Pictures: Unlocking Icy Methane Hydrates, a Vast Energy Store

Test Tower in the Tundra

Photograph courtesy U.S. Department of Energy

A drilling rig towers over a temporary ice platform built on Alaska's North Slope. It was the Iġnik Sikumi well, site of a successful U.S. government-sponsored 2012 field test of a promising "gas exchange" technology for tapping into methane hydrates.

Named for the Iñupiaq words for "fire in the ice," the experiment aimed to trade one gas for another: From unusual ice cage structures beneath the tundra, the researchers coaxed the valuable fuel, methane—the primary component of natural gas—by offering carbon dioxide in its place.

The implications of the idea are staggering: The method could serve to sequester the world's most problematic and abundant waste gas, CO2, while tapping into one of the largest stores of energy on Earth.

The science suggested it was an idea worth trying.

Based on chemical thermodynamics, researchers predicted that the clathrates would have a greater affinity for CO2 than for methane, explained David Schoderbek, director of gas hydrates from ConocoPhillips, which had been researching the technology since 2003 in a partnership with the University of Bergen in Norway.

The well's production was not great: about 800,000 standard cubic feet  of natural gas, approximately the amount it would take to heat 14 average U.S. homes.

But conducting the field test with ConocoPhillips on Alaska's North Slope, a process that had to be done in stages over two seasons in the Arctic conditions, was a milestone after years of laboratory research.

"Ultimately, these processes, as potential commercial ventures, have to work in the messy unconstrained world of nature," said Ray Boswell, technology manager for the methane hydrates program at the U.S. Department of Energy's National Energy Technology Laboratory. "You have to take these ideas that look promising in the laboratory and try them in a field setting."

He said that DOE's goal is to evaluate the response of the gas hydrates to a variety of potential production methods, aiming for one that optimizes production efficiency while making the process as carbon neutral as possible.

Published March 27, 2013

Methane Mound

Image courtesy NOAA Okeanos Explorer Program

A methane hydrate mound appears to glow eerily beneath the seafloor in the spring of 2012 on the Biloxi Salt Dome in the northern Gulf of Mexico, a trick of the photographer's light shining on the ice-like structure.

These strange formations in the deep have attracted interest not only for their energy potential, but for scientists studying the history of the Earth's climate.

Will the warming of the planet cause the methane hydrates to melt, destabilize, and release their gas to the atmosphere? If so, the fear is that warming will lead to more warming in a feedback loop, because methane is itself 25 times more potent than carbon dioxide as a greenhouse gas.

The U.S. Geological Survey says that a catastrophic methane hydrate release is unlikely, even though gas likely is bubbling out of formations now as subsea permafrost thaws beneath shallow water on the continental shelves that circle the Arctic Ocean. Less than one percent of gas hydrates are found in permafrost, says USGS. Instead, most of the Earth's gas hydrates, about 95 percent, occur in water depths greater than 3,000 feet (1,000 meters). Under high pressure, they are likely to remain stable even with a sustained increase in temperatures at the sea bottom over thousands of years, says USGS.

Nevertheless, climate scientists continue to study methane hydrates, because ice core data reveals such a close correlation between the rise and fall of methane in the atmosphere and abrupt planetary warming and cooling. Scientists have traced connections between methane and the Permian-Triassic Extinction, some 250 million years ago, when 90 percent of the world's species were extinguished, and the Paleocene-Eocene Thermal Maximum, an intense warming 56 million years ago that ushered in plagues, drought, floods, and more extinctions. (See related: "World Without Ice.") One theory, the "clathrate gun hypothesis," holds that methane hydrates were somehow destabilized and massively released, then recharged and rereleased, repeatedly over eons. Other research suggests that deep sea methane hydrates stayed stable even during prehistoric warming periods.

Even if a quick, massive release from methane hydrates is unlikely, a slow release of methane from them could contribute to ocean acidification and oxygen depletion. Some studies aim to quantify this risk, taking into account factors such as the circulation of the oceans and the consumption of methane by microbes in undersea sediments.

Published March 27, 2013

Molecular Mystery

Illustration by Masakazu Matsumoto

Only under the right conditions does nature produce methane hydrates, fuel trapped in ice crystals.

The environment must be extremely cold and wet, and under relatively high pressure. And there must be methane. The simplest, and most purely refined hydrocarbon, methane consists of one carbon atom surrounded by four hydrogen atoms. The methane is formed when organic material is broken down, either by heat or by microbes, in an oxygen-poor environment.

Methane hydrates are "unusual substances," said Boswell. The methane is not chemically bound with the ice, but trapped in the cavity of a lattice-like cage of frozen water molecules.

The U.S. government-sponsored ConocoPhillips experiment to swap CO2 molecules for the methane was the result of experiments that showed that the structure is actually more stable with CO2 inside the cage. The hydrates appear to prefer CO2, so they release the methane.

But Boswell notes that the process is atomic and can't be seen, only inferred and modeled.

"Nobody can actually tell how it happens," he said. "Does the top of the cage open up like a door and let the molecules exchange? Or does the lattice break down completely to liquid water and then reform? I don't think we know the mechanism, but it does happen."

Published March 27, 2013

A Feast for Ice Worms

Image courtesy NOAA Okeanos Explorer Program

Otherworldly ice worms graze on the surface of a methane hydrate deposit some 4,600 feet (1,400 meters) below the surface of the Gulf of Mexico. The deposit, lit by a remotely operated vehicle, was tucked into a small cavern along the side of an oblong formation called the Biloxi Salt Dome.

Roughly one to two inches long (two to four centimeters), such worms feed on bacteria that in turn feed on the sulfide located within methane hydrates, which they convert directly into energy. These chemosynthetic bacteria are the foundation of a food chain in waters so deep and free of sunlight that photosynthesis, the conversion of sunlight into energy by plants, cannot occur.

When the ice worms scrape their legs, called parapodia, across the surface of the hydrate, it helps the bacteria get nutrients they need from the seawater, and also dissolves the hydrate deposit, creating the scalloped nooks visible across the surface.

This image was captured by the U.S. National Oceanic and Atmospheric Administration's Okeanos Explorer. The scientists aboard were attempting to test the effectiveness of sonar measurement to identify methane seeps, where bubbles from underground deposits of oil and gas escape into the water. Before this work, scientists had to use the less reliable method of looking for features on the seafloor that have been associated with such seeps. In addition to identifying seeps, this new method may help estimate the total volume of methane entering the ocean from such locations.

Published March 27, 2013

Igniting Interest

Photograph by Taiichi Sato, Jiji Press/PANA

A researcher lights a sample of methane hydrates on fire in Japan.

Scientists in the early 1800s recognized that gases could become encased in ice crystals when mixed with water and cooled. But they did not know that gas hydrates existed outside the laboratory.

In the 1930s, as a network of natural gas pipelines began to take shape to deliver fuel, operators observed hydrates forming in cold temperatures, blocking the flow of gas. Much scientific work was aimed at developing techniques to inhibit gas hydrate formation.

It wasn't until the 1960s that methane hydrates were discovered in the natural world, under the Messoyahka gas field in western Siberia. In the following decade, methane hydrates also appeared in well samples from Alaska's North Slope. When deep-sea drilling off the coast of Guatemala turned up large samples of pure hydrate, it became clear that methane hydrates were potentially widespread. In 1995, the U.S. Geological Survey's first systematic assessment of gas hydrates in the United States concluded they greatly exceeded all other known conventional gas resources.

At the end of 2012, the U.S. Department of the Interior's Bureau of Ocean Energy Management estimated that the total methane hydrate resource buried on the outer continental shelf of the Lower 48 states totals 51,338 trillion cubic feet. That's 27 times greater that all other known natural gas resources in the United States.

In 2002, an international consortium led by Japan and Canada and including the United States demonstrated for the first time that methane could be produced from hydrates at a test site in the Canadian Arctic off the Beaufort Sea.

Although global estimates of the resource are immense, the amount that appears suitable for tapped for energy is a far smaller subset. "The challenge with most of these hydrates is they are in very low concentrations in low-quality reservoirs in deep water marine environments," said Schoderbek of ConocoPhillips. "Not only are they relatively inaccessible, but present in concentrations that are very low."

ConocoPhillips and the U.S. Department of Energy chose a location on the North Slope of Alaska in part because the formation was a highly porous sandstone, enabling a high concentration of methane hydrates to accumulate.

In 2012, the U.S. Department of Energy selected 14 new research projects in 11 states to receive funding to better understand methane hydrates. The Department said more research is needed to demonstrate that gas hydrates can be produced commercially and in an environmentally responsible manner.

Published March 27, 2013

Striking Fire

Photograph courtesy U.S. Department of Energy

A single flare illuminates the sky above the Ignik Sikumi test site in Prudhoe Bay, Alaska, signaling the success of a U.S. government-sponsored field trial of methane hydrate production technology.

The researchers took advantage of the brief window of opportunity in late winter and spring when they could construct and carry out their work on temporary ice pads. Two field programs a year apart were required to prepare, drill, and finally produce methane from the well, using a unique technology in which carbon dioxide swaps places with the methane gas in the hydrate formation.

In early 2011, with a work crew of 70 people, the team drilled a well extending a half-mile below the surface, using a chilled oil-based drilling fluid to minimize disturbance to the permafrost and the methane hydrates. The researchers that year did not extract methane but collected data on the rock and fluids in the formation. They then installed a well equipped with instruments to measure temperature and pressure continuously, and closed the well.

Upon returning in February 2012 and building a new ice pad, the team reopened the well and injected a mixture of carbon dioxide and nitrogen into the formation for two weeks. Then, after reconfiguring the well, they installed a downwell pump to enable production of methane and other gases and fluids released by injection. Later, further pumping reduced pressures sufficiently to enable additional methane production through a process called "depressurization." Because there is no pipeline infrastructure for capturing the methane on site, they disposed of methane by flaring the flammable gas. (This protects workers at the site and also the atmosphere, because unburned methane has a global warming potential 25 times greater than that of the carbon dioxide that is emitted from burning the gas.)

Methane flowed from the well for 30 days before the test ended in April 2012, making it the longest-ever field test of methane hydrate extraction. (The only previous record was six days, in a test conducted by Japan and Canada in 2008 on the northern edge of Canada's Northwest Territories off the Beaufort Sea.)

The National Energy Technology Laboratory recently released to the public a voluminous data record from the experiment, and will pursue further study of the data to aid in the understanding of methane hydrates and in design of future scientific field tests. The $29 million project, which received a little over half its funding from the U.S. government, was conducted in partnership with ConocoPhillips and the Japan Oil, Gas and Metals National Corporation.

Published March 27, 2013

Tanks and Trade-offs

Photograph courtesy U.S. Department of Energy

The work crew hoists a carbon dioxide tank to place it at the site of a successful U.S.-government sponsored experiment to tap into methane hydrates on Alaska's North Slope in 2012.

Alaska's stores of methane hydrates are small compared to those in deep water, but there were advantages to conducting the CO2-methane exchange experiment in the Prudhoe Bay region, said David Schoderbek of ConocoPhillips. The team had access to the roads, equipment suppliers, and personnel of the bustling oil-production business of the North Slope.

Of course, the proximity came with its own challenges. "Doing it in the heart of their business infrastructure, that's a complex arrangement," said Ray Boswell of the U.S. Department of Energy's National Energy Technology Laboratory. "You're staging a scientific experiment of something that is not imminently commercial, and those few places where you can sit and do science for a long period of time are fully engaged in producing oil."

That's why the researchers built temporary ice pads as the platform for their experiments, compressing their window of opportunity to a 90-day period in late winter and early spring.

"We had several episodes of -40 °F temperatures with wind chill at -70°F," recalled Schoderbek. "Typical North Slope winter weather."

Published March 27, 2013

Shipping Gas

Photograph by Issei Kato, Reuters

A liquefied natural gas (LNG) tanker docks at Tokyo Electric Power's Futtsu power station early in early 2013, as Japan's imports of the fuel reached record levels.

Methane, the primary component of natural gas, has many advantages as a fuel, but its use has always been somewhat constrained because of the difficulties in transporting it from one place to another. But natural gas may be poised to play an increasing role in the world's energy future, says the International Energy Agency (IEA).

That's primarily due to the fracking boom in the United States: Hydraulic fracturing has unlocked abundant stores of methane from shale formations in a nation that already had an extensive pipeline network for transporting gas. Methane burns with half the carbon emissions of coal, and produces no mercury, sulfur, or other hazardous pollutants. So other countries want to share in the shale gas boom, either by fracking domestically or importing more natural gas.

If the energy industry found a way to unlock the natural gas from methane hydrates, it would make the changes wrought by the fracking boom seem small. The U.S. Geological Survey says even the most conservative estimates conclude that 1,000 times more natural gas is trapped in methane hydrates than is consumed annually worldwide.

A global ramp-up of natural gas production would have a major implications for climate change. The IEA notes that if the world dramatically increased its use of natural gas, without making other changes to curb carbon emissions, global temperature would continue to rise beyond 2°C, the limit that nations have agreed is needed to avoid the worst impact of climate change. Abundant natural gas could displace not only coal but carbon-free electricity generation, like nuclear power, IEA warned.

Indeed, Japan, which is leading research into methane hydrates as an energy source, already has been displacing nuclear power with natural gas since the Fukushima disaster.

Japan's hopes for a new domestic supply of gas were raised by initial figures from its offshore methane hydrates test this month: 120,000 cubic meters (4.2 million cubic feet) of gas over six days. At that rate, the flow surpassed production in last year's 30-day U.S. government-ConocoPhillips onshore field trial in less than two days.

Methane hydrate researchers say that at this early stage, it's important to learn as much as possible about this potential fuel source.  "Energy is going to be an issue—how secure is it, where is it going to come from," said Boswell. "Our goal is to do a rigorous scientific evaluation, so that if folks are thinking about how and when to incorporate it into our energy supply, we'll know a lot about it, and what its impact might be."

Published March 27, 2013