Intermittent and stochastic character of renewable energy sources: Consequences, cost of intermittence and benefit of forecasting

Abstract

Solar and wind energy are inherently time-varying sources of energy on scales from minutes to seasons. Thus, the incorporation of such intermittent and stochastic renewable energy systems (ISRES) into an electricity grid provides some new challenges in managing a stable and safe energy supply, in using energy storage and/or 'back-up' energy from other sources. In such cases, the ability to accurately forecast the output of "unpredictable" energy facilities is essential for ensuring an optimal management of the energy production means. This review syntheses the reasons to predict solar or wind fluctuations, it shows that variability and stochastic variation of renewable sources have a cost, sometimes high. It provides useful information on the intermittence cost and on the decreasing of this cost due to an efficient forecasting of the source fluctuation; this paper is for engineers and researchers who are not necessarily familiar with the issue of the notions of cost and economy and justify future investments in the ISRES production forecasting.

Mechanistic Study on the Photogeneration of Hydrogen by Decamethylruthenocene

“…[18,28,39] Herein,w es ignificantly advance our earlier work by investigating the photoreduction of organic protons in as ingle organic phase. The multistep photomechanism leadingt oH 2 evolution with [Cp* 2 Ru II ]w as fully elucidated by using electrochemical, GC, and spectroscopic (UV/Vis, 1 Ha nd 13 CNMR) experimental approaches, with corroboration by DFT calculations. Ac omprehensive guide describing the influences of the nature of [Cp* 2 Ru II ]i tself (in comparisont os imilare xperiments performed with [Cp* 2 Os II ]), the organic acid, and the organic solvento ne ach step of the photogeneration of H 2 in acidified organic media is presented.…”

“…Ideally, as trong organic acid that reacts in a1:1 ratio with [Cp* 2 Ru II ]t o facilitate1 00 %c onversion to [Cp* 2 Ru IV (H)] + is desirable in order to remove any ambiguity whether all of the [Cp* 2 Ru II ] present is converted to [Cp* 2 Ru IV (H)] + and preclude underestimation of the maximum possible experimental yields of H 2 gas. 1 HNMR spectroscopy can be used to monitor the conversion of [Cp* 2 Ru II ]t o[ Cp* 2 Ru IV (H)] + . 1 HNMR spectra were obtained in CD 2 Cl 2 with DCE (31.2 mm)a si nternal standard,i n the dark, at ambient temperature, and under anaerobic conditions.…”

“…One of the majori ssues facing the development of renewable energy strategies (solar and wind in particular) is the intermittent nature of energy production via these routes( no electricity is produced when the sun does not shine andw hen there is no wind). [1] Therefore, reliance on renewable energy requires energy storage. Although batteries are ablet oc ost effectively store the produced electricity on as cale of hours, [2,3] different strategies are required for long-term energy storage.…”

Feature engineering and forecasting via derivative-free optimization and ensemble of sequence-to-sequence networks with applications in renewable energy

“…Dense wind farms across the globe are generating considerable amounts of electric power. The inherently time-varying nature of wind energy necessitates the development of a systematic framework to construct and forecast future wind characteristics [48]. Such a framework greatly enhances the flexibility of power systems to cope with irregular wind power patterns integrated in their portfolios.…”

Multi-Objective Optimal Capacity Planning for 100% Renewable Energy-Based Microgrid Incorporating Cost of Demand-Side Flexibility Management

“…However, an accurate and reliable VREs output forecasting can serve as a core and vital component of energy management systems (EMS) implementation [33]. The role of forecasting also has significant value in the implementation of pricing schemes in the power markets to decrease the rate of market volatility [34].…”