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Integrating Renewables into the Generation Mix: Challenges and Unknowns. È questo il titolo dell’ultima iniziativa dell’editore americano PSI Media con il quale Nuova Energia ha in essere ormai da due anni una partnership editoriale.
Si tratta di un report focalizzato sulle conseguenze dell’incremento delle rinnovabili sulla reliability delle reti elettriche di trasmissione e, più in generale, sul sistema elettrico di un Paese. L’esperienza maturata in questi anni negli Usa dimostra che il vento - l’opzione preferita in questa fase di espansione delle rinnovabili - spesso non riesce a mettersi d’accordo con i picchi della domanda. Intatti, tendenzialmente le wind farm producono di più la sera, quando la richiesta della rete è più bassa. Si crea così uno squilibrio di fondo che impone l’adozione di sistemi di back up (con particolare riguardo per le turbine a gas naturale), l’aumento delle interconnessioni, il ricorso a soluzioni tecnologiche che possano compensare improvvisi o imprevisti cali nella generazione da rinnovabili intermittenti.
Il report affronta nel dettaglio queste tematiche (valutando anche le opportunità delle smart grid e del demand-side management) e presenta 14 approfondimenti, realizzati da esperti del settore, sull’interazione tra rinnovabili e reti da una parte, e tra rinnovabili e sistemi convenzionali di generazione dall’altra.
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by Robert G. Schwieger
 Integrating Renewables Into the Generation Mix: Challenges and Unknowns, a special report by the editors of Las Vegas based PSI Media, has been released at the end of November 2010. It explores how governments promoting massive development of renewable technologies through overly aggressive tax benefits and financial grants may negatively impact the reliability of their national grids.
PSI Media works collaboratively with Editrice Alkes of Milano on editorial projects of mutual interest - in particular, those focusing on the development of sustainable clean-energy resources and conservation strategies and technologies. Giorgio Dodero, chairman of Milano-based IPG, assists PSI Media as its European Technical Advisor.
Experience in the United States indicates that wind - the country’s preferred renewable resource based on installed capacity and planned additions - often does not blow when power is needed most. In fact, wind generation maybe at its peak in the evening, when demand is lowest.
But laws promulgated by three dozen American states typically specify that 10% of the electricity sold by electric utilities today must come from renewable resources. In most states, the percentage of renewable power must increase annually until it reaches 20% of the total electricity sold in 2020; some - such as California and Colorado - require that 30% or more of the power sold come from renewable resources by 2020. To meet such demanding regulations, utilities without bulk energy-storage assets must send out renewable power as it is produced. At night or during the spring and fall, kilowatt-hours from renewables can be 50% of the total energy supplied - possibly more.
 Mother Nature may be somewhat predictable, but not entirely so. This dictates the need for back-up generation resources, energy from neighbors via the grid, load shedding, and/or other [IT] immediate [RM] solutions to compensate for the shortfalls in energy production from intermittent renewables. Where faststart/ rapid-ramp assets are optimal for backing up renewables, or at least part of the solution, gas turbines are the likely generation option.
The report begins with an executive summary for those interested only in the highlights. That is followed by in-depth coverage of 14 presentations by experts in the field discussing the challenges renewables present to grid operators and the wear and tear wind and solar assets can inflict on conventional generating units selected for backup service. A couple of presentations profiled discuss the promise of the smart grid and demand-side management (DSM) solutions for mitigating renewables impacts; two case studies illustrate real-world experience.
The report is available at www.integrating-renewables.org. This website is designed to enable the free flow of information and ideas, share experiences, identify best practices, etcetera, to facilitate the transition to an electricity supply system with a large renewables component. Discussion forums include grid operations, smart grid/DSM, O&M impacts on conventional generation, and energy storage. Sign up and join the dialogue.
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