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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Pumped Thermal Electricity Storage with Supercritical CO2 Cycles and Solar Heat Input: Preprint

Pumped Thermal Electricity Storage (PTES) is an energy storage device that uses grid electricity to drive a heat pump to generate hot and cold storage reservoirs. This thermal potential is later used to power a heat engine and return electricity to the grid. In this article, a PTES variant that uses supercritical carbon dioxide (sCO2) as the working fluid is introduced. sCO2-PTES cycles have higher work ratios and power densities than the systems based on ideal gases that have been investigated to date. Furthermore, sCO2-PTES cycles may achieve higher round-trip efficiencies for a given hot storage temperature (up to 78% at 560 degrees C). The sensitivity of PTES cycles to loss factors such as isentropic efficiencies and temperature differences between the power cycle and storage fluid is investigated. A second concept whereby an sCO2-PTES cycle is integrated with concentrating solar power (CSP) is introduced. This concept 'time-shifts' the recompression of an sCO2 recompression cycle to a period of lower electricity prices and stores the heat. When solar heat is dispatched, the recompressor may be avoided as the required heat is obtained from storage, thereby leading to increased heat engine efficiencies. The net work output of this integrated system is 10-18% greater than the conventional recompression cycle. Combining PTES with a CSP power cycle is therefore shown to improve the dispatch of solar heat as well as providing electricity storage services.

14 SOLAR ENERGY↗
DOE OSTI2018

Uncertainty Input Development for Natural Gas Systems in the U.S. GHG Inventory

This work was presented at the U.S. EPA workshop on modeling oil and natural gas sector emissions in Washington, DC on June 22, 2018. It discusses the data sources that NETL uses for its upstream life cycle natural gas model and prioritizes opportunities for uncertainty characterization. An objective of uncertainty characterization is to understand the role of system variability without introducing more uncertainty to the data. Non-parametric statistical bootstrapping is one technique for accomplishing this objective and is especially useful for skewed, irregularly-shaped probability distributions. When data are not available, expert judgement is appropriate, but should be differentiated from assumptions and data gaps.

Littlefield, James↗