US Greenhouse Gas Research Articles

Hourly Power Grid Variations, Electric Vehicle Charging Patterns, and Operating Emissions.

Light-duty vehicles emit ∼20% of net US greenhouse gases. Deployment of electric vehicles (EVs) can reduce these emissions. The magnitude of the reduction depends significantly on EV charging patterns and hourly power grid variations. Previous US EV studies either do not use hourly grid data, or use data from 2012 or earlier. Since 2012, US grids have undergone major emission-relevant changes, including growth of solar from ∼1 to ∼20% of generation in California, and >30% reduction of coal power countrywide. This study uses hourly grid data from 2018 and 2019 (alongside hourly charging, driving, and temperature data) to estimate EV use emissions in 60 cases spanning the US. The emission impact of charging pattern varies by region. In California and New York, respectively, overnight EV charging produces ∼70% more and ∼20% fewer emissions than daytime charging. We quantify error from two common approximations in EV emission analysis, ignoring hourly variation in grid power and ignoring temperature-driven variation in fuel economy. The combined error exceeds 10% in 30% of cases, and reaches 50% in California, home to half of US EVs. A novel EV emission approximation is introduced, validated (<1% error), and used to estimate EV emissions in future scenarios.

Electrochemical Synthesis of Polyaniline on Onion-like Carbon Nanoparticles Using the RoDSE Technique

The world's main source of energy is fossil fuels, but fossil fuels are finite resources and can also irreparably harm the environment. According to the United States Energy Information Administration, the burning of fossil fuels was responsible for 76 percent of the US greenhouse gas emissions. Fossil fuels not only pollute the environment, but also affect human health. My research focuses on making a catalyst that is economical, efficient and above all friendly to the environment. The oxygen reduction reaction is an important reaction for energy conversion systems, such as fuel cells. The fuel cells generate electricity directly by electrochemically reducing oxygen and oxidizing fuel in water as the only by-product. Onion-like carbon (OLC) are used as a catalytic support for fuel cell applications due to their high conductivity and high surface-to-volume ratio. The combination of carbon compounds with conductive polymers results in new materials and devices with possible practical applications. In recent decades, several studies have been conducted on nitrogen doped structures in carbon materials for the oxygen reduction reaction. In my research we obtain OLC from nanodiamonds (ND) through a pyrolysis process. After this process, we oxidize the OLCs using sulfuric acid and potassium permanganate. These particles are then polymerized using the aniline and pyrrole monomers to dope the OLCs with nitrogen. These particles are characterized using the following techniques, Raman, Fourier-transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS), X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). After characterizing them, the oxygen reduction reaction experiments are carried out. In the Raman, the characteristic bands of carbon materials were obtained, the D, G and double D bands. In the FTIR, vibrations of the C-N bonds were obtained at 1299 cm-1. In future works we will be adding to the particles nonprecious metals like cobalt and iron for oxygen reduction reaction, and characterize this samples using synchrotron techniques.

Natural Gas Gathering and Boosting Stations Are Ripe for Mitigation of Emissions

As an operator of 30,000 miles of natural gas pipeline systems, including gathering and boosting (G&amp;B) facilities, Williams is taking steps to further mitigate greenhouse gas (GHG) associated with its operations (see sidebar). The US Environmental Protection Agency (EPA) compiled data for GHG quantities as metric tons of CO2 equivalent (CO2e) based on self-reported data from the facilities as of 4 August 2019. Among the results are 13 of Williams’ onshore gathering and boosting facilities (Table 1). While this is a snapshot of one segment of a company’s operations, it illustrates the importance of mitigation throughout the natural gas value chain. Leak detection and equipment upgrades play a significant role in the mitigation of methane and carbon dioxide emissions. Various equipment components involved in G&amp;B systems such as compressors, tanks, dehydrators, acid-gas-removal units, separators, and yard piping are recognized emitters. An EPA report issued in April, Inventory of US Greenhouse Gas Emissions and Sinks 1990-2018, (https://www. epa.gov/sites/production/files/2020-04/documents/us-ghg-inventory-2020- main-text.pdf) identified the sources of GHG emissions from G&amp;B systems as the G&amp;B stations and gathering pipelines. G&amp;B stations receive natural gas from production sites and transfer it via gathering pipelines to transmission pipelines or processing facilities. Boosting processes include compression, dehydration, and transport of gas to a processing facility or pipeline. The EPA identified five major segments of the natural gas system: exploration, production (including G&amp;B), processing, transmission and storage, and distribution. It categorized “production” as beginning at the withdrawing of raw gas at the wellsite. Emissions arise from the wells themselves and from wellsite equipment and activities such as pneumatic controllers, tanks and separators, and liquids unloading. The EPA included G&amp;B emission sources within the production sector. In 2018, emissions from production (including G&amp;B) accounted for 58% of methane emissions and 27% of carbon dioxide emissions from natural gas systems. Within the production data, G&amp;B sources took the top position for the most emissions in several categories.

The greenhouse gas effects of increased US oil and gas production

Increased oil and natural gas production in the United States has decreased domestic natural gas prices and global oil prices. The resulting greenhouse gas (GHG) impacts have received substantial attention, with most focus on natural gas and relatively little on oil. In this paper, I provide an estimate of how increased production affects these emissions through changes in the US energy mix, methane emissions, and—crucially—global oil prices. Under a high oil and gas production scenario, US GHG emissions in 2030 are 100–600 million metric tons of carbon dioxide equivalent (2–10%) higher than under a low production scenario. Under the high production scenario, lower global oil prices and increased consumption raise non-US carbon dioxide emissions by 450–900 million metric tons relative to a low production scenario in 2030. These estimates assume that OPEC does not strategically reduce production to offset U.S. gains.

The Climate-Smart Emergency Department: A Primer

Climate change and environmental pollution from health care present urgent, complex challenges. The US health care sector produces 10% of total US greenhouse gas emissions, which have negative influences on human and environmental health. The emergency department (ED) is an important place in the hospital to become more environmentally responsible and "climate smart," a term referring to the combination of low-carbon and resilient health care strategies. Our intent is to educate and motivate emergency providers to action by providing a guide to sustainable health care and an approach to creating a climate-smart ED.

Carbon-Equivalent Taxes on US Meat

Almost 6 percent of US greenhouse gas emissions come from methane and nitrous oxide in the livestock sector. This study calculates carbon-equivalent consumption taxes for beef, milk, pork and chicken that could accompany fossil-fuel taxes or regulations in the rest of the economy. Beef production is much more emissions-intensive than that of pork or chicken. At a social cost of carbon dioxide of $75 per ton, the carbon-equivalent tax would be about 20 percent on beef, 4 percent on milk, and about 3 percent on pork and chicken. Compensation to low-income households would be appropriate, as would partial exemption for certified farms and ranches once low-emission feeding and genetic techniques become clearer or widespread testing of animals for enteric methane becomes feasible.

Have greenhouse gas emissions from US energy production peaked? State level evidence from six subsectors

Analyses of the Environmental Kuznet’s Curve (EKC) hypothesis have largely focused on economy level data with occasional analyses exploring sector level data. This paper exploits a new data set which contains sector level data on greenhouse gas emissions from the US energy sector as well as subsector data from six disjoint subsectors which together comprise the entire energy sector. The data contained in this data set is annual data at the state level from 1990 through 2011. Using differenced data, we specify an econometrically sound EKC model and compare it against a model containing only a linear GDP per capita term. We find that using a subsector level modeling approach, evidence for the EKC hypothesis is virtually nonexistent. Moreover, we find that aggregated subsector level estimates outperform sector-level estimate on in-sample accuracy. These estimated models are then used to forecast emissions for the energy sector. We find evidence that US greenhouse gas emissions from energy production are at or near a peak.

Trade groups under climate pressure

The French oil and gas firm Total says it will leave the American Fuel & Petrochemical Manufacturers because the trade association is not aligned with Total’s policies on climate change. The move follows a similar announcement by Shell, which said in April it would leave the group in 2020. Unlike the trade group, Total and Shell say they support the goals of the 2015 Paris climate agreement, as well as policies that support a price on carbon and investment in low-carbon technologies. Total says it may also pull out of other trade groups, including the American Chemistry Council, that have only “partial alignment” with the firm’s policies. The ACC’s climate policy principles do not mention the Paris Agreement or explicitly support a price on carbon. The group’s policy document calls for meaningful reduction in US greenhouse gas emissions “while minimizing the costs to society.” It also says policy should focus

Addressing the health, safety, welfare, and dignity of all humans: PAs and climate change.

Addressing the health, safety, welfare, and dignity of all humans: PAs and climate change.

Where should we apply biochar?

The heating of biomass under low-oxygen conditions generates three co-products, bio-oil, biogas, and biochar. Bio-oil can be stabilized and used as fuel oil or be further refined for various applications and biogas can be used as an energy source during the low-oxygen heating process. Biochar can be used to sequester carbon in soil and has the potential to increase crop yields when it is used to improve yield-limiting soil properties. Complex bio-physical interactions have made it challenging to answer the question of where biochar should be applied for the maximum agronomic and economic benefits. We address this challenge by developing an extensive informatics workflow for processing and analyzing crop yield response data as well as a large spatial-scale modeling platform. We use a probabilistic graphical model to study the relationships between soil and biochar variables and predict the probability and magnitude of crop yield response to biochar application. Our results show an average increase in crop yields ranging from 4.7% to 6.4% depending on the biochar feedstock and application rate. Expected yield increases of at least 6.1% and 8.8% are necessary to cover 25% and 10% of US cropland with biochar. We find that biochar application to crop area with an expected yield increase of at least 5.3%–5.9% would result in carbon sequestration offsetting 0.57%–0.67% of US greenhouse gas emissions. Applying biochar to corn area is the most profitable from a revenue perspective when compared to soybeans and wheat because additional revenues accrued by farmers are not enough to cover the costs of biochar applications in many regions of the United States.

Nitrous Oxide Emissions from Annual and Perennial Biofuel Cropping Systems

Core Ideas A majority (40–80%) of N2O was emitted in the first 10 wk of the growing season. No consistent significant differences were found in N2O emissions among crops. Most N2O was emitted during large events of short duration after substantial rainfall. Burning of fossil fuels in the transportation sector accounts for 28% of US greenhouse gas (GHG) emissions. Substitution of cellulosic biofuel in place of conventional gasoline or diesel could reduce GHG emissions from transportation; however, the effectiveness of cellulosic biofuel in reducing emissions depends on emissions during the growth of biofuel crops. The objectives of this study were (i) to measure N2O emissions of potential cellulosic biofuel cropping systems, and (ii) to characterize the temporal variations in N2O emissions in these cropping systems. Annual N2O emissions were measured in corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] and photoperiod‐sensitive sorghum [Sorghum bicolor (L.) Moench]–soybean rotations as well as in switchgrass (Panicum virgatum L.) and miscanthus (Miscanthus sacchariflorus) from 2011–2013 in Manhattan, KS, using static chambers. No consistent significant differences were found in N2O emissions among crop species, though miscanthus tended to have the least emissions. Most N2O was emitted during large events of short duration (1–3 d) that occurred after substantial rainfall events with high soil NO3−. In 2011 and 2012, most N2O was emitted during the growing season. In 2013, 30–50% of the N2O emissions were emitted after September which was attributed to freeze–thaw cycles.

Two birds, one stone? Local pollution regulation and greenhouse gas emissions

In most countries, environmental regulation focuses on local pollution, which causes damages near the emission source, while regulation on global pollutants such as greenhouse gases (GHGs) has been slow. Theoretically, local and global pollutants can either be substitutes or complements in production. A firm's response to local pollution regulation can lead greenhouse gas emissions to decrease if the firm switches energy source from oil to natural gas, or to increase if it reduces the temperature of a natural gas-fired boiler, which causes NOx emissions to fall but CO2 emissions to rise. Consequently, local pollution regulation may either intensify or reduce global warming concerns. We exploit new data on US GHG emissions and variation in local pollution regulation across US counties to estimate this relationship. We find no evidence that more stringent local pollution regulation changes GHG emissions from the non-energy sectors. The lack of a statistically detectable effect cannot be explained by a decrease in production or by firms switching production to less regulated countries, and it is true on aggregate as well as for individual polluting industries, though in some instances the coefficients are not precisely estimated. Therefore, local pollution regulation is unlikely to suffice to address global warming.

Impact of convenient away-from-home charging infrastructure

This work uses market analysis and simulation to explore the potential impact of workplace and similarly convenient away-from-home charging infrastructure (CAFHCI) in reducing US light duty vehicle (LDV) petroleum use and greenhouse gas emissions. The ParaChoice model simulates the evolution of LDV sales, fuel use, and emissions through 2050, considering consumer responses to different options of electric range extension made available through CAFHCI, fraction of the population with access, and delay in infrastructure implementation. Results indicate that providing a greater fraction of the population access to CAFHCI at level 1 charging rates for a full workday (∼16–20 miles of range extension) may lead to more petroleum use reduction than providing level 2 charging to a lesser fraction. This result holds even considering the fraction of the population without at-home charging. 2050 battery electric vehicle sales increase 40% (85%) if the entire population is guaranteed daily access to one full workday of level 1 CAFHCI (half a workday of level 2, ∼80 miles of range extension). Plug-in hybrid sales increase when CAFHCI enables range extension below 20–40 miles/day, most significantly in households without at-home charging capability. Faster CAFHCI may decrease plug-in hybrid sales as less expensive BEVs become attractive to a greater fraction of the market.

US greenhouse gas emissions declined in 2016

US greenhouse gas emissions declined in 2016

Co-emission and welfare effects of electricity policy and market changes: Results from the EMF 32 model intercomparison project

From the simulation results of the Energy Modeling Forum's recently completed project on US greenhouse gas emission mitigation policies, this paper estimates and examines welfare effects of carbon dioxide (CO2) pricing policies, fuel and technology cost changes, higher electricity demand growth, and limited nuclear generator lifetimes. Eight of the models in the study reported outputs sufficient to estimate damage from CO2, sulfur dioxide (SO2), nitrogen oxides (NOX), and methane, and three of those eight reported outputs sufficient to calculate consumer surplus, supplier profit, government revenue, and therefore total social surplus. Over approximately thirty years, the four CO2 tax policies reduce emissions enough to reduce estimated CO2 damage by $1 to $1.5 trillion, SO2 damage by $1 to $1.3 trillion, and NOX and methane damage by smaller amounts, based on averaging the results from the relevant models. The estimated non-environmental social surplus cost of each of these policies is between 23% and 29% of its environmental benefit. The CO2 cap-and-trade scenario, modeled after the Clean Power Plan, reduces estimated CO2 damage and other emission damage each by $0.4 trillion, at a non-environmental social surplus cost estimated to be 17% of the environmental benefit. Changing the natural gas price changes SO2 damage more than twice as much as it changes CO2 damage. Estimated methane emissions move in the same direction as CO2 emissions in every scenario other than the low natural gas price scenario, in which the methane increase counteracts an estimated 27% of the benefit from the CO2 reduction but only 5% of the total net benefit. In addition, the paper explains the set of assumptions and methods used to estimate environmental damage, and briefly explains how the non-environmental parts of total social surplus can sometimes be computed from more common results if necessary.

Reforestation can sequester two petagrams of carbon in US topsoils in a century

Soils are Earth's largest terrestrial carbon (C) pool, and their responsiveness to land use and management make them appealing targets for strategies to enhance C sequestration. Numerous studies have identified practices that increase soil C, but their inferences are often based on limited data extrapolated over large areas. Here, we combine 15,000 observations from two national-level databases with remote sensing information to address the impacts of reforestation on the sequestration of C in topsoils (uppermost mineral soil horizons). We quantify C stocks in cultivated, reforesting, and natural forest topsoils; rates of C accumulation in reforesting topsoils; and their contribution to the US forest C sink. Our results indicate that reforestation increases topsoil C storage, and that reforesting lands, currently occupying >500,000 km2 in the United States, will sequester a cumulative 1.3-2.1 Pg C within a century (13-21 Tg C·y-1). Annually, these C gains constitute 10% of the US forest sector C sink and offset 1% of all US greenhouse gas emissions.

A Land Use and Resource Allocation (LURA) modeling system for projecting localized forest CO2 effects of alternative macroeconomic futures

The United States has recently set ambitious national goals for greenhouse gas (GHG) reductions over the coming decades. A portion of these reductions are based on expected sequestration and storage contributions from land use, land use change, and forestry (LULUCF). Significant uncertainty exists in future forest markets and thus the potential LULUCF contribution to US GHG reduction goals. This study seeks to inform the discussion by modeling US forest GHG accounts per different simulated demand scenarios across a grid of over 130,000 USDA Forest Service Forest Inventory and Analysis (FIA) forestland plots over the conterminous United States. This spatially disaggregated future supply is based on empirical yield functions for log volume, biomass and carbon. Demand data is based on a spatial database of over 2300 forest product manufacturing facilities representing 11 intermediate and 13 final solid and pulpwood products. Transportation costs are derived from fuel prices and the locations of FIA plot from which a log is harvested and mill or port destination. Trade between mills in intermediate products such as sawmill residues or planer shavings is also captured within the model formulation. The resulting partial spatial equilibrium model of the US forest sector is solved annually for the period 2015–2035 with demand shifted by energy prices and macroeconomic indicators from the US EIA's Annual Energy Outlook for a Reference, Low Economic Growth, and High Economic Growth case. For each macroeconomic scenario simulated, figures showing historic and scenario-specific live tree carnon emissions and sequestration are generated. Maps of the spatial allocation of both forest harvesting and related carbon fluxes are presented at the National level and detail is given for both regions and ownerships.

Landfill gas-powered atmospheric water harvesting for oilfield operations in the United States

Landfill gas accounts for 18% of US greenhouse gas emissions. The energy wasted via venting/flaring methane in landfill gas can be valued at 7.5 billion USD (annually). This work presents a novel utilization concept, wherein landfill gas-powered refrigeration enables large-scale atmospheric water harvesting, via dehumidification. This work analyzes the potential of landfill gas-powered atmospheric water harvesting towards meeting the water requirements of oilfields located near landfills. Heat and mass transfer-based analytical modeling is used to estimate the seasonal water harvest, and techno-economic analyses are presented to quantify the benefits for US oilfields. This technology is seen to be attractive for the Barnett Shale (Texas) and Kern County (California), which can be served by 30 landfills each, and are located in hot-humid and water-stressed areas. Results show that landfill gas-powered water harvesting can meet 34% of water requirements (hydraulic fracturing) in the Barnett Shale and 12–26% of water requirements (enhanced oil recovery) in Kern County oilfields, respectively. Landfill gas projects are economically more viable in the Barnett as compared to Kern County. The impact of landfill gas-powered water harvesting on CO2e emissions from landfills is quantified. Constraints and challenges associated with water harvesting are discussed. Importantly, this waste-to-value concept has worldwide relevance since landfills co-exist with population centers.

Infrastructure, Social Practice, and Environmentalism: The Case of Bicycle-Commuting

Automobile travel is a major contributor to US greenhouse gas emissions. Reducing car travel could slow climate change, but this goal is made difficult by the constellation of economic, political, cultural, and infrastructural forces that form a mutually reinforcing “system of automobility.” This complexity suggests the need for an approach that attends to both the reciprocal relationship between infrastructure and practice and the moderating influence of cultural factors, but policies to encourage sustainable practices rely on asocial conceptions of behavior. With longitudinal data on bicycle-commuting in sixty-two large US cities from 2000 to 2014, I use fixed-effects regression and structural equation modeling to perform two strong tests of whether the expansion of bikeway facilities induces more bicycling, and whether this effect depends on the strength of environmentalism in a city. I also use structural equation modeling to perform a preliminary test of the reverse causal effect—whether bicycle-commuting can spur bikeway creation, again allowing for a moderating effect of environmentalism. My results add to existing evidence that bikeways induce bicycling, and provide preliminary support for the reverse effect, but also indicate that both effects are moderated by local environmentalism. Implications for the persistence of auto-dominance are discussed.

Gridded National Inventory of U.S. Methane Emissions.

We present a gridded inventory of US anthropogenic methane emissions with 0.1° × 0.1° spatial resolution, monthly temporal resolution, and detailed scale-dependent error characterization. The inventory is designed to be consistent with the 2016 US Environmental Protection Agency (EPA) Inventory of US Greenhouse Gas Emissions and Sinks (GHGI) for 2012. The EPA inventory is available only as national totals for different source types. We use a wide range of databases at the state, county, local, and point source level to disaggregate the inventory and allocate the spatial and temporal distribution of emissions for individual source types. Results show large differences with the EDGAR v4.2 global gridded inventory commonly used as a priori estimate in inversions of atmospheric methane observations. We derive grid-dependent error statistics for individual source types from comparison with the Environmental Defense Fund (EDF) regional inventory for Northeast Texas. These error statistics are independently verified by comparison with the California Greenhouse Gas Emissions Measurement (CALGEM) grid-resolved emission inventory. Our gridded, time-resolved inventory provides an improved basis for inversion of atmospheric methane observations to estimate US methane emissions and interpret the results in terms of the underlying processes.