What’s in a microgrid? The ability to mix in multiple-power sources and run independently of the larger grid in case it fails. They’re also promising because they can manage energy use more efficiently and smartly at the local level. That’s the premise behind the new 400 kilowatt (kW) Mesa del Sol Aperture Center Smart Grid system, which incorporates photovoltaics, fuel cells, batteries and natural gas generation in Albuquerque, N.M.
The new smart grid is coupled to PNM’s larger electric grid, but is capable of running entirely independently of it. It consists of a 50 kW solar photovoltaic system installed by Japan’s New Energy and Industrial Technology Development Organization (NEDO), an 80 kW fuel cell, a 240 kW natural gas powered generator and a battery storage system capable of storing 160 kilowatt hours of electricity. It’s coupled with a sensor-based building energy management system (BEMS) designed to control energy use in the building.
The system’s fuel cell is also powered by natural gas, said Manny Barrera, P.E., a director of engineering with Forest City Enterprises, which owns the project. The variability of power sources for the microgrid gives it additional energy security.
In the event of a blackout the system could keep operating, also called islanding, Barrera said. “In a power only black out the system can run the building completely for as long as needed,” he said. “In a power and gas outage—the sources of energy available will be the 50 kW PV solar array and the 160 kW hour battery.” In such a situation the buildings’s BEMS identifies critical loads and rations power. It should be able to run for a minimum of several hours, assuming it is during the day and the PV is producing.
The unique system allows the battery to be charged by all the sources, according to Barrera. “The battery system is interconnected through the BEMS therefore it can be powered by any available source—PV, fuel cell, natural gas generator, or even the standard grid,” he said.
Although the system is a 400 kW system it could be expanded. “The existing PV system includes a 100 kw inverter and 50kw of solar panels. That leaves an available capacity of an additional 50 kw of available capacity,” Barrera said.
Other partners in the project include Sandia National Laboratories, the University of New Mexico and nine Japanese companies including Shimizu. The will be used by the University of New Mexico’s Center for Emerging Energy Technologies, use it for research and smart grid development.