Utility Scale Solar Power with Minimal Energy Storage

Abstract

Smart grid functionality creating an internet of energy has been a topic of increasing interest. It is opening up several real time functions: pricing, network and consumption tracking, and integration of solar and wind power. The report from Department of Energy (DOE, 2008; 2009) supplies accessible details. At the present time, utilities run coal thermal power plants and nuclear plants as base load (Srivastava & Flueck, 2009) and use land based gas turbine plants to absorb unexpected demand surges (Nuqui, 2009). Solar energy, though envisioned as one of the panaceas to power from fossil fuels, suffers from two deficiencies: the density of energy available, and the unreliability of power production. Density limits mean solar power will never quite replace coal and nuclear plants for base load. However, the factor that limits penetration of solar power is the unreliability of supply that stems from uncertainty in incident solar radiation. A 100MW plant can produce much less power output in a matter of minutes if a cloud passes over it. It can also jump the other way. This can potentially result in large and undesirable transients being introduced into the grid. Large currents can damage grid equipment, such as power lines or transformers, in a very short period of time. This means that solar power needs backup power in the grid in the form of polluting coal or expensive gas. This is the main reason that grid operators and utilities are reluctant to integrate solar energy into their systems. This also means that solar or wind power at present may actually be contributing to greater use of fossil fuels in some regions. In this paper, we focus on solutions to three approaches to avoid the usage of grid storage: Distributing solar production to minimize its variance, correlation of solar power production to power consumption in air conditioning to determine the upper limits of solar penetration possible without storage, and grid failure probability with different levels of solar penetration.