Tankless Thermal Energy Storage Using Bitumen and Earth Barriers
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Solution Overview
Problem
Current systems for storing thermal energy, particularly in Concentrating Solar Power (CSP) plants, are costly due to the expense of heat-carrier fluids and storage systems, and they have a significant environmental impact.
Innovation Solution
A process and system for accumulating thermal energy using tankless accumulation sections made of materials with high thermal inertia, which are constructed without metal vessels, utilizing primary heat-carrier fluids like bitumens that can be heated to high temperatures without excessive degradation, and featuring geological or artificial barriers for containment, reducing material costs and environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional heat-carrier fluids (molten salts, mineral oils) are used in metal tanks for thermal energy storage, then thermal energy can be stored at high temperatures, but the cost of the heat-carrier fluid and storage system becomes very high
Solution Approach 1:
The patent replaces expensive molten salts and metal tanks with cheap bitumen and earth barriers. The bitumen, while having a lower maximum temperature threshold, is significantly cheaper and can be contained in simple earth structures rather than expensive metal vessels, resolving the cost contradiction.
Solution Approach 2:
The patent changes the operating temperature parameters from high-temperature molten salts (500-570°C) to medium-temperature bitumen (100-300°C). This parameter change allows the use of cheaper materials and simpler containment structures, reducing overall system cost while still providing useful thermal energy storage.
2Reliability
If molten salts are used as heat-carrier fluid, then high thermal stability and low environmental impact are achieved, but the cost of the fluid and storage infrastructure increases significantly
Solution Approach 1:
The patent substitutes expensive molten salts with cheap bitumen, and replaces complex metal storage infrastructure with simple earth barriers. While bitumen has different thermal properties, it provides adequate performance for the application at a fraction of the cost, resolving the contradiction between reliability and manufacturing cost.
Solution Approach 2:
The patent uses the earth barrier approach as a simplified copy/alternative to metal tank containment. Instead of replicating the complex metal vessel structure, it uses naturally available earth materials with appropriate thermal and containment properties, reducing infrastructure cost while maintaining functional reliability.
3Quantity of substance
If metal tanks insulated with refractory material are used for storing heat-carrier fluid, then thermal energy storage capacity is achieved, but the construction cost becomes particularly onerous
Solution Approach 1:
The patent replaces expensive metal tanks with simple earth structures. The earth barrier provides adequate containment and thermal properties for bitumen storage at a fraction of the cost of metal vessels with refractory insulation, while maintaining sufficient storage capacity.
Solution Approach 2:
The patent changes the containment material from metal to earth, and operates at lower temperatures suitable for bitumen. This parameter change allows the use of inexpensive earth structures instead of expensive metal vessels, reducing construction cost while maintaining adequate storage capacity for the application.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces the costs of thermal energy storage and accumulation while minimizing environmental impact, enabling efficient generation of mechanical and electrical energy using organic Rankine cycles and other thermodynamic cycles.
Implementation Method 1
heating of the primary fluid in one or more of these heating subsections; thermal energy for heating the primary fluid comes, totally or partially, from discontinuous or variable sources and preferably from solar radiation
Implementation Method 2
subsequent feeding and accumulation of the primary fluid, at the maximum temperature, in the primary accumulation section
Implementation Method 3
collection from this primary accumulation section of the previously heated primary fluid and its feeding to a plant section where there is heat exchange between the primary fluid and a secondary fluid at a lower temperature
Implementation Method 4
accumulation sections which are constructed by means of material with high thermal inertia
Data Source
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AI summary
A process and a corresponding system for the accumulation and use of thermal energy at medium or high temperatures, wherein a primary heat-carrier fluid is accumulated in a secondary accumulation section; it is subsequently fed to a heating section, where the primary fluid is heated and receives thermal energy; then, once heated, it is fed to a primary accumulation section, where the primary fluid is accumulated at the maximum temperature and from where it is collected for heat exchange with a secondary fluid, as part of a thermodynamic cycle for the production of electrical/mechanical energy; and wherein finally the primary fluid, after transferring heat to the secondary fluid and thereby cooling down, is fed and returns again to the secondary accumulation chamber, thus closing the cycle. Advantageously, the primary and secondary accumulation sections of the primary fluid, both epigeal and hypogeal, are of the tankless type, so that they do not involve the use of self- supporting tanks, or similar containers, and can be constructed in various ways, for example with a geological/artificial barrier, or in one or more natural cavities, such as those formed in a rock salt mine, or artificial cavities, provided or not with reinforcement and/or containment works. Moreover the primary heat-carrier fluid, used in this process to accumulate thermal energy, can be of the type including organic substances such as bitumen and/or the like.