No abstract

No abstract

a b s t r a c tAn RO (reverse osmosis) desalination plant is proposed as an effective, FLR (flexible load resource) to be integrated into HES (hybrid energy systems) to support various types of ancillary services to the electric grid, under variable operating conditions. To study the dynamic analysis of such system, special attention is given here to the detailed dynamic modeling and control design of RO desalination process that employs a spiral-wound membrane module. In particular, the solution-diffusion model modified with the concentration polarization theory is applied to predict RO performance over a large range of operating conditions. Simulation results involving several case studies suggest that an RO desalination plant can provide operational flexibility to participate in energy management at the utility scale by dynamically optimizing the use of excess electrical energy. The incorporation of additional commodity (fresh water) produced from a FLR allows a broader range of HES operations for maximizing overall system performance and profitability.Published by Elsevier Ltd.

In support of more efficient utilization of clean energy generation sources, including renewable and nuclear options, hybrid energy systems (HES) can be designed and operated as flexible energy resources (FER) to meet both electrical and thermal energy needs in the electric grid and industrial sectors. These conceptual systems could effectively and economically be utilized, for example, to manage the increasing levels of dynamic variability and uncertainty introduced by variable energy resources (VER) such as renewable sources (e.g., wind, solar), distributed energy resources, demand response schemes, and modern energy demands (e.g., electric vehicles) with their ever changing usage patterns. HES typically integrate multiple energy inputs (e.g., nuclear and renewable generation) and multiple energy outputs (e.g., electricity, gasoline, fresh water) using complementary energy conversion processes. This paper reports a dynamic analysis of two realistic HES including a nuclear reactor as the main baseload heat generator and to assess the local (e.g., HES owners) and system (e.g., the electric grid) benefits attainable by their application in scenarios with multiple commodity production and high renewable penetration. It is performed for regional cases-not generic examples-based on available resources, existing infrastructure, and markets within the selected regions. This study also briefly addresses the computational capabilities developed to conduct such analyses.

This document reports the application of the Nuclear-Renewable Hybrid Energy System (N-R HES) software framework to a case study conducted in collaboration with Arizona Public Service (APS). The study is a work in progress; this report presents a detailed description of the current model inputs and the corresponding results.APS is currently anticipating several operational challenges: First, APS is coping with the rapid growth of Variable Renewable Energy (VRE) sources on the grid in the APS service region. To mitigate the resulting demand volatility, APS is seeking to add more baseload. The second challenge to APS is that the cooling water acquisition contract with the Sub Regional Operating Group (SROG) will expire soon and a renewal is only available for a significantly higher price of water. An opportunity for less expensive water may be to pump brackish water from the regional ground water. One caveat is that the salinity of the brackish water is so high that it could, depending on the percentage used, need additional treatment via an on-site Reverse Osmosis (RO) desalination plant. The RO plant would help resolve both problems APS is facing, i.e. increasing the baseload to help mitigate VRE-induced demand volatility and, in addition, the clean water produced can be used by APS for plant cooling to lower their water acquisition cost.The analysis in this report considers three scenarios: (1) The status quo, where all cooling water is purchased from the SROG and no RO is built (CASE 0); (2) A case in which one RO is built on-site to treat the blend of SROG and brackish water (CASE 1); and (3) A case in which two ROs are built, one on-site and another one close to the brackish water well (CASE 2). The second RO could produce clean (potable) water that can be sold to generate additional revenue for APS. The analysis evaluates the differential Net Present Value (NPV) between the scenarios.To model the three APS cases, additional functionality for the N-R HES software framework was needed. In particular, the RAVEN CashFlow plugin was updated to add more flexibility in project and component definitions and the synthetic time history generator was updated to include the possibility to correlate the noise portion of different signals after Fourier de-trending. The report also includes description of how the reduced order RO model was derived from a high fidelity Modelica model. Furthermore, the physical models used for water flows and chemistry, as well as the economic models detailing the assumptions made and data used, are described.The report shows that the recently implemented correlated Auto-Regressive, Moving Average model (FVARMA) capability is working as intended. However, after removing the long-term trends and correlations by Fourier de-trending, no correlation could be found between the demand and the rooftop solar photovoltaics (rPV) or between the demand and the hub price in the stochastic portion of the signal, although it is suspected that such correlations exist and are important drivers for the econo...