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Texas Space Grant Consortium

Space Solar Power

Ground-Based Energy Storage

Texas Tech University

12/10/97

EE 4334 / ME 4370

Jerry Dinkins

Kerry Lee

Sam Mahserjian

Bryon Pinkoski

Instructor: Dr. D.L.Vines

Advisors: Dr. M. Parten

J. Jones

Abstract

The purpose of this project was to design a system to store energy transmitted via microwave from a space solar satellite system. The RF energy will be received by a large, ground-based rectenna. This rectenna system converts the microwave energy being sent by the satellite system into electricity. The storage system should be able to collect energy for one hour every six hours (tentatively), and disperse it onto the utility grid as needed.

This project involved the evaluation of nine different energy storage systems according to a set of criteria determined by the Texas Space Grant Consortium. Of the nine systems, three systems met the established criteria: Ultra-capacitors, Flywheels, and Superconducting Magnetic Energy Storage. In the continuation of this project, the selected systems will be modeled to demonstrate their effectiveness as an energy storage system.

Introduction

Currently, energy sources in the electric utility industry are oil, coal, natural gas, nuclear, and hydroelectric. These sources are either at their peak production, environmentally unsafe, or are available only for a finite amount of time. A new source of energy for the future has to be environmentally safe, non-depletable, and cost competitive with current sources.

Interest in alternative fuels greatly increased during the oil crisis in the early '70s. During that time, the federal government formed the Department of Energy (DOE) in order to respond to the increasing demand for reliable energy. The purpose of the DOE was to seek viable alternative energy sources. Some of the energy solutions proposed include hydroelectric plants, nuclear power, and solar power satellites. The DOE has suggested that an immediate solution to the energy crises is conservation. Conservation was easily accomplished due to the increasing price of oil, which in turn directly affected the public.

Clearly, conservation was not the final answer; it was just a temporary fix to an ever-increasing problem. Nearly every river in the United States is used by the hydroelectric industry, which is why it is at its peak production. Yet the need for energy is continuing to rise, thus another solution is needed. Nuclear power is efficient, but its by-products are neither environmentally friendly nor popular with the public. Billions of dollars have been spent on the study of fusion energy, with no foreseeable breakthroughs in the near future. A 1979 study of solar power satellites suggested that they were feasible and could be paid for by selling the energy at the current rates. Unfortunately, this energy source lost its funding during the early '80s. Recently, NASA performed a 'fresh look' study on the solar space power (SSP) system concept. This study shows that SSP's were more cost effective and feasible now than in the late '70s due to the decreased cost of producing more efficient photovoltaic cells. Various facilities that are necessary for production of the SSP system are already in use for industrial purposes.

Currently, there are several entities working on the SSP system concept. One of these is the Texas Space Grant Consortium (TSGC), which is an organization that funds the preliminary design of projects that NASA is considering. The TSGC works with universities in Texas to accomplish its goals. Several different universities are accomplishing the TSGC SSP effort; each is assigned to perform preliminary design and analysis of a major system element. Texas Tech University was assigned to work on the energy storage aspect of the complete SSP system.

The Texas Tech group is to design an energy storage system that periodically receives power and constantly distributes power on the electric utility grid.

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