Thermal storage system

Abstract

Apparatus and method for efficiently storing thermal energy, in particular thermal energy transferred from a concentrated solar energy receiver. The apparatus consists of a collection of modular thin walled tube pressure vessels enclosing solid sensible heat thermal storage elements. The high temperature solid is separated from the thin wall by thermal insulation and two thin gaps that carry the cold in and cold out high-pressure working fluids. Hot in and hot out working fluids circulate in counter flow channels within the solid sensible heat thermal storage elements. The solar receiver can also be modular to match the thermal storage elements, facilitating manufacturing and on site assembly. The design enables scalable thermal storage and concurrent thermal charging and discharging with no circuit switching between charge and discharge.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]Non-provisional application Ser. No. 12 / 430,869, filed on Apr. 27, 2009. Non-provisional application Ser. No. 12 / 488,852, filed on Jun. 22, 2009. Non-provisional application Ser. No. 12 / 579,849, filed on Oct. 15, 2009.FEDERALLY SPONSORED RESEARCH[0002]Not ApplicableSEQUENCE LISTING OR PROGRAM[0003]Not ApplicableBACKGROUND[0004]1. Field[0005]This invention generally relates to thermal storage systems, and more particularly to high temperature, high efficiency, sensible heat thermal storage systems.[0006]2. Prior Art[0007]Concentrating Solar energy systems use optical components such as lenses and mirrors to collect and concentrate the sun's radiation and then absorb it for practical use. The main practical use is to provide high temperature working fluids to drive heat engines that in turn drive electricity generators. Other uses for concentrated sunlight include high intensity photovoltaic electricity generation, direct high temperature “...

AI Technical Summary

Benefits of technology

[0026]Thermal storage is a necessary part of a solution to deliver electricity 24 / 7. The current Research & Development focus in thermal storage for concentrating solar power (CSP) plants uses nitrate and fluoride salt mixtures to both store and transfer heat. However, the molten salts have several serious shortcomings. They have a relatively low range of temperatures where they are liquid, and they solidify at room temperature. Considerable engineering is required to keep them molten under all circumstances. Corrosion and chemical reactions from impurities cloud the long-term reliability picture.

Problems solved by technology

Current Concentrating Solar systems suffer from several problems that have limited their success.

Their high capital costs make the cost of the energy they produce uncompetitive without subsidy.

They also have high ancillary costs to compensate for the unpredictability of their energy output and the long transmission distance from the system to the average power user.

Current systems are severely negatively affected by effects of weather such as rain, clouds, moisture and dust in the atmosphere.

This restricts their geographical location to hot dry desert areas which are relatively scarce and far from consumers of electricity.

In addition, even in deserts, bad weather sometimes restricts electric power output availability, necessitating the provision of alternate sources of supply.

Current systems consequently consume large areas of land and significant quantities of construction materials like glass and steel needed to fabricate this large aperture collector.

Also weather in the form of dust, wind, rain, hail frost and snow require that structures be strong and durable which adds significantly to their cost.

Robust motors, gears, electrical equipment etc are needed for each collector element, contributing significantly to overall cost.

The cost problem is compounded by the generally low overall energy conversion efficiency of current systems, which consequentially requires a larger surface area and more material to produce a given power output compared to higher conversion efficiency systems.

Corrosion and chemical reactions from impurities cloud the long-term reliability picture.

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