Aharon Roy/Department of Chemical Engineering/Ben-Gurion University, P. O. Box 653, Beer-Sheva 84105, Israel. <rovaaron@baumail. bau. ac. il>

Phone: +(972)8-646-1484; Fax: +(972)8-647-2916.

Introduction

A major driver of renewable energy is its use as a means of reducing greenhouse gas (GHG) emissions associated with energy generated from fossil fuels. The reduction of GHG emissions is linked to financial incentives, and fuel avoidance becomes a key design criterion. Renewable-hybrid systems have the potential of playing a decisive role in massive supply of renewable energy in the near-term, creating new markets and accelerating systems deployment while driving costs down. However, the hybridization of renewable energy with fuel-fired generators has to be appropriately designed; otherwise, environmental goals may be missed. In some cases the absolute quantity of the environmental benefit (fuel avoidance) generated by the renewable subsystem may significantly decrease or even be erased by the fuel subsystem in the solar-fuel hybrid plant. There is a problem to elucidate and solve. It will help perfect the global strategy of expanding the use of renewable energies.

Green energy and GHG control

The term "green power” has come to signify electricity generated from renewable energy sources like wind, hydropower, solar, geo-thermal and bio-mass. The key point is that every kilo-Watt-hour electricity (kWhe) generated from a renewable energy source is a kWhe that need not be generated from fossil or nuclear source [1]. Namely, every green kWhe output replaces a fossil-derived kWhe; and thus must decrease the use of fuel by the amount needed for producing one kWhe. The task of green power is to reduce various kinds of pollution and also slow down the dwindling of world fossil reserves. Thus, green power fosters a sustainable world. Various technologies are being developed worldwide for intensifying the effectiveness and economics of renewable energy systems.