# On Hybrid Nanogrids Energy Management Systems--An Insight into Embedded Systems
## 4 Energy Storage Systems  
While EMSs are proving to be the key to intelligent energy management in nanogrids, they are closely linked to energy storage solutions. EMSs have the ability to anticipate energy demand in real-time and monitor the status of power generation resources, especially renewables that are intermittent. When the EMS detects excess energy being generated, it can direct it to an ESS like lithium-ion batteries, thermal storage, or supercapacitors. This exchange of information between EMSs and ESS optimizes the use of resources and ensures a constant supply of energy, even during fluctuations in production or peaks in demand. As a result, nanogrids equipped with these advanced EMSs are able to maximize their energy efficiency while offering greater reliability in power distribution. Electrical energy storage involves various technologies, including electrostatic energy storage such as capacitors and supercapacitors, as well as magnetic/current energy storage like superconducting magnetic energy storage (SMES) [25]. Thermal energy storage involves different methods, such as sensible heat storage, latent heat storage, and thermochemical heat storage [83; 84; 85; 86]. Mechanical energy storage involves storing kinetic energy through mechanisms like flywheels and potential energy through systems like pumped-storage hydropower (PSH) and compressed air energy storage (CAES) [87]. Chemical energy storage includes options such as hydrogen and methane [25]. Lastly, electrochemical energy storage encompasses batteries such as lead-acid, lithium-ion, and nickel-cadmium, as well as fuel cells [88]. Among all these energy storage technologies, batteries have been proven to be the most adapted for energy storage in embedded systems. In common with solar PV and wind technologies, battery storage has shown rapid declines in cost in recent years, which are expected to continue decreasing in the future. By 2030, the total installed cost of lithium-ion batteries in stationary applications has the potential to decrease by at least 54%, creating new economic opportunities for electricity storage and expanding their role in offering grid flexibility services [89]. Additionally, other battery storage technologies show significant potential for cost reduction. \"Flow batteries\" could experience a two-thirds decrease in total installed cost by 2030. High-temperature sodium sulfur (NaS) and sodium nickel chloride batteries are also expected to become more affordable, with projected cost reductions of 56-60% by 2033 and improved performance. Flywheels could have a 35% reduction in installed costs by 2030. Furthermore, compressed air energy storage (CAES), leveraging mature technologies, could witness a 17% cost decline by the same timeframe [89]. Therefore, by utilizing battery storage, the need to rely on diesel generators as a backup or supplementary power source can be reduced or eliminated, thereby reducing carbon emissions and dependence on fossil fuels. The proposed storage technologies are listed in Figure 5 based on the values of various technical and commercial parameters of different energy storage technologies with data from [90]. Each parameter can be given a competitive score from 1 to 5, with 5 being the best and 1 being the worst. Energy storage systems have the potential to improve the performance of various applications, with particular emphasis on their suitability for transport and utility-scale applications. In some cases, ESSs play a key role in determining the adoption of certain technologies, such as electric vehicles. For transport applications, the time and power ranges are from seconds to hundreds of minutes and from tens of kilowatts to tens of megawatts [91]. For utility applications, the time and power ranges are from tens of minutes to hours and from MW to GW. In the context of utility or renewable energy integration, key performance criteria include energy storage capacity, power output, and the overall life cycle of the system.