Scientists Investigate Mysteries of Methane Hydrates
- Monday, Apr 15, 2013
Dylan Meyer, a graduate student with the Jackson School of Geosciences, confers with petroleum engineering professor Steven Bryant on a methane hydrates equation.
Methane hydrates — flammable ice-like compounds found in rocks deep beneath the sea — are gaining interest as a potential source of natural gas, but there is still much to discover about the long-term viability of such an energy source, and what extracting that gas may mean for the environment.
Deposits of methane hydrates, which are lattices of ice with methane molecules locked inside, are found in sea-floor sediments off the coastlines of many countries, as well as in the Arctic permafrost. Experts estimate that more than 200,000 trillion cubic feet (tcf) of methane is in hydrates in coastline areas surrounding the United States. Both the U.S. and Japan have invested in the study of methane hydrates. Last month, Japan became the first to successfully extract natural gas from hydrates beneath the ocean floor.
But for all its promise, the field of methane hydrates is still not well-understood, particularly aspects of how the hydrates are formed and the qualities they carry.
Enter The University of Texas at Austin, which is one of the top universities leading the charge to unlock the mystery of these natural-gas ice cages.
A few months ago, a team of researchers, led by professors Steven Bryant of the Cockrell School Department of Petroleum and Geosystems Engineering and Peter Flemings of the Jackson School of Geosciences, began studying how warmer temperatures and rising sea levels might set off the release of methane gas. The UT researchers teamed up with geological scientist Tim Kneafsey of Lawrence Berkeley National Laboratory on the three-year, $1.1 million study funded by the Department of Energy.
Methane is the principal component of natural gas, and it is one of the most potent greenhouse gases. When warmed to a certain temperature, methane hydrates act like an uncorked champagne bottle releasing bubbles of methane gas into the sea. Melting methane hydrates could have consequences for marine life and the atmosphere, depending on the rate and quantity of release of those gases.
The research team hopes to be the first to deliver numerical models and lab experiments explaining what happens to methane hydrates when they are warmed up. This work could help other scientists figure out how melting methane hydrate might impact the environment.
Photo courtesy of William Christensen
Gases released from methane hydrates form bubbles in the frozen waters of Abraham Lake in western Canada.
Cockrell School’s Bryant said that even though the U.S. is focused on leveraging an estimated 100-year supply of natural gas from existing reservoirs, it’s important to look for and gain a better understanding of other potential fuel sources, such as methane hydrates.
“If we understand how methane hydrates work, we can start to make much more informed decisions,” Bryant said. “We can decide as a society whether or not methane hydrates are worth pursuing.”
With temperatures rising and glaciers on Greenland and Antarctica melting, the sea level will rise and change the temperature for Arctic deposits of methane hydrates, Bryant said.
The UT Austin researchers are working on advanced mathematical equations that will allow them to predict what may occur in natural accumulations of methane hydrates when temperature changes and sea levels rise.
Dylan Meyer, a graduate student with the Jackson School, is working with Bryant on equations that will help quantify the exact level of hydrates locked in ocean sediments.
When samples of methane hydrates are removed from their environments, they immediately begin to release gases, making it impossible to quantify the levels of gas once contained in the ice.
“By the time you get a core of sediment containing methane hydrates back on a ship’s deck all of the hydrates are gone, so you can’t get a sense of hydrate saturation,” Meyer said. “So, what our group is working on is models to determine hydrate saturation at depth.”
The collaboration between the Cockrell School of Engineering and the Jackson School has been an advantage for the study, Meyer said.
“I’ve learned from [PGE’s] experiments and understanding of how methane hydrates are formed in the lab, and vice versa,” he said.
UT’s research team rounded out the expertise needed for this study with geological scientist and mechanical engineer Tim Kneafsey at Berkeley. Bryant and Flemings will work with Kneafsey to execute lab experiments using man-made methane hydrates.
“It’s a hard experiment to do,” Bryant said. “This is why we teamed up with Tim. He’s the one guy in the world, we think, who can do this experiment.”
Eventually, the UT Austin team hopes it will be the first to conduct a controlled methane hydrates experiment in the lab that mimics the driving forces for methane hydrates melting in nature.
Photo courtesy of Nasa Earth Observatory
A NASA photo of the ice cover in the Arctic Ocean north of Alaska, where Harvard University researchers measured increased methane levels while flying at low altitudes.
“We are going to be able to validate a physical model and processes against the lab experiment, then we will make predictions about hydrates in ocean sediments and answer the questions set early on,” Bryant said. “If sea level rises and things warm up, this model will give us the rate of methane being released.”
He hopes this and other UT Austin studies on methane hydrates will give government and industry much-needed insight into how methane hydrates work.
“Just because there are a lot of methane hydrates doesn’t mean we can or should exploit it today,” Bryant said. "We are looking beyond what the current energy situation is, and we are thinking ahead to what we might need 10 or 15 or 20 years down the road.”