Introduction
This study explores the integration of a Liquid Air Energy Storage (LAES) system with a
power generation system based on Liquid Hydrogen (LH2) regasification. The integration
aims to address the fluctuating nature of power demand and enhance the economic viability
of hydrogen as an energy carrier. The study proposes three configurations: no-storage,
partial-storage, and full-storage systems, each with distinct operational modes and economic
implications. Governments and industries are striving to transition towards a net-zero society
by replacing fossil fuel-based systems with low-carbon alternatives. Hydrogen, particularly
green hydrogen produced via electrolysis using renewable energy, is seen as a key technology
in this transition. However, the geographical disparity in renewable energy resources
necessitates the strategic importation of green hydrogen. Liquid hydrogen (LH2) is a
promising carrier due to its high energy density and ease of regasification.
Summary
Liquid hydrogen (LH2) can serve as a carrier for hydrogen and renewable energy by
recovering the cold energy during LH2 regasification to generate electricity
The study provides a detailed analysis of heat exchange, energy, exergy, and techno-
economic performance for the proposed systems. The analysis reveals that
approximately 86% of the cold energy from LH2 can be recovered for power
generation. The energy analysis compares the net power output of the three
systems, with the full-storage system outperforming in peak power generation due to
its higher energy storage capacity. Exergy analysis assesses the irreversibility of
each system, highlighting the efficient heat exchange achieved through multi-stage
compression. The techno-economic analysis evaluates the economic feasibility of
the proposed systems under various scenarios, showing that the full-storage system
demonstrates greater economic viability, especially with government subsidies. The
study underscores the potential economic benefits, particularly with appropriate
government support.
Proposed Systems
1. No-Storage System:
o Configuration: Utilizes a recuperated Brayton cycle and two Organic
Rankine Cycles (ORCs) without energy storage.
o Operation: Generates power continuously, irrespective of power demand
fluctuations.
o Advantages: Simple configuration and operation, does not require additional
infrastructure for energy storage.
o Disadvantages: Does not benefit from the cold energy available from liquid
hydrogen, may be less efficient in meeting variable power demand.
2. Partial-Storage System:
o Configuration: Offers flexible operational modes, switching between power
generation and energy storage based on demand.
o Operation: During peak times, cold energy is used for power generation;
during off-peak times, it is diverted to store liquid air.
oAdvantages: Flexibility in operation to meet variable power demand, can
improve the efficiency of cold energy utilization.
o Disadvantages: Requires additional infrastructure for liquid air storage, may
be more complex to operate and maintain.
3. Full-Storage System:
o Configuration: Simplifies the configuration by eliminating the need for
operational mode transitions.
o Operation: Stores a portion of the produced energy as liquid air throughout
the day, maximizing the difference in power production between peak and off-
peak times.
o Advantages: Highest efficiency in utilizing cold energy, can maximize the
benefits of variable power demand, shows greater economic viability
especially with government subsidies.
o Disadvantages: Requires significant infrastructure for liquid air storage, may
be more expensive to implement.
Heat Exchange Analysis
Objective
The heat exchange analysis aims to evaluate the performance of cold energy recovery from
liquid hydrogen (LH2) in the proposed systems.
Results
• Recuperated Brayton Cycle (RBC): Plays a dominant role in recovering cold
energy, with approximately 47% of the total cold energy recovered using this process.
• Organic Rankine Cycles (ORCs): Performance varies based on system
configuration. In the partial-storage system, cold energy is used to liquefy air during
off-peak times and generate power during peak times.
• Full-Storage System: Benefits from a larger liquid air storage capacity, increasing
the difference in power production between peak and off-peak times.
Energy Analysis
Objective
The energy analysis aims to evaluate and compare the power generation performance of the
three systems.
Results
• No-Storage System: Consistently generates 7.21 MW of power regardless of demand
fluctuations.
• Partial-Storage System: Consumes approximately 0.5 MW of power for liquefying
and storing air, leading to additional power generation during peak times.
• Full-Storage System: Stores liquid air throughout the day and uses it to generate
additional power during peak times, enhancing energy storage capacity and power
production.
Exergy Analysis
Objective
The exergy analysis aims to assess the irreversibility of each system and identify the
equipment most associated with exergy destruction and loss.
Results
• Exergy Efficiency: Varies between systems based on configuration and operational
modes. The highest proportion of exergy destruction occurs in the RBC section.
• Partial-Storage System: Experiences greater exergy loss during compression and
expansion in the air storage and release sections compared to the ORC1 section.
• Full-Storage System: Achieves higher heat exchange efficiency by reducing
irreversibility through multi-stage compression and heat exchange.
Techno-Economic Analysis
Objective
The techno-economic analysis aims to evaluate the economic feasibility of the proposed
systems under various scenarios.
Results
• Capital Costs: Introducing a liquid air storage system significantly increases capital
costs due to the need for compressors, expanders, and storage tanks.
• Annual Revenue: The full-storage system increases annual revenue due to its larger
liquid air storage capacity.
• Government Subsidies: The analysis shows that the full-storage system becomes
more economically viable than the no-storage system when subsidies exceed 14.9%.
Scenario Analysis
Scenario 1: Changes in Peak Time Hours
• Impact of Peak Time Duration: Longer peak times significantly influence system
performance in terms of energy and economics, particularly revenue from electricity
sales.
• Full-Storage System: Shows the steepest increase in net present value (NPV) with
longer peak times due to reduced capital costs and increased profits from electricity
sales.
Scenario 2: Changes in Subsidy Policies
• Role of Government Support: Energy storage systems play a crucial role in
addressing power demand fluctuations by storing energy during low demand and
supplying it during high demand.
• Analysis: The full-storage system becomes more economically viable than the no-
storage system when subsidies exceed 14.9%. The partial-storage system requires
more substantial support up to 34.2% to surpass the no-storage system’s economic
feasibility.
Scenario 3: Fluctuations in Electricity Prices
• Importance of Electricity Prices: Energy storage systems generate profits by storing
energy when electricity prices are low and selling it at higher prices. The full-storage
system gains economic superiority with higher on-peak electricity prices.
Conclusion
The integration of LAES with LH2-based power generation systems offers a promising
approach to enhancing thermodynamic performance and meeting high power demand. The
study’s findings highlight the potential for significant economic benefits, particularly with
appropriate government support. Further exploration into integrating other energy storage
systems could address the imbalance between power demand and supply, paving the way for
sustainable energy solutions.
