Analysis and Detailed Explanation of Electric Energy Management Model in Costa Energy Storage Data Center
In recent years, the development of electrochemical energy storage is in full swing. In this paper, the development of data center energy storage to create a rich profit model and business model as a starting point to discuss with you.
The data center gains revenue by providing cabinet rental, bandwidth rental and server agent operation and maintenance services to customers. For data centers, ensuring safe and reliable power and network supply is the two most basic functions of data centers, so data centers are equipped with uninterruptible power supply (UPS). When the power supply is normal, UPS supplies power to the load after "filtering the impurities in the city electricity" and charges the battery at the same time. When the power supply is abnormal (interruption of power supply), battery discharge guarantees power supply through the UPS supply load. This traditional data center power standby mode has the following application pain points:
1. High electricity expenditure. After the completion of the data center, its main operating cost comes from electricity. Statistics show that electricity expenditure accounts for more than 60% of data center operating expenditure. Taking the medium-sized data center with 2000 cabinets in Jiangsu as an example, assuming that the average power of cabinets is 5 kW, the annual power consumption of cabinets is 2,000 *5 kW *24 h *365 days = 87.6 million kWh. The average electricity price of Jiangsu Province is about 0.68 yuan, while the electricity cost of cabinets alone is as high as 59.57 million yuan. The electricity consumption of air conditioning, UPS and other power facilities such as lighting has not yet been calculated. Therefore, how to reduce the data center electricity expenditure is very important to improve the profits of data center enterprises.
2. The high investment of batteries, and the non-discharge of batteries in the service cycle, resulting in waste of resources, is the sunk cost. Our country produces more than 200 GWh lead-acid batteries every year, and a large proportion of them are used in Data Center for reserve power. The life of these batteries is usually about 5 years. In order to ensure the safety of reserve power, a batch of batteries must be replaced every 5 years. At present, the reliability of power supply in most areas of our country is over 99.9%. Because the data center usually adopts the dual-way city power guarantee + 2N backup structure, the battery seldom discharges and is in a long-term idle state, which causes a great waste of resources.
3. Batteries are in floating charge for a long time, and their health status is unknown. As mentioned above, due to the high reliability of power supply in data centers, batteries have been in floating charge state, and almost no power is released once a year. Some data centers even need periodic false load testing to test the performance of batteries, and the cost of testing is considerable.
Understanding the pain points of data center operations and UPS usage helps us to know how to solve existing problems. Thanks to the development of energy storage technology in recent years, the construction of energy storage data center has become an important means to solve the above application pain points.
Data Center Energy Storage Requirements for Batteries and UPS Hosts
There is a dynamic balance between grid power generation and user power consumption. In order to improve unit utilization rate, reduce generation cost and increase efficiency and emission reduction in the period of low power consumption, China has implemented peak and valley price system since 1993. The original intention of this system is to guide the society to use staggered peak power by economic means. The existence of price difference between peak and valley provides arbitrage space for energy storage through "low storage and high yield". However, due to the limitation of energy storage cost, it is difficult to obtain sustainable profit space for a simple peak-cutting and valley-filling project. The construction of data center itself requires a large number of batteries and UPS mainframe input, which provides a necessary condition for peak-valley arbitrage, but it needs to solve the battery cycle life and the function of energy-storing UPS mainframe.
Battery Requirements for Energy Storage in Data Center
Traditional lead-acid batteries can not meet the requirements of long cycle life of batteries in peak-shaving and valley-filling mode, so it is imperative to develop new cycle batteries. Thanks to the inspiration and guidance of Obama's Clean Energy Program in 2006, a worldwide research boom on lead-carbon batteries has been launched and products have been launched.
The so-called lead-carbon batteries are based on the electrochemical system of lead-acid batteries, through the technology of adding carbon to the negative pole and prolonging the life of the positive pole and electrolyte, the cycle performance of lead-acid batteries is greatly improved, and the cycle life of lead-acid batteries is 3-5 times that of ordinary lead-acid batteries. Solving the problem of battery cycle performance creates a precondition for building energy storage data center. In data center energy storage applications, besides peak shaving and valley filling, batteries also need to ensure the standby time. Therefore, the discharge depth of batteries is generally controlled at about 50%, and the remaining power is used to ensure the standby time. As we all know, the deeper the discharge depth of the battery, the shorter its cycle life, about 50% of the discharge depth, which can not only meet the requirements of the data center for battery life (10 years), but also ensure better peak-shaving and valley-filling benefits, perfect match of performance and requirements.
Requirements of UPS Energy Storage for UPS Host
(1) The discharge rate will affect the discharge quantity of electrochemical power supply. The smaller the discharge rate, the more the discharge quantity will be. On the contrary, the less the discharge rate will be. For example, for lead-acid or lead-carbon batteries, if discharged at a rate of 0.1C (A), the total discharge capacity is 1C (Ah), but if discharged at a rate of 1.5C, the total discharge capacity is only about 15 minutes, and the total discharge capacity is 0.375C (Ah), and large discharge rate will seriously affect the battery life. In peak-cutting and valley-filling, the larger the discharge amount, the more the profit will be. Because the peak-price power time, i.e. the discharge time (usually 8 hours), is long enough, it is possible to choose a small-rate discharge mode that meets the discharge characteristics of lead-acid batteries, which requires UPS mainframe to have the combined power supply function of electricity and batteries.
(2) Because of the reliability of power supply, the conventional data center seldom discharges batteries, even if there are occasional discharges, the charging time is very long.
Contact：Li Sheng Yuan
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