Background Posterior pelvic ring reconstruction can be challenging and controversial. The choice regarding whether to reconstruct and how to reconstitute the pelvic ring is unclear. Many methods provide stability but often are technically difficult and require excessive dissection.
This paper numerically explores a high-temperature sensible-latent hybrid thermal energy storage system designed to store heat with output temperatures stabilized at approximately 550–600 °C for direct coupling with supercritical carbon dioxide (sCO2) power cycles operating at their design point. sCO2 and dry air at 25 MPa are used as heat transfer fluid (HTF) in a packed bed storage system that combines rocks as sensible heat storage and AlSi12 as latent heat storage. The base model using dry air at atmospheric pressure is compared to similar work done at ETH Zurich; the model is then extended for use with sCO2 to compare the performance of air and sCO2 at similar volumetric flow rates. It was found that sCO2 is capable of storing a significantly larger amount of energy (∼40 kWh) in the same time period as the air system (∼19 kWh), and can discharge that energy much quicker (1.5 hours compared to 4 hours). However, in order to achieve similar degrees of temperature stabilization, the total height of PCM had to be increased significantly, from 9 cm to 45 cm or more.
This paper focuses on the economics of integrating thermal energy storage into natural gas combined cycle power plants for improved operational and economic performance of the utility grid. Costs and fuel consumption are modeled based on a Florida electric utility’s hour-by-hour load data under two scenarios: 1) no storage, and 2) thermal storage attached to intermediate load, NGCC plants, displacing energy production from older, less efficient NGCT peaking units. Due to the nature of the power grid, several of the older units feature abnormally high fuel costs and abnormally low thermal efficiencies. By shifting load from the most expensive peaking units to more cost-effective combined cycles with a 204 MWhth storage system costing about $4 million, savings of more than $1 million per year can be realized while also reducing CO2 emissions by about 5000 metric tons per year. These savings represent an internal rate of returns of up to 23% over a 30-year lifetime, depending on the initial cost of the storage system.
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