On the institutional side, the Pennsylvania State University system has used a DC system for more than a year at its Penn State Berks site, mostly for teaching purposes, according to Greg Dobbs, the university's director of distributed generation research and education at its site in Philadelphia. The university also is actively involved in a DC power demo project in the Philadelphia Naval Yard.
The endeavor, a DOE-funded GridSTAR project, serves as a living educational tool that demonstrates how smart grids and smart microgrids work with an emphasis on behind the meter applications. The initial system will be in a renewable energy training structure.
"Because it is still early in development, the understanding so far has mostly centered on installation and potential benefits," Dobbs explains, adding that instrumentation should permit capturing operational data as it becomes available.
NextEnergy has taken use of DC power into the realm of alternate energy. The center's DC power system is fed directly from an on-site solar power generation system. "Because we now are able to get more effective use from our on-site solar, we have been able to integrate other applications to pull directly in DC," Saber says. "We have installed a DC-power, high-performance computing center and vehicle charging."
While NextEnergy still is in data-collection mode with these applications, Saber says the organization anticipates seeing 10 percent energy savings, while minimizing the number of components needed.
In the bigger picture, EMerge Alliance's Patterson says standards already are being crafted to facilitate system reliability and better power surety with energy savings at all levels. These standards also will help maximize the opportunity for highly articulated digital control. EMerge Alliance already has completed and issued standards for occupied space and data and telecom centers. Registered products are now available to the market.
"Perhaps most importantly, the standards facilitate the direct integration of site-based, renewable energy sources and storage devices without the use of complex and costly power inverters," Patterson says. "Simply put, EMerge believes that hybrid AC-DC microgrids can do for power what the Internet did for data and telephony. We see the power domain going down the same path, perhaps at a brisker pace because all the technology to do so is already available."
The mission of the EMerge Alliance is to develop standards to spur the use of DC power distribution throughout commercial buildings. Two standards have been completed so far, and products are available on the market today. The EMerge Alliance Occupied Space Standard creates an integrated, open platform for power, interior infrastructures, controls and a wide variety of peripheral devices to facilitate the hybrid use of AC and DC power within commercial interiors.
The EMerge Alliance Data/Telecom Center Standard provides a practical guide for the hybrid use of DC power in data centers, offering improved reliability and efficiency, smaller footprint, and lower capital and installation costs. The standard is based on 380 volt DC power because that is the global sweet spot for standardized components with the best balance of economics and safety.
For more information about the EMerge Alliance, go to emergealliance.org.
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