Electrolytic Cell Power Ramping for Variable Renewable Surplus

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Solution Overview

Problem

Conventional water electrolysis systems face inefficiencies in utilizing renewable energy due to limitations in following power variations and high hydrogen production costs, primarily due to poor prediction accuracy and mismatched response speeds between renewable energy and electrolytic cell capabilities.

Innovation Solution

A water electrolysis system that calculates an estimate of renewable energy power and surplus power, then uses a conversion process based on the acceptable ramp rate of the electrolytic cell to generate an electrolysis power command value, which is filtered to manage power input effectively, thereby improving utilization efficiency and reducing hydrogen production costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If renewable energy power is directly input into the electrolytic cell, then the electrolysis apparatus can operate at high capacity, but the electrolytic cell cannot follow rapid changes in renewable energy power due to its response speed limitations

Engineering Contradiction:
Improvehydrogen production capacityVSAvoidresponse speed of electrolytic cell
Core Design Contradiction:
ProductivityVSSpeed

Solution Approach 1:

The control device performs preliminary calculations to predict future renewable energy power and determines electrolysis power command values in advance, considering the acceptable ramp rate of the electrolytic cell. This allows the system to prepare appropriate power commands before the renewable energy power actually changes, enabling the electrolytic cell to operate at high capacity while smoothly following power variations within its response capabilities.

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If the electrolysis apparatus capacity is increased to utilize the full variation range of renewable energy power, then more renewable energy can be utilized, but the utilization rate of the electrolytic cell decreases due to idle capacity

Engineering Contradiction:
Improveutilization of renewable energy variation rangeVSAvoidutilization rate of electrolytic cell
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The system dynamically adjusts the electrolysis power command value based on predicted renewable energy power and the acceptable ramp rate, rather than operating at a fixed capacity. This allows the electrolysis apparatus to utilize its full capacity when renewable energy is abundant while smoothly ramping up or down to match actual power availability, maintaining high utilization rates across varying conditions.

Inventive Principle:
Principle #15Dynamics

3Productivity

If the electrolytic cell operates at maximum capacity to produce hydrogen efficiently, then hydrogen production cost decreases, but the system cannot accommodate variations in renewable energy power

Engineering Contradiction:
Improvehydrogen production efficiencyVSAvoidaccommodation of renewable energy variations
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The control device continuously monitors renewable energy power and uses feedback control to calculate appropriate electrolysis power command values. By considering the acceptable ramp rate and predicting future power levels, the system adjusts the electrolysis power dynamically to maintain efficient operation while accommodating renewable energy variations, preventing both overcapacity and underutilization.

Inventive Principle:
Principle #23Feedback

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 the utilization rate of the electrolysis apparatus, reduces power wastage, and increases the operational efficiency of hydrogen production, even under varying renewable energy conditions, by moderating power changes and optimizing power allocation.

Implementation Method 1

hydrogen is produced by inputting a part of the power into an electrolytic cell

Methodology Applied
Scientific EffectElectrolysis: Electrolysis

Data Source

PatentEP4283813A1Water electrolysis system managing power supply of renewable energy
Publication Date: 2023.11.29 HITACHI LTD
  • EP4283813A1 patent drawingFigure 1A~1B
  • EP4283813A1 patent drawingFigure 2
  • EP4283813A1 patent drawingFigure 3A~3B

AI summary

To improve utilization rate of a water electrolysis apparatus in a water electrolysis system that manages power supply of renewable energy. A water electrolysis system manages power supply of renewable energy for a system and an electrolytic cell of a water electrolysis apparatus. The water electrolysis system: obtains renewable energy power and operation information of renewable energy device from a power conversion apparatus connected to the renewable energy device; calculates an estimate value of the renewable energy power based on the renewable energy power and the operation information; calculates an estimate value of a surplus power at a predetermined timing based on the estimate value of the renewable energy power and a sold power; calculates an electrolysis power command value by performing a conversion process based on an acceptable ramp rate of the electrolytic cell with respect to the estimate value of the surplus power before the predetermined timing and the estimate value of the surplus power at the predetermined timing; and inputs the electrolysis power command value into a power conversion apparatus of the electrolytic cell.