Hydrogen Storage via Methane Conversion in Natural Gas Grid
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Solution Overview
Problem
Hydrogen as a secondary energy carrier faces challenges in distribution and storage due to its physical and fire-related differences from natural gas, requiring conversion into methane for safe transportation and storage in the natural gas grid, and subsequent conversion back into hydrogen for efficient energy conversion in fuel cells, which results in inefficiencies and the need for a separate infrastructure.
Innovation Solution
Converting electrolysis-derived hydrogen into methane with synthesis gas, storing and transporting it in the natural gas grid, and then reforming it back into hydrogen in a steam reformer, which doubles the hydrogen quantity, allowing for efficient energy conversion in fuel cells and utilizing carbon dioxide in a closed loop for carbon neutrality and chemical raw material purposes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrogen is transported and stored directly, then storage and transport infrastructure is required, but hydrogen has physical and fire-related differences from natural gas leading to safety problems and infrastructure complexity
Solution Approach 1:
The patent changes the chemical composition parameter of hydrogen by converting it into methane through methanation process. This parameter change allows the energy carrier to be transported and stored using existing natural gas infrastructure, eliminating safety issues associated with hydrogen transport while maintaining the ability to convert back to hydrogen at the point of use through steam reforming
Solution Approach 2:
The patent introduces methane as an intermediary substance between electrolysis-produced hydrogen and the natural gas distribution network. The methane serves as a carrier that can be safely transported through existing infrastructure, and can be converted back to hydrogen at the consumption point, thus mediating between the production and utilization requirements
2Ease of operation
If hydrogen is converted into methane and then back into hydrogen, then transportation and storage in existing gas grid is enabled, but hydrogen quantity is lost in the conversion process
Solution Approach 1:
The patent applies preliminary action by mixing synthesis gas with electrolysis-produced hydrogen before methanation. This preliminary enrichment of the synthesis gas with additional hydrogen ensures that when methane is later converted back to hydrogen through steam reforming, the total hydrogen yield exceeds the original input, thereby compensating for losses and achieving net hydrogen gain
Solution Approach 2:
The patent changes the stoichiometric parameters of the methanation and steam reforming processes by introducing additional hydrogen in the preliminary mixing stage. This parameter modification ensures that the chemical reactions produce more hydrogen upon reforming than was originally input, transforming the conversion process from a lossy operation to a hydrogen-generating operation
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 method effectively doubles the volume of hydrogen for energy conversion, enhances energy efficiency, and reduces carbon emissions by utilizing biomass-derived carbon dioxide, providing a more efficient and climate-neutral energy storage and conversion system.
Implementation Method 1
hydrogen produced by electrolysis using energy from the power grid or a wind or solar system
Implementation Method 2
hydrogen produced by electrolysis using energy from the power grid or a wind or solar system is converted into methane with synthesis gas
Implementation Method 3
the amount of natural gas corresponding to the methane introduced is taken from the gas network and broken down into hydrogen and carbon dioxide in a steam reformer
Implementation Method 4
the hydrogen separated from the carbon dioxide is used to generate electricity in a fuel cell
Data Source
AI summary
Hydrogen is a secondary energy carrier for renewable energies. Hydrogen is usually produced by electrolysis of water to store electrical energy. In a fuel cell, the hydrogen can be converted back into electrical energy. The natural gas network is suitable for storing hydrogen. Owing to the great physical and combustive differences between natural gas and hydrogen, the accommodation of the latter in the gas network is very restricted. The invention relates to a method by which hydrogen originating from electrolysis is reacted with synthesis gas to form methane, and the methane is introduced into the gas network. The introduced methane or the equivalent thereof in natural gas is withdrawn from the gas network and converted back into hydrogen and carbon dioxide in a reformer. To form 1 mole of methane, 2 mol of hydrogen from the electrolysis must be added to the synthesis gas. When the methane is decomposed again, twice the amount of hydrogen, 4 mol, is obtained. The synthesis gas can be obtained from biomass, e.g. wood, coal, or carbon compounds. A preferred method is to react the carbon dioxide that is formed in the reformer and hydrogen with an equimolar amount of fresh methane/natural gas. This produces a particularly economical and pure synthesis gas. The carbon dioxide is circulated and does not pass into the environment. The secondary energy carrier, hydrogen, is stored and distributed in the natural gas network as methane, similar to natural gas, is doubled in quantity when withdrawn, and is supplied as hydrogen to fuel cells for conversion back into electricity.