Electrolysis-Desalination Heat Integration for eFuels
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Solution Overview
Problem
Current processes for producing synthetic hydrocarbons face challenges in achieving high energy efficiency, minimizing carbon footprint, and stabilizing electrical grid demand, particularly due to fluctuations in renewable energy sources and grid stability.
Innovation Solution
A process integrating a hydrocarbon synthesis system with a renewable feed and carbon/energy recovery system, including heat integration between a thermal desalination unit and an electrolysis unit, which uses seawater and thermal energy to produce desalinated water and hydrogen, optimizing energy use and carbon efficiency while stabilizing grid frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electrolysis unit operates continuously to produce hydrogen, then hydrogen production is maintained, but electrical grid stability deteriorates due to fluctuating renewable energy supply
Solution Approach 1:
The patent implements a preliminary action by storing hydrogen produced during periods of high renewable energy availability in underground salt caverns. This allows the electrolysis unit to operate when energy is abundant and inexpensive, storing the product for later use when grid stability concerns arise or when energy demand is high, thus decoupling hydrogen production from real-time grid conditions.
Solution Approach 2:
The patent introduces an intermediary storage system (underground salt caverns) between the electrolysis unit and the hydrogen consumption processes. This intermediary buffer absorbs the fluctuations in renewable energy supply, allowing continuous hydrogen production during favorable conditions while providing a reserve during periods of grid instability, effectively mediating between variable supply and steady demand.
2Productivity
If thermal desalination unit uses high temperature heat transfer fluid, then desalination efficiency is improved, but energy consumption increases
Solution Approach 1:
The patent merges the thermal desalination unit with the electrolysis unit by integrating their thermal systems. The heat transfer fluid loop connects both units, allowing thermal energy to be shared and reused. High-temperature heat from the electrolysis process heats the desalination unit, while the desalination unit's lower-temperature output heat is returned to the electrolysis unit, creating a combined system that improves overall efficiency.
Solution Approach 2:
The patent recovers thermal energy that would otherwise be discarded. The heat transfer fluid circulates through both the electrolysis unit and the thermal desalination unit, capturing waste heat from one process and utilizing it in the other. This recovery system converts what would be wasted thermal energy into useful heating for desalination, reducing overall energy consumption.
3Loss of energy
If heat transfer fluid circulates between electrolysis and desalination units, then energy efficiency is improved, but system complexity increases
Solution Approach 1:
The patent implements a universal heat transfer fluid system that serves multiple functions: it provides cooling for the electrolysis unit, heating for the thermal desalination unit, and acts as a heat storage medium. This single multi-functional system replaces what would otherwise require separate cooling and heating systems, reducing overall system complexity despite the integrated nature of the solution.
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 integrated system enhances energy efficiency, reduces carbon footprint, and stabilizes electrical grid demand by minimizing external energy reliance and maximizing hydrogen and carbon efficiency, allowing continuous operation despite grid fluctuations.
Implementation Method 1
adding seawater and a first amount of thermal energy to a thermal desalination unit to produce a desalinated water stream
Implementation Method 2
exchanging heat between fluidly segregated 1a) saline water and 2a) first water vapor to produce fluidly segregated 1b) preheated saline water and 2b) first condensed desalinated water
Implementation Method 3
The demineralized water stream and an amount of electrical energy are added to an electrolysis unit to produce a hydrogen stream, an oxygen stream, and a second amount of thermal energy
Implementation Method 4
A portion of the second high temperature heat transfer fluid stream is heated to form the first high temperature heat transfer fluid stream
Implementation Method 5
exchanging heat between fluidly segregated 1a) saline water and 2a) first water vapor to produce fluidly segregated 1b) preheated saline water and 2b) first condensed desalinated water
Data Source
AI summary
An eFuels plant and process for producing synthetic hydrocarbons using renewable energy are disclosed. The eFuels plant comprises a hydrocarbon synthesis (HS) system and a renewable feed and carbon/energy recovery (RFCER) system. The RFCER comprises a heat integration system between an electrolysis unit and a thermal desalination unit. The thermal desalination unit is configured to receive seawater and a first amount of thermal energy and to produce a desalinated water stream and a brine effluent stream. The electrolysis unit is configured to receive a demineralized water stream and an amount of electrical energy to produce a hydrogen stream, an oxygen stream, and a second amount of thermal energy, wherein the second amount of thermal energy is absorbed by a second low temperature heat transfer fluid stream to produce a second high temperature heat transfer fluid stream. A fluidly segregated piping system containing a heat transfer fluid is configured to withdraw heat from the electrolysis unit and deliver heat to the thermal desalination unit. A control system manages flows of the heat transfer fluid between the electrolysis unit and the thermal desalination unit, the addition of heat to the flow to the thermal desalination unit, and/or the removal of heat from the flow to the electrolysis unit.