Techno-economic analysis of the Li-ion batteries and reversible fuel cells as energy-storage systems used in green and energy-efficient buildings

Abstract

Green buildings have become broadly adopted in commercial and residential sectors with the objective of minimizing environmental impacts through reductions in energy usage and water usage and, to a lesser extent, minimizing environmental disturbances from the building site. In this paper, we develop and discuss a techno-economic model for a green commercial building that is 100% powered by a photovoltaic (PV) system in stand-alone configuration. A medium-sized office building in El Paso, TX was modelled to rely on a photovoltaic system to supply all of its electricity needs either directly from the PV system or through an energy-storage system (ESS) using Li-ion batteries (LIBs) or reversible fuel cells (RFCs). Cost results show that a 400-kW PV system can generate electricity at a cost of 2.21 cents/kWh in El Paso, TX and the average levelized cost of energy storage (LCOS) using 450-kW RFC is ~31.3 cents/kWh, while this could reach as low as 25.5 cents/kWh using a small LIB ESS. While the RFC provides the flexibility required to meet building-energy demand, LIBs may not be able to meet building needs unless the storage size is increased substantially, which in turn incurs more energy-storage cost, making LIBs less favourable from an economic perspective. Sensitivity analysis revealed that capital cost, discount rate and expected system lifetime play key roles in shaping the LCOS in both systems.

Uncertainty and simulation‐based cost analyses for energy storage systems used in green buildings

“…20 This technology usually operates at temperatures between 600 C and 800 C. Reversible fuel cells based on the proton exchange membrane (PEM) use a polymeric membrane deposited with catalyst layers using platinum group metals from both sides. This technology operates at temperatures between 70 C and 120 C. 5 On the other hand, fuel cells differ from batteries in the operating schemes. In essence, fuel cells can operate continuously as long as the feedstock is available; thus, can have zero idle time.…”

“…Excess and shortage cases are considered losses because they both induce financial losses. To minimize the losses and avoid curtailing the generated electricity if not used, energy storage systems (ESS) are often introduced as a viable economic solution that can reduce the energy losses and improve the building's resiliency at the same time 5 …”

“…The BOP consists of several subsystems that maintain the operations of the fuel cell and electrolysis modes. That is done by transporting required gases and power to the stack, regulating temperature and humidity inside the stack, and finally regulating the humidity and pressure of the hydrogen in the hydrogen dryer, compressor, and storage tanks 5 . On the other hand, LIBs have a higher response time and tend to remain idle most of the time depending on the storage capacity and charging rate 12 …”

“…To minimize the losses and avoid curtailing the generated electricity if not used, energy storage systems (ESS) are often introduced as a viable economic solution that can reduce the energy losses and improve the building's resiliency at the same time. 5 There are five major types of ESS: electrical, chemical, electrochemical, mechanical, and thermal. 6 ESS differ majorly in structure, mode of operation, roundtrip efficiency, and expected lifetimes.…”

“…That is done by transporting required gases and power to the stack, regulating temperature and humidity inside the stack, and finally regulating the humidity and pressure of the hydrogen in the hydrogen dryer, compressor, and storage tanks. 5 On the other hand, LIBs have a higher response time and tend to remain idle most of the time depending on the storage capacity and charging rate. 12 Most research on the economics of energy storage systems tends to do a techno-economic analysis while disregarding the risk posed on the levelized cost of storage (LCOS) by ignoring uncertainty in parameters.…”