Two days ago, Santa Barbara’s Dr. David Valentine published a theoretical technique he thinks will help the United States determine how much oil has seeped into the Gulf of Mexico since BP’s drilling rig exploded and sank over a month ago. In an opinion article featured on May 23 in the British journal Nature, the UCSB earth scientist explains that 40 percent of the leaking petroleum’s mass is methane gas and, because methane dissolves uniformly in water and the tools exist to accurately measure it, calculating the amount of gas now in the ocean may be the best way to gauge how large the oil slick is and where it’s headed. Valentine, who’s an expert on the behavior of oil and methane in the ocean and has published several authoritative papers on the subject, writes, “Although methane from surface-vessel spills or shallow-water blowouts escapes into the air, I expect that the vast majority of methane making the long trip to the sea surface from a deep-water spill would dissolve.”
While BP has tried over the weeks to plug the geysering gash in the seabed with a number of ultimately-failed techniques, company officials have struggled to come up with a definitive figure of how much oil is, and has been, escaping into the ocean on a daily basis. Publicized numbers have varied widely — as few as 1,000 barrels per day to as many as 100,000 barrels per day — and, thus far, no private or federal agency has been able to put its finger on an amount with any certainty. The latest release rate being thrown around is 5,000 barrels per day but that piece of data and all others, said Valentine, is based only on inherently inaccurate and highly variable visual, spot, and satellite observations. In his article, Valentine points out that knowing exactly how much oil has been spilled will help predict ecological impacts, determine current and future mop-up efforts, and allow scientists to compare this incident to others. He also brings up the U.S. Pollution Act of 1990 that, as he writes, “requires the completion of natural-resource damage assessment to determine liability, and the quantity spilled is a factor in damage assessment models.” In short, states Valentine, pinpointing a number will help answer the question that’s been on everyone’s mind: “How big of an environmental disaster is this?”
In a call to action, aimed at the US government, BP and Deepwater Horizon representatives, as well as the international community, Valentine suggests that a fleet of research vessels begin to map methane plumes as soon as possible. Confident that the equipment is available, in-country, and up to the task — “The US academic research fleet alone has a dozen vessels capable of such work,” he writes — Valentine wants to first get a sense of the size and shape of the plumes by tracking water flow with “drifting profiling floats” coupled with additional spot analyses in real time.
Once that’s done, he argues, a two-vessel mission should set out to “ensure the plumes are quantified as comprehensively as possible.” Ships could be easily equipped with sensors that, dragged through the water, would quickly measure methane in different areas at different depths. This gameplan, Valentine writes, would at least provide a lower limit on how much oil is flowing. “Measures of methane-plume movement could also be used to estimate the rate of the spill,” he says. But, Valentine asserts, it must be done soon before the plumes start to disperse.
What caused the worst mass extinction in Earth's history 251 million years ago? This event is one of the most catastrophic in life's history: the P/T extinction.
A Northwestern University chemical engineer believes the culprit may be an enormous explosion of methane (natural gas) erupting from the ocean depths. This explanation is closer to the inverse of an external impact, like an asteroid, and more like a disgorging of trapped energy that erupts from deep below the oceans. Such a global catastrophe has a more local precedent, as a similar eruption happened in Africa at Lake Nyos in 1986, killing 1700 people and rippling as far away as 25 kilometers.
According to Gregory Ryskin, associate professor of chemical engineering at Northwestern University, "explosive clouds of methane gas, initially trapped in stagnant bodies of water and suddenly released, could have killed off the majority of marine life and land animals and plants at the end of the Permian era" — long before dinosaurs lived and died. Ruskin believes that methane may have been the driving force in previous catastrophic changes of the earth's climate, where 95 percent of marine species and 70 percent of land species were lost in - geologically speaking - the blink of an eye.
Methane is a paradox. It increases global warming at the same time that it promises abundant alternative energy. The gas is all around the planet, from the atmosphere to deep below seabeds. Here are 10 trends and discoveries that may determine methane's ultimate role in the health of the environment:
Methane is about 21 times more powerful at warming the atmosphere than carbon dioxide (CO2) by weight (see box below). Methane's chemical lifetime in the atmosphere is approximately 12 years. Methane’s relatively short atmospheric lifetime, coupled with its potency as a greenhouse gas, makes it a candidate for mitigating global warming over the near-term (i.e., next 25 years or so).
Did Deepwater methane hydrates cause the BP Gulf explosion?
Strange and dangerous hydrocarbon offers no room for human error
...Methane hydrates are volatile compounds — natural gas compressed into molecular cages of ice. They are stable in the extreme cold and crushing weight of deepwater, but are extremely dangerous when they build up inside the drill column of a well. If destabilized by heat or a decrease in pressure, methane hydrates can quickly expand to 164 times their volume.
Survivors of the BP rig explosion told interviewers that right before the April 20 blast, workers had decreased the pressure in the drill column and applied heat to set the cement seal around the wellhead. Then a quickly expanding bubble of methane gas shot up the drill column before exploding on the platform on the ocean's surface.
Even a solid steel pipe has little chance against a 164-fold expansion of volume — something that would render a man six feet six inches tall suddenly the height of the Eiffel Tower...
Professor Sum said geologists know much less about these hydrate-bearing sediments than conventional ocean sediments, and that there is "little knowledge of the risks" of drilling into them.
The Deepwater Horizon rig was drilling in Block 252 of an area known as the Mississippi Canyon of the Gulf, thought to contain methane hydrate-bearing sediments, according to government maps. The platform was operating less than 20 miles from a methane hydrate research site located in the same canyon at Block 118.
From the sea floor a mile down, the Deepwater Horizon rig had penetrated another 18,000 feet — almost another five miles down — into the earth's crust with pipe.
According to the National Academy of Sciences, which published a bullish report on the energy potential of methane hydrates,
"Industry practice is to avoid methane-bearing areas during drilling for conventional oil and gas resources for safety reasons."
Professor Sum explained that because "with oil there is usually gas present," it is possible for methane hydrates to form in the pipe even when not drilling through hydrate-bearing sediments. The pressure and cold of the deepwater create conditions that encourage gas flowing into the pipe to form hydrates, and if the rate of crystallization is rapid enough, the hydrates can clog the pipe.
The cofferdam that BP lowered over the broken pipe gushing oil to contain the spill was almost immediately clogged by methane hydrates, which formed spontaneously. Gas escaping with the oil from the well, when trapped in the steel structure with cold water under great pressure, rapidly accumulated into an ice-like matrix.
Texas A&M professor heads out to study Gulf oil spill with first NSF grant
COLLEGE STATION, May 26, 2010 – A Texas A&M University oceanographer has been awarded a $160,000 grant from the National Science Foundation (NSF) to examine methane gas in the Gulf oil spill, believed to be one of the first such grants given to any Texas scientist. John Kessler, assistant professor in the Department of Oceanography who specializes in ocean chemistry, says he will leave Gulfport, Miss., June 11 to travel to the oil spill, now as large as Maryland and Delaware combined. Kessler will be leading a team composed of other Texas A&M University oceanographers (Shari Yvon-Lewis, Tom Bianchi and Heath Mills) as well as 4-6 graduate students, and they expect to return around June 20.
The team will use the research vessel Cape Hatteras, which is operated by the Duke University/University of North Carolina Oceanographic Consortium, and will look mainly at the huge quantities of methane gas that are mixed in with oil spewing up from the seafloor. They will collaborate with researchers from the University of California at Santa Barbara, who will be studying the oil rising up from the seafloor.
"The mixture coming up is now about 40 percent methane and 60 percent oil," Kessler explains. "This means there are immense amounts of methane, a potent greenhouse gas, being input into the Gulf.
"We know that millions of years ago, there were vast undersea eruptions where methane gas escaped just like it is doing right now," he adds. "It is thought that this methane eventually contributed to climate change millions of years ago, so this gives us a chance to study the methane from that perspective as we measure how much is entering the atmosphere today."
Another question the team hopes to examine is how much oxygen is being consumed in the Gulf waters by the methane gas. While some of the methane is emitted to the Earth's atmosphere, other parts of it dissolve in the Gulf waters and are literally eaten by living microorganisms, a process which consumes oxygen.
"We hope to find out the effects of all this methane on the dissolved oxygen content in this area of the Gulf," Kessler says.
"We know that there are large areas of the Gulf that have oxygen-depleted waters that occur annually, and these are known as 'the dead zone.' But will these large amounts of methane make the dead zone areas even larger or the oxygen-depletion more severe? What are the links between methane and oxygen down there? We hope to find out."
Kessler says that the oil spill, while no doubt an environmental and economic disaster to much of the Gulf Coast, with at least 65 miles of shoreline already affected by oil making landfall in the marshes and wetlands, provides a once-in-a-lifetime window of research on many levels.
"No one would never ever be allowed to 'dump' this much methane and oil into the Gulf to replicate any scientific experiment," he notes. "So this oil spill gives us a very rare opportunity to study what has happened in the past, and perhaps to give us some good clues about what might happen in the future."
Northcoast Ocean and River Protection Association (NORPA)
PO Box 1000
Trinidad, CA 95575
To: Ms. Renee Orr Chief, Leasing Division Minerals Management Service, MS 4010
381 Elden Street
Herndon, VA 20170-4817
The primary cause of blowouts, spills and uncontrolled releases of gases from offshore operations is drilling into methane hydrates, or through them into free gas trapped below (SINTEF 2008, MMS 2007, Izon 2007, Bourgoyne 2001). Methane hydrate (MH), also known as methane clathrate, is frozen methane gas, or more specifically a methane molecule under intense pressure wrapped in ice. When released it expands 164 times it's current size, creating intense pressure.
MH is found primarily along continental margins in shallow submarine environments, where high plankton productivity and high sedimentation rates yield large amounts of organic matter. This organic input becomes the basis for the production of biogenic methane in the seafloor sediment. MH is also formed thermogenicly from hydrocarbons venting from depth along fault systems, structurally deformed carrier beds (Milkov 2005), and mud volcanoes (Milkov 2000), where they can form massive deep sea floor “mounds” (often associated with unique chemosynthetic biota).
Once thought to be relatively rare in nature, hydrate is now widely considered to store immense volumes of organic carbon, rivaling, if not exceeding, that stored in all the world’s oil, natural gas, and coal deposits combined (DOE 2006b)...
Disasters Caused by Drilling Into or Through Methane Hydrates
The worst offshore oil spill ever, other than the gulf war, was the Ixtoc 1 1979 blowout in the Gulf Of Mexico (GOM), which was caused by loss of drilling mud circulation. Drilling mud is pumped down a well during drilling operations to lubricate operations and keep pressure in the line, not allowing hydrocarbons to escape. The most common cause of circulation loss is drilling into hydrate beds and gas pockets (Bourgoyne 2001). When drilling into, or through, hydrate beds, the high temperatures and pressure changes from drilling operations dissociates the methane from the ice, causing it to expand 164 times, creating a massive pressure increase that can penetrate the wellbore. This offsets backpressure from the mud, causing gas kicks and blow-outs, as happened at Ixtoc 1.
Even though Ixtoc 1 continued for months, this explosive release was probably not the worst gas release from a blowout. Oil yes, but gas no. Blowouts that are primarily gas, with no large oil spill associated with them, occur more often, and usually slip under the public eye. Yet the gas released is beyond comprehension, as the photos and the Actinia video below, illustrate.
As the ice turns to water, the high pressure gas (mixed with sand) is released, exploding out and up. This causes the seafloor to subside, collapsing and sinking platforms and leaving craters and pockmarks in it's wake (Rupple 2008). At the surface, roiling seas have sunk floating rigs, drillships and emergency rescue boats (Gerwick, 2007).
Since the only evidence these ice beds and gas pockets left after melting was the gas, sand and water blown out the well head, these deposits came to be known as gaseous sands, shallow gas sands, shallow overpressured sands, and a host of other similar titles. All mean the same thing, hydrate beds of primarily frozen methane gas and sand that has dissociated.
It was also discovered that drilling operations could cause slope instability and slides on even the slightest of slopes (
May 28th, 01:00. Today we saw some new things around the area. A fleet of skimmer ships was doing a surface burn to reduce the size of an oil slick. We were a couple of miles away from the burn but the large cloud of black smoke caught everyone’s eye. I’m still amazed by the ‘city of ships’ around the spill site. The rigs drilling the relief wells and the ‘siphon’ ship (large ship to the left in photo), as well as many support vessels are visible in this shot.
Burning off surface oil Our sampling and general operations are going very smoothly. We ran CTD profiles all through Wednesday night and Thursday morning, thanks to the efforts of Vernon Asper from the University of Southern Mississippi. We tracked the ‘new’ plume along a S/SW line by doing CTD casts about every half mile. The main plume features were fairly consistent along the line can concentrations of CDOM decreased with distance from the spill site.
Around 10AM Thursday morning, we moved slightly to the North and found another very interesting plume that was different from the previous one. The second plume contained less CDOM but exhibited more oxygen depletion. Perhaps this plume is older than the other one? The oxygen concentrations are not low enough to harm animal life but they are substantially lower (by ~25%) than the waters outside the plume at similar depths. Methane concentrations in this feature are the highest we’ve measured anywhere so far during this cruise.
This is an extensive plume. We’ve been tracking it now for approximately 7 miles and both the CDOM signal as well as oxygen depletion are strong and they co-vary. The samples with oxygen depletion also contain high concentrations of methane. Our hypothesis is that methane oxidation and CDOM degradation are driving oxygen consumption. We will be testing this hypothesis directly by measuring methane oxidation rates and oxygen consumption rates. Back at the UGA lab, we’ll be doing experiments to determine what factors regulate methane oxidation rates in these samples.
The last (and only) defense against the ongoing Deepwater Horizon oil spill in the Gulf of Mexico is tiny—billions of hydrocarbon-chewing microbes, such as Alcanivorax borkumensis. In fact, the primary motive for using the more than 830,000 gallons of chemical dispersants on the oil slick both above and below the surface of the sea is to break the oil into smaller droplets that bacteria can more easily consume...
...Nor is it easy to help the existing communities of thousands of microbes, such as various species of Vibrio and Pseudomonads, to eat the oil faster—seeding experiments have generally failed. "Microbes are a lot like teenagers, they are hard to control," says marine chemist Chris Reddy of the Woods Hole Oceanographic Institution. "The concept that nature will eat it all up is not accurate, at least not on the time scale we're worried about."
Just like your automobile, these marine-dwelling bacteria and fungi use the hydrocarbons as fuel—and emit the greenhouse gas carbon dioxide (CO2) as a result. In essence, the microbes break down the ring structures of the hydrocarbons in seaborne oil using enzymes and oxygen in the seawater. The end result is ancient oil turned into modern-day bacterial biomass—populations can grow exponentially in days. "Down in the Gulf of Mexico there is an indigenous population [of microbes] adapted to oil from so much marine traffic and daily spills. Oil is not new," says Lee, who has also been monitoring the plumes of oil beneath the surface. "There are so many natural seeps around the world that if it wasn't for microbes we would have a lot of oil in the oceans."
Already, measurements of oxygen depletion of as much as 30 percent in the Gulf of Mexico seawater suggest that the microbes are hard at work eating oil. "I take the 30 percent depletion of oxygen in water near the oil as indicating bacterial degradation," Atlas says.
That happens best near the surface, whether at land or sea, where warm-water bacteria such as Thalassolituus oleivorans can thrive; colder, deeper waters inhibit microbial growth. "Metabolism slows by about a factor of two or three for every 10 degree[s] Celsius you drop in temperature," notes biogeochemist David Valentine of the University of California, Santa Barbara, who just received funding from the National Science Foundation to characterize the microbial response to the ongoing oil spill. "The deeper stuff, that's going to happen very slowly because the temperature is so low."
Unfortunately, that's exactly where some of the Deepwater Horizon oil seems to be ending up. "They saw the oil at 800 to 1,400 meters depth," says microbial ecologist Andreas Teske of the University of North Carolina at Chapel Hill, whose graduate student Luke McKay was on the research vessel Pelican that first reported such subsurface plumes—as predicted by small-scale experiments, such as the U.S. Minerals Management Services Project "Deep Spill". "It is either at the surface or hanging in the water column and possibly sinking down to the sediment."...
...But sediment, whether the muck of Louisiana marshland or the deep ocean seafloor, suffers from a dearth of oxygen. That means it's up to anaerobic microbes—ancient organisms that live via sulfate rather than oxygen—to do the dirty work of consuming the spill. "What occurred in 10 days aerobically, took 365 days to occur anaerobically," says Atlas of the breakdown of oil in the wake of the Amoco Cadiz spill off the coast of France in 1978. Adds Teske: "The heavy components are sinking to the sediment and forming an oily or tarry carpet or getting buried. Then they are much harder to degrade."
Such anaerobic environments can develop locally in the seawater itself, thanks to a ready supply of oil and blooming microbes eager to devour it. In deepwater, where there's less mixing with the surface waters to provide fresh supplies of oxygen, a dead zone may result. "It's not exchanging with the atmosphere," Joye notes. "Once the oxygen is gone, how are you going to replace it? It's not going to get mixed up by winter storms." That's bad news for the speedy breakdown of oil as well as for the Lophelia coral and other sessile deepwater life.
The Gulf Of Mexico Before The Oil Spill
The oil leak on the Mississippi Canyon seafloor of the Gulf of Mexico proceeds apace. It is not clear that recent actions have succeeded in plugging the leak. The widely dispersed petroleum is a great disaster, but I get the distinct impression that this oil is seen as despoiling a pristine environment. Nothing could be further from the truth. I have this impression because, to my knowledge, the sorry state of the Gulf of Mexico before the oil spill is not being discussed. Before the oil spill, the Gulf of Mexico was being ravaged by—
hypoxia (very low oxygen)
harmful algal blooms (red tides)
These ongoing, slower-acting environmental disasters have a common cause: human activity. Let's start with coastal erosion.
The Louisiana coast depended for thousands of years on the routine overflow of the Mississippi River to deposit its sediment load and build land. But, beginning around the 1930s, in order to save lives and cities, the federal government built massive levees to constrain and control the river, effectively stopping it from doing what nature wants it to do.
As a result, for the past 70 years or so, the sinking of the delta coast has continued unabated. As salt water pushes inland from the gulf, it kills wetlands and marshes, habitat for wildlife and fish, and is increasingly threatening homes for many thousands of people.
Let's move on to hypoxia and the Gulf of Mexico Dead Zone.
The Gulf of Mexico dead zone is an area of hypoxic (less than 2 ppm dissolved oxygen) waters at the mouth of the Mississippi River. Its area varies in size, but can cover up to 6,000-7,000 square miles. The zone occurs between the inner and mid-continental shelf in the northern Gulf of Mexico, beginning at the Mississippi River delta and extending westward to the upper Texas coast... Dead zones can be found worldwide. The Gulf of Mexico dead zone is one of the largest in the world.
The dead zone is caused by nutrient enrichment from the Mississippi River, particularly nitrogen and phosphorous. Watersheds within the Mississippi River Basin drain much of the United States, from Montana to Pennsylvania and extending southward along the Mississippi River. Most of the nitrogen input comes from major farming states in the Mississippi River Valley... Nitrogen and phosphorous enter the river through upstream runoff of fertilizers, soil erosion, animal wastes, and sewage. In a natural system, these nutrients aren't significant factors in algae growth because they are depleted in the soil by plants. However, with anthropogenically [human-caused] increased nitrogen and phosphorus input, algae growth is no longer limited. Consequently, algal blooms develop, the food chain is altered, and dissolved oxygen in the area is depleted. The size of the dead zone fluctuates seasonally, as it is exacerbated by farming practices. It is also affected by weather events such as flooding (more info) and hurricanes...
Nutrient overloading and algal blooms lead to eutrophication, which has been shown to reduce benthic biomass and biodiversity. Hypoxic water supports fewer organisms and has been linked to massive fish kills in the Black Sea and Gulf of Mexico...
...So there you have it. Is this brief presentation meant to detract from the awfulness of the oil spill? Not at all. I merely wish to point out that the oil spill is a case of piling on—we made a bad situation much, much worse. Many species in the Gulf were already under severe pressure before the blow-out. Everything, including the wildlife, is covered with oil, which just accelerates the ongoing environmental deterioration & species die-off. See my:
to understand the full extent of our destruction of the world's oceans.
Using the most conservative estimate, 450,000 barrels of oil, or 19 million gallons, have leaked into the Gulf since the accident that sank the Deepwater Horizon oil rig five weeks ago, the USGS reports. Under the higher estimate, more than 700,000 barrels of oil, or 29 million gallons, may have spilled to date.
The size of the Exxon Valdez spill in March 1989 was 250,000 barrels of oil, or about 11 million gallons.
In an announcement Thursday (May 27), USGS director Marcia McNutt said the National Incident Command's Flow Rate Technical Group was asked last week to develop an independent, preliminary estimate of the amount of oil flowing from BP's leaking oil well.
That group's analysis determined that the overall best initial estimate for the lower levels, or boundaries, of flow rates of oil is in the range of 12,000-19,000 barrels per day, the USGS reports.
According to the USGS, "the team used three separate methodologies to calculate their initial estimate, which they deemed the most scientifically sound approach, because measurement of the flow of oil is extremely challenging, given the environment, unique nature of the flow, limited visibility and lack of human access to BP's leaking oil well."
One team looked at oil on the surface and came up with the estimate of 12,000-19,000 barrels per day. A second team that included Wereley used a different method and came up with a range of 12,000-25,000 barrels per day, the USGS reported. The official government estimate uses the overlapping range of both estimates.
Wereley said the consensus of his Plume Modeling Team is that the leakage at the time of the viewed video clips averaged at least 12,000-25,000 barrels of oil per day, plus considerable natural gas. That figure, he said, could possibly be significantly larger if the conservative assumptions used to make the estimate were relaxed.
When an initial 30-second video clip of the oil gushing from the 21.5-inch pipe was released by BP on May 12, Wereley deployed a technique called particle image velocimetry (PIV) to create freeze-frame shots of the video. From there, he ran a computer analysis to estimate the number of pixels based on the pipe's size.
Wereley, who has co-written a textbook on particle image velocimetry, created a conversion from pixels to inches to compute how fast oil was flowing from the pipe. Using the area of the pipe and the speed of the oil, he concluded that two feet of oil was leaking per second.
From that calculation, Wereley determined that 56,000-84,000 barrels of oil, plus gas, had been leaking daily into the Gulf - a flow that was nearly 10 times higher than other estimates at that time. Wereley said that accounting for decrease in oil volume due to the gas coming out of solution, the flow rates released by the panel of experts Thursday (May 27) align with those he calculated two weeks ago using the first BP video.
Using a longer and clearer video clip of the oil leak for the USGS analysis, Wereley said the figure from his team was reduced to the 12,000-25,000 per-barrel range because of the amount of methane gas and other natural gases consistently gushing out of the pipe.
We must first quantify the severity of the spill. Unfortunately, BP has only provided approximations of the spill rate and has refused to allow outside involvement in undersea measurements. We can only estimate the spill based on scattered information released by BP, main news streams, government agencies, and scientists.
The Official Word:
» Last Thursday BP reported oil capture (via an interception tube) at a rate of 5,000 barrels per day, but soon afterwards revised the amount to 2,200 barrels per day
» BP estimates that half of the volume spilling out of the deepwater rupture is comprised of natural gas. BP’s interception tube was able to capture 15 million cubic feet of natural gas in a 24-hour period last week in addition to its reported capture of 2,200 barrels of oil.
» A federal task force dubbed the “ Flow Rate Technical Team” will try to produce a scientifically credible estimate of the spill rate this week once it has had time to model the spill.
» Steven Wereley, associate professor of mechanical engineering at Purdue University, modeled the leak based on a video from BP. Last Wednesday, Wereley told the House Energy Committee that about 70,000 barrels were spewing out of the rig rupture each day (± 20%).
Most experts agree that the Deepwater Horizon spill is more severe than the Exxon Valdez tanker spill of 1989. Exxon Valdez spilled 10.8 million gallons over the surface of the ocean off the Alaskan coast. At the lower end of Wereley’s estimate, the Deepwater Horizon rig could be spilling 56,000 barrels (by volume) per day into deep ocean currents.
After subtracting a conservative 5000 intercepted barrels per day (BP’s highest reported capture rate) and assuming 50% of the spill volume is methane gas, the spill could release about 25,500 barrels of crude to the environment per day. At this rate it would take just over 10 days for the rig to spill the same volume released by the Exxon Valdez. Thirty-six days have passed since the spill first erupted.
Natural gas, an odorless and invisible gas, is difficult to intercept once released to the environment. At 5000 feet deep, the ocean pressure is about 140-150 times the air pressure at sea level. If half of the leaked volume is indeed natural gas as BP claims it is, we can calculate that 25,500 barrels of gas is released per day. At deep ocean pressure and temperature (145 atmospheres and an assumed 0 °C), this amounts to about 280 tonnes of natural gas released to the environment each day.* Natural gas has about 20 times the global warming potential of CO2 over a 100-year span.
The amount of CO2 equivalent to the natural gas leak (280 tonnes * 20 = 5600 tonnes CO2 per day) is emitted daily by 390,000 average American cars (MPG = 20.4, traveling 11720 miles per year). It would take over 140,000 tree seedlings grown for 10 years to sequester the carbon in 5600 tonnes of CO2. All equivalencies were calculated with US EPA equivalency calculator.
Today, BP engineers are preparing a “top-kill” procedure to plug up the leak. If top-kill is successful, the leak could stop as early as this week. Such a procedure is commonly performed to stop sub-surface oil leaks, but never at depths as great as the Deepwater Horizon rupture. We can only guess when BP will successfully stop the leak. A worst-case scenario offered by BP chief operating officer Doug Suttles projects leak stoppage in August of this year.
*This is calculated using the ideal gas law and a molecular weight of 16 grams per mole (methane), assuming that all natural gas is in gaseous form. At high pressures and low temperatures the ideal gas law becomes less reliable, but the equation errs in the conservative direction. Real gas law calculations with van der Waal’s constants for methane yield a mass flow rate about 50% higher than the 280 tonnes per day calculated with the ideal gas law.
Note: The back-of-the-envelope calculations in this article are based on estimates provided by BP and Professor Wereley of Purdue University. These quick calculations help us appreciate the scale of the disaster, but they are not offered as facts. If you have better calculations or find errors in ours, we welcome you to comment!
Finally someone asked whether there is a “methane cloud” emanating from the wellhead. (that would be me)
The plumes we’ve found are enriched in methane as well as higher alkanes.
The dissolved methane concentrations are higher than we’ve ever seen at comparable depths on previous Gulf of Mexico cruises. Some of the methane is almost certainly venting to the atmosphere but those fluxes have not been quantified yet to my knowledge.
Scientists on board the R/V Cape Hatteras will be quantifying atmospheric methane fluxes about two weeks from now. One of our major goals for this cruise is to map the methane concentration fields around the wellhead. We’ve made good progress towards achieving that goal so far.
May 31st, 23:58.
Happy Memorial Day.
Today we’ve been trying to trace the deepwater plume as close as possible to the leaking wellhead. Finally, after about 14 hours of searching and 5 unsuccessful CTD casts, we closed in on the source of the plume. After a very long day, we finally have this feature well constrained. We found more visible oil in the deepwater today – at different sites from yesterday – which increases our confidence in this finding.
Several people have asked me how much methane versus oil is in these plumes. We can’t answer that question yet. But, the plumes are very much enriched in gas. After we complete the sample analysis, we’ll be able to do this calculation. I’ll try to make some rough calculations tomorrow to get a feel for the volume and magnitudes we are dealing with.
Subsea operational update:
• The LMRP cap was placed on top of the LMRP at approximately 8:35 pm CDT on June 3.
• Gas first reached the Discoverer Enterprise at approximately 11:00 pm CDT on June 3; oil followed at approximately 11:10 pm CDT.
• On June 4, a total of 6,077 barrels of oil was collected and 15.7 million standard cubic feet of natural gas was flared.
• Optimization continues and improvement in oil collection is expected over the next several days.
5 June 2010 9:00am CDT