Looking for Treasure under the Seabed

For Taiwan Review 

Scientists are circling in on Taiwan’s gas hydrates.

Those few people who have come close to it say it looks like ice, and when one holds it, there is a sensation of sizzling or of bursting bubbles. When scientists and energy companies talk of gas hydrates, otherwise known as methane hydrates, clathrate hydrates, flammable ice or fire ice, they mean methane that is trapped in water. Whereas free-floating methane would simply escape into the atmosphere, if there is enough of the gas, the pressure is sufficiently high and the water temperature low enough, water molecules form cage-like structures that trap the methane. These conditions occur naturally in the permafrost of polar regions, on high mountains or beneath the ocean floor.

Taiwanese scientists have long conducted basic research on the subject as the use of gas hydrates as a fuel source is very attractive to many energy researchers. According to the US Geological Survey, “even the most conservative estimates conclude that about 1,000 times more methane is trapped in hydrates than is consumed annually worldwide to meet energy needs.” The seabed southwest of otherwise energy-strapped Taiwan is believed to harbor a handsome share of them, although commercial offshore extraction of gas hydrates is still prohibitively expensive.

As research has borne fruit, teams from other countries have joined Taiwan’s efforts. One recent example involves the German research vessel Sonne, which sailed the waters southwest of Taiwan from March 30 to May 2 this year as part of the TAIFLUX project. Germany has committed 1.2 million euros in total to TAIFLUX. Taiwan has budgeted roughly that amount for all Taiwanese-German gas hydrate projects this year.

The Sonne voyage was the result of six years of collaboration between the two countries. A second TAIFLUX expedition took place from June 2 to 16 aboard a Taiwanese vessel led by Chi Wu-cheng (戚務正) of Academia Sinica, Taiwan’s foremost research institution.

“To us, Taiwan is an ideal playing field because Taiwanese scientists have obtained an essential understanding of where the geological structures needed for the formation of gas hydrate reservoirs can be found,” says Christian Berndt, a geoscientist at Germany’s GEOMAR Helmholtz Centre for Ocean Research Kiel. Berndt led the GEOMAR team onboard the Sonne, a 40-year old vessel outfitted with the latest technology in gas hydrate exploration.

“Another of Taiwan’s attractions is its unique geology, which allows us to have a close look at things we couldn’t possibly find together in any other one location,” Berndt says. He explains that Taiwan sits at a junction of a passive continental margin extending from mainland China’s southeastern coast into the South China Sea and the active plate boundary where the Eurasian tectonic plate is pushed under the Philippine plate. The ocean floor of the passive margin is undisturbed by tectonic forces, while the active plate boundary has faults, crusts and squeezes that at times move violently, creating earthquakes and tsunamis. By having both a passive continental margin and the active Eurasian tectonic plate so close together, researchers can investigate how these fundamentally different environments influence gas hydrates, the German scientist says.

Taiwan Preferred

There is yet another intriguing reason for choosing Taiwan, however. According to Berndt, the island’s scientific culture is significantly closer to that in the West than other countries in the region, such as India, Japan or mainland China. “There’s more openness and less hierarchy in Taiwan, which in turn greatly facilitates better scientific results,” he says.

Liu Char-shine (劉家瑄), a geophysicist at the Institute of Oceanography at Taipei’s National Taiwan University (NTU), is one of Taiwan’s leading scientists in the search for gas hydrates. Liu has concentrated on using seismic techniques to learn about gas hydrates since the early 1990s, and it was on his recommendation that the Central Geological Survey (CGS) under the Ministry of Economic Affairs (MOEA) initiated a gas hydrate study in 2004. The first four years of investigation had the primary purpose of mapping the offshore area southwest of Taiwan, and it was discovered that gas hydrates are distributed very widely and intensively in that area, a good indication of potentially large amounts of the energy resource. A second four-year phase focused on detailed investigations of the geological structures that facilitate the formation of reservoirs of frozen methane.

“If you consider gas hydrates from an energy resource point of view, it is just like exploring for natural gas or petroleum—only where there is a natural mechanism that concentrates the resource, commercial extraction can be feasible,” Liu says. “We’re looking for geological layers with high porosity where a large amount of gas hydrate is stored and little gas leaks out unless you drill a hole.”

Three main approaches are being used in the search for gas hydrates under the CGS investigation, although the programs are currently being integrated, Liu says. “Our research is now supported across several ministries through the National Science and Technology Program for Energy,” he adds.

Liu’s team mainly uses a seismic technique, a procedure that can be likened to the medical sonography used to examine a patient’s internal organs or during pregnancy to provide an image of an unborn child. The device used for gas hydrate exploration emits a low frequency sound that travels through water and the sea floor and penetrates the sediment layers below. If there are differences in physical properties—for example, changes in material composition—variations in the returning sound waves are picked up by the equipment. Different sound waves can indicate the structure of the substrata, and even whether the pore space in the sediment is filled with water, gas or gas hydrates.

Another group, led by Hsu Shu-kun (許樹坤), a professor in the Institute of Geophysics at National Central University, uses ultra high resolution optical instruments to map the seafloor for special features, such as cracks, mud volcanoes or other holes associated with gas outflows. Hsu’s team does not work as part of the TAIFLUX project.

The third approach uses geochemical methods to investigate gas hydrates. That group is led by Saulwood Lin (林曉武), also a geoscientist at NTU’s Institute of Oceanography and Taiwan’s principal investigator in the TAIFLUX project. Funded by the Central Geological Survey and now also by the National Science Council (NSC), Taiwan’s umbrella agency for scientific research, Lin’s team collects samples from the seafloor and analyzes them for features such as methane concentration and the age of sediments, both of which help in understanding the potential of this new energy resource and the geological environment in which it is situated.

The Sonne carried with it four German-developed systems that have never been employed before in the waters around Taiwan, Berndt says. The first system uses sonar to create 3-D images of what is underneath the seafloor. “Our Taiwanese colleagues have previously only had the chance to use 2-D technology, which provides ‘slices’ of the seafloor, but with our method, we see it on the monitor as a cube, similar to a sophisticated computer tomography [CT] scan,” he says.

High-Tech Made in Germany

Berndt explains that the resolution of the 3-D images is extremely high, a feature made possible as gas hydrates exist up to a maximum of around 1 kilometer below the seafloor, unlike oil exploration systems, which must often handle depths of up to 5 kilometers below the sea floor. The range limit for hydrates exists because the deeper it gets, the hotter the Earth’s interior, meaning that they would melt at depths exceeding that mark, he says.

The Sonne’s second system measures the electrical resistance of sediment below the seabed. Berndt explains that in this method a dozen or so receptors are placed on the seafloor, each of which has several 10-meter-long “arms” that touch the ground. An antenna then transmits an electromagnetic signal. If gas hydrates are present, the receptors will record a change in the conductivity in the sediment as salt water stored in the porous sediment swamps out. “We do this for 15 minutes, then repeat the procedure 100 meters further on, thereby creating a profile,” Berndt says.

The third system onboard the Sonne is HyBis, a brand-new robot with sophisticated cameras used to examine the seafloor. The images HyBis creates steer the fourth system, which is a remote controlled picker arm strong enough to collect rock samples of a considerable size.

Whereas much of the 3-D data is evaluated almost instantly onboard the Sonne, the other data has been split quite evenly between the German and Taiwanese teams. “That will keep them rather busy for at least three years,” Berndt says. That is not to say that the Sonne expedition has not already produced a number of interesting preliminary findings. Intriguing anomalies not found in geology textbooks have been identified, such as gas being trapped in unlikely places. “It could mean that there are record-high concentrations of gas hydrates, but we have to wait for the electromagnetic and seismic data to confirm this suspicion,” he says.

Another discovery is the existence of a gas seep system on the active Eurasian tectonic plate. Such spots, where methane streams out of the seabed, feed bacteria, in turn keeping alive a whole ecosystem of fish, crabs and clams. Around Taiwan, living communities of seafloor creatures supported by gas were previously known to exist only on the passive continental margin. “For fish and other marine life, such methane seeps are like an oasis in the desert,” Berndt says. If environmental changes caused the conversion of methane gas into gas hydrates, these ecosystems would die quickly, a situation with unknown repercussions for ocean ecology in general, he says.

According to the GEOMAR team leader, two other major aspects still not well understood are the potential impact of gas hydrates on the stability of the seabed—a crucial question with implications for the safety of oil rigs and other man-made structures—and global warming. There is concern that if the temperature of the seabed rises, more gas hydrates would dissolve, causing more methane to be emitted into the atmosphere, which would speed up global warming, forming a vicious cycle, he says.

In March this year, Japan recorded a world first by extracting methane from gas hydrates in a field 50 kilometers off its central coast, causing environmentalists around the globe to throw their hands up in horror. Opponents argue that if humans learn how to get their hands on yet another abundant fossil fuel that, at the end of the day, will be burned just like oil and gas, any meaningful development of renewable energy will inevitably take a backseat, and climate change will speed up. In other words, countries serious about climate change ought to leave newly discovered fossil fuel reserves such as gas hydrates in the ground, they say.

“Cleaner” than Other Fuels

In Berndt’s eyes, however, gas hydrates are still much more environmentally friendly than traditional fossil fuels, and therefore could be a valuable interim solution. “If you take a close look at the energy mix of normal industrialized nations, coal, oil and nuclear power are all significantly dirtier. Whereas methane turns into pure carbon dioxide if burned, coal and oil also blow out nitrogen oxides and sulfur compounds into the atmosphere,” he says.

Research is underway at the GEOMAR Helmholtz Centre for Ocean Research Kiel to determine if it is possible to pump carbon dioxide into sediment underneath the seabed, Berndt says. If that could be done, gas hydrates could be extracted, the methane burned in order to harvest energy, and the resulting greenhouse gas buried in the pores previously occupied by the gas hydrates. “This could be tried before long in the waters off Taiwan with carbon dioxide collected from Taiwanese coal and gas power plants,” he says.

On average, Liu goes to sea twice a year as part of his research on Taiwan’s gas hydrates, with each trip lasting around two weeks. The scientific teams working with him use several research vessels belonging to either local universities or the Taiwan Ocean Research Institute, a nonprofit organization under the National Applied Research Laboratories. According to the schedule mapped out in Taiwan’s National Science and Technology Program for Energy, the first stage of the gas hydrate master project, which began in 2012, will run through 2015, during which the primary goal is to define where to drill and conduct investigative drilling to evaluate the availability of gas hydrates. The second stage, planned from 2016 to 2020, would focus on the production of gas hydrates.

Liu is leading the drilling investigation project, which focuses on six areas within a 5,000 square kilometer area southwest of Taiwan, the closest point of which is located just some 50 kilometers off the coast. Although the NSC’s next budget for gas hydrate research is still undecided, it is clear that the work will be very expensive. “In 2008, the Central Geological Survey came up with a drilling proposal asking for US$60 million, but that did not pass; in our new proposal we have downsized the scale of the drilling investigation and are asking for around US$25 million, which would facilitate drilling at six or seven sites,” Liu says.

The NTU professor is confident that Japan’s successful methane extraction from gas hydrates has left a positive mark on the government’s decision-making process in Taiwan. Although Japanese production costs are still too high and the flow of gas produced is much too low for commercial development, Liu believes new technology will develop at breakneck speed to resolve those issues, just as happened with breakthroughs in shale gas extraction, an energy resource that is currently creating windfall profits in the United States.

The outlook is also encouraging regarding the amount of gas hydrate reserves Taiwan possesses. Liu says he has worked with scientists from India, South Korea, the United States and several other countries to study gas hydrates in many places around the world. In some locations, indicators signaling the presence of gas hydrates were quite weak, meaning that they might be present or might not, but areas off Taiwan’s southwest coast are a decisively different story. “Here, the signals are very strong, and there’s no doubt that the amount of gas hydrates trapped in reservoirs under the seabed is huge,” he says. “I’ve made presentations on Taiwan’s gas hydrate investigation results at many international conferences, and the question I hear the most often is: ‘Why aren’t you drilling?’”

______________________________
Jens Kastner is a freelance journalist based in Taipei.

Copyright © 2013 by Jens Kastner

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