Robin Newmark

Operational water consumption and withdrawal factors for electricity generating technologies: a review of existing literature

This report provides estimates of operational water withdrawal and water consumption factors for electricity generating technologies in the United States. Estimates of water factors were collected from published primary literature and were not modified except for unit conversions. The water factors presented may be useful in modeling and policy analyses where reliable power plant level data are not available. Major findings of the report include: water withdrawal and consumption factors vary greatly across and within fuel technologies, and water factors show greater agreement when organized according to cooling technologies as opposed to fuel technologies; a transition to a less carbon-intensive electricity sector could result in either an increase or a decrease in water use, depending on the choice of technologies and cooling systems employed; concentrating solar power technologies and coal facilities with carbon capture and sequestration capabilities have the highest water consumption values when using a recirculating cooling system; and non-thermal renewables, such as photovoltaics and wind, have the lowest water consumption factors. Improved power plant data and further studies into the water requirements of energy technologies in different climatic regions would facilitate greater resolution in analyses of water impacts of future energy and economic scenarios. This report provides the foundation for conducting water use impact assessments of the power sector while also identifying gaps in data that could guide future research.

Review of Operational Water Consumption and Withdrawal Factors for Electricity Generating Technologies

Various studies have attempted to consolidate published estimates of water use impacts of electricity generating technologies, resulting in a wide range of technologies and values based on different primary sources of literature. The goal of this work is to consolidate the various primary literature estimates of water use during the generation of electricity by conventional and renewable electricity generating technologies in the United States to more completely convey the variability and uncertainty associated with water use in electricity generating technologies.

Water use for electricity in the United States: an analysis of reported and calculated water use information for 2008

Water use by the electricity sector represents a significant portion of the United States water budget (41% of total freshwater withdrawals; 3% consumed). Sustainable management of water resources necessitates an accurate accounting of all water demands, including water use for generation of electricity. Since 1985, the Department of Energy (DOE) Energy Information Administration (EIA) has collected self-reported data on water consumption and withdrawals from individual power generators. These data represent the only annual collection of water consumption and withdrawals by the electricity sector. Here, we compile publically available information into a comprehensive database and then calculate water withdrawals and consumptive use for power plants in the US. In effect, we evaluate the quality of water use data reported by EIA for the year 2008. Significant differences between reported and calculated water data are evident, yet no consistent reason for the discrepancies emerges.

Monitoring Carbon Dioxide Floods Using Electrical Resistance Tomography (ERT): Sensitivity Studies

We have conducted a numerical and physical modeling study to evaluate the sensitivity of electrical resistance tomography (ERT) to electrical resistivity changes caused by CO2 injection and sequestration in geologic reservoirs. We chose the Maljamar CO2 flood (pilot study) as a basis for our numerical modeling study. We also constructed physical models consisting of blocks of various materials inserted in a water tank to evaluate some of the conclusions of the numerical study. This study quantifies the effects of a variety of factors that affect the resolution and accuracy of the ERT method, under realistic conditions of scale, contrast, and measurement error. It considers scenarios where vertical arrays of point electrodes are used and where metal-cased boreholes are used as long electrodes. Long electrode tomographs provide information such as the shape, location, and lateral extent of the flood. When point electrode arrays or horizontal wells are available, the approximate vertical extent of the flood ...

Water Challenges for Geologic Carbon Capture and Sequestration

Carbon capture and sequestration (CCS) has been proposed as a means to dramatically reduce greenhouse gas emissions with the continued use of fossil fuels. For geologic sequestration, the carbon dioxide is captured from large point sources (e.g., power plants or other industrial sources), transported to the injection site and injected into deep geological formations for storage. This will produce new water challenges, such as the amount of water used in energy resource development and utilization and the “capture penalty” for water use. At depth, brine displacement within formations, storage reservoir pressure increases resulting from injection, and leakage are potential concerns. Potential impacts range from increasing water demand for capture to contamination of groundwater through leakage or brine displacement. Understanding these potential impacts and the conditions under which they arise informs the design and implementation of appropriate monitoring and controls, important both for assurance of environmental safety and for accounting purposes. Potential benefits also exist, such as co-production and treatment of water to both offset reservoir pressure increase and to provide local water for beneficial use.

Electrical Resistance Tomography for Steam Injection Monitoring and Process Control

We used electrical resistance tomography (ERT) to map, in near‐real time, the subsurface effects of two in situ thermal treatment processes: steam injection and ohmic heating. These effects were monitored at a gasoline‐contaminated site as part of a demonstration of an environmental restoration process known as Dynamic Underground Stripping. ERT uses a dipole‐dipole measurement technique to measure the bulk electrical resistivity distribution in the soil mass. We detected the effects of steam invasion and ohmic heating by mapping spatial and temporal changes in soil resistivity. During steam injection, there sistivity changes in the saturated zone were caused primarily by increases in pore water and soil temperatures, and to a lesser extent by changes in liquid saturation and groundwater electrical conductivity. During ohmic heating, the resistivity changes were caused by temperature increases, liquid saturation changes, and changes in the groundwaters electrical conductivity. This test demonstrated that...

Monitoring DNAPL Pumping Using Integrated Geophysical Techniques

The removal of DNAPL during pumping has been monitored using integrated in situ geophysical techniques. At Hill Air Force Base in Utah, a free‐product DNAPL plume (consisting predominantly of TCE) is pooled in water‐wet soil on a thick clay aquitard. Groundwater pumping at Operable Unit 2 (OU 2) began in 1994; to date, over 30,000 gallons of DNAPL have been recovered from the site. From September, 1994 through September, 1995, changes in the basin during DNAPL pumping were monitored using fiber optic chemical sensors, neutron logs and electrical resistance tomography (ERT). Fiber optic sensors and neutron logs verify the presence of DNAPL in the vicinity of three boreholes which form a cross section from the perimeter of the basin to its center. Cross borehole ERT images the changes in formation electrical properties due to the removal of DNAPL, extending the understanding of DNAPL removal between the boreholes. During pumping, electrical resistivities decreased; we suggest that these decreases are direct...

Imaging UXO Using Electrical Impedance Tomography

This paper reports the results of tests where electrical impedance tomography (EIT) was evaluated as a tool for detecting and locating buried unexploded ordnance (UXO). The method relies on the electrolytic polarization induced at the boundary between soil and buried metal. This induced polarization (IP) produces a measurable phase delay between the electric current imposed on the subsurface and the resulting voltage distribution. If natural sources of induced polarization are small compared to those due to buried metal objects, then tomographs of impedance phase may be used to indicate where metal-soil polarization may be present. Three controlled tests were performed at a field site containing inert UXO buried in known locations. These tests produced a phase anomaly of about 20 milliradians that closely matched the known location of buried UXO objects. A fourth uncontrolled or blind test was performed under a building without prior knowledge of UXO presence. That test yielded phase anomalies as high as 75 milliradians. Limited excavation was performed at some of these anomalies but only a small amount (a few tens of grams) of metal was recovered. More extensive excavations are too costly until the building is razed. BACKGROUND Locating UXO is a partially solved problem, meaning that many solutions exist but none work universally. UXO is typically detected using magnetometers, metal detectors, ground penetrating radar or controlled source electromagnetic induction. Except for the radar, these techniques provide little information regarding the depth of burial of potential targets and are sensitive to cultural artifacts such as metal fences, power lines or buildings. Factors that affect performance of traditional methods include soil moisture content, depth of burial or non-metallic targets. In some cases, the soil itself generates signals that can confuse the diagnostic method and data interpretation.

Water Constraints in an Electric Sector Capacity Expansion Model

This analysis provides a description of the first U.S. national electricity capacity expansion model to incorporate water resource availability and costs as a constraint for the future development of the electricity sector. The Regional Energy Deployment System (ReEDS) model was modified to incorporate water resource availability constraints and costs in each of its 134 Balancing Area (BA) regions along with differences in costs and efficiencies of cooling systems. Water resource availability and cost data are from recently completed research at Sandia National Laboratories (Tidwell et al. 2013b). Scenarios analyzed include a business-as-usual 3 This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. scenario without water constraints as well as four scenarios that include water constraints and allow for different cooling systems and types of water resources to be utilized. This analysis provides insight into where water resource constraints could affect the choice, configuration, or location of new electricity technologies.

Vulnerabilities and opportunities at the nexus of electricity, water and climate

The articles in this special issue examine the critical nexus of electricity, water, and climate, emphasizing connections among resources; the prospect of increasing vulnerabilities of water resources and electricity generation in a changing climate; and the opportunities for research to inform integrated energy and water policy and management measures aimed at reducing vulnerability and increasing resilience. Here, we characterize several major themes emerging from this research and highlight some of the uptake of this work in both scientific and public spheres. Underpinning much of this research is the recognition that water resources are expected to undergo substantial changes based on the global warming that results primarily from fossil energy-based carbon emissions. At the same time, the production of electricity from fossil fuels, nuclear power, and some renewable technologies (biomass, geothermal and concentrating solar power) can be highly water-intensive. Energy choices now and in the near future will have a major impact not just on the global climate, but also on water supplies and the resilience of energy systems that currently depend heavily on them.