**4.1. Cogeneration facilities**

In this project, we introduce a district heating and cooling system for the Shinchi Station area that utilizes natural gas supplied by pipelines. Additionally, the total energy efficiency is increased by introducing a CGS that utilizes waste heat from power generation.

This project involves cogeneration for cooling requirements during the summer. In Japan, power peaks occur during the summer when air conditioning is being used; thus, to reduce peak loads, the use of absorption chiller-heaters has become widespread. Absorption chillerheaters produce cold and hot water using waste heat from power generation. These waste heat recovery absorption chiller-heaters are known as "genelink" systems in Japan. Some of these CGSs obtain steam using gas turbines. However, due to the small scale of this project, the CGSs in this case utilize gas engines, and the waste heat only provides hot water. In this project, cooling and heating requirements are satisfied using genelink systems to produce hot wastewater from power generation. Compared with conventional facilities, genelink systems provide a 10 to 15% increase in energy conservation. Therefore, genelink technology has the potential to be very useful, especially in Asia, where the climate is hot and humid.

### **4.2. Community energy management system**

A CEMS is used to manage the energy consumption for the whole system and to increase the efficiency of energy use. Multiple autonomous power supplies are managed to conserve energy and to reduce CO2 emissions.

One of the functions of the CEMS is to provide the necessary information for management of the community energy center. Cogeneration equipment is combined with multiple auxiliary heat sources and power purchased from existing power companies (grid power), thus reducing excess heat while avoiding production of unnecessary excess power. With this system, prediction of energy demands and power generation via renewable sources such as solar power becomes essential. Under such complex conditions, the information necessary for energy management personnel to make appropriate decisions is provided by the CEMS, which improves efficient operation of the community energy center.

The second function of the CEMS is demand response control during periods of insufficient power. Demand response control is performed in three steps. The first step is battery storage control at the community energy center. The CEMS controls the charge and discharge of batteries installed at the community energy center. Batteries are charged at night, and when the power procured from the grid exceeds a threshold, it is automatically released. The second step is automatic control of the lighting in public facilities. A control signal from the CEMS is sent to lighting control devices installed in the public facilities. These devices control lighting in areas with minimal impact to users. The third step is transmission of an energy-saving request to facility staff. Facility staff control power usage through predetermined energy-saving activities such as turning off lighting and air conditioning in unoccupied rooms.

#### **4.3. The use of CO2 by agricultural facilities**

**3.3. Energy system overview**

106 Sustainable Air Conditioning Systems

**4. Environmental features**

**4.1. Cogeneration facilities**

An overview of the energy system being planned for this project is shown in **Figure 5**. The system composition follows the plans that were developed during the design of the master plan. The capacity of the solar panels was changed to approximately 75 kW to address actual conditions.

**Figure 5.** Components of the regional energy center equipment (revised by authors based on reference [23]).

In this project, we introduce a district heating and cooling system for the Shinchi Station area that utilizes natural gas supplied by pipelines. Additionally, the total energy efficiency is

This project involves cogeneration for cooling requirements during the summer. In Japan, power peaks occur during the summer when air conditioning is being used; thus, to reduce peak loads, the use of absorption chiller-heaters has become widespread. Absorption chillerheaters produce cold and hot water using waste heat from power generation. These waste heat recovery absorption chiller-heaters are known as "genelink" systems in Japan. Some of

increased by introducing a CGS that utilizes waste heat from power generation.

It is well known that increased CO2 concentration improves crop production in greenhouses. Therefore, by sending gas engine exhaust with a high CO<sup>2</sup> concentration into greenhouses, crop growth can be promoted.

The city of Tomakomai in the Hokkaido Prefecture of Japan has been using a trigeneration system (a system involving heat, power, and CO2 ) since 2015. Presently, the project is at the stage of recruiting companies that operate agricultural facilities and preparing these facilities so that a supply of CO2 can be started immediately upon completion of the company recruitment process.
