Modeling Ecological Constraints on a CO2 Pipeline Network.

Carbon capture, utilization, and storage (CCUS) are a critical set of strategies to decarbonize the industrial and power sectors and to mitigate global climate change. Pipeline infrastructure connecting CO2 sources and sinks, if not planned strategically, can cause environmental and social impacts by disturbing local landscapes. We investigated the impacts of these considerations on optimal CO2 pipeline routing and sink locations by modifying and leveraging an open-source CCUS infrastructure model, SimCCS. We expanded SimCCS from a cost-minimizing to a multiobjective framework, explicitly incorporating environmental protection objectives. We estimated trade-offs between private costs and environmental and social impacts. Using a version of the model focused on the southeastern United States, we modeled seven scenarios with varying weights given to environmental impacts to evaluate how the pipeline network responds to the multiobjective optimization. We found that the optimal path is sensitive to environmental and social impact considerations in that a small increase in pipeline length (and cost) significantly avoids large environmental and social impacts. We hope such a tool can be used to improve the pipeline permitting and siting processes and contribute to the achievement of decarbonization goals with minimal environmental impacts.

Energy policy and coastal water quality: An integrated energy, air and water quality modeling approach.

Federal policy changes in the management of carbon emissions from power plants offer a potent real-world example for examining air-land-water interactions and their implications for coastal water quality. We integrate models of energy (Integrated Planning Model (IPM)), air quality (Community Multiscale Air Quality (CMAQ) and water quality (SPAtially Referenced Regression On Watershed attributes (SPARROW)) to investigate the potential water quality impacts of policy-driven changes in total nitrogen deposition in watersheds draining to US coastal areas. We estimate the combined effects of three recently proposed energy policy scenarios, population growth, and climate change. We decompose the combined effects into the roles of the individual components on the supply of riverine nitrogen for the entire US and eight coastal regions. We find that population growth is the most important driver of changes in coastal nitrogen flux. Energy policies play a minor role in offsetting the negative effects of population growth, although the effect varies by energy policy and region. The greatest population and policy effects are projected for the Gulf of Mexico. Given limited reductions in nitrogen emissions and deposition associated with energy policies, the net effect of policy and population changes is an increase in total nitrogen flux to all estuaries relative to the 2010 baseline. While population growth increases flux, and energy policies decrease flux in all regions, climate change can either increase or decrease flux depending on the region. That is because the relatively large individual effects of temperature and precipitation on watershed nitrogen processes work in opposing directions. The net result of the offsetting nature of individual climate processes varies in both magnitude and direction by coastal region. Further research is needed to sort out individual temperature and precipitation effects in different regions.

Systematically Incorporating Environmental Objectives into Shale Gas Pipeline Development: A Binary Integer, Multiobjective Spatial Optimization Model.

Shale gas pipeline development can have negative environmental impacts, including adverse effects on species and ecosystems through habitat degradation and loss. From a societal perspective, pipeline development planning processes should account for such externalities. We develop a multiobjective binary integer-programming model, called the Multi Objective Pipeline Siting (MOPS) model, to incorporate habitat externalities into pipeline development and to estimate the trade-offs between pipeline development costs and habitat impacts. We demonstrate the utility of the model using an application from Bradford and Susquehanna counties in northeastern Pennsylvania. We find that significant habitat impacts can be avoided for relatively low cost, but the avoidance of the additional habitat impacts becomes gradually and increasingly costly. For example, 10% of the habitat impacts can be avoided at less than a two percent pipeline cost increase relative to a configuration that ignores habitat impacts. MOPS or a similar model could be integrated into the pipeline siting and permitting process so oil and gas companies, communities, and states can identify cost-effective options for habitat conservation near shale gas development.

Managing Environmental Liability: An Evaluation of Bonding Requirements for Oil and Gas Wells in the United States.

Inactive oil and gas wells present an environmental hazard if not properly plugged. Upon drilling a well, operators are required to post a bond, which ensures that the operator has an incentive to plug and abandon (P&A) at the end of the well's life, and that, if the state is left with the liability of managing "orphaned" wells, it can cover the cost of P&A. Using data from 13 state agencies on their orphaned well plugging expenditures, we provide new estimates of P&A costs in the United States and compare them to bond amounts. Current state bonding requirements are insufficient to cover the average P&A cost of orphan wells in 11 of these 13 states. These should be reviewed and revised where necessary. We also examine the factors influencing P&A costs using detailed data on orphaned wells in Kansas. Given the variability of P&A costs, bonds would be more effective if they varied by factors that are meaningful in explaining P&A costs, such as well depth, location, and proximity to groundwater. State regulators can use the statistical approach developed in this paper to improve bonding requirements and to better predict the P&A costs of their orphaned wells.

Spatial patterns and environmental controls of particulate organic carbon in surface waters in the conterminous United States.

Carbon cycling in inland waters has been identified as an important, but poorly constrained component of the global carbon cycle. In this study, we compile and analyze particulate organic carbon (POC) concentration data from 1145 U.S. Geological Survey (USGS) gauge stations to investigate the spatial variability and environmental controls of POC concentration. We observe substantial spatial variability in POC concentration (1.43 ± 2.56 mg C/L, mean ± one standard deviation), with the Upper Mississippi River basin and the Piedmont region in the eastern U.S. having the highest POC concentration. Further, we employ generalized linear models (GLMs) to analyze the impacts of sediment transport and algae growth as well as twenty-one other environmental factors on the POC variability. Suspended sediment and chlorophyll-a explain 26% and 17% of the variability in POC concentration, respectively. At the national level, the twenty-one environmental factors combined can explain ca. 40% of the spatial variance in POC concentration. At the national scale, urban area and soil clay content show significant negative correlations with POC concentration, whereas soil water content and soil bulk density correlate positively with POC. In addition, total phosphorus concentration and dam density correlate positively with POC concentration. Furthermore, regional scale analyses reveal substantial variation in environmental controls of POC concentration across eighteen major water resource regions in the U.S. The POC concentration and associated environmental controls also vary non-monotonically from headwaters to large rivers. These findings indicate complex interactions among multiple factors in regulating POC concentration over different spatial scales and across various sections of the river networks. This complexity, together with the large unexplained uncertainty, highlights the need for considering non-linear interplays of multiple environmental factors and developing appropriate methodologies to track the transformation and transport of POC along the terrestrial-aquatic interfaces.

Characterization and Analysis of Liquid Waste from Marcellus Shale Gas Development.

Hydraulic fracturing of shale for gas production in Pennsylvania generates large quantities of wastewater, the composition of which has been inadequately characterized. We compiled a unique data set from state-required wastewater generator reports filed in 2009-2011. The resulting data set, comprising 160 samples of flowback, produced water, and drilling wastes, analyzed for 84 different chemicals, is the most comprehensive available to date for Marcellus Shale wastewater. We analyzed the data set using the Kaplan-Meier method to deal with the high prevalence of nondetects for some analytes, and compared wastewater characteristics with permitted effluent limits and ambient monitoring limits and capacity. Major-ion concentrations suggested that most wastewater samples originated from dilution of brines, although some of our samples were more concentrated than any Marcellus brines previously reported. One problematic aspect of this wastewater was the very high concentrations of soluble constituents such as chloride, which are poorly removed by wastewater treatment plants; the vast majority of samples exceeded relevant water quality thresholds, generally by 2-3 orders of magnitude. We also examine the capacity of regional regulatory monitoring to assess and control these risks.

Shale gas development impacts on surface water quality in Pennsylvania.

Concern has been raised in the scientific literature about the environmental implications of extracting natural gas from deep shale formations, and published studies suggest that shale gas development may affect local groundwater quality. The potential for surface water quality degradation has been discussed in prior work, although no empirical analysis of this issue has been published. The potential for large-scale surface water quality degradation has affected regulatory approaches to shale gas development in some US states, despite the dearth of evidence. This paper conducts a large-scale examination of the extent to which shale gas development activities affect surface water quality. Focusing on the Marcellus Shale in Pennsylvania, we estimate the effect of shale gas wells and the release of treated shale gas waste by permitted treatment facilities on observed downstream concentrations of chloride (Cl(-)) and total suspended solids (TSS), controlling for other factors. Results suggest that (i) the treatment of shale gas waste by treatment plants in a watershed raises downstream Cl(-) concentrations but not TSS concentrations, and (ii) the presence of shale gas wells in a watershed raises downstream TSS concentrations but not Cl(-) concentrations. These results can inform future voluntary measures taken by shale gas operators and policy approaches taken by regulators to protect surface water quality as the scale of this economically important activity increases.

Accountability analysis of title IV phase 2 of the 1990 Clean Air Act Amendments.

In this study, we sought to assess what portion, if any, of the reductions in ambient concentrations of particulate matter (PM*) < or = 2.5 microm in aerodynamic diameter (PM2.5) that occurred in the United States between the years 1999 and 2006 can be attributed to reductions in emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) resulting from implementation of Phase 2 of Title IV of the 1990 Clean Air Act Amendments. To this end, a detailed statistical model linking sources and monitors over time and space was used to estimate associations between the observed emissions reductions and improvements in air quality. Overall, it turned out to be quite feasible to use relatively transparent statistical methods to assess these outcomes of the Phase 2 program, which was designed to reduce long-range transport of emissions. Associations between changes in emissions from individual power plants and monitor-specific estimates of changes in concentrations of PM2.5, our indicator pollutant, were highly significant and were mostly of the expected relative magnitudes with respect to distances and directions from sources. Originally estimated on monthly data for a set of 193 monitors between 1999 and 2005, our preferred model performed equally well using data for the same 193 monitors for 2006 as well as for an additional 217 monitors not in the original set in 2006. Although substantial model uncertainty was observed, we were able to estimate that the Title IV Phase 2 emissions reduction program implemented between 1999 and 2005 reduced PM2.5 concentrations in the eastern United States by an average of 1.07 microg/m3 (standard deviation [SD] = 0.11 microg/m3) compared with a counterfactual case defined as there having been no change in emission rates per unit of energy input (1 million British thermal units [BTUs]). On a population-weighted basis, the comparable reduction in PM2.5 was 0.89 microg/m3. Compared with the air quality fate and transport models used by the U.S. Environmental Protection Agency (EPA) to estimate air quality improvements associated with the Clean Air Interstate Rule (CAIR) for 2010 and 2015, when baseline PM2.5 concentrations were expected to be about one-third lower, our statistical model yielded roughly similar results per ton of SO2 reduced, well within the estimated confidence intervals of the models. We have proposed a number of steps to advance air quality outcomes research using statistical methods. Specifically, we have emphasized the value of updating our analysis with post-2005 data to try to corroborate our findings. We have also recommended extending the work on air quality outcomes to include changes in health outcomes that might be associated with the implementation of Title IV Phase 2.

Air emissions of ammonia and methane from livestock operations: valuation and policy options.

The animal husbandry industry is a major emitter of ammonia (NH3), which is a precursor of fine particulate matter (PM2.5)--arguably, the number-one environment-related public health threat facing the nation. The industry is also a major emitter of methane (CH4), which is an important greenhouse gas (GHG). We present an integrated process model of the engineering economics of technologies to reduce NH3 and CH4 emissions at dairy operations in California. Three policy options are explored: PM offset credits for NH3 control, GHG offset credits for CH4 control, and expanded net metering policies to provide revenue for the sale of electricity generated from captured methane (CH4) gas. Individually these policies vary substantially in the economic incentives they provide for farm operators to reduce emissions. We report on initial steps to fully develop the integrated process model that will provide guidance for policy-makers.

Regional air quality: local and interstate impacts of NO(x) and SO2 emissions on ozone and fine particulate matter in the eastern United States.

While the U.S. air quality management system is largely designed and managed on a state level, many critical air quality problems are now recognized as regional. In particular, concentrations of two secondary pollutants, ozone and particulate matter, are often above regulated levels and can be dependent on emissions from upwind states. Here, impacts of statewide emissions on concentrations of local and downwind states' ozone and fine particulate matter are simulated for three seasonal periods in the eastern United States using a regional Eulerian photochemical model. Impacts of ground level NO(x) (e.g., mobile and area sources), elevated NO(x) (e.g., power plants and large industrial sources), and SO2 emissions are examined. An average of 77% of each state's ozone and PM(2.5) concentrations that are sensitive to the emissions evaluated here are found to be caused by emissions from other states. Delaware, Maryland, New Jersey, Virginia, Kentucky, and West Virginia are shown to have high concentrations of ozone and PM(2.5) caused by interstate emissions. When weighted by population, New York receives increased interstate contributions to these pollutants and contributions to ozone from local emissions are generally higher. When accounting for emission rates, combined states from the western side of the modeling domain and individual states such as Illinois, Tennessee, Indiana, Kentucky, and Georgia are major contributors to interstate ozone. Ohio, Indiana, Tennessee, Kentucky, and Illinois are the major contributors to interstate PM(2.5). When accounting for an equivalent mass of emissions, Tennessee, Kentucky, West Virginia, Virginia, and Alabama contribute large fractions of these pollutants to other states.

The benefits and costs of reducing emissions from the electricity sector.

Recent federal policy proposals to reduce emissions of sulfur dioxide (SO(2)), nitrogen oxides (NO(x)), and mercury from the US electricity sector promise important improvements in air quality and reductions in acid deposition. The cost of achieving these reductions depends on the form and stringency of the regulation. In this research, we analyze the economic benefits and costs of the US Environmental Protection Agency's (EPA's) Clean Air Interstate Rule (CAIR) as characterized in the supplemental rule proposed in June 2004, and the Clean Air Mercury Rule (CAMR) as proposed in February 2004. The assessment integrates a model of the electricity sector, two models of atmospheric transport of air pollutants, and a model of environmental and public health endpoints affected by pollution. We model explicitly the emissions of SO(2), NO(x), mercury and carbon dioxide (CO(2)) and the effects of changes in emissions of SO(2) and NO(x) on environmental and public health. The manner in which mercury emissions are regulated will have important implications not only for the cost of the regulation, but also for emission levels for SO(2) and NO(x) and where those emissions are located. We find the economic benefits of CAIR and CAMR are far greater than the costs. Recent estimates of benefits of reductions in mercury and acidification indicate that our model captures the lion's share of quantifiable benefits. We also find that the EPA would have been justified on economic grounds in pursuing additional SO(2) emissions reductions beyond the requirements of CAIR.

Dealing with electronic waste: modeling the costs and environmental benefits of computer monitor disposal.

The importance of information technology to the world economy has brought about a surge in demand for electronic equipment. With rapid technological change, a growing fraction of the increasing stock of many types of electronics becomes obsolete each year. We model the costs and benefits of policies to manage 'e-waste' by focusing on a large component of the electronic waste stream-computer monitors-and the environmental concerns associated with disposal of the lead embodied in cathode ray tubes (CRTs) used in most monitors. We find that the benefits of avoiding health effects associated with CRT disposal appear far outweighed by the costs for a wide range of policies. For the stock of monitors disposed of in the United States in 1998, we find that policies restricting or banning some popular disposal options would increase disposal costs from about US dollar 1 per monitor to between US dollars 3 and US dollars 20 per monitor. Policies to promote a modest amount of recycling of monitor parts, including lead, can be less expensive. In all cases, however, the costs of the policies exceed the value of the avoided health effects of CRT disposal.