Cleanup of inactive Gulf of Mexico wells estimated at $30 billion

Wetlands, coastal areas and offshore waters near Alabama, Louisiana and Texas have more inactive oil and gas wells than producing ones, and the cost to permanently plug and abandon them could be $30 billion, University of California, Davis, researchers suggest.

A paper published today in the journal Nature Energy examines the cost to plug 14,000 wells that are inactive, have not produced for five years and are unlikely to be reactivated in the Gulf of Mexico region, which is the epicenter of U.S. offshore oil and gas operations.

The wells could pose future environmental and financial risks to the public, and the cost differential for plugging onshore wells versus those in offshore waters is large, said Mark Agerton, an assistant professor at UC Davis and lead author of the paper.

Leaks from wells closer to shore are more likely to damage coastal ecosystems and release greenhouse gases like methane into the atmosphere, compared to wells in deep waters. The study found that more than 90% of inactive wells are in shallow areas, and the cost to plug those would be $7.6 billion, or 25% of a total $30 billion.

Informing policy decisions

"The wells aren't supposed to be leaking into the environment, but sometimes they do," said Agerton, of the Department of Agricultural and Resource Economics. "How do you get the most environmental benefit for the least amount of money?"

The findings could help states decide cleanup priorities, especially as they access $4.7 billion in federal money authorized by the Infrastructure Investment and Jobs Act. That money is set aside for methane reduction programs, including cleanup of old oil and gas wells, said Gregory Upton, an associate research professor at the Louisiana State University Center for Energy Studies and co-author of the paper.

"States have a pretty good idea of what it costs to plug these wells on land, but there is really a lot of uncertainty as to what the costs were for these offshore wells," Upton said during a media briefing about the paper.

Liability for cleaning up wells abandoned in federal waters falls to prior owners if the current owner becomes insolvent and is unable to cover costs. Large American oil companies currently own or have owned 88% of the wells in federal Gulf of Mexico waters and would legally shoulder cleanup liabilities before taxpayers, Agerton said.

But in state waters, each jurisdiction handles liability differently, and prior ownership doesn't come into play. States oversee plugging programs for orphaned wells whose owners have gone bankrupt, though the cost to plug an abandoned offshore well increases with the length of the well and the depth of the water.

"The bulk of the costs comes from plugging wells in deeper water where the environmental consequences are less than for a shallow well closer to shore," Agerton said. "That money is probably better spent on state waters where they can't go after prior owners for cleanup costs and it's going to be a cheaper cleanup job with more environmental benefit."

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Shutting down nuclear power could increase air pollution

Nearly 20 percent of today's electricity in the United States comes from nuclear power. The U.S. has the largest nuclear fleet in the world, with 92 reactors scattered around the country. Many of these power plants have run for more than half a century and are approaching the end of their expected lifetimes.

Policymakers are debating whether to retire the aging reactors or reinforce their structures to continue producing nuclear energy, which many consider a low-carbon alternative to climate-warming coal, oil, and natural gas.

Now, MIT researchers say there's another factor to consider in weighing the future of nuclear power: air quality. In addition to being a low carbon-emitting source, nuclear power is relatively clean in terms of the air pollution it generates. Without nuclear power, how would the pattern of air pollution shift, and who would feel its effects?

The MIT team took on these questions in a new study appearing in Nature Energy. They lay out a scenario in which every nuclear power plant in the country has shut down, and consider how other sources such as coal, natural gas, and renewable energy would fill the resulting energy needs throughout an entire year.

Their analysis reveals that indeed, air pollution would increase, as coal, gas, and oil sources ramp up to compensate for nuclear power's absence. This in itself may not be surprising, but the team has put numbers to the prediction, estimating that the increase in air pollution would have serious health effects, resulting in an additional 5,200 pollution-related deaths over a single year.

If, however, more renewable energy sources become available to supply the energy grid, as they are expected to by the year 2030, air pollution would be curtailed, though not entirely. The team found that even under this heartier renewable scenario, there is still a slight increase in air pollution in some parts of the country, resulting in a total of 260 pollution-related deaths over one year.

When they looked at the populations directly affected by the increased pollution, they found that Black or African American communities -- a disproportionate number of whom live near fossil-fuel plants -- experienced the greatest exposure.

"This adds one more layer to the environmental health and social impacts equation when you're thinking about nuclear shutdowns, where the conversation often focuses on local risks due to accidents and mining or long-term climate impacts," says lead author Lyssa Freese, a graduate student in MIT's Department of Earth, Atmospheric and Planetary Sciences (EAPS).

"In the debate over keeping nuclear power plants open, air quality has not been a focus of that discussion," adds study author Noelle Selin, a professor in MIT's Institute for Data, Systems, and Society (IDSS) and EAPS. "What we found was that air pollution from fossil fuel plants is so damaging, that anything that increases it, such as a nuclear shutdown, is going to have substantial impacts, and for some people more than others."

The study's MIT-affiliated co-authors also include Principal Research Scientist Sebastian Eastham and Guillaume Chossière SM '17, PhD '20, along with Alan Jenn of the University of California at Davis.

Future phase-outs

When nuclear power plants have closed in the past, fossil fuel use increased in response. In 1985, the closure of reactors in Tennessee Valley prompted a spike in coal use, while the 2012 shutdown of a plant in California led to an increase in natural gas. In Germany, where nuclear power has almost completely been phased out, coal-fired power increased initially to fill the gap.

Noting these trends, the MIT team wondered how the U.S. energy grid would respond if nuclear power were completely phased out.

"We wanted to think about what future changes were expected in the energy grid," Freese says. "We knew that coal use was declining, and there was a lot of work already looking at the impact of what that would have on air quality. But no one had looked at air quality and nuclear power, which we also noticed was on the decline."

In the new study, the team used an energy grid dispatch model developed by Jenn to assess how the U.S. energy system would respond to a shutdown of nuclear power. The model simulates the production of every power plant in the country and runs continuously to estimate, hour by hour, the energy demands in 64 regions across the country.

Much like the way the actual energy market operates, the model chooses to turn a plant's production up or down based on cost: Plants producing the cheapest energy at any given time are given priority to supply the grid over more costly energy sources.

The team fed the model available data on each plant's changing emissions and energy costs throughout an entire year. They then ran the model under different scenarios, including: an energy grid with no nuclear power, a baseline grid similar to today's that includes nuclear power, and a grid with no nuclear power that also incorporates the additional renewable sources that are expected to be added by 2030.

They combined each simulation with an atmospheric chemistry model to simulate how each plant's various emissions travel around the country and to overlay these tracks onto maps of population density. For populations in the path of pollution, they calculated the risk of premature death based on their degree of exposure.

System response

Their analysis showed a clear pattern: Without nuclear power, air pollution worsened in general, mainly affecting regions in the East Coast, where nuclear power plants are mostly concentrated. Without those plants, the team observed an uptick in production from coal and gas plants, resulting in 5,200 pollution-related deaths across the country, compared to the baseline scenario.

They also calculated that more people are also likely to die prematurely due to climate impacts from the increase in carbon dioxide emissions, as the grid compensates for nuclear power's absence. The climate-related effects from this additional influx of carbon dioxide could lead to 160,000 additional deaths over the next century.

"We need to be thoughtful about how we're retiring nuclear power plants if we are trying to think about them as part of an energy system," Freese says. "Shutting down something that doesn't have direct emissions itself can still lead to increases in emissions, because the grid system will respond."

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Major North American oil source yields clues to one of earth's deadliest mass extinctions

The Bakken Shale Formation -- a 200,000-square-mile shale deposit below parts of Canada and North Dakota -- has supplied billions of barrels of oil and natural gas to North America for 70 years. A new discovery reveals that the rocks also open a uniquely informative window into Earth's complicated geological history.

A research team, which included geologists from the University of Maryland, George Mason University and the Norwegian oil and gas company Equinor, developed a new framework for analyzing paleontological and biogeochemical data extracted from the formation's rock. Using this technique, the team pinpointed a major trigger of several closely spaced biotic crises during the late Devonian Period almost 350 million years ago: euxinia, or the depletion of oxygen and expansion of hydrogen sulfide in large bodies of water. Published in the journal Nature on March 8, 2023, the team's findings demonstrate links between sea level, climate, ocean chemistry and biotic disruption.

"For the first time, we can point to a specific kill mechanism responsible for a series of significant biotic disruptions during the late Devonian Period," said UMD Geology Professor Alan Jay Kaufman, a senior author of the paper. "There have been other mass extinctions presumably caused by expansions of hydrogen sulfide before, but no one has ever studied the effects of this kill mechanism so thoroughly during such a critical period of Earth's history."

According to Kaufman, the late Devonian Period was a "perfect storm" of factors that played a large role in how Earth is today. Vascular plants and trees were especially crucial to the process; as they expanded on land, plants stabilized soil structure, helped spread nutrients to the ocean, and added oxygen and water vapor to the atmosphere while pulling carbon dioxide out of it.

"The introduction of terrestrial plants capable of photosynthesis and transpiration stimulated the hydrological cycle, which kick-started the Earth's capacity for more complex life as we know it today," Kaufman said.

The Devonian Period ended around the same time the Bakken sediments accumulated, allowing the layers of organic-rich shale to 'record' the environmental conditions that occurred there. Because the Earth's continents were flooded during that time, various sediments including black shale gradually accumulated in inland seas that formed within geological depressions like the Williston Basin, the preserved the Bakken formation.

Undergraduate laboratory assistant Tytrice Faison (B.S. '22, geology) -- who joined Kaufman's lab after taking a course with him through the Carillon Communities living-learning program -- prepared and analyzed more than 100 shale and carbonate samples taken from the formation. After analyzing the samples, Kaufman, Faison and the rest of the Bakken team deciphered clear layers of sediment representing three key biotic crises known as the Annulata, Dasberg and Hangenberg events, with the last crisis associated with one of the greatest mass extinctions in Earth history.

"We could see anoxic events distinctly marked by black shale and other geochemical deposits, which are likely linked to a series of rapid rises in sea level," Kaufman explained. "We suspect that sea levels may have risen during the pulsed events due to the melting ice sheets around the South Pole at this time."

Higher sea levels would have resulted in the flooding of interior continental margins, or the transitional region between oceanic and continental crusts. In these settings, high levels of nutrients, such as phosphorus and nitrogen, could have triggered algal blooms which create low oxygen zones in large bodies of water. These zones in turn would have increased toxic hydrogen sulfide right where most marine animals would have lived. Under those conditions, animals in the oceans and on land around the shoreline would have died during these late Devonian events.

The team's research is not exclusive to global biotic disruptions from hundreds of millions of years ago. Kaufman suggests that their findings are not just applicable to the shallow inland seas of the Devonian Period, but perhaps also to the oceans of today affected by global warming. He compared the ocean's circulatory system to a "conveyor belt" carrying nutrients, oxygen and microorganisms from place to place.

"Cold, salty water develops in the North Atlantic region before it sinks and eventually makes its way to the Indian and Pacific Oceans, cycling around the globe. This oceanic jet stream helps to spread life-sustaining oxygen through the oceans," Kaufman explained. "If that conveyor belt were to be slowed down due to global warming, parts of the ocean might be deprived of oxygen and potentially become euxinic."

The collateral damage caused by global warming might then promote animal migration out of dead zones or put Earth on a path to decreased diversity and increased rates of extinction, he added.

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The single oil spill that can disrupt the global energy supply

Over the last year, the world's energy market has been highly volatile. The warmer-than-average winter in Europe helped avoid a gas crisis this year, but the forecast for the next winter is unclear as instabilities persist. More than 20% of global liquefied natural gas exports originate from a single port in Qatar. A new paper in Nature Sustainability byateam of researchers at the University of Louvain, the University of Southern California (USC) Viterbi School of Engineering, and the Qatar Environment and Energy Research Institute, pinpoints the location of what the authors call a "high vulnerability zone," where an oil spill could cause liquified natural gas export facilities and desalination plants on the coast to be completely shut down for several days. (In the presence of an oil spill, tankers cannot navigate through thick oil slicks. Further, desalination plants, which rely on the intake of seawater, cannot perform normal operations with a heavily polluted water source) This shutdown, the researchers explain, could cause significant disruption in the global gas supply and cause an unprecedented water shortage for inhabitants of the Qatari Peninsula, while simultaneously compromising containment efforts.

Awareness of such a vulnerability is imperative, say the researchers. Qatar's export capacity is expected to increase by approximately 64% in the next five years. Thus, this key port will continue to be a crucial hotspot for the global energy supply chain. The researchers also note that the increasing number of tanker accidents in the Gulf adds a level of concern, particularly related to how such accidents could impact critical coastal infrastructures that export a vital source of energy for the planet and ensure the safety of desalinated water for one of the world's most arid climates.

The paper uses advanced numerical modeling to corollate maritime data transports, atmospheric circulation, ocean currents, waves, and seafloor topographic map data acquired over a period of five years to locate specific, offshore areas of the Qatar Peninsula that are vulnerable to oil spills and assess potential disruptions to the global supply of liquid natural gas.

The study suggests that tankers crossing this area are the principal risks for oil spills and, not the numerous oil rigs in the northern part of the Peninsula. Should there be a spill in this area, the researchers contend, Qatar would have only a few days to contain the oil spills before such spills would reach the country's main liquified gas export facility and main desalination plant. The authors indicate that these events could potentially cause disruptions or even a total shutdown for day for the desalination plants, pushing the nation to rely on its small freshwater reserve and sending liquified natural gas prices to higher values.

To put the size of the issue in context, experts believe that the largest liquid natural gas tankers from Qatar provide enough energy to heat the entire city of London for one week.

The study advocates for increased remote sensing using satellite and airborne images in the Gulf's most vulnerable areas to provide early warning for spills and better model their evolution. The above actions are crucial, say the researchers, to guide mitigation efforts to avoid negative consequences both locally and globally.

Co-author Essam Heggy of the USC Arid Climate and Water Research Center argues that the Middle East's vulnerability to environmental and climatic hazards is largely underestimated. "Global containment of major oil spills has always been challenging, but it is even harder in the shallow water of the Gulf where any intervention has to account for the complex circulation currents, a harsh operational environment, and the presence of highly-sensitive ecosystems on which three million humans rely for drinking water." He added, "I hope serious resources are put into resolving this vulnerability."

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Microbes can provide sustainable hydrocarbons for the petrochemical industry

If the petrochemical industry is ever to wean itself off oil and gas, it has to find sustainably-sourced chemicals that slip effortlessly into existing processes for making products such as fuels, lubricants and plastics.

Making those chemicals biologically is the obvious option, but microbial products are different from fossil fuel hydrocarbons in two key ways: They contain too much oxygen, and they have too many other atoms hanging off the carbons. In order for microbial hydrocarbons to work in existing synthetic processes, they often have to be de-oxygenated -- in chemical parlance, reduced -- and stripped of extraneous chemical groups, all of which takes energy.

A team of chemists from the University of California, Berkeley, and the University of Minnesota has now engineered microbes to make hydrocarbon chains that can be deoxygenated more easily and using less energy -- basically just the sugar glucose that the bacteria eat, plus a little heat.

The process allows microbial production of a broad range of chemicals currently made from oil and gas -- in particular, products like lubricants made from medium-chain hydrocarbons, which contain between eight and 10 carbon atoms in the chain.

"Part of the issue with trying to move to something like glucose as a feedstock for making molecules or to drive the chemical industry is that the fossil fuel structures of petrochemicals are so different -- they're usually fully reduced, with no oxygen substitutions," said Michelle Chang, UC Berkeley professor of chemistry and of chemical and biomolecular engineering. "Bacteria know how to make all these complex molecules that have all these functional groups sticking out from them, like all natural products, but making petrochemicals that we're used to using as precursors for the chemical industry is a bit of a challenge for them."

"This process is one step towards deoxygenating these microbial products, and it allows us to start making things that can replace petrochemicals, using just glucose from plant biomass, which is more sustainable and renewable," she said. "That way we can get away from petrochemicals and other fossil fuels."

The bacteria were engineered to make hydrocarbon chains of medium length, which has not been achieved before, though others have developed microbial processes for making shorter and longer chains, up to about 20 carbons. But the process can be readily adapted to make chains of other lengths, Chang said, including short-chain hydrocarbons used as precursors to the most popular plastics, such as polyethylene.

She and her colleagues published their results this week in the journal Nature Chemistry.

A bioprocess to make olefins

Fossil hydrocarbons are simple linear chains of carbon atoms with a hydrogen atom attached to each carbon. But the chemical processes optimized for turning these into high-value products don't easily allow substitution by microbially produced precursors that are oxygenated and have carbon atoms decorated with lots of other atoms and small molecules.

To get bacteria to produce something that can replace these fossil fuel precursors, Chang and her team, including co-first authors Zhen Wang and Heng Song, former UC Berkeley postdoctoral fellows, searched databases for enzymes from other bacteria that can synthesize medium-chain hydrocarbons. They also sought an enzyme that could add a special chemical group, carboxylic acid, at one end of the hydrocarbon, turning it into what's called a fatty acid.

All told, the researchers inserted five separate genes into E. coli bacteria, forcing the bacteria to ferment glucose and produce the desired medium-chain fatty acid. The added enzymatic reactions were independent of, or orthogonal to, the bacteria's own enzyme pathways, which worked better than trying to tweak the bacteria's complex metabolic network.

"We identified new enzymes that could actually make these mid-size hydrocarbon chains and that were orthogonal, so separate from fatty acid biosynthesis by the bacteria. That allows us to run it separately, and it uses less energy than it would if you use the native synthase pathway," Chang said. "The cells consume enough glucose to survive, but then alongside that, you have your pathway chewing through all the sugar to get higher conversions and a high yield."

That final step to create a medium-chain fatty acid primed the product for easy conversion by catalytic reaction to olefins, which are precursors to polymers and lubricants.

The UC Berkeley group collaborated with the Minnesota group led by Paul Dauenhauer, which showed that a simple, acid-based catalytic reaction called a Lewis acid catalysis (after famed UC Berkeley chemist Gilbert Newton Lewis) easily removed the carboxylic acid from the final microbial products -- 3-hydroxyoctanoic and 3-hydroxydecanoic acids -- to produce the olefins heptene and nonene, respectively. Lewis acid catalysis uses much less energy than the redox reactions typically needed to remove oxygen from natural products to produce pure hydrocarbons.

"The biorenewable molecules that Professor Chang's group made were perfect raw materials for catalytic refining," said Dauenhauer, who refers to these precursor molecules as bio-petroleum. "These molecules contained just enough oxygen that we could readily convert them to larger, more useful molecules using metal nanoparticle catalysts. This allowed us to tune the distribution of molecular products as needed, just like conventional petroleum products, except this time we were using renewable resources."

Heptene, with seven carbons, and nonene, with nine, can be employed directly as lubricants, cracked to smaller hydrocarbons and used as precursors to plastic polymers, such as polyethylene or polypropylene, or linked to form even longer hydrocarbons, like those in waxes and diesel fuel.

"This is a general process for making target compounds, no matter what chain length they are," Chang said. "And you don't have to engineer an enzyme system every time you want to change a functional group or the chain length or how branched it is."

Despite their feat of metabolic engineering, Chang noted that the long-term and more sustainable goal would be to completely redesign processes for synthesizing industrial hydrocarbons, including plastics, so that they are optimized to use the types of chemicals that microbes normally produce, rather than altering microbial products to fit into existing synthetic processes.

"There's a lot of interest in the question, 'What if we look at entirely new polymer structures?'," she said. "Can we make monomers from glucose by fermentation for plastics with similar properties to the plastics that we use today, but not the same structures as polyethylene or polypropylene, which are not easy to recycle."

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We can expect more emissions from oil refineries in the near-term future, analysis finds

A global inventory has revealed that CO2 emissions from oil refineries were 1.3 Gigatonnes (Gt) in 2018 and could be as large as 16.5 Gt from 2020 to 2030. Based on the results, the researchers recommend distinct mitigation strategies for refineries in different regions and age groups. The findings appear August 20 in the journal One Earth.

"This study provides a detailed picture of oil refining capacity and CO2 emissions worldwide," says Dabo Guan of Tsinghua University. "Understanding the past and future development trends of the oil refining industry is crucial for guiding regional and global emissions reduction."

Climate change is one of the most fundamental challenges facing humanity today, and continuous expansion of fossil-fuel-based energy infrastructure may be one of the key obstacles in achieving the Paris Agreement goals. The oil refining industry plays a crucial role in both the energy supply chain and climate change. The petroleum oil refining industry is the third-largest stationary emitter of greenhouse gases in the world, contributing 6% of all industrial greenhouse gas emissions. In particular, CO2 accounts for approximately 98% of greenhouse gases emitted by petroleum refineries.

In the new study, Guan and his collaborators developed a publicly available global inventory of CO2 emissions from 1,056 oil refineries from 2000 to 2018. CO2 emissions of the refinery industry were about 1.3 Gt in 2018. If all existing and proposed refineries operate as usual, without the adoption of any low-carbon measures, they could emit up to 16.5Gt of CO2 from 2020 to 2030. Based on the findings, the authors recommend mitigation strategies, such as improving refinery efficiency and upgrading heavy oil-processing technologies, which could potentially reduce global cumulative emissions by 10% from 2020 to 2030. The inventory will be updated and improved in the future as more and better data become available.

The study also showed that the average output of global oil refineries gradually increased from 2000 to 2018, in terms of barrels per day. But the results varied by refinery age group. Specifically, the average capacity of young refineries, which are mainly distributed in Asia-Pacific and the Middle East, increased significantly from 2000 to 2018, while the average capacity of refineries older than 19 years remained stable. "Given the greater committed emissions brought about by the long remaining operating time of young refineries, there is an urgent need for these refineries to adopt low-carbon technologies to reduce their CO2 emissions," Guan says. "As for middle-aged and old refineries, improving operational efficiency, eliminating the backward capacity, and speeding up the upgrading of refining configuration are the key means to balance growing demand and reducing CO2 emissions."

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Development of ultrathin durable membrane for efficient oil and water separation

Researchers led by Professor MATSUYAMA Hideto and Professor YOSHIOKA Tomohisa at Kobe University's Research Center for Membrane and Film Technology have succeeded in developing an ultrathin membrane with a fouling-resistant silica surface treatment for high performance separation of oil from water.

Furthermore, this membrane was shown to be versatile; it was able to separate water from a wide variety of different oily substances.

These results were published online in the Journal of Materials Chemistry A on October 3 2019.

Introduction

The development of technology to separate oil from water is crucial for dealing with oil spills and water pollution generated by various industries. By 2025, it is predicted that two thirds of the world's population won't have sufficient access to clean water. Therefore the development of technologies to filter oily emulsions and thus increase the amount of available clean water is gaining increasing attention.

Compared with traditional purification methods including centrifugation and chemical coagulation, membrane separation has been proposed as a low cost, energy efficient alternative. Although this technology has been greatly developed, most membranes suffer from fouling issues whereby droplets of oil get irreversibly absorbed onto the surface. This leads to membrane pore blocking, subsequently reducing its lifespan and efficiency.

One method of mitigating the fouling issues is to add surface treatments to the membrane. However, many experiments with this method have encountered problems such as changes in the original surface structure and the deterioration of the treated surface layer by strong acid, alkaline and salt solutions. These issues limit the practical applications of such membranes in the harsh conditions during wastewater treatment.

Research Methodology

In this study, researchers succeeded in developing a membrane consisting of a porous polyketone (PK) support with a 10 nano-meter thick silica layer applied on the top surface. This silica layer was formed onto the PK fibrils using electrostatic attraction- the negatively charged silica was attracted to the positively charged PK.

The PK membrane has a high water permeance due to its large pores and high porosity. The silicification process- the addition of silica on the PK fibrils- provides a strong oil-repellant coating to protect the surface modified membrane from fouling issues.

Another advantage of this membrane is that it requires no large pressure application to achieve high water penetration. The membrane exhibited water permeation by gravity- even when a water level as low as 10cm (with a pressure of approx. 0.01atm) was utilized. In addition, the developed membrane was able to reject 99.9% of oil droplets- including those with a size of 10 nanometers. By using this membrane with an area of 1m2, 6000 liters of wastewater can be treated in one hour under an applied pressure of 1atm. It was also shown to be effective at separating water from various different oily emulsions.

As mentioned, the silification provided a strong oil repellant coating. Through the experiments carried out on the membrane to test its durability against fouling, it was discovered that oil did not become adsorbed onto the surface and that the oil droplets could be easily cleaned off. This membrane showed great tolerance against a variety of acidic, alkaline, solvent and salt solutions.

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