The need to reduce greenhouse gas emissions has catalysed the rapid growth of renewable energy worldwide. However, the intermittent nature of renewable energy requires the support of energy storage systems (ESS) to provide ancillary services and save excess energy for use at a later time. ESS policies have been proposed in some countries to support the renewable energy integration and grid stability. These policies are mostly concentrated a. The need to reduce greenhouse gas emissions has catalysed the rapid growth of renewable energy worldwide. However, the intermittent nature of renewable energy requires the support of energy storage systems (ESS) to provide ancillary services and save excess energy for use at a later time. ESS policies have been proposed in some countries to support the renewable energy integration and grid stability. These policies are mostly concentrated around battery storage system, which is considered to be the fastest growing energy storage technology due to its efficiency, flexibility and rapidly decreasing cost. ESS policies are primarily found in regions with highly developed economies, that have advanced knowledge and expertise in the sector. This paper provides a comprehensive review of ESS policies worldwide, identifying the different goals, objectives and the expected outcomes. It discusses the benefits of having such policies, the impact they have and opportunities they have created in the energy sector. Some of the countries that have been identified to have mature ESS policies are United States of America, United Kingdom, Germany, South Korea, Japan, China and Australia. These countries have the most advanced storage technologies and are constantly undertaking research, development and demonstration (RD&D) projects sponsored by the industry and government. ESS policies mostly promote energy storage by providing incentives, soft loans, targets and a level playing field. Nevertheless, a relative. ••Prominent tools and facilitators that are considered when making ESS policy to act as a guide for creating effective policy.••Trends in ESS policy worldwide.••Similarities in policy, which in most cases encourages incentives, soft loans, targets and competition.••Impacts and opportunities attached to ESS policy for emerging economies are presented.Battery energy storage systemEnergy storage systemPolicyRenewable energyEnergy storage systems (ESS) have been around for a long time with the earliest and most popular form being the Pumped Hydro Storage. Other forms of ESS are compressed air, flywheel, super-capacitor and battery. All these ESS technologies have their advantages and disadvantages and are used according to the application of the ESS and some other considerations such as cost, location and whether high energy or high power functions are needed. In order to reduce the carbon output from traditional fossil fuel powered power plants and vehicles, several countries have promoted the use of renewable energy sources such as solar PV, wind and electrical vehicle (EV). Renewable energy sources are intermittent in nature and as such need ESS to provide ancillary services and to stabilize the output or to store electricity for use at a later time when required. ESS technologies are also used in the power sector for grid stability, power back up and energy arbitrage. These functions contribute in stabilising the power sector and hence save a lot of money for the sector.Many energy related policies, such as renewable energy policies and market reforms have been implemented in many parts of the world. However, ESS policies have only recently started to be adopted and promoted in some countries. It is only with ESS policies that barriers blocking the development o. In general, policies are designed to establish boundaries and provide regulatory guidelines. According to the Energy Storage Association (ESA), the policy tools fall under three categories which are value, access and competition. The policy should increase the value of ESS by establishing deployment targets, incentive programs and creating markets for it. The policy should establish access to ESS by reducing limitations for grid interconnection, adjusting codes and standards and promoting multiple use functionality of storage. The drivers of an ESS policy are illustrated in Fig. 1. The prime objectives of an ESS policy are:••To inaugurate the best practices that will sustain the positive economic impact of energy storage development on consumers and local communities.••To promote and encourage ESS implementations amongst ratepayers.••.
