Tracking emissions in the US electricity system.

Understanding electricity consumption and production patterns is a necessary first step toward reducing the health and climate impacts of associated emissions. In this work, the economic input-output model is adapted to track emissions flows through electric grids and quantify the pollution embodied in electricity production, exchanges, and, ultimately, consumption for the 66 continental US Balancing Authorities (BAs). The hourly and BA-level dataset we generate and release leverages multiple publicly available datasets for the year 2016. Our analysis demonstrates the importance of considering location and temporal effects as well as electricity exchanges in estimating emissions footprints. While increasing electricity exchanges makes the integration of renewable electricity easier, importing electricity may also run counter to climate-change goals, and citizens in regions exporting electricity from high-emission-generating sources bear a disproportionate air-pollution burden. For example, 40% of the carbon emissions related to electricity consumption in California's main BA were produced in a different region. From 30 to 50% of the sulfur dioxide and nitrogen oxides released in some of the coal-heavy Rocky Mountain regions were related to electricity produced that was then exported. Whether for policymakers designing energy efficiency and renewable programs, regulators enforcing emissions standards, or large electricity consumers greening their supply, greater resolution is needed for electric-sector emissions indices to evaluate progress against current and future goals.

Geospatial analysis of near-term potential for carbon-negative bioenergy in the United States.

Bioenergy with carbon capture and storage (BECCS) is a negative-emissions technology that may play a crucial role in climate change mitigation. BECCS relies on the capture and sequestration of carbon dioxide (CO2) following bioenergy production to remove and reliably sequester atmospheric CO2 Previous BECCS deployment assessments have largely overlooked the potential lack of spatial colocation of suitable storage basins and biomass availability, in the absence of long-distance biomass and CO2 transport. These conditions could constrain the near-term technical deployment potential of BECCS due to social and economic barriers that exist for biomass and CO2 transport. This study leverages biomass production data and site-specific injection and storage capacity estimates at high spatial resolution to assess the near-term deployment opportunities for BECCS in the United States. If the total biomass resource available in the United States was mobilized for BECCS, an estimated 370 Mt CO2⋅y-1 of negative emissions could be supplied in 2020. However, the absence of long-distance biomass and CO2 transport, as well as limitations imposed by unsuitable regional storage and injection capacities, collectively decrease the technical potential of negative emissions to 100 Mt CO2⋅y-1 Meeting this technical potential may require large-scale deployment of BECCS technology in more than 1,000 counties, as well as widespread deployment of dedicated energy crops. Specifically, the Illinois basin, Gulf region, and western North Dakota have the greatest potential for near-term BECCS deployment. High-resolution spatial assessment as conducted in this study can inform near-term opportunities that minimize social and economic barriers to BECCS deployment.

Registration of the rotation axis in X-ray tomography.

There is high demand for efficient, robust and automated routines for tomographic data reduction, particularly for synchrotron data. Registration of the rotation axis in data processing is a critical step affecting the quality of the reconstruction and is not easily implemented with automation. Existing methods for calculating the center of rotation have been reviewed and an improved algorithm to register the rotation axis in tomographic data is presented. The performance of the proposed method is evaluated using synchrotron-based microtomography data on geological samples with and without artificial reduction of the signal-to-noise ratio. The proposed method improves the reconstruction quality by correcting both the tilting error and the translational offset of the rotation axis. The limitation of this promising method is also discussed.

Energy balance of the global photovoltaic (PV) industry--is the PV industry a net electricity producer?

A combination of declining costs and policy measures motivated by greenhouse gas (GHG) emissions reduction and energy security have driven rapid growth in the global installed capacity of solar photovoltaics (PV). This paper develops a number of unique data sets, namely the following: calculation of distribution of global capacity factor for PV deployment; meta-analysis of energy consumption in PV system manufacture and deployment; and documentation of reduction in energetic costs of PV system production. These data are used as input into a new net energy analysis of the global PV industry, as opposed to device level analysis. In addition, the paper introduces a new concept: a model tracking energetic costs of manufacturing and installing PV systems, including balance of system (BOS) components. The model is used to forecast electrical energy requirements to scale up the PV industry and determine the electricity balance of the global PV industry to 2020. Results suggest that the industry was a net consumer of electricity as recently as 2010. However, there is a >50% that in 2012 the PV industry is a net electricity provider and will "pay back" the electrical energy required for its early growth before 2020. Further reducing energetic costs of PV deployment will enable more rapid growth of the PV industry. There is also great potential to increase the capacity factor of PV deployment. These conclusions have a number of implications for R&D and deployment, including the following: monitoring of the energy embodied within PV systems; designing more efficient and durable systems; and deploying PV systems in locations that will achieve high capacity factors.

Real-time tracking of CO2 injected into a subsurface coal fire through high-frequency measurements of the ¹³CO2 signature.

CO2 was injected into a coal fire burning at a depth of 15 m in the subsurface in southwestern Colorado, USA. Measurements were made of the ¹³CO2 isotopic signature of gas exhaust from an observation well and two surface fissures. The goal of the test was to determine (1) whether CO2 with a distinct isotopic signature could be used as a tracer to identify flow pathways and travel times in a combustion setting where CO2 was present in significant quantities in the gases being emitted from the coalbed fire, and (2) to confirm the existence of a self-propagating system of air-intake and combustion gas exhaust that has been previously proposed. CO2 was injected in three separate periods. The ¹³CO2 isotopic signature was measured at high frequency (0.5 Hz) before, during, and after the injection periods for gas flowing from fissures over the fire and from gas entering an observation well drilled into the formation just above the fire but near the combustion zone. In two cases, a shift in the isotopic signature of outgassing CO2 provided clear evidence that injected CO2 had traveled from the injection well to the observation point, while in a third case, no response was seen and the fissure could not be assumed to have a flowpath connected with the injection well. High-frequency measurements of the ¹³CO2 signature of gas in observation wells is identified as a viable technique for tracking CO2 injected into subsurface formations in real-time. In addition, a chimney-like coupled air-intake and exhaust outlet system feeding the combustion of the coal seam was confirmed. This can be used to further develop strategies for extinguishing the fire.

Coreflooding data on nine sandstone cores to measure CO2 residual trapping.

This data article provides detailed explanation and data on CO2/water coreflooding experiments performed on nine sandstone rock cores. Refer to the research article "Predicting CO2 Residual Trapping Ability Based on Experimental Petrophysical Properties for Different Sandstone Types" [1] for data interpretation. The reader can expect to find experimental conditions including temperature, pressure, fluid pair types, as well as flow rates. Furthermore, the raw CT images and the processed three-dimensional (3D) voxel-level porosity, permeability, and CO2 saturation maps for each of the nine sandstone samples are also supplied.

Net-zero emissions energy systems.

Some energy services and industrial processes-such as long-distance freight transport, air travel, highly reliable electricity, and steel and cement manufacturing-are particularly difficult to provide without adding carbon dioxide (CO2) to the atmosphere. Rapidly growing demand for these services, combined with long lead times for technology development and long lifetimes of energy infrastructure, make decarbonization of these services both essential and urgent. We examine barriers and opportunities associated with these difficult-to-decarbonize services and processes, including possible technological solutions and research and development priorities. A range of existing technologies could meet future demands for these services and processes without net addition of CO2 to the atmosphere, but their use may depend on a combination of cost reductions via research and innovation, as well as coordinated deployment and integration of operations across currently discrete energy industries.

Extraction of pore-morphology and capillary pressure curves of porous media from synchrotron-based tomography data.

The elevated level of atmospheric carbon dioxide (CO2) has caused serious concern of the progression of global warming. Geological sequestration is considered as one of the most promising techniques for mitigating the damaging effect of global climate change. Investigations over wide range of length-scales are important for systematic evaluation of the underground formations from prospective CO2 reservoir. Understanding the relationship between the micro morphology and the observed macro phenomena is even more crucial. Here we show Synchrotron based X-ray micro tomographic study of the morphological buildup of Sandstones. We present a numerical method to extract the pore sizes distribution of the porous structure directly, without approximation or complex calculation. We have also demonstrated its capability in predicting the capillary pressure curve in a mercury intrusion porosimetry (MIP) measurement. The method presented in this work can be directly applied to the morphological studies of heterogeneous systems in various research fields, ranging from Carbon Capture and Storage, and Enhanced Oil Recovery to environmental remediation in the vadose zone.

Selenium speciation, solubility, and mobility in land-disposed dredged sediments.

Pilot-scale tests for the land disposal of Se-enriched sediments from the San Luis Drain were performed in the San Joaquin Valley, California. Three test plots were instrumented and monitored on a dirt-road embankment near the sediment source area, providing an opportunity to measure Se oxidation and solubilization rates over a period of 2-3 yr. Soil, soil water, and groundwater data indicated that the amendment did not cause movement of dissolved Se below a depth of 15 cm. The low permeability of underlying sediments and the overall low Se solubility limit Se movement toward the groundwater table. Selenium remained in reduced forms and largely immobile at this site, although in-situ Se oxidation was measurable. Soluble Se concentrations increased from less than 0.5% to approximately 2.5% in the first 207 d following sediment application. Minor Se solubilization occurred after 439 and 704 d. Changes in Se fractionation measured using sequential extractions and Se speciation based on X-ray spectroscopy (XANES) results were in qualitative agreement. XANES results indicated initially rapid oxidation of organo-Se and/or elemental Se to selenite during the first 207 d, followed by minor oxidation after 439 d. Further solubilization of the Se inventory is anticipated, but at a low rate of 1-2% per year, comparable to rates measured in other studies.