Deep-Sixing CO2 Emissions
Buffeted by crosswinds, the lone helicopter flew on for an hour across the shale-gray waves of the North Sea with no destination in sight.
A relief crew huddled unsteadily inside, sweating in their 20-pound immersion suits, festooned with safety whistles, buddy lines, emergency lights and inflatable life vests. Even in summer, survival in the choppy 40-degree water is measured in minutes.
Finally -- far off the coast of Norway -- the superstructure of the Sleipner platform came into view, towering 500 feet above the swell at this watery crossroads of 3,000 miles of undersea petroleum pipelines that carry natural gas for 50 million European customers.
Only one pipe led from the platform back into the seafloor. It carried industrial carbon dioxide deep into the earth from which it came.
Here, on the remote Sleipner refinery complex, the business of global warming is taking shape.
Since 1996, Norway’s largest petroleum company -- Statoil -- has been injecting 1 million tons of carbon dioxide every year from the Sleipner complex into undersea sediments to keep the potent greenhouse gas from venting into the atmosphere.
Statoil’s engineers aren’t doing it to save the environment, but to save money. The Sleipner injection facility, which cost about $80 million to build, saves Statoil $53 million every year in Norwegian taxes on carbon dioxide emissions.
In areas such as California -- where lawmakers passed a bill last week to curb industrial carbon dioxide emissions 25% by 2020 -- the Sleipner platform is a harbinger of the future of fossil fuels, in which energy companies and power utilities retool for new greenhouse gas standards.
Though business executives generally oppose such controls, energy company planners here believe there may be opportunities in the financial balance sheet of global warming.
Even before all the scientific, safety and legal questions are settled, energy companies from Scotland to Southern California are gambling billions of dollars on the hope that they can meet growing demands for electricity with oil, gas and coal, and avoid the increasing financial penalties by burying the greenhouse gases they generate.
The work can be as dangerous and grueling as extracting oil.
Standing on a blue walkway inside the Sleipner platform, Tor Fjaeran, Statoil’s senior vice president for the environment, braced himself against the trunk of Control Valve A-16, where a ring of 12 bolts -- each the size of a fist -- secured it to a vertical pipe channeling pressurized carbon dioxide almost half a mile underground.
Far below, 70-seat lifeboats hang nose-down in harnesses 60 feet above the water like bullets in a bandolier. In an emergency, they free-fall into the sea. Fjaeran has ridden the boats down twice during training.
“Those 2 1/2 seconds in the air ... are very long,” he said.
The Sleipner platform, about 140 miles from the city of Stavanger on the Norwegian coast, is a 34,000-ton Rubik’s cube of color-coded conduits, control valves and compressors.
The 240 men and women here are engaged in what the United Nations’ International Labor Organization has ranked as the world’s most hazardous employment.
The threat of a gas explosion is omnipresent.
Flash photography is banned, lest automatic sensors interpret the burst of light as a fire and instantly shut down production, at a cost of millions.
In the most severe weather, winds top 130 mph and 70-foot waves slap against the platform’s concrete pilings.
The complex comprises three platforms linked by catwalks -- each a pad for the intricate network of turbines and pressure chambers required to pump and refine so much fossil fuel.
Raw natural gas comes into the platform containing as much as 9% carbon dioxide. To reduce the CO2 to acceptable levels, the natural gas is chemically treated in an 11-story carbon-capture unit.
Almost all energy companies vent excess gas into the air. On the Sleipner platform, however, four turbines compress the trapped carbon dioxide to 80 times the normal atmospheric pressure and inject it into a subterranean plateau of porous sandstone 2,600 feet below the seabed. This vast natural storage tank is sealed by a cap of impermeable shale 2,000 feet thick, the same oil dome that trapped the reservoir of North Sea petroleum in place for eons.
By 2050, experts estimate, carbon-capture and storage operations such as those at the Sleipner platform could account for half the reduction in CO2 needed to stabilize rising emissions in the atmosphere.
To avoid rising temperatures, climate experts say carbon dioxide emissions from fossil fuels -- which have added 152 billion tons of carbon to the atmosphere since the mid-1970s -- must be cut in half by the end of the century.
Energy demand, however, is expected to double in coming decades, much of it to be met by fossil fuels, energy analysts and climate experts say. Consequently, world CO2 emissions are expected to reach 38.8 billion tons annually by 2025 unless something is done, energy analysts predict.
The North Sea aquifer could safely hold all the carbon dioxide emitted by Europe’s power plants during the next 600 years, oil company researchers think. Undersea sediments along the U.S. coastline may be sufficient to store the nation’s annual CO2 emissions for thousands of years, researchers at Harvard and Columbia universities and MIT determined in August.
“The capacity is essentially infinite,” said Harvard climatologist Daniel P. Schrag. “We would run out of coal long before we would run out of storage space.”
The technology of injection is well-known. For decades, oil companies have boosted production by raising the pressure in depleted fields with CO2 injections.
Until recently, however, few cared so much about how long the carbon dioxide stayed put.
That is starting to change. Since 2000, the North American energy company EnCana Corp. has boosted oil production 50% at Weyburn, Canada, by injecting millions of tons of surplus CO2 from North Dakota. Plans call for at least 20 million tons in all to be sequestered permanently there in coming decades -- an amount equal to the annual emissions of 6.8 million cars.
So far, monitoring indicates that most of it will stay underground but, by one report, about 2,500 tons a day bubble to the surface where it must be recaptured and re-injected.
Critics of the storage operations worry about the long-term safety of the reservoirs. No one knows whether excess carbon dioxide will remain stable underground for hundreds or thousands of years.
“If it can find any well, crack or conduit in the rock, it will escape,” said Harvard carbon storage researcher Kurt Zenz House.
With more than 3.5 million oil wells drilled in the U.S. since petroleum exploration began in earnest 150 years ago, there is no shortage of potential leaks.
Experts also worry how so much carbon dioxide will alter the chemistry of the storage formations themselves. Bubbles composed of millions of tons of sequestered CO2 could form an acid that could etch away the confining rocks or erode the concrete caps on well heads.
To test the effects of carbon dioxide storage, researchers funded by the U.S. Department of Energy recently injected 2,000 tons -- about half a day’s power plant emissions -- into a mile-deep well northeast of Houston.
After monitoring the site for two years, researchers at the U.S. Geological Survey found no leaks.
But in a study made public in July, they did discover that the buried CO2 increased the acidity of the saltwater in the rock enough to dissolve the surrounding minerals. Should enough minerals be eaten away, the gas could seep slowly into the atmosphere again, they reported. The acidic solution also could combine with trace metals and organic compounds to contaminate groundwater.
“We can’t just dump this CO2 anywhere without knowing what is there underground and what is happening to it,” said USGS scientist Yousif Kharaka, who conducted the analysis.
At Harvard, House and his colleagues believe the most effective way to store excess carbon dioxide is to sequester it offshore in ocean sediments under water more than 9,000 feet deep. In theory, they said, the combination of extreme pressure and severe cold would make the CO2 slurry so dense that it would sink of its own weight.
Since starting injections in 1996, Statoil technicians surveyed the carbon dioxide with 3-D seismic sensors that can track the gas as it moves through the brine-soaked rock. So far, it has stayed where they put it.
If Statoil’s computer simulations are correct, the immense CO2 pool may be safely sequestered for at least 5,000 years.
“At Sleipner we know it works,” said Julio Friedmann, director of the Carbon Storage Initiative at Lawrence Livermore National Laboratory. “What we don’t know is if it works everywhere you need it. The question is whether you can do it a hundred times, a thousand times. Can you do it in the places where the power plants are?”
Ideally, excess CO2 from power generation would be injected into sediments close to the power plant that generated it.
Such is the strategy of BP and Edison International, which have been preparing to build a $1-billion hydrogen fuel plant south of Los Angeles in Carson, in anticipation of new state curbs on carbon dioxide emissions. They expect to dispose of 4 million tons of CO2 per year from the proposed 500-megawatt power plant by injecting it into depleted oil fields throughout Southern California.
In the absence of taxes or federal regulations to encourage its use, the technology of carbon storage so far is too expensive for many power plants to adopt voluntarily, especially coal-fired plants. In the U.S., CO2 emissions from the largest plants can run as high as 18 million tons annually.
But as greenhouse gases in the atmosphere reach increasingly higher levels, the need to sequester carbon dioxide safely may become a profitable enterprise.
“This is the only way for the fossil fuel industries to survive -- to become part of the solution,” said Fjaeran of Statoil.
Statoil and Royal Dutch Shell announced a proposal in March for a $1.4-billion, 860-megawatt power plant that involves one of the world’s largest carbon-capture and storage operations. Almost half of the project’s cost stems from its carbon storage plan, but the companies will use the excess CO2 to boost production of even more oil and natural gas from their depleted fields.
That is what worries critics most.
The CO2 storage schemes offer energy companies a way to perpetuate the use of carbon-rich fossil fuels for decades to come. To avoid potentially catastrophic consequences of global warming, environmental critics contend, the world should instead be weaning itself completely from petroleum in favor of alternative energy sources.
Deep in the heart of the Sleipner complex, platform manager Helge Smaamo pursed his lips as he surveyed a leaking CO2 compressor. To avoid the risk of fire, the carbon dioxide injection system had to be shut down until the leak could be repaired.
The platform fell silent.
Inside the industrial intestines of the 8,000-ton CO2 unit, three workers in orange jumpsuits crouched over the leaking turbine, heaving at the bolts on its green cowl with wrenches the size of their leg bones.
Smaamo hurried onto a walkway overlooking the carbon dioxide capture unit. Before his eyes, its 500-foot-high flare tower started to stream flame as venting natural gas ignited safely. His eyes turned to the smaller exhaust stack next to it.
In a few moments, a wispy white plume spilled from its mouth. The company’s carbon dioxide was escaping into the atmosphere, to be taxed at more than $50 a ton.
Smaamo grimaced.
He watched money -- and more -- disappear up the flue.
