Margaret A. Cook

Mapping water availability, projected use and cost in the western United States

New demands for water can be satisfied through a variety of source options. In some basins surface and/or groundwater may be available through permitting with the state water management agency (termed unappropriated water), alternatively water might be purchased and transferred out of its current use to another (termed appropriated water), or non-traditional water sources can be captured and treated (e.g., wastewater). The relative availability and cost of each source are key factors in the development decision. Unfortunately, these measures are location dependent with no consistent or comparable set of data available for evaluating competing water sources. With the help of western water managers, water availability was mapped for over 1200 watersheds throughout the western US. Five water sources were individually examined, including unappropriated surface water, unappropriated groundwater, appropriated water, municipal wastewater and brackish groundwater. Also mapped was projected change in consumptive water use from 2010 to 2030. Associated costs to acquire, convey and treat the water, as necessary, for each of the five sources were estimated. These metrics were developed to support regional water planning and policy analysis with initial application to electric transmission planning in the western US.

Impacts of Temperature Thresholds on Power Generation in the Upper Mississippi River Basin Under Different Climate Scenarios

Recent droughts and heat waves have revealed the vulnerability of some power plants to effects from higher temperature intake water for cooling. To avoid heating the cooling water beyond temperature thresholds set by the EPA, some plants have been forced to reduce their power generation. At the same time, future warming of water resources from heat waves, droughts, or climate change might increase ambient air temperature (one of the primary factors affecting intake temperature, and thus cooling effluent temperature) putting plants at risk of even greater de-rating. In this evaluation, we sought to model and predict which plants would have the greatest risk of de-rating due to thermal discharge limits. To do so, we created a regression model of average monthly intake temperatures for open loop and recirculating cooling pond systems for power plants in the Upper Mississippi River Basin using ambient air temperature, wind speed, historical intake temperatures, and historical effluent temperatures. We then integrate that information into a thermodynamic model of energy flows within each power plant to determine the change in cooling water temperature that occurs at each plant. We use these models in tandem to determine effluent temperature at 43 power plants in the Upper Mississippi River Basin. For the years modeled, 2010–2012, the model estimated the intake temperature using the linear regression within 2.2 °C of the observed values and estimated the effluent temperature within 5.0 °C of the observed values. For years outside of the estimation period, 2008–2009, the model estimated effluent temperature within 5.1 °C of the observed values.Copyright

Implications of thermal discharge limits on future power generation in Texas

The recent drought in Texas revealed the vulnerability of curtailment for some power plants due to cooling water supplies being too hot. Assessing the risk of reduced operations at thermoelectric power plants associated with thermal discharge limits, as well the potential for cooperation between power plants, can increase the resiliency of the electricity grid in Texas and aid future planning. This evaluation compares the observed effluent discharge water temperatures from thermoelectric power plants in the Electric Reliability Council of Texas (ERCOT) interconnection with Environmental Protection Agency (EPA) discharge temperature limits. Results indicate that at least two major power plants representing over 3,000 MW of cumulative generation capacity have operated at or near these temperature limits in the past. Predicted warming from heat waves, droughts, or climate change might increase ambient air temperature (one of the primary factors affecting effluent temperature) causing even higher derating in the future.We modeled current and future average monthly cooling water effluent temperature for open loop and recirculating cooling pond systems in ERCOT using current climate data and predictions of ambient air temperature, electricity generation, dew point, and wind speed for 2027–2032. While there are some power plants that are projected to be exposed to thermal effluent-related curtailment, we estimate that there is six times as much electricity generation potential available from other existing generators that can meet demand without reaching thermal effluent temperature limits. That is, this work’s analysis indicates that other existing power plants could generate additional electricity to offset the curtailment of the particular power plants at greatest risk from derating to maintain grid reliability.Copyright

Communication Science for Science Communication: Water Management for Oil and Natural Gas Extraction

AbstractWater management for oil and natural gas extraction in the United States has become a topic of public interest and concern. This societal relevance simultaneously heightens the need for rig...

Alternative water sources for hydraulic fracturing in Texas

This paper describes an evaluation of cross-sector investments in water efficiency to enable increased water availability for hydraulic fracturing. In particular, water needs in Texas are examined to identify the water balances and cost requirements to deploy efficient irrigation water systems for the agricultural sector as a way to make available more water for the energy sector. The Rio Grande Valley in Texas is examined for these water savings that could be transferred to gas and oil production in the Eagle Ford shale formation. To evaluate water availability for use in oil and gas production, a model of water and cost savings from conservation technologies is shown at county-wide resolution. To demonstrate this methodology, we use irrigation districts on the Lower Rio Grande River in Texas to assess the feasibility of retrofitting alternative irrigation techniques for current agricultural sites. We found that between 420 and 800 million cubic meters (m 3 ) or between 340,000 and 650,000 acre-feet (ac-ft) of water could be spared per year over a ten year period, enabling freshwater use in oil and gas production in more than 26,000 wells in the Lower Rio Grande Valley alone.

Potential Drought Impacts on Electricity Generation in Texas

Many power plants in the Electric Reliability Council of Texas (ERCOT) region require a large amount of water for system cooling. To improve the understanding of potential risks of electricity generation curtailment due to drought, an assessment of water availability and its potential impacts on generation during drought was performed. For this impact analysis, we identified three drought scenarios based on historical drought records and projected climate data from the Geophysical Fluid Dynamics Laboratory global climate model, for greenhouse gas emission scenario A2 defined by the Intergovernmental Panel on Climate Change. The three drought scenarios are (1) 2011 drought conditions (the worst drought in history), with the current level of water use; (2) a single-year drought (2022) projected for the period of 2020–2030, with the assumed projected water use level for 2030; and (3) a multiple-year drought constructed with climate data for 1950–1957 and water demand projected for 2030. The projected drought scenario in 2022 and the historical droughts in 2011 and 1950–1957 represent two different precipitation patterns in the Texas-Gulf river basin.The hydrologic model constructed for the Texas-Gulf river basin covers most of the ERCOT region. The model incorporates climate and water use data that correspond to three drought scenarios, respectively, to estimate evapotranspiration, water yield from watersheds, stream flow and water storage in reservoirs. Using criteria based on observed (< 50% storage) and predicted (< 55% storage) reservoir data, we identified 15 low-storage reservoirs in 2011, 10 in 2022, and 20 in 1956 (the last year of the multiple-year drought). The power plants that are supported by these reservoirs would be potentially at risk of being derated for thermoelectric cooling because of a lack of water supply. These power plants are located mainly in watersheds near and between Houston and Austin, as well as surrounding Dallas.Copyright