Municipal Sewer System Design, Construction, Inspection, Maintenance, and Leak Detection

 

     Sanitary sewer systems are considered to be wastewater collection and treatment systems. Sewers and wastewater treatment systems are considered to be the most common form of pollution control in the country. Exact specifications for design vary by state and local jurisdiction. According to an online course in gravity sewer design based on rules from the State of Florida and Dade County:

“Gravity sanitary sewer systems are a collection of underground pipes or drains used primarily to convey wastewater from a community to an authorized point of discharge such as a lift station, pump station or a wastewater treatment facility.”

“A gravity sanitary sewer system transports wastewater mainly by gravity along a downward-sloping pipe and it should be designed based on the pipe size and slope to maintain adequate flow towards the discharge point without surcharging manholes or pressurizing the system.”

 

Sewer System Design and Construction

     Typical designs are for gravity sewer sewers but lift pumps, also known as lift stations, may be employed where gravity drainage is unsuitable due to soil, topography, or bedrock issues. In addition, there may be pump stations that convey the wastewater to the treatment plant.

     Accurate estimation of daily wastewater flow rates is very important to sewer system design, and future additions to the system must also be considered. Minimum, average, and peak daily flow rates are estimated. Peak daily flow rates are used to design for adequate capacity. Estimating design capacity is typically done by house size or number of bedrooms for household septic systems. I assume it is done similarly for sewer lines.

      The totality of the drainage area is known as the tributary area or basin. If there is an addition to an existing sewer system, then as-built drawings and sewer maps must be consulted. Since drainage around the buried components of the system may affect those components, additional information about the water table and soil permeability is desirable.

     The design period must be considered. Sewer mains and laterals less than 18” can be designed to last 100 years. Other mains, trunks, interceptors, and outfalls should be built to last 50-100 years. EPA recommends 50+ years.

     It is useful to derive a ‘design average flow’ rate for the wastewater, in gallons per day (gpd). This may be the same as the average annual daily flow rate for a system that is used evenly, or it may be changed to accommodate peak usage where there is increased seasonal usage. These wastewater flow calculations are important to deriving the ultimate system size. Population, population density, per capita flows, residential flows, commercial flows, and industrial flows must all be considered. Two other important considerations are groundwater infiltration (GWI) and stormwater inflow. For subsurface wastewater conveyance systems what leaks in as well as what leaks out must be considered. These extraneous flows, GWI and inflow, and are commonly known as infiltration/Inflow (I/I) flows. They must be estimated and added into the flow rate calculations. I/I flows can vary considerably by system.

     The hydraulic design of the sewer pipe is evaluated based on the size and type of the pipe, design period, design depth and peak flows. Wastewater flow is of two types: open channel flow or pressure flow.

 

“When flow fills the conduit and the Hydraulic Grade Line (HGL) rises above the sewer crown, the flow is classified as pressure flow. When the conduit is partially full and the HGL is below the sewer crown and a freewater surface develops in the sewer, the flow is classified as an open channel flow.”

 

Open channel flow is the basis for a gravity sewer system. Hydraulic slope (S) in sewers refers to the slope of the channel bottom and is the basis for estimating flow. The types of open channel flow in a gravity sewer system are steady flow, unsteady flow, uniform flow, non-uniform flow, steady uniform flow, unsteady uniform flow, steady non-uniform flow and unsteady non-uniform flow. Steady and unsteady flow refers to the depth of flow being constant flow or not over time. Uniform and non-uniform flow means that the depth of flow is constant or not over a location. In steady-uniform flow the depth of flow is constant with respect to time and location and the hydraulic grade line (HGL) is parallel to the sewer invert slope. Steady-uniform flow is the default analysis. “Unsteady uniform flow occurs when the HGL remains parallel to the sewer invert and fluctuates up and down as the rate of flow fluctuates with time.” This type of flow is uncommon. Steady non-uniform flow is considered to be the situation when multiple laterals are entering main lines but is usually estimated as steady uniform flow.

“Unsteady non-uniform flow develops during the onset and termination of peak flows. However, design of sewers based on this flow regime is seldom required, as it involves extensive calculations for flow routing, wave and water surface profiles.”

     The Manning Equation is used to determine open channel flow characteristics. It was first presented by Philippe Gauckler in 1867 and re-developed by Robert Manning in 1890.

     It is important to maintain minimum slope and velocity so that solids are not deposited in the lines. This can help prevent the need for future maintenance due to solids and sulfides. Adequate velocity helps to keep the pipes clean of solids and greasy scum and to prevent problems with corrosion and odors caused by sulfides.

“Slope is the key criterion in designing sewer collection systems to avoid odor and corrosion problems due to sulfides in wastewater. Sewer systems designed with long runs at minimum slopes are prone to sulfide generation due to long residence times, poor oxygen transfer, and deposition of solids.”

“Sewer system design is based on achieving self-cleaning velocities during normal daily peak flow periods to transport any grit which may enter the sewer system, scour grease and re-suspended solids that have settle in sewer during low flow.”

     Recommended minimum slopes from the recommended standards for wastewater flow (RSWF) are given in the table below.

Minimum velocities for all sewer lines are at 2 ft/sec when “flowing full.” Manning’s formula is applied using an “n” value of 0.013. Daily or hourly peak flows can be estimated. Peak hourly flow rates can be important since the wastewater flows can vary significantly by hour.

     System layout includes the design of the main and trunklines and where to install lift or pumping stations, if applicable. Surface topography is generally followed where possible for slope maintenance. Sewer lines typically run through the middle of a street so that they can more easily collect wastewater from both sides of the street. Other location issues include location relative to water lines and other utilities, easements, and rights-of-way. Other considerations include the location of manholes, terminal cleanouts, service connections, inverted siphons, junction chambers, and other structures or devices.

     Manholes provide access for observation and maintenance. They are recommended to be at least 48 inches in diameter by RSWF but the minimum is 24 inches.

 

“As per RSWF, manholes shall be installed: at the end of each line; at all changes in grade, size, or alignment; at all intersections; and at distances not greater than 400 feet for sewers 15 inches or less, and 500 feet for sewers 18 inches to 30 inches, except that distances up to 600 feet may be approved in cases where adequate modern cleaning equipment for such spacing is provided; As per MD WASD design requirements, manhole to manhole runs shall be kept in a range no more than 400 feet without permission. Greater spacing may be permitted in larger sewers.”

The flow channel of a manhole should be constructed to conformable to that of the flow channel within the sewer main with a similar slope. Manholes are made of precast or poured concrete. Gasketed flexible watertight connections are recommended, or any watertight connection arrangement that allows differential settlement of the pipe and manhole wall to occur. The covers also must be watertight in order to prevent inflow. If a sewer inflow is 2 ft or higher above the manhole channel, then a drop manhole is required. A drop manhole design is shown below. Manholes are typically inspected for damage and watertightness before the system is activated.

     Inverted siphons, or depressed sewers, are designed to stand full even if there is no flow. The siphon is designed to “carry the flow under an obstruction such as stream or depressed highway and to regain as much elevation as possible after the obstruction has been passed.” They are often constructed with multiple barrels. Adequate self-cleansing velocities and maintenance flexibility under widely variable flow conditions are important considerations. The design should permit cleaning and maintenance.

     Sewer connections, or service laterals, are the pipes that connect individual homes and buildings to a main sewer line. They are typically 4-, 5-, or 6-inch sewer-grade pipes with a minimum slope of 2%. Design schematics for shallow and deep laterals are shown below.

     Equalization storage tanks may be installed where peak flow rates may exceed design capacity. The tank contents collect wastewater during peak flow and feed it back into the sewer pipe system during times of lower flow. Sewer lines must be installed deep enough to prevent freezing and to accommodate wastewater from basements. Pipes are typically different grades of plastic such as PVC but may also be iron-based, cement, concrete, or vitrified clay. Plastic pipes are more flexible.

     Corrosion due to hydrogen sulfide (H2S), other sulfides, and sulfuric acid can be a problem for sewer pipes. Metal pipes are more susceptible so may need corrosion-resistance measures.

     Stream crossings should be minimized and where used should be perpendicular to stream flow and have no gradient. They must be at least 1 foot below the base of the stream where it cuts rock, 3 feet below the base of the stream where there is soil, and more than 3 feet if it is a wide stream.

     Sewer pipes must be at least 6-12 inches away from water main lines and preferably more. Any connections between pipes must be as far away from the water main as possible. Structural support may be required where sewer and water lines cross. The water or sewer lines may be required to either be encased in a watertight sleeve or the sewer pipe must be constructed to the standards of water pipe and be pressure tested to 150 psi.

     Construction may have to contend with high water tables which can make pipes buoyant. Watertightness is a factor for any pipe joints and service connections. There are also requirements for making the trenches, bedding the pipes, and backfilling around them. The ultimate goal of these measures is to prevent infiltration and root penetration.

“As per RSWF, deflection tests shall be performed on all flexible pipes. The test shall be conducted after the final backfill has been in place at least 30 days to permit stabilization of the soil-pipe system.”

 “No pipe shall exceed a deflection of 5 percent. If deflection exceeds 5 percent, the pipe shall be excavated. Replacement or correction shall be accomplished in accordance with requirements in the approved specifications.”

“As per MD-WASD standards, the deflection, or deformation of the pipe due to external loading, shall not exceed approximately 7.5 percent. Deflection shall be determined by passing an approved go/no go mandrel through the gravity sewer main. Deflection will be based on the average inside diameter as presented in ANSI/AWWA C900.”

 A lamping test uses light:

“For lamping test, each section of installed sewer lines shall show, from each end, a full circle of light.”

 

 

Leak Detection

     Water and air pressure may be utilized to determine leakage rate.

“As per RSWF, the leakage exfiltration or infiltration shall not exceed 200 gallons per inch of pipe diameter per mile per day for any section of the system. An exfiltration or infiltration test shall be performed with a minimum positive head of 2 feet.”

     A sewer system is recommended to be pumped out before an infiltration test is performed. Pumping into or out of calibrated drums is the recommended method for infiltration and exfiltration testing.

 The water level for testing should provide a minimum head of 2 feet in a lateral connected to the test portion, or, in the event there are no laterals in the test or a minimum difference in elevation of 5 feet between the crown of the highest portion of the drain or sewer and the test level.

“Where infiltration or exfiltration exceeds the allowable limits specified herein, the defective pipe, joints, or other faulty construction shall be located and repaired.”

     Air pressure tests may also determine leakage rates. Procedures vary by pipe material.

“As per RSWF, the air test shall, as a minimum, conform to the test procedure described in ASTM C 828 for clay pipe, ASTM C 924 for concrete pipe, ASTM F 1417 for plastic pipe, and for other materials test procedures approved by the regulatory agency.”

 

Smoke Testing for Leak Detection

     Smoke testing may be done to find leaks and even to locate lost manholes. A smoke test uses non-toxic smoke and high-capacity blowers to blow smoke through the sanitary sewer pipes. Pumping smoke down through the sewer line can be used to locate leaks. The smoke can enter people’s houses and reveal system leaks within the house. If there are no leaks the smoke will exit via the house plumbing vents. Finding plumbing leaks is secondary to the main goal which is to find leaks in the public part of the sewer system. Typically, a section of the sewer system is plugged off and workers walk around the neighborhood looking for smoke. It is best to prepare for a smoke test.

“Prior to testing date, pour ½ gallon of water in all basement floor drains or seldom used sink/shower drains and be sure to flush any seldom used toilets.  This ensures that drain traps are filled with water and smoke will not enter the house through any normal, working sewer-line connections. This “traps” water in the pipes, and is called “filling your traps.”

Below is shown a smoke test planned for this week in a town in West Virginia.

 

Sewer Lateral/Service Connection Inspection

     I have a little bit of experience inspecting sewer lateral connections in small-town sanitary sewer additions. We would go out to each house connection before the contractor covered up the new connection. These are usually 4-inch lines going into an 8-inch or larger main sewer line, or sewer main. We would record the drop from the house to the main sewer line. We would make sure the proper sewer line was used. We would note and GPS any nearby manholes we found. We would note where the sewer line went into the house, where it met the main sewer line, and the location of the cleanout line to the surface, usually close to the house. We would do a water test with a bucket of water to confirm water was flowing down the lateral. We would do an air pressure test which involves plugging off both ends of the line and observing whether the pressure was sustained without dropping. On the near end, a device called an inflatable pipe plug balloon plug, pipe pressure test plug, plumbing test ball, and sewer test plug with a pressure gauge was attached, and the pressure was increased to about 3.5 psi for about 2.5 minutes. If there was no drop in pressure, the test would be good. This is an easy way to do leak detection on a short section of sewer lateral. Other states, localities, and situations may require different pressure drop limits. We would also sketch a drawing to indicate the house, the lateral, the main line, and any nearby manholes, if applicable. Typically, it was a short and non-complicated process.

      We also permitted the laterals. In addition to the new laterals, there would often be existing household sewage systems, or septic systems, that would now be required to be abandoned. This involves getting an abandonment permit, having the septic tank pumped out, crushing it inward, filling the space with gravel, and covering it over with topsoil.  

 

Sewer System Replacement Needs and Wastewater Treatment Challenges

     The table below from the U.S. EPA summarizes the current challenges facing wastewater treatment professionals. Many systems are old and in need of replacement, which can be slow and expensive in densly populated areas.

 

References:

 

Smoke Testing Sewers in Your Community. Information Flyer. Thrasher Group and Town of Elizabeth. November 2024.

Gravity Sanitary Sewer Design and Construction. Second Edition. Prepared by a Joint Task Force of the Environmental and Water Resources Institute and the Pipeline Division Committee on Pipeline Planning of the American Society of Civil Engineers and the Collection Systems Subcommittee of the Technical Practice Committee of the Water Environment Federation. Edited by Paul Bizier. ASCE Manuals and Reports on Engineering Practice No. 60 WEF Manual of Practice No. FD-5. 2007. Front Matter

Gravity Sewer Design. PDH online Course C606 (8 PDH).  Instructor: Jorge Acevedo, PE.  2020. Gravity Sewer Design

Manning Formula for Determining Open Channel Flow. OpenChannelFlow.com. Manning Formula for Determining Open Channel Flows | Open Channel Flow

Municipal Wastewater. U.S. EPA. Municipal Wastewater | US EPA

Primer for Municipal Wastewater Treatment Systems. U.S. EPA. September 2015. Primer for Municipal Wastewater Treatment Systems

Smoke Testing: What Homeowners Need to Know. Superior Smoke. Smoke Testing: What Homeowners Need to Know

Environmental Psychology: Summary & Review of Chapter 5 of Environmental Health: From Global to Local. Daniel Stocols & Chip Clithero. Ed. Howard Frumkin, pgs 96-127. (2005, Wiley)

 

     Environmental psychology considers environmental health to result from harmonious relationships between individuals and groups and the environments they inhabit. That includes the sociophysical environment, which is often more subjectively defined.

“Environmental psychologists study the myriad ways in which sociophysical milieus, or contexts, affect individuals and groups, including affecting their health.”

Perceptions and feelings about the environment or one’s relationship to it are important aspects of environmental psychology. Emotional health or wellbeing is established as a variety of human health or wellbeing. Contexts are considered to be holistic, complex, naturally occurring, and time dependent. Settings are considered to be important in environmental psychology since they influence both physical and psychological wellbeing. Settings refer to the sociophysical environment where physical and psychological aspects are interdependent. Environmental psychology seeks to analyze all influences on health and environmental stress. The field is sometimes referred to as environmental behavior studies (EBS).      

     Settings, or environments, include residential, occupational. Educational, recreational, public, and virtual places. Environmental psychology studies how these settings affect behavior, public health, and wellbeing, including psychological wellbeing.

     The field of environmental psychology began in the 1960s and expanded in 1980s as the social factors of health became more apparent to researchers. It has been noted that one’s ‘sense of place’ can be an important factor in one’s wellbeing. One’s life circumstances are also a major factor in how one responds to environmental stresses. Categories, or levels of environmental analysis are shown in the recreated table below.

 

 

Three Principles of Contextual Analysis

 

1.        The relationship between environment and health is influenced by interdependencies among immediate situations, settings, and more remote environmental conditions. Each of the levels of environmental analysis noted above overlaps to some extent and human environments are environments with many relationships including the social relationships that humans cultivate. People are also affected by regulatory decisions. These policy impacts may be beneficial or detrimental. They are required to be considered at the federal level by the EPA and other federal agencies, as part of the required cost-benefit analyses. Our psychological health can be affected by events from local to global in scale. What is happening in the world causes stress. Environmental stress as I will note later includes stress caused by a physical environment or a social environment.

2.        The different environments in which an individual participates exert a cumulative, synergistic effect on his or her health. When this includes the myriad social environments we encounter, it can be difficult to tease out causes of stress. The combined influence of settings and life domains is often considered.

3.        Health is the result of an interaction among the objective features of the environments in which individuals participate, individuals’ personal perception of those features, and individuals’ personal attributes. This is important. In cases where risk needs to be evaluated, the perception of risk is often a very big factor, whether that perception best supports the facts or not. It is also important that the principle notes one’s personal attributes such as genetic dispositions, psychological dispositions, coping skills and their effect on one’s interpretation of events and situations. An example given is noise and its physiological effect on children. Work-family conflict and work-related stress are other examples.

 

 

 

The Neighborhood as Context

 

     The authors chose to explore environmental psychology through the context of a neighborhood, and to consider its potential effects on health. A neighborhood is a broad concept that often includes multiple stimuli, situations, settings, and life domains. It is a consequential context and a frequent part of people’s day-to-day lives and quality of life. Traditional neighborhoods have changed somewhat as we now have other convenient means of social and work-related interaction from a distance with our smart phones and computers in virtual neighborhoods of a sort. Still, when we think of a neighborhood, we most often mean a geographically constrained place. However, where we communicate from has been radically expanded with technology.

     Place-based neighborhoods have geographic boundaries and identifiable physical features. There are indoor neighborhood settings and outdoor neighborhood settings. The table below gives the common social functions of a neighborhood.

 

 

 

     A demand made on an individual by a physical or social environment is an environmental stress, which may also be considered a stimulus, requiring a physiological or psychological response. “Psychological stress can occur when perceived environmental demands exceed the individual’s perceived ability to cope with them.”  One’s subjective interpretation is an important factor. Again, the example on children of chronic noise exposure is given. Hearing impairments, poor reading skills, lower academic performance, and elevation of blood pressure were noted in multiple studies. Along with noise, crowding, and other challenges to one’s privacy have been found to be environmental stressors, especially in indoor settings. One’s perceptions of one’s ability or lack of ability to control and predict one’s environment is a big factor in environmental stress.  

     Outdoor neighborhood settings are what we usually refer to as the neighborhood and have similar concerns. Some features of a neighborhood, like pleasant places where people could meet, may facilitate positive social interaction and others, such as the presence of traffic, do the opposite.

     The concepts of physical incivilities and social incivilities are introduced in the neighborhood context. The presence of litter, graffiti, or houses, properties, and streets in disrepair are examples of physical incivilities. Social incivilities include things such as public drunkenness, drug dealing, prostitutes, or a threatening atmosphere. Certain neighborhoods may become stigmatized for these reasons. They may have higher crime rates and less investment. The concept of defensible space is also introduced. This involves strategic and practical positioning to allow optimal surveillance of outdoor areas and barriers like fences and shrubbery that may help discourage would-be burglars.

     A neighborhood with positively perceived features might enhance one’s sense of place. Sense of place is a perception often influenced by aesthetics and physical features such as landmarks, distinctness of boundaries, and recreational, historical, and commercial activities. Distinctness of boundaries can enhance the imageability (ability to evoke memories) and legibility, or visual clarity of a neighborhood. Legibility influences the navigability of a neighborhood. Features like path systems, unique cultural or commercial districts, physical landmarks, and nodes where social interaction occurs, influence sense of place.

     A neighborhood’s behavior settings, includes recreational, commercial, educational, cultural, and civic places. These settings are multiple. The ability to accommodate different groups, ages, and ethnicities, etc. enhances a neighborhood’s appeal. The presence of “nature” or natural settings within a neighborhood has long been recognized as psychologically beneficial. When nature is present in a neighborhood there are different sensory stimuli that we encounter. Our physical and virtual environments may interact or overlap. The authors mention real-virtual, or r-v situations where our virtual activities may impact our physical ones. Cellphone use during driving or being overly distracted by virtual activities when trying to multitask them with physical activities are examples. Ideas like stimulation overload and social media addiction are other r-v siuations that can affect quality of life.

     The notion of the digital divide, where people without adequate access or connectivity is less of an issue than it was 20 years ago when this edition came out.

     In conclusion, the authors summarize the topics introduced that need more research: examining the relationships between physical environmental health and social environmental health, incorporating the concept of psychological wellbeing into environmental health, consideration of the subjective aspects of an environment, a revised and expanded understanding of the context of neighborhood, and the analysis of virtual settings and how they interact with physical settings. 

Trump and Republicans Win ‘Unprecedented and Powerful Mandate’ (No, Not Really). I Think Perceived Liberal Policy Overreach is a Big Factor, Including Regulatory Overreach

 

     I admit I am both surprised and disappointed by Trump’s victory. I read one article that determined it was entirely the fault of the American people, the voters, and so we deserve what we get. That may well be true in part, but the deeper issue is why people voted the way they did. Despite Trump’s great popularity and his perceived ‘charisma,’ I think the main reason voters chose him is to show disapproval of liberal policies and government overreach.

     Trump overcame great odds. The odds of re-electing someone after he refused (and still refuses) to accept the adjudicated 2020 election results, heavily interfered with the peaceful transfer of power, and incited an abominable and deadly riot at the nation’s capital, seemed slim to me. The odds of re-electing a convicted felon with several additional pending cases (soon to be abandoned, no doubt) also seemed slim to me.

     He also overcame other odds such as his age, his incendiary rhetoric (although that often seems to help rather than hinder him), his past record as president (and all the chaos that went with it), his two impeachments, his lackluster performance debating Harris, and the seemingly formidable army of former Trump staff and once-prominent Republicans who actively campaigned against him.  

     It also appears Trump may win the popular vote this time, which would be a first for him and make it a clean sweep. I may not like it, but America chooses MAGA.

    

 

Demographics, More of the Same but More to Trump

   Some things I noted in the last election seem to be ringing true in this one: 1) men love Trump, women, mainly don’t. White men especially love Trump. 2) black voters mainly don’t like Trump, but Trump gained numbers in this demographic. Black males like Trump much more than black females. 3) less educated and rural voters favor Trump by huge margins. Plenty of Latino voters like Trump, more than in the last election.

 

Who Else is Celebrating

     Inevitably, with the populist Trump, there is ‘collateral damage’ as Steve Bannon called it. That includes approval from marginal white supremacy and anti-immigration groups like the KKK.

     Trump’s own cult following – the loyal deep MAGA enthusiasts, has to be ecstatic. They have been vindicated by the less dedicated MAGA. When I say cult following, I am harkening back to the Stop the Steal rallies, rhetoric, QANON conspiracies, and attempts to derail the democratic process. There are other peripheral Trumpist cults as well, perhaps more of that extremist wing "collateral damage." The link leads to an article about a rather disturbing ‘Christian Gun Cult’ led by the son of Reverend Sun Myung Moon, the infamous leader of the “Moonies” cult.

 

     Putin and the Kremlin are already talking about a reset with the U.S. Putin’s plan to wait for Trump to be re-elected, as some have speculated, paid off. Ukraine’s future is now significantly less certain.

     The right-wing populist movements in Europe and elsewhere are likely pleased with the results. Hungary’s Orban is likely pleased.  Argentina’s Milei congratulated Trump early. Thus far, Milei’s work for his country has been good, I believe. I see Milei as a better alternative to the left-wing socialist governments of other Latin American countries. He is a bit too libertarian for me, though.  

      Billionaires will certainly benefit. The likelihood of a tax increase for the super wealthy is essentially nil now. It was reported that the initial post-election Trump stock rally resulted in the richest 10 billionaires increasing their met worth by about $63 billion.

     The January 6 felons will likely be pardoned as soon as is expedient. While I think some of the sentences were much too harsh, there is a good argument to be made that in some cases harsher sentences are a deterrent to future anti-government rioters. 

Who Isn’t Celebrating  

      Some disenfranchised groups of people such as the LGTBQ community and vulnerable immigrants are no doubt experiencing new levels of anxiety.

     Those who had hoped to revive the old Republican party must wait half a decade to even begin in earnest as MAGA Republicans become the vast majority of Republicans. Trump has firmly sown his mark into the very fabric of the Republican party.

     Any of those he named for retribution in his rhetoric, might be a bit nervous now. Those in the government who might be replaced by loyalists are not celebrating.

     Iran will not be happy. In that case, I prefer Trump’s hard-line approach. 

     Some of our allies in the EU and elsewhere are likely not happy about a Trump victory. I just hope he doesn’t spend too much time trashing the EU and Canada when he could be trashing Russia, Iran, and North Korea.

 

Perceived Liberal Policy Overreach

     I believe that the perceived overreach of liberal policies was a major contributor to Trump’s victory. These include many issues including perceived censorship, perceived mandates and perceived ESG, DEI, and wokeness overreach, and things like threatened bans of gas stoves. Several people and authors have noted that things like wokeness overreach or political correctness overreach lead to strong backlashes against it.

     Regarding the censorship issue, I do think there were some unfair activities done by tech companies with shadow-banning and overambitious fact-checking. I was, however, OK with the fact-checking about the COVID conspiracies and fake claims, as these certainly led to unnecessary harm and loss of life. I highly value free speech but I do think there can be exceptions. I am not quite the free-speech absolutist that Elon Musk is. He generally sticks to his principles as people Musk personally doesn’t like are much more likely to get banned on the platform than say, white supremacists. Thus, his few exemptions mean he is not really an absolutist, as he claims.

     The policies pushed by the Progressive wing of the Democrats such as the anti-Israel/pro-Palestine protests no doubt boosted Trump. Perhaps the perceived failure of the Biden administration to address immigration was the biggest factor for Trump.  

 

Some Regulatory Changes Are Ahead

     With control of both houses of Congress, Trump is poised for a big regulatory purge. There are a few obvious things that will likely happen quickly: 1) The end of the ‘pause’ in approving LNG export projects. 2) permit reform that especially favors fossil fuel and nuclear projects (but also renewables). 3) Cutting out chunks of the IRA. Most of those changes will be a net improvement for the economy and fine for the environment. I am in favor of these measures, but I would limit cutting IRA funding to obvious mistakes such as giving money to activist advocacy groups (see future post). I am sure there will be many more regulatory changes, and it should be interesting to see what happens and who ends up working to implement these changes. With people like RFK Jr. Tulsi Gabbard, Elon Musk, and Margerie Taylor Green likely to be in high-level positions it even seems like regulatory issues could arise in a number of strange ways. I have already heard about RFK Jr. recommending the end of water fluoridation. He was also adamantly against vaccines of any sort and against genetically engineered products. Both he and Gabbard were once adamantly against fracking but I’m not sure of their current positions. Musk already has billions in government contracts with SpaceX, Starlink, and other companies. Tesla continues to receive government subsidies for EVs and batteries. I am not sure how or if IRA-funded projects associated with CCS, hydrogen, geothermal, batteries, and other clean energy tech will be affected.

     Another uncertainty is whether Trump will implement the solutions recommended in Project 2025. Even though he had previously distanced himself from the document, he now will have little resistance if he does decide to follow it. It should be interesting to see how this will play out as well.  

     Few economists see Trump’s tariff plans as being a net benefit for American consumers. His plan to deport undocumented and temporarily protected classes of immigrants could result in a low-wage labor shortage and higher food and housing prices.

The Future and Better Collaboration

     I am a fan of the middle, but the middle is lonely these days. I believe sensible moderate policies are the best approach. I think we saw in the debate of Vance and Walz that policy positions are not really as far apart as often depicted, and they can be debated in a civil manner. The middle is where collaboration happens. With Trump’s clean sweep, the middle is probably less empowered but there are still opportunities to collaborate. Non-MAGA Republicans are a vanishing breed.

     We have once again handed Trump the keys to the kingdom and now we must brace ourselves for a future where he is unimpeded by the courts, non-loyalists, and likely by the whole of Congress. He is also unimpeded by the recent Supreme Court decision that increases presidential power and immunity for the executive branch. 

     He says and I repeat with my article title that he has won an unprecedented and powerful mandate. I should qualify that statement. Even though the margin of victory for Trump and the Republicans was significant, it was not unprecedented or necessarily powerful. The margin of the popular vote (still counting) is still less than the margin by which Biden won it in 2020.

     If he really wants to be a good leader, he should dispense with the symbolic machismo and admit he was wrong about the 2020 election. I think he should apologize to the American people for this and for harassing election officials and workers. He won’t do that but if he did, I might take him more seriously as a leader. As an American I wish his negotiations to be successful (as long as they are not whacko or harmful) and for people of different political persuasions to work together. It would be better if there was more bipartisan collaboration no matter which party is in power. 

     Another thing is clear: a majority of Americans are willing to let his past and current lies go unchallenged. This election he focused repeatedly on a narrative that the Biden administration was working hard to gather the votes of undocumented migrants to rig the election, clearly another preposterous allegation. Right wing sites are now amplifying bogus arguments that the high number of votes Biden got in 2020 and lower number now are proof of 2020 fraud. These are lies, bald-faced lies with absolutely no support. Of one thing there is little doubt: Trump is a liar. This is not a judgment, rather it is simply a fact. 

     Since Trump is well known for his transactional nature, his rewarding of loyalty, and punishing of disloyalty, it seems logical to assume gestures towards or away from loyalty will be judged based on that rather than on merit.

     Trump is a populist, and a populist is part folk hero. Apparently, his fist up and rally to “Fight!” has inspired many people. My neighbor has a banner with the picture up as a political sign. (He also rallied his loyal supporters to march to the capital to "Fight like hell!" lest we forget). It seems most candidates are trying to cultivate a mythos about them. We have Dark Brandon and Dark MAGA. Perhaps that is healthy in a limited sense to cultivate folk hero-ness but when it crosses over into whacko conspiracy theories like QANON we are doomed. It is nice that we have not heard much about that twisted mythos lately and hopefully, it will stay that way. 

Magnet-Free Electric Motor Prototypes: Valeo and MAHLE’s Inner Brushless Electrical Excitation Motor, Vitesco Technologies’ Externally Excited Synchronous Machine (EESM), and ZF’s In-Rotor Inductive-Excited Synchronous Motor (I2SM)

     Magnets made of neodymium, a rare earth element, are standard in most brushless electric motors. They are required for maintaining a high coercive field which is necessary for motor operation. However, there are now in the works, some new electric motor designs that do not need rare earth magnets. These new designs may offer improved performance, lower cost, reduced dependence on China for neodymium and neodymium processing, and significant decreases in overall carbon footprint.

MAHLE'S Magnet-Free Motor with Valeo's Inverter and Controls

     German mobility technology company MAHLE developed a magnet-free electric motor in the early 2020s. It was reported in a June 2021 article in AutoEvolution:

“It works by generating the required magnetic field using excitation copper coils located inside the rotor that replace conventionally used permanent magnets. The power is transmitted wirelessly, contact-free, and consequently wear-free.”

“The key part of the assembly is a wireless transmitter that uses an alternating field to send energy to the rotor. This field is then converted into direct current for the aforementioned coils, producing an additional magnetic field that enables the motor to generate torque.”

“According to Mahle, the ability to adjust the parameters of the rotor’s magnetism instead of being limited by the use of traditional magnets has led to maximum performance through the full range of operating speeds. It’s thus capable of achieving an efficiency above 96%,”

     Contact-free means little to no mechanical wear. Few moving parts means it is easy to service if it ever needs it. Other expected advantages are a lower-cost motor and an increased range. MAHLE noted then that they expect mass production to begin by the end of 2023.

 

MAHLE’s Magnet-Free E-Motor vs. Magnet E-Motors

     As explained in a 2022 article in GlobalSpec, conventional permanent magnet generators (PMGs) used in current EVs use neodymium magnets (usually) to create a magnetic field that can convert mechanical energy into electrical energy. The magnetic field is used to rotate the rotor which creates torque. The MAHLE magnet-free motor uses electromagnetic induction instead of a neodymium magnet to generate the magnetic field that provides the rotational energy. The process is more efficient than PMGs. Magnet-free motors also generate less electromagnetic interference (EMI). EMI can interfere with nearby electronic equipment. If these induction-based motors can be produced and provided to the EV industry and to other industries as well they have the potential to decrease costs, energy use, and emissions anywhere an electric motor is used.

 

Source: MAHLE

Valeo and MAHLE October 2024 Joint Development Agreement

     According to the October press release announcing the joint development agreement between Valeo and MAHLE:

“Valeo and MAHLE have joined forces to develop an innovative magnet-free electric axle system, targeting upper segment electric vehicles with peak power ranging from 220 kW to 350 kW. Introducing the iBEE system (inner Brushless Electrical Excitation), this cutting-edge technology aims to revolutionize performance and efficiency of magnet free electric motor.’

Valeo provides expertise with electric motors, highly efficient inverters and associated controls. MAHLE provides expertise on a magnet-free rotor with its MAHLE Contactless Transmitter (MCT) technology.

“Valeo and MAHLE are working on an innovative cooling concept in order to achieve an outstanding continuous to peak power ratio.”

Valeo notes that testing of the first prototypes will be finished by the end of this year. Valeo’s new stator and cooling technology could potentially increase power density by 30% over current numbers. In 2020 MAHLE built a test bench in Fellbach/Germany for electric drives in order to develop and test e-axles and e-drive units for a wide range of electric and hybrid vehicles. They describe the Valeo/MAHLE partnership as a collaborative breakthrough.

“The motor's design incorporates Mahle's Magnet-free Contactless Transmitter (MCT) system, which enables energy transfer from the battery to the rotor through induction, eliminating the need for physical contact. This innovative approach not only removes the requirement for rare earth magnets but also promises enhanced longevity due to reduced mechanical wear.”

“Valeo's contribution includes a high-performance inverter and advanced motor control technology, integrated seamlessly with Mahle's rotor design. This synergy has resulted in a motor that not only matches but potentially surpasses the performance of traditional permanent magnet motors.”

To summarize, the new e-motor includes:

・Magnet-free design

・Induction-based energy transfer

・High efficiency (over 95%)

・Exceptional durability due to reduced mechanical wear

・Power output of up to 350 kW

     It is estimated that the carbon footprint of the vehicles in which the motor is used will be reduced by more than 40%. The life-cycle environmental impacts will also be reduced significantly as well as dependence on China for materials and materials processing. This collaboration and magnet-free e-drives in general, may have lasting impacts on EV design and may be able to be used for electric motors in many applications, including household appliances and industrial machinery. It could also reduce e-waste, resulting from the efficiency increase, I believe.

 

 

Vitesco Technologies’ Externally Excited Synchronous Machine (EESM)

     Vitesco Technologies, now part of Schaeffler Group AG, was an early developer of axle-drive EV electric motors. The graphics below compare their magnet-free externally excited synchronous machine (EESM) to permanent magnet synchronous machines (PMSMs). EESMs beat PMSMs in sustainability (due to no need for a magnet) and costs. They equal them in peak power but trail them in continuous power and they are slightly less efficient. That decrease in efficiency can take away some of the sustainability advantages since decreased efficiency=higher emissions. EESMs can provide more power and constant power at higher speeds. The last graphic shows different configurations. Two of the three utilize PMSMs for part of the drive, one for main drive and one for auxiliary drive. They ask if EESMs will replace PMSMs. If the Valeo/MAHLE motor can run at efficiencies exceeding those of PMSMs, then that will be the likely technology solution.

Advantages

·        High efficiency at WLTC and highway driving

·        High power density

·        Innovative rotor cooling enables high torques and efficiency

·        Minimized cost and supply chain risk, increased sustainability by optimized CO2-footprint

·        Universally applicable

·               Space neutral rotor power supply

Features

·         Adaptable rotor field

·         High slot fill factor due to optimized needle winding process

·         Effective rotor cooling due to slot cooler close to the winding

·         No rare earth magnets

·         Scalable design

·                 High integrated, non-contract rotor power supply

 

 

ZF’s In-Rotor Inductive-Excited Synchronous Motor (I2SM)

     ZF has developed a magnet-free electric motor that “transmits the energy for the magnetic field via an inductive exciter inside the rotor shaft. This makes the motor uniquely compact with maximum power and torque density.” They believe their design offers a significant improvement over EESM motors:

“Compared to common SESM systems {EESMs}, the inductive exciter can reduce losses for the energy transmission into the rotor by 15 percent.”

     Something that all of these magnet-free motors offer is increased efficiency at fast highway speeds. This is due to the elimination of drag losses.

“To ensure that the magnetic field in the rotor is built up by current instead of magnets, the conventional SESM concepts currently still require sliding or brush elements in most cases, which force compromises: A dry installation space, i.e. not accessible for oil cooling and with additional seals, is necessary. As a result, conventional SESMs take up around 90 mm more space axially. As a result, manufacturers generally cannot flexibly vary between PSM and SESM variants in their model planning without additional effort.”

“In order to offer the advantages of separately excited synchronous machines competitively, ZF has succeeded in compensating for the design-related disadvantages of common separately excited synchronous machines. In particular, the torque density has been significantly increased compared to the state of the art thanks to an innovative rotor design. The space-neutral integration of the exciter into the rotor means that there are no axial space disadvantages. In addition, an increase in power density in the rotor leads to an improvement in performance.”

     The I2SM is a brushless induction motor design (as is the MAHLE motor).

     ZF recently launched a new 800V Test & Validation Laboratory in the UK.

“The main aim is to accelerate the adoption of 800V architectures with improved efficiency, charging and vehicle performance advantages for electric vehicles (EVs).”

They will also offer validation testing to third parties and work with Tier 1 suppliers and OEMs. Most current EVs are based on 400V architecture. 800V architecture offers faster charging times (10 minutes vs. 20 minutes) and lighter, less expensive, lower gauge wiring. If combined with “Silicon Carbide MOSFETs, up to 10 percent efficiency gains are possible, which could ultimately lead to downsized batteries or improved vehicle range.” ZF is also developing these motors for better hydrogen fuel cell FCEVs.

     It should be interesting to see which motor designs win out and get mass-produced, how the industry is impacted, what are the final improvement numbers on overall efficiency, overall cost, and overall emissions reduction, and what happens regarding further improvements.

 

References:

IBee: Really? This magnet-free engine could reduce the carbon footprint by 40%. Samir Sebti. Daily Galaxy. October 28, 2024. IBee: Really? This magnet-free engine could reduce the carbon footprint by 40%

Valeo and MAHLE expand their product range of magnet free electric motors to upper segment applications through a Joint Development of iBEE (Inner Brushless Electrical Excitation). Valeo. Press Release. October 14, 2024. Valeo and MAHLE expand their product range of magnet free electric motors to upper segment applications through a Joint Development of iBEE (Inner Brushless Electrical Excitation) | Valeo

Externally Excited Synchronous Machine (EESM) as Main and Auxiliary Drive. Dr.-Ing. Gerd Rösel, Nico Daun, Artur Giedymin, Dragan Stojkovic, and Matthias Töns. Vitesco Technologies. April 28, 2023. Vitesco Technologies Standard Presentation

No need for rare earths: Vitesco Technologies presents electric drive for maximum sustainability. Vienna Motor Symposium 2023. Vitesco Technologies. April 27, 2023. Vitesco Technologies - 23-04-27

Electric drives for every application. Mahle. Electric Drive Systems - MAHLE Group

Mahle’s Innovative Magnet-Free EV Motor: How It Works and Why It’s a Big Deal. Auto Evolution. June 8, 2021. Mahle’s Innovative Magnet-Free EV Motor: How It Works and Why It’s a Big Deal - autoevolution

ZF Develops Magnet-Free Electric Motor. Power Transmission Engineering. September 1, 2023. ZF Develops Magnet-Free Electric Motor | Power Transmission Engineering Magazine

ZF’s new 800V Test & Validation Laboratory in the UK unlocks benefits for next-generation mobility. ZF Group. Press Release. October 14, 2024. ZF’s new 800V Test & Validation Laboratory in the UK unlocks benefits for next-generation mobility - ZF

Highly efficient magnet-free electric motor. Ryan Clancy. GlobalSpec. November 30, 2022. Highly efficient magnet-free electric motor | GlobalSpec

Permanent Magnet Generators. Electricity Magnetism. Permanent Magnet Generators | How it works, Application & Advantages

Electrically Excited Synchronous Machine. Shaeffler. Electrically Excited Synchronous Machine | Schaeffler Group USA Inc.

GHGSat Finds a 25% Increase in Methane Super-Emitter Sites and March 2024 Study Showing Higher Emissions at U.S. Oil & Gas Sites: AP’s Reporting on the Issue and Global Methane Emissions Monitoring

     Canadian satellite gas detection company GHGSat reported in October 2024 that since late 2023 they found 20,000 so-called super-emitters, up from 15,000 the year before. These sites include oil and gas facilities, coal mines, and landfills. Super-emitters are defined as those sites that emit at least 100 kilograms (220 pounds) of methane per hour.

“Almost half of the methane emissions detected are coming from the oil and gas industry, Germain said. About one-third came from “waste management emissions,” and mining accounted for 16%.

     Germain also noted that North America and Eurasia were the biggest sources of emissions and that landfill emissions were the largest source in Canada. The company added three satellites in 2023 but did not think that added significantly to the emissions total.

 

 

Source: GHGSat website

Global Methane Detection Satellites and Companies

“GHGSat, based in Montreal, is one of a number of for-profit and philanthropy-backed nonprofit methane satellite measurement and analysis efforts that both collaborate and compete to provide an increasingly clear view of the global issue. Others include Carbon Mapper, Kayrros and MethaneSAT.”

     It is great that we now have much-improved emissions monitoring via satellites and that regions and even companies emitting methane can be called out. GHGSat’s Stephane Germain noted in a Real Clear Science op-ed:

“For our part, GHGSat has built a constellation of twelve satellites producing more than three million site-level readings in 2023 alone. In the coming years, that fleet will expand to 40+ satellites, with plans to monitor every industrial site worldwide in near real-time by 2026.”  

     Carbon Mapper just released its first images which I reported on a few weeks ago. MethaneSat involves the Environmental Defense Fund which has been involved for several years in methane emissions reduction efforts in partial collaboration with the oil & gas industry.

     Germain also emphasized the need to act on the data and to involve collaboration with industrial emitters:

“With effective emissions monitoring technologies now more readily available than ever, both private industry and policymakers must commit to incentivizing uptake globally. The data created by emissions-detecting technologies is simply too critical to languish in a database or on a website. It must be used for progress.”

“For emissions monitoring companies, the first step is ensuring data accessibility for decisionmakers and encouraging its use. Collaboration is key here. Working with the industry community most able to solve the problem facilitates swift action. On the other hand, publicly shaming industry operators risks disincentivizing emissions data use, undermining the acceptance of satellites as a useful tool. It’s incumbent on industry to ensure that decision-makers are presented with data that’s clear, relevant, and facilitates action.”

“Organizations looking to effectively utilize emissions data must adopt a data-centric approach that permeates all aspects of their strategic planning processes, beyond a siloed view of meeting regulatory requirements. For example, emissions data can inform financial planning by pinpointing opportunities to capture methane before it leaks into the atmosphere, minimizing product loss. Additionally, this data can be used as an effective indicator of asset health, identifying critical infrastructure needs and informing decisions about maintenance planning. Harnessing and deploying emissions data beyond environmental reporting workflows empowers stakeholders to fully capitalize on its value throughout their operations.”

     The bottom line is that the data cannot be ignored. Oil & gas operators need to be aware of all of their emissions, particularly the super-emitters which are more consequential to fix. The satellite networks can find and now quantify emissions. This better detection should result in better mitigation, but as Germain notes, the companies must adopt that “data-centered approach” and do what id needed to reduce emissions.

 

 

AP’s Reporting and Reliance on Minority-View Scientists for Commentary

 

     Recently, I posted about new research that identified the main sources, via carbon isotope analysis, of global increases in atmospheric methane. The isotopes identified the vast majority of the methane as coming from biogenic sources. The vast majority of fossil fuel methane is thermogenic, not biogenic. Thus, the increases we have been seeing over the last couple of decades have not come from the oil & gas industry but from natural sources like wetlands and other anthropogenic sources like landfills. Coal mines are another major source, with more emissions coming from Chinese coal mines than the entire U.S. oil & gas industry.

     A paper published in Environmental Research Letters in September reported that global atmospheric methane increased by 12% from 2000 to 2020, with natural emissions rising just 2% and anthropogenic emissions rising 28% over that period. The study’s lead author, Stanford climate scientist Rob Jackson, also the head of the Global Carbon Project, noted: “Methane is a climate menace that the world is ignoring,” The study concluded that in 2000, about 60% of global methane emissions were made by humans and by 2020 that share increased by 5% to 65%.

“In the last 20 years, methane emissions from coal mining, oil and gas have jumped 33%, while landfill and waste increased 20% and agriculture emissions rose 14%, according to the study. The biggest single human-connected source of emissions are cows, Jackson said.

     AP’s Seth Borenstein has reported on the issue throughout the year and often utilizes Rob Jackson and Robert Howarth as commentators. Both of these scientists seem to get disproportionate mentions as experts on the subject and I would argue that both are biased. Howarth, in particular, represents a minority view in that he has a long history of inflating the emissions rates from the oil & gas sector far beyond that of other studies. Jackson also has a history of trying to link stray gas, emissions, and the dangers of gas stoves to the oil & gas industry. I mention this because if one were to get a scientific opinion on a subject, one generally would not go to a questionable minority source that disagreed with the vast majority of other sources.    

     Borenstein, apparently often relies on frequent comments from minority sources: i.e. Howarth and Jackson. He is not the only one. The Biden administration, in enacting the pause of LNG facility permitting, was directly influenced by Howarth’s minority analysis of LNG emissions which includes (as always) his incorrect analysis of methane emissions from the natural gas sector. While it is true that some LNG will come from Permian Basin associated gas, much of it will come from the Haynesville and Appalachian dry natural gas regions which have very low emissions rates. Much of that gas has been certified through third-party analysis as low emissions. Jackson was proved wrong as part of a group of researchers attempting to link stray gas occurrences in Northeastern Pennsylvania early in the Marcellus Shale play with Marcellus gas. In that case, it was also carbon isotope analysis that confirmed that the source was not Marcellus but shallow gas zones that occur naturally just below groundwater aquifers. He has also been instrumental in doing studies trying to link natural gas stoves with dangerous levels of contaminants like nitrogen oxides (NOx) and other contaminants utilizing non-real-world conditions such as a complete lack of ventilation. The study was challenged as inaccurate. Both of these scientists seem to be frequent commentators on any study that challenges mainstream science on these issues, and both seem to be adamantly against fossil fuel development. Jackson was a contributing author on the recent paper that linked the global methane emissions increase to biogenic microbial gas. In that case, he was not being biased. He is also head of the Global Carbon Project and as such, he should not be biased. I am working on another post arguing against mixing politics with science in which these two scientists are mentioned as examples of politicizing science.  

     One of Borenstein’s September 2024 articles summarizes commentary by Howarth:

“Cornell University climate scientist Robert Howarth faulted the study for not sufficiently emphasizing methane emissions from the boom in shale gas drilling, known as fracking. He said that boom began in 2005 and coincided with a sharp rise in methane emissions, including a spike of about 13 million tons (11.7 million metric tons) in the United States alone since then.”

     I would only note that the methane released before 2015 is now long gone from the atmosphere since it only stays in the atmosphere for about 10 years. Thus, I am not sure what he is trying to say there. While there may have been more methane released during the early part of shale gas drilling, that rate came down a few years later as better leak detection and repair and prevention of emissions became more widespread.

     Jackson is probably right that warmer global temperatures have caused natural methane to increase since the microbes that produce it do it better at warmer temperatures. The biggest human-caused increases in global methane were found in Asia, mostly in China and India.

     Jackson’s colleague at Stanford, Evan Sherwin, now a science and policy researcher at Berkeley Labs, led a study, published in Nature in March 2024 that concluded that average emissions from oil & gas systems were up to 3% of gas produced. The study utilized “one million anonymized measurements from airplanes that flew over 52% of American oil wells and 29% of gas production and delivery system sites over a decade.” Even so, the study was not comprehensive. The fact that most methane emissions come from the oil sector rather than the natural gas sector means that it is weighted over the higher emitters. Thus, the average, over the whole oil & gas sector is likely much less than 3%. Satellite detection has indeed gotten better at quantifying emissions. One of its best capabilities is to detect super-emitters. While Howarth may believe the study vindicates his high estimates, it does not, since it does not address the emissions from natural gas plays.

     The study noted that the biggest area of leakage is clearly the Permian Basin of West Texas and New Mexico, where flaring of gas is still rampant, although it has been regulated more recently. As the natural gas play emissions clearly show, mitigation is possible, However, it is more difficult and potentially much more costly in oil play areas.

“Contrast that with tiny leak rates found in drilling in the Denver region and the Pennsylvania area. Denver leaks are so low because of local strictly enforced regulations and Pennsylvania is more gas-oriented, Sherwin said.

     Jackson and Howarth both commented in Borenstein’s article about the study, noting that this is proof the emissions are undercounted and that the industry basically ignores the issue. There may be truth to that in the Permian Basin. New federal methane emissions rules should help to reduce those emissions further. It is not just flaring but also some methane venting (which is far worse) and other issues where a lot of natural gas is dissolved in the oil and comes out as it is produced, leaking from separators and tanks. It is clear, however, that Permian Basin companies can and should do more to reduce emissions.

     As noted, no studies have shown any increases in methane emissions from the natural gas sector. The so-called dry gas plays in the Appalachian Basin, the Utica and Marcellus plays, have the lowest emissions rates along with the dry gas play in the Haynesville Shale in Louisiana and Texas. Those rates are demonstrably lower than the EPA estimates. Thus, methane emissions from the oil sector are by far the main issue.  

 

References:

 

US energy industry methane emissions are triple what government thinks, study finds. Seth Borenstein. AP. March 13, 2024. US energy industry methane emissions are triple what government thinks, study finds | AP News

Pollution of the potent warming gas methane soars and people are mostly to blame. Seth Borenstein. AP. September 10, 2024. Pollution of the potent warming gas methane soars and people are mostly to blame | AP News

World may be merely scratching the surface on the scope of climate-changing methane emissions. Seth Borenstein. AP. October 31, 2024. World may be merely scratching the surface on the scope of climate-changing methane emissions

Rocket Science Is Easy, Now We Must Turn Emissions Data into Action. Stephane Germain. Real Clear Science. September 17, 2024. Rocket Science Is Easy, Now We Must Turn Emissions Data into Action | RealClearScience

GHGSat. (website). Oil and Gas Global | Emissions Monitoring - GHGSat

US oil and gas system emissions from nearly one million aerial site measurements. Evan D. Sherwin, Jeffrey S. Rutherford, Zhan Zhang, Yuanlei Chen, Erin B. Wetherley, Petr V. Yakovlev, Elena S. F. Berman, Brian B. Jones, Daniel H. Cusworth, Andrew K. Thorpe, Alana K. Ayasse, Riley M. Duren & Adam R. Brandt. Nature volume 627, pages328–334 (March 2024). US oil and gas system emissions from nearly one million aerial site measurements | Nature