires.
But they can also be triggered by humans. "In China there is a lot of uncontrolled mining, nobody knows how the air circulates in the corridors," says Krause. If there is enough atmospheric oxygen, the porous coal can spontaneously begin to glow. If the heat is not transported quickly enough, the process increases, it continues. This is particularly problematic in the subta service because toxic gases can get to the miners and endanger them, says the researcher.
During firefighting, the burning seams are exposed and covered to prevent further spread: with loess, concrete or power plant ash. "The covers often tear open again after years, air is added again and the fire continues," says Krause. "I am not aware of any case where the fire has been proven to have started."
The phenomenon can also be visited in Germany in miniature. On the "burning mountain" in Saarland, where a seam caught fire in the 17th century and still smoldering today. Old fires continue to smolder on the "Hohen Meißner" in Northern Hesse. Krause: "But that's more of a tourist attraction than a safety problem."
