ENERES Co., Ltd.
Rinnai Corporation

ENERES Co., Ltd. and Rinnai Corporation will begin a DRready^[1],^[2] demonstration experiment (hereinafter “demonstration”) with the hybrid water heating and heating system (hereinafter “hybrid water heater”) ECO ONE starting in February 2025.

This demonstration will test the potential of hybrid water heaters for use in wholesale electricity trading markets, capacity markets, and as low-voltage resources^[3] in the balancing market starting in fiscal 2026.

■Background of the demonstration
As renewable energy (hereinafter “renewables”) becomes the main power source, demand response (hereinafter “DR”) is gaining attention as a means of obtaining balancing capacity to compensate for renewables’ unstable output. In particular, low-voltage resources owned by households, such as home storage batteries, heat pump water heaters, and electric vehicles, are expected to become more widespread. Efforts to make them DRready, enabling remote operation through communication networks to respond to DR, are spreading, centered on the Ministry of Economy, Trade and Industry.

■Demonstration Objectives
ENERES has participated in the Ministry of Economy, Trade and Industry’s VPP^[4] demonstrations since fiscal 2016, advancing demonstrations of both high and low-voltage resource utilization. By using MEC^[5] with control technologies cultivated through these demonstrations, we have built a mechanism to manage and control large numbers of resources in groups. In this demonstration, we will maximize the potential of hybrid water heaters using ENERES’s aggregation technology and knowledge, and verify their potential for use as social infrastructure, their response as DRready devices, and their practicality for aggregation business.

Rinnai plans to sell 300,000 hybrid water heaters annually by 2030 toward achieving carbon neutrality by 2050. In addition to contributing to Rinnai’s social challenges of “addressing global environmental issues” and “improving quality of life,” through this demonstration, we will examine mechanisms and conditions for utilizing hybrid water heaters as balancing capacity in the balancing market and as supply capacity in the capacity market, working toward DRready compatibility.

■Potential for DR with hybrid water heaters
Hybrid water heaters are home water heating and heating systems that combine electric heat pumps with gas water heaters to deliver excellent energy-saving performance. The tank unit normally stores the minimum necessary amount of hot water heated by the heat pump unit using atmospheric heat, but if the tank runs out of hot water, it can switch to the gas auxiliary heat source to instantly supply the needed hot water. A key feature compared to heat pump water heaters is “no worry about running out of hot water.”
This characteristic allows for both types of DR without compromising user convenience: “upward DR,” which actively increases power consumption by heating water during times of surplus electricity, and “downward DR,” which reduces power consumption by stopping heating during times of tight supply and demand, such as winter. It therefore shows potential to deliver a greater amount of energy.”
On the other hand, as a device specialized for energy saving, each unit’s power consumption is limited, making it a challenge to maintain overall control precision when numerous resources are gathered for utilization. In this demonstration, we will verify whether this challenge can be solved by using MEC technology to manage and control resources in groups, including combinations with other devices.

Through this demonstration, ENERES and Rinnai will pioneer the use of low-voltage resources, including hybrid water heaters, as balancing capacity in the balancing market and supply capacity in the capacity market, contributing to the realization of renewables as the main power source and a decarbonized society.

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[1] DR: Abbreviation for Demand Response. A mechanism to control demand according to power supply. Energy conservation and shifting power usage times are examples.

[2] DRready: Making consumer-side devices responsive to DR through remote operation via communication networks.

[3] Equipment installed at low-voltage consumers such as general households, including home storage batteries. Plays a role as balancing capacity in the power balancing market.

[4] Abbreviation for Virtual Power Plant. A system that manages small-scale power equipment collectively to function as a power plant.

[5] Abbreviation for Multi-access Edge Computing. A technology that provides low-latency communication by distributing servers near terminals and processing data close to users.