Abrahim Lavi

Ocean thermal energy conversion: a general introduction

The ocean thermal energy conversion (OTEC) concept is discussed with emphasis on the closed Rankine cycle using ammonia as a working fluid. The main features of OTEC, such as low efficiency high flow rates, and high capital cost are put in perspective in terms of energy cost at the bus bar. Sensitivity analyses of net output power to key design variables and to performance uncertainty are performed. It is concluded that even with a large error in estimating performance conditions, the plant produces net output power. This indicates the robust nature of current designs. Finally, cost figures of major system components are given and electricity cost based on a hypothetical capital cost is computed.

Analysis of a class of nonlinear discrete systems using multidimensional modified z transforms

This paper presents an analysis procedure for determining the continuous output of a pulsed continuous-time system with small nonlinearities. The analysis technique uses Volterra series representation and higher-dimensional modified z transforms. The method is compared and contrasted with the linear transform theory. Like the latter, it has certain advantages in treating cascaded and feedback systems, but the technique is more involved than in the linear method.

Plumbing the ocean depths: a new source of power

The main difficulty in harnessing solar energy is collecting it. The collection mechanism for solar sea power is the ocean. Solar energy, absorbed by the surface waters of tropical oceans, can be converted first into electric power by solar sea power plants, then convented by electrolysis into chemical energy, and transported by ship for distribution to heat homes, power transportation facilities, and form a basic ingredient in materials processing. The problems involved for a SSPP are insufficient temperature difference, corrosiveness of sea water, microbial fouling, plant anchoring, diluteness of solar energy in the ocean, and environmental effects. (MCW)

Ocean thermal energy conversion (OTEC): Social and environmental issues

OTEC converts the solar energy, collected and stored in tropical waters, into electricity. The electricity may be either cabled to shore or used in situ for the manufacture of energyintensive products. Two countries, U.S.A. and Japan, are seriously pursuing OTEC. The development programs in both countries are similar. Presently, the emphasis is on the closed Rankine cycle with ammonia as the working fluid. The power plants are to be housed on floating platforms. If the electricity is to be cabled to shore, the platforms will be moored to the ocean floor. If the plants are to produce chemical products, they will graze from one location to another on the open sea to capture the largest available thermal resource.

The economics of solar sea power plants

Of the many novel solar energy schemes being investigated in the United States, the Ocean Thermal Energy Conversion Concept, OTEC, appears to be the one most likely to put the U.S. on the road towards energy self-sufficiency in the shortest possible time. The paper will illustrate how a solar sea power plant will convert the thermal energy stored in the tropical oceans into electricity. The main emphasis will be on capital plant cost and energy cost. Comparison with conventional nuclear plants will be made based on cost, energy pay-back and development time.

An Evolutionary Approach to Process Control with Application to Lithography

A new approach to process control is presented. Complete automation is, from the outset, considered undesirable. Instead, an evolutionary approach is proposed, and the successive stages of growth of the control system are described, from a totally human-controlled process to a greater degree of automation. A man?machine control of a lithography printing press is presented. Instead of proposing a new kind of automatic controller intended for eliminating the human operator, cooperation between the pressman and the computer control system is advocated in order to use their complementary characteristics. An application of the approach on a computer-based model of a press and a discussion of the results obtained by experienced pressmen are given.

Introducing OTEC to mainland utilities

The adoption of advanced technology by a large electric utility must be preceded by a lengthy assessment process involving cost, performance, reliability, technology availability, environmental impact, legal, institutional, and other factors. Over the past 25 years, the most important technological development to take place in the electric utility business has been that of nuclear power generation. This technology, though proven technically, has encountered significant problems. The time to site and construct a nuclear plant has grown because of environmental and regulatory restrictions. The absence of a national policy with respect to nuclear waste disposal and fuel recycling has created what appears to utility planners to be a very unfavorable political environment. For these and other reasons, the capital cost of nuclear plants has been steadily increasing and utility managements have begun to look to other fuel technologies such as coal.

Signal Transfer Function of Optical Components

The effect of an optical component or subsystem on an electromagnetic wave is considered and a signal transfer function associated with the propagation is derived. A coordinate transformation is introduced which makes it possible to compute this transfer function. A lens can be characterized by the zeros of this transfer function in the complex plane and the effect of variations of the usual optical parameters on this transfer function is expressible in terms of root loci. These loci are simple functions of the lens parameters and one basic set of loci defines the properties of a large class of rotationally symmetric lenses. Their use in the preliminary design of optical systems is indicated and a simple case is carried to completion.