Kristen Averyt

The water implications of generating electricity: water use across the United States based on different electricity pathways through 2050

The power sector withdraws more freshwater annually than any other sector in the US. The current portfolio of electricity generating technologies in the US has highly regionalized and technology-specific requirements for water. Water availability differs widely throughout the nation. As a result, assessments of water impacts from the power sector must have a high geographic resolution and consider regional, basin-level differences. The US electricity portfolio is expected to evolve in coming years, shaped by various policy and economic drivers on the international, national and regional level; that evolution will impact power sector water demands. Analysis of future electricity scenarios that incorporate technology options and constraints can provide useful insights about water impacts related to changes to the technology mix. Utilizing outputs from the regional energy deployment system (ReEDS) model, a national electricity sector capacity expansion model with high geographical resolution, we explore potential changes in water use by the US electric sector over the next four decades under various low carbon energy scenarios, nationally and regionally.

Sectoral contributions to surface water stress in the coterminous United States

Here, we assess current stress in the freshwater system based on the best available data in order to understand possible risks and vulnerabilities to regional water resources and the sectors dependent on freshwater. We present watershed-scale measures of surface water supply stress for the coterminous United States (US) using the water supply stress index (WaSSI) model which considers regional trends in both water supply and demand. A snapshot of contemporary annual water demand is compared against different water supply regimes, including current average supplies, current extreme-year supplies, and projected future average surface water flows under a changing climate. In addition, we investigate the contributions of different water demand sectors to current water stress. On average, water supplies are stressed, meaning that demands for water outstrip natural supplies in over 9% of the 2103 watersheds examined. These watersheds rely on reservoir storage, conveyance systems, and groundwater to meet current water demands. Overall, agriculture is the major demand-side driver of water stress in the US, whereas municipal stress is isolated to southern California. Water stress introduced by cooling water demands for power plants is punctuated across the US, indicating that a single power plant has the potential to stress water supplies at the watershed scale. On the supply side, watersheds in the western US are particularly sensitive to low flow events and projected long-term shifts in flow driven by climate change. The WaSSI results imply that not only are water resources in the southwest in particular at risk, but that there are also potential vulnerabilities to specific sectors, even in the ‘water-rich’ southeast.

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.

The influence of future electricity mix alternatives on southwestern US water resources

A climate driven, water resource systems model of the southwestern US was used to explore the implications of growth, extended drought, and climate warming on the allocation of water among competing uses. The analysis focused on the water benefits from alternative thermoelectric generation mixes, but included other uses, namely irrigated agriculture, municipal indoor and outdoor use, and environmental and inter-state compact requirements. The model, referred to as WEAP-SW, was developed on the Water Evaluation and Planning (WEAP) platform, and is scenario-based and forward projecting from 2008 to 2050. The scenario includes a southwest population that grows from about 55 million to more than 100 million, a prolonged dry period, and a long-term warming trend of 2 C by mid-century. In addition, the scenario assumes that water allocation under shortage conditions would prioritize thermoelectric, environmental, and inter-state compacts by shorting first irrigated agriculture, then municipal demands. We show that while thermoelectric cooling water consumption is relatively small compared with other uses, the physical realities and the legal and institutional structures of water use in the region mean that relatively small differences in regional water use across different electricity mix scenarios correspond with more substantial impacts on individual basins and water use sectors. At a region-wide level, these choices influence the buffer against further water stress afforded the region through its generous storage capacity in reservoirs.

Are We Successfully Adapting Science to Climate Change

AMeRICAn MeTeOROLOGICAL SOCIeTY | 723 AffiliAtion: Averyt—University of Colorado at Boulder, National Oceanic and Atmospheric Administration, Western Water Assessment, Boulder, Colorado Corresponding Author: Kristen Averyt, University of Colorado at Boulder, National Oceanic and Atmospheric Administration, Western Water Assessment, 325 Broadway, DSRC/PSDI, Boulder, CO 80305 E-mail: kristen.averyt@noaa.gov

Climate and Energy-Water-Land System Interactions Technical Report to the U.S. Department of Energy in Support of the National Climate Assessment

This report provides a framework to characterize and understand the important elements of climate and energy-water-land (EWL) system interactions. It identifies many of the important issues, discusses our understanding of those issues, and presents a long-term research program research needs to address the priority scientific challenges and gaps in our understanding. Much of the discussion is organized around two discrete case studies with the broad themes of (1) extreme events and (2) regional intercomparisons. These case studies help demonstrate unique ways in which energy-water-land interactions can occur and be influenced by climate.

Modeling Climate-Water Impacts on Electricity Sector Capacity Expansion

Climate change has the potential to exacerbate water availability concerns for thermal power plant cooling, which is responsible for 41% of U.S. water withdrawals. This analysis describes an initial link between climate, water, and electricity systems using the National Renewable Energy Laboratory (NREL) Regional Energy Deployment System (ReEDS) electricity system capacity expansion model. Average surface water projections from Coupled Model Intercomparison Project 3 (CMIP3) data are applied to surface water rights available to new generating capacity in ReEDS, and electric sector growth is compared with and without climate-influenced water rights. The mean climate projection has only a small impact on national or regional capacity growth and water use because most regions have sufficient unappropriated or previously retired water rights to offset climate impacts. Climate impacts are notable in southwestern states, which experience reduced water rights purchases and a greater share of rights acquired from wastewater and other higher-cost water resources. The electric sector climate impacts demonstrated herein establish a methodology to be later exercised with more extreme climate scenarios and a more rigorous representation of legal and physical water availability.Copyright

Reply to comment by D. Wang et al. on “Empirical partition coefficients for Sr and Ca in marine barite: Implications for reconstructing seawater Sr and Ca concentrations”

[1] Wang et al. [2007] argue that the empirical distribution coefficient for Sr in marine barite obtained from the Sr/Ba composition of Holocene core top marine barite could not be used to reconstruct past seawater Sr concentrations. The premise for this argument is that Sr substitution into barite is not primarily a function of ambient Sr concentrations at the time barite precipitated. Wang et al. [2007] base their argument on the relatively large range of Sr/Ba ratios measured by Averyt and Paytan [2003] in the core top barite. They suggest that variable spatial and temporal ocean temperatures are responsible for the variations and without knowledge of the seawater temperature at the time and location of barite precipitation, the empirical distribution coefficient may not be used. However, we believe that we arrived at the best possible partition coefficient for Sr in marine barite based on the data available in 2003 and that despite ignoring the temperature effects this coefficient is useful if applied correctly.

A water resources model to explore the implications of energy alternatives in the southwestern US

This letter documents the development and validation of a climate-driven, southwestern-US-wide water resources planning model that is being used to explore the implications of extended drought and climate warming on the allocation of water among competing uses. These model uses include a separate accounting for irrigated agriculture; municipal indoor use based on local population and per-capita consumption; climate-driven municipal outdoor turf and amenity watering; and thermoelectric cooling. The model simulates the natural and managed flows of rivers throughout the southwest, including the South Platte, the Arkansas, the Colorado, the Green, the Salt, the Sacramento, the San Joaquin, the Owens, and more than 50 others. Calibration was performed on parameters of land cover, snow accumulation and melt, and water capacity and hydraulic conductivity of soil horizons. Goodness of fit statistics and other measures of performance are shown for a select number of locations and are used to summarize the model’s ability to represent monthly streamflow, reservoir storages, surface and ground water deliveries, etc, under 1980–2010 levels of sectoral water use.

River Forecast Application for Water Management: Oil and Water?

AbstractManaging water resources generally and managing reservoir operations specifically have been touted as opportunities for applying forecasts to improve decision making. Previous studies have shown that the application of forecasts into water management is not pervasive. This study uses a scenario-based approach to explore whether and how people implement forecast information into reservoir operations decisions in a workshop setting. Although it was found that participants do utilize both forecast and observed information, they generally do not utilize probabilistic forecast information in a manner to appropriately minimize risks associated with the tail end of the forecast distribution. This study found strong tendencies for participants to wait for observed information, as opposed to forecast information, before making decisions. In addition, study participants tended to make decisions based on median forecast values instead of considering forecast probability. These findings support the developmen...