U.S.A (2): Advanced Building-Scale Smart Grid Demonstration at Mesa del Sol

Project Background

This commercial-scale microgrid was built as a result of US-Japan collaboration on microgrids, funded by Japan’s New Energy and Technology Development Organization (NEDO). Since the system was commissioned in March 2012, Japan’s Shimizu Corporation and Tokyo Gas, the University of New Mexico, Public Service Company of New Mexico (DSO/TSO), and Sandia National Laboratories have used the infrastructure to conduct research and demonstration, sponsored by NEDO and the US Department of Energy. The technical objectives directly empower commercial-class consumers to more effectively manage electricity and thermal demand, improve supply reliability, and become an active distribution network resource.

The following technical capabilities were demonstrated:

1. Scheduling of the building’s net power flow at the utility interface, by compensating short-term PV and load fluctuations.
2. Stable operation of the entire commercial building in islanded mode.
3. Uninterrupted transition between grid-interconnected operation and isolated operation
4. Demand response control connected with the commercial system
5. Load tracking control by air conditioning heat source utilizing hot and cold thermal storage

The system’s host building, known as the Aperture Center, anchors a new residential community called Mesa del Sol (Table of the Sun) in the City of Albuquerque, New Mexico, USA. The Aperture Center is a three-story commercial building housing stores and offices, with total floor space ~7,000m2. Peak building demand is ~300kW. The site is in a high desert location, at an elevation of 1,600 meters above sea level.

Even though the building is to the highest energy efficiency standards, heating and cooling loads are significant given that that ambient temperatures vary widely throughout the year, from a monthly average low of -5 ℃ in January to an average high of 35 ℃ in July. The microgrid consists of a 240kW gas engine generator with heat recovery, an 80kW fuel cell, a 50kW PV system, and a 160kWh lead-acid battery. The thermal system consists of a 70 USRT air-cooling type chiller, a 20 USRT absorption-type chiller, two 75m3 chilled water thermal storage tank, and two 110m3 hot water thermal storage tanks. All components are controlled by building energy management system (BEMS) that manages both electrical and thermal supply to the commercial building. The system also has a 100kW load bank that can be controlled in 5KW microgrid devices according to the control bojective selected by the consumer. A smart meter is used to monitor the building grid interface. The BEMS also has the ability to process supplemental control signals from the utility.

Case Description

The objective of this project is to demonstrate full integration of distributed resources (configured as a microgrid) and a commercial building. The system enables the building owner (consumer) to manage its energy demand and enhance reliability and resilience. In addition to supplying electricity and thermal (hot and chilled water) to the building, the microgrid allows for scheduling of net demand (importing or exporting), participation in demand response, and smoothly transition to and from islanded mode. The microgrid controller has the ability to interact with the utility (DSO), enabling the consumer to also provide dispatchable grid support services. Although the microgrid is in a region with limited market participations options, the key technical capabilities have been successfully demonstrated at full-scale. In addition, the project enhances the environmental sustainability core values embraced by the host (commercial customer/customer).

Key outcomes related to consumer engagement and empowerment of commercial-class consumers are:

1. Provides an efficient and fully integrated self-supply option for thermal energy and electricity
2. Enables commercial consumer to engage in market transactions (where that option exists) or provide grid support services that require dispatch of net building load
3. Provides higher supply reliability and resiliency to the consumer by enabling the building to island in case of a grid outage
4. Allows the consumer to host a large amount of variable renewable variable resources without degrading power quality at the utility interface

Project Outcomes

This project has generated outcomes that exhibit excellence from several points of view. The impact is well beyond successful completion of the stated technical objectives.

1. Potential Impact: By involving the consumer, uility and research entities, the project has found solutions for complex technical and nontechnical challenges that, in other settings, represent barriers to deployment of customer-owned microgrids, including technology integration, interconnection requirements, and regulatory treatment. The project is impactful because it successfully demonstrated, in a real scenario, the range of benefits that commercial microgrids provide to consumers and to the grid. Also, the project’s safety and performance track record is an excellent example for the industry.
2. Consumer Benefit: Customer-owned grid-interactive distributed resources are often deployed to enable demand response flexibility (e.g. peak shaving). This project goes well beyond. By coordinating generation resources, demand response and electricity/thermal storage, the consumer has the ability to dispatch net demand within a wide range (importing or exporting). The capability can be used by the consumer to maximize market participation opportunities. The system also provides higher supply reliability to the consumer.
3. Potential for Replication: The system is implemented in a medium-scale high-efficiency (LEED Gold certified) commercial building with standard utility service and thermal load. This project demonstrates how a system consisting of several generation technologies, heat recovery and storage can supplement building efficiency and demand response measure to make future zero-net-energy buildings possible.
4. Level of Innovation: The project has a state-of-the-art building energy management system (BEMS) that controls all aspects of the microgrid operation. It dispatches the microgrid assets to meet both electricity and thermal demand to an occupied commercial building in the most cost-effective manner. The highly innovative feature is the ability to smoothly transition the building from grid connected to islanded mode, in which the microgrid is responsible for controlling voltage and frequency. Another innovative feature is the use of low-cost secured communications to enable microgrid interaction with the utility for real-time control.
5. Alignment with ISGAN Mission: This aligns with ISGAN’s mission to “accelerate progress on key aspects of smart grid policy, technology and related standards. It deploys commercial products from the US and Japan, which required identifying and resolving gaps related to policies, standards, certification and interoperability of smart grid equipment. This project also provided valuable experience with the integration of a wide range of generation, protection, measurement, control technologies, and data management technologies.