Techno-economic analysis and optimization of electrochemical energy storage solutions
Abstract: The need to integrate the rapidly growing share of variable renewable energy sources in the power sector requires solutions that are capable of mitigating the intermittent nature of these sources. They are expected to constitute the backbone of the electricity generation system in the coming years in order to reach ambitious goals in terms of energy security and reduction of environmental impact. Energy storage appears a promising solution to improve the capability of variable renewable plants to meet the energy demand at all times, mainly through the re-allocation of the generation surplus.Among the several options that can favor the integration of variable renewables, electrochemical storage technologies - batteries and electrolysis cells - constitute the focus of this dissertation. These approaches can be used to defer substantial quantities of energy for medium to long time intervals, are largely location independent, and are considered a strategic part of the decarbonization pathway in the European Union, which represents the geo-political framework under investigation.Battery storage systems are analyzed in both small- and large-scale settings to quantify the energetic and economic benefits deriving from a more efficient use of renewable energy. A small-scale battery system connected to a residential PV plant is analyzed and the results are compared to a demand response strategy for load shifting. The integration of a large-scale battery facility in the energy system of an island is also simulated and the results show a much lower level of renewable energy curtailment. In both the situations the projected costs of the battery technologies are used to assess their techno-economic performance.Solid oxide electrolysis cells (SOECs) as employed in power-to-gas upgrading of biogas constitute the second electrochemical energy storage pathway that was studied. The upgrading process sought to increase the methane content in the biogas by directly converting the embedded carbon dioxide through high-temperature electrolysis and methanation. This process showed energy conversion efficiencies higher than 80%. However, its economic viability depends on the cost of electricity, the cost of the core components, and the price of natural gas.
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