PTQ Gas 2022 Issue

Digital twins heat up the capabilities of energy storage plants How to support future energy security by enhancing energy storagewith automated digital twins

ALAN MESSENGER Optimal Industrial Automation

R enewable natural gas (RNG), solar, wind, and other sus- tainable resources are at the core of decarbonisation and energy transition strategies. To effectively support their large-scale adoption, it is necessary to ensure dispatch- able generation and predictable supply to the grid. Future-oriented energy storage plants that leverage cutting-edge industrial automation, such as digital twin technology, can succeed in this by taking advantage of accurate, real-time simulation models. Renewable energy sources, such as RNG, provide multiple benefits. In addition to supporting ambitious decarbonisation and net-zero goals, they offer the most economical way to create a decentralised power sys- tem. This, in turn, can help achieve universal, reliable and affordable access to power. For these reasons, the use of alter- native energy sources is increasing in popularity, representing almost 11% of power generated globally and forming a major part of the energy mix in many counties. 1 For example, renewable energy use in Norway covered more than 60% of total consumption in 2018. 2 One of the key challenges that must be overcome to support the increasing adoption of renewable natural gas and other replenisha- ble resources for power generation is balancing fluctuating electric - ity demands with the intermittent nature of some renewable sources. For example, to succeed in decar - bonisation efforts and avoid any wastage, it is essential to prevent curtailment. This occurs when a power generation system is pre - vented from exporting to the grid,

usually because of a temporary con - straint caused by congestion, essen- tially wasting potential low-carbon energy supplies. Importance of advanced energy storage solutions To fully utilise generation capac- ity, robust, reliable, and highly effi - cient energy storage solutions are required, as they can provide the level of flexibility needed to main - tain stable and consistent supply to the grid. Strategies such as these can support peak shaving and load shifting activities. Compressed-air energy storage (CAES), in its various thermo-me - chanical forms, is among the most promising technologies available at a commercial scale for high-capac - ity energy management. By saving potential energy in the form of com - pressed air, these systems are able to generate large amounts of power on demand. Also, apart from access to a cav - ern, CAES facilities are not depend- ant on specific geographies, unlike pumped hydropower, and their daily self-discharge is very low, making it possible to effectively keep the stored energy for long periods without any considerable losses. In addition, due to the well- proven nature of the underlying equipment, CAES plants typically have a designed lifetime of over 40 years, which keeps the overall costs per unit of energy (or power) among the lowest for all available storage technologies. To achieve these results, CAES facilities can utilise different config - urations, one being the innovative liquid air energy storage method, which leverages thermo-mechanical

principles to advance the benefits of CAES. In the liquid air variant, air is purified and cooled to its liquid state during the charge phase. It is then stored at cryogenic tempera - tures and low pressure in suitable tanks. When discharged, the liquid air is pumped to a high pressure, evaporated, and heated to expand the liquid air stream. The resulting high-pressure gas drives a set of turbines in a power recovery unit. Liquid air energy storage The liquid air energy storage cycle described above utilises compo - nents that are commonly found in conventional power stations and industrial air separation plants. Therefore, they offer multiple advantages. Firstly, they are well proven and broadly accepted. Secondly, this equipment is widely available to support commer - cial-scale facilities. Finally, they have well-understood maintenance requirements. Furthermore, the use of liquid air energy storage systems leads to energy densities that can be up to 8.5 times higher than conven - tional compressed air alternatives. 3 Therefore, it is possible to create compact plants that are more eco - nomical, efficient, easier to imple - ment, and suitable for sites with limited available space. In addition, the power generation cycle eliminates the need for com - bustion and the associated carbon emissions while also supporting ‘cold recycle’ practices. Waste heat from the liquefier compressors is recovered within the process for highly efficient operations and the storage and recycling of thermal energy released during discharge

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