Just imagine, if you pour half hot water and half cold water into a cup, it will instantly turn into warm water. But with water heat storage technology, through the water distributor device to achieve the stratification of cold and hot water, cold and hot water can "coexist" in one container, capable of both heat and cold storage.

The recently put into operation Beijing Baozhigu Comprehensive Smart Energy Demonstration Project has adopted this water distributor cold and hot dual storage technology. This project was invested and constructed by China Power Smart Comprehensive Energy Co., LTD., a subsidiary of State Power Investment Corporation. The water storage technology was independently developed by the Central Research Institute of State Power Investment Corporation.

Cold and hot dual water storage tanks for the Beijing Baozhigu Integrated Smart Energy Project

In addition, another innovative demonstration project of State Power Investment Corporation - the "Nuclear Energy Comprehensive Utilization + Smart Energy" project of Shandong Nuclear Power - will also adopt cold and hot dual storage technology. The project officially started construction on July 6th and will create a new business card of State Power Investment Corporation's comprehensive smart energy by building a smart park with nuclear energy as its feature.

Schematic diagram of nuclear energy comprehensive utilization + smart energy project

From a technical perspective, using water or ice as energy storage media can basically achieve the system design of dual cold and heat storage. In recent years, many dual cold and heat storage projects have been successively built across the country, which to a certain extent also proves its technical feasibility. Under the current development trend of the cold and heat combined supply and comprehensive energy service market in the southern region, the use of cold and heat dual storage technology in series to supply cooling and heating systems is even more of a choice.

Under normal circumstances, projects equipped with heat storage technology enjoy benefits when using peak-valley electricity prices. However, some regions have also introduced special electricity price policies. For instance, Guangdong has introduced a cold storage electricity price policy, and Hebei has implemented a "dual storage" electricity price policy for users of electric heat storage for heating and electric ice storage for cooling, etc. If the actual situation of the project can be combined and the off-peak electricity price can be fully utilized, the cold and heat dual storage technology will provide a new idea for reducing the cost of the integrated energy system.

The energy supply system of the Xiongan New Area Citizen Service Center, which was completed and put into operation in 2018, has already adopted the new concept of comprehensive energy utilization. The energy consumption system uses the technology of "shallow geothermal energy + recycled water source + cold and heat dual storage" to provide winter heating, summer cooling and year-round domestic hot water services for the entire Citizen Service center.

In light of the significant difference in peak and off-peak electricity prices between day and night in Hebei Province, this project has set up a 1,500-cubic-meter energy storage pool for energy storage regulation, storing energy at night and releasing it during the day, further reducing electricity expenses. The design capacity of the cold and hot dual storage system is 1885kW for heating and 1885kW for cooling. The maximum cooling load of the entire energy supply system in summer is 8684kW, and the maximum heating load in winter is 7723kW. It can provide up to 100 tons of domestic hot water per day at most.

Compared with the energy supply scheme that solely uses electricity, under the condition that the initial investment is basically the same, the electricity consumption of the Citizen Service center in winter is reduced by two-thirds and in summer by one-third.