Geothermal Osmotic Power Generation Process
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Solution Overview
Problem
Current methods for generating electricity from geothermal sources, particularly using pressure retarded osmosis, are inefficient and uneconomic due to low power densities achieved with existing membrane technology, and no process effectively harnesses the maximum energy from warm saline streams in underground geothermal formations.
Innovation Solution
A process that extracts both thermal energy and latent osmotic energy from warm saline streams using a semi-permeable membrane to separate water and salts, with the thermal energy being converted into electricity before or after osmotic energy is harnessed, thereby increasing efficiency and reducing fouling and inefficiencies in the energy extraction processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If pressure retarded osmosis is used to generate electricity from geothermal streams, then osmotic energy is converted into electricity, but power density is low and the process is uneconomic
Solution Approach 1:
The patent combines two energy conversion processes: thermal energy conversion (via heat exchanger and turbine) and osmotic energy conversion (via semi-permeable membrane). The warm saline stream first passes through a thermal power unit to generate electricity from thermal energy, then the cooled stream enters an osmotic power unit to generate additional electricity from osmotic pressure. This merging of processes maximizes power density and economic viability by harvesting both thermal and osmotic energy from the same geothermal stream.
2Power
If thermal energy is converted to electricity before osmotic energy extraction, then thermal power is generated, but the warm stream may cause membrane fouling and reduce osmotic efficiency
Solution Approach 1:
The patent applies preliminary action by first cooling the warm saline stream through thermal energy conversion before subjecting it to osmotic energy extraction. The stream passes through a heat exchanger and turbine to generate thermal power, which reduces the stream temperature. This preliminary cooling action prevents membrane fouling and maintains optimal membrane performance during subsequent osmotic energy conversion, as the membrane operates within its temperature tolerance range.
3Power
If the semi-permeable membrane separates water and salts in warm saline streams, then osmotic energy is harnessed, but membrane fouling increases and reduces power density
Solution Approach 1:
The patent applies preliminary cooling action by passing the warm saline stream through a thermal power unit before it enters the osmotic power unit. This preliminary temperature reduction prevents thermal fouling of the semi-permeable membrane, maintaining its separation efficiency and preventing performance degradation. The cooled stream then undergoes osmotic energy conversion with minimal fouling, maximizing power density.
4Loss of energy
If both thermal and osmotic energy are extracted from the same geothermal stream, then energy efficiency is maximized, but system complexity increases
Solution Approach 1:
The patent merges two energy conversion systems into a sequential configuration where the output of one process feeds into the other. The thermal power unit (heat exchanger and turbine) is connected in series with the osmotic power unit, allowing the same geothermal stream to undergo both thermal and osmotic energy conversion. This merging approach maximizes energy extraction efficiency while managing system complexity through a straightforward series arrangement.
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 enhances power generation efficiency by leveraging both thermal and osmotic energy from geothermal streams, reducing membrane fouling and increasing power density, making the process more economically viable by complementing the energy extraction methods and optimizing membrane performance.
Implementation Method 1
a semipermeable membrane is used to separate a less concentrated solution from a more concentrated solution. The membrane causes solvent to pass from the less concentrated solution (with low osmotic pressure) to the more concentrated solution (with high osmotic pressure) by osmosis, and this leads to an increase in pressure on the side of the membrane to which the solvent diffuses
Implementation Method 2
the temperature of said warm saline stream is reduced before said stream enters the osmotic power unit by passage through a thermal power unit in which thermal energy present in said stream is converted into electricity
Data Source
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AI summary
A process for the generation of electricity comprises the steps of extracting a warm saline stream from a geothermal formation, and converting latent osmotic energy present in said stream into electricity by passage through an osmotic power unit in which said stream is passed over one side of a semi-permeable membrane which permits the passage of water but not the passage of salts, an aqueous stream of lower salinity than said stream being passed over the other side of said membrane. The temperature of said warm saline stream is reduced before said stream enters the osmotic power unit by passage through a thermal power unit in which thermal energy present in said stream is converted into electricity.