# Proxy Signature-Based Management Model of Sharing Energy Storage in Blockchain Environment
## 1 Introduction  
With the increase in renewable energy sources (RESs) such as wind turbines and photovoltaic generation, massive amounts of clean energy are supplied to users all over the country, reducing carbon dioxide emissions and slowing down fossil energy consumption significantly [1]. However, the security and stability of power systems are worsening because of the intermittent, highly erratic and weather-dependent characteristics of RESs [2; 3]. On the other hand, China has put forward rigid requirements for the consumption rate of RESs in each province in order to accelerate the energy transformation and stimulate the development of RESs' industry chain [4]. To address the above problems, energy storage systems are employed to provide a reliable solution [5; 6]. By the end of 2019, the total installed capacity of China's energy storage projects reached 32.4 GW, of which the installed capacity of electrochemical energy storage was 1706.9 MW, with a year-on-year increase of 59.4%. Although the development of energy storage technology and related projects is extremely rapid, the return on investment in energy storage projects is not optimistic because of the smaller price difference of peak and valley electricity, the developing and incomplete electricity ancillary service market and the lower utilization rate. In this situation, sharing energy storage (SES) will be a novel business model in the energy storage field, improving the utilization rate of idle energy storage resources and making profits in a competitive market. In [7], based on a sharing economy, a newbusiness model of battery energy storage systems is proposed. The study demonstrates that SES can bring additional profits for the owners of energy storage facilities and will attract investors. An investment decision model of SES is proposed in [8], which is a non-convex storage investment game admitting a unique Nash equilibrium. Cooperative game theory is applied in the modeling of participants (i.e., suppliers and demanders of energy storage resources), and the cooperative benefits in SES can be proved [9]. In [10], a concept of cloud energy storage (CES), where demanders can gain on-demand access to a sharing pool of grid-scale energy storage resources, is proposed. The energy storage facility of CES is large-scale and centrally controlled by the CES operator. Although the feasibility and economy of SES have been verified, its further operation and promotion still have a few problems such as the lack of a sharing transaction platform, difficulties in information disclosure and sharing, and the high construction costs of the credit system. In past few years, blockchains have been applied in many fields including energy [11; 12; 13], transportation [14] and the Internet of Things (IoT) [15] due to the characteristics of decentralization, tamper proof and data traceability [11; 12; 13; 14; 15; 16]. In [17], a large number of projects of blockchains in the energy sector are reviewed and summarized. For example, the Brooklyn Microgrid project set up a blockchain platform called Exergy, and the producers and consumers of clean energy could sell and purchase electricity on it [18]. Energo Labs, a Chinese startup company, utilizes blockchain solutions for community energy projects comprising prosumers, consumers, energy storage and smart grid devices to enable peer-to-peer (P2P) energy sharing [19]. In [20], a blockchain-based smart contract architecture for decentralized energy trading and management is presented, where a three-step peer-to-peer (P2P) energy trading mechanism adopts the double auction principle to enhance market vitality. In [21], an optimization model and blockchain-based architecture to manage the operation of crowdsourced energy systems with P2P energy trading transactions is proposed, allowing the system operator to manage the network users to seamlessly trade energy.