Basic Concept of the ASC
The ASC provides a solution for the technical problems that commercially existing concentrators are facing. Fundamentally, it is a lens-like, metallic point concentrator which concentrates solar radiation to a lower focal area fixed to the ground.
For the last decade the reflective concentrators used in Concentrated Solar Power (CSP) and Concentrated Solar Heat (CSH) systems are based on four types of concepts to concentrate sun rays shown in the illustrations below. In principle, the concentrator purpose is to reflect the solar rays such that they are concentrated on a focal area smaller than that of gross area of the concentrator (aperture area) resulting in high temperature and solar flux. The ratio between the focal receiving area and the aperture area is called the concentration ratio. Higher concentration ratio results in higher receiver temperature. To understand the concept of the ASC we will briefly explain the characteristics and the problems facing the existing concentrators and how by solving each of the weakness areas have created a highly efficient, scalable, reliable and most importantly financially competitive solution for Green Energy, Green Heat & Green Desalination, 24 hours a day with proven Thermal Storage solution...
Four Current CSP Solutions
Solar Tower
Linear Fresnal Concentrator
The challenges with Solar Towers has been well documented.
The cost of the power produced is uncompetitive, due to in most part to the following:​
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Single points of failure, particularly the solar tower and heliostat mirrors.
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Cost of maintenance and poor reliability.
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Efficiency, the heliostats are up to 500m away from the focal point which means significant energy lost to the air, aprox. 40% losses.
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System relies on heliostats surrounding the tower which is inefficient on land required and cost, both CAPEX and OPEX.
The challenges with Linear Fresnal Concentrators (LFC) are:
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The mirrors are fixed, so are only efficient when the sun is directly overhead.
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The concentration ratio for LFC is very low and consequently the temperature achievable are limited to circa 450c. Sufficient for steam generation for industrial use, but insufficient for electrical power generation.
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Cost of maintenance due to mirror cleaning. Lenses close to the ground and require daily attention.
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Reliability, as the system is in 'series' and failure will result in system shutdown.
Parabolic Dish
The Parabolic Dish also has a number of benefits as well as challenges. The Parabolic Dish is highly efficient optically with a short focal range and high levels of concentration. However;
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The focal point moves as the sun tracks across the sky which requires flexible joints for the high temperature fluid. The implication of this is:
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Reliability, flexible joints are unreliable and any failure is a potential health hazard and results in system shutdown and loss of production.
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Additionally, the dish is solid so can't operate in moderate to high winds due to wind sheer / loading.
Parabolic Trough
The Parabolic Trough is perhaps the most widely adopted of the CSP technologies to date. There are however, some severely limiting factors:
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As with the LFC the optical concentration is limited to around 80x, this limits the temperature achievable to circa 450 deg c. As such, limiting the application to steam generation or a pre heat for electricity generation.
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The system only tracks the sun on one axis, so only optimal when the sun is directly overhead.
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High maintenance due to proximity to the ground and dust. The mirrors require frequent cleaning and maintenance.
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The system runs in 'series' and failure of one element will result in system shutdown.
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Moving HTF joints present a challenge through wear and potential hazard if joint fails.
ASC 15 - The 5th Generation Solar Concentrator
ASC MK 1 - Test bed, MASDAR
ASC MK 2 - Optimised for Commercialisation
CSP Technology Comparator - Summary
Renewable Energy Application Comparator
