DC power is of great interest at the PNC Financial Services Group because of potential savings and reduction of energy loss that accompanies the power-consuming conversion of AC to DC, says Nana Wilberforce, vice president and energy manager. "On average, a DC power system can reduce the energy loss that accompanies the conversion of AC to DC by more than 20 percent."
One thing that makes this hybrid infrastructure attractive is that it doesn't have to be an "all or nothing," Patterson notes. Like computer networks, DC microgrids can be implemented anywhere from room level to an entire campus within an otherwise traditional AC system.
"That's because DC distribution is made up of a number of sub-layer microgrids that, when interconnected, form the entire hybrid AC-DC microgrid," Patterson explains. "This allows a building's power system to transform in stages, perhaps opportunistically, based on resources and needs over time."
The EMerge Alliance is "making significant progress" toward its vision of DC microgrids throughout commercial buildings, Patterson says. "We see great opportunities with lighting and computing technology, as well as electric vehicle charging and larger building loads, such as variable speed HVAC and motor loads, as well as high-bay/industrial applications, which often are DC-based and ideally suited for DC microgrids."
Those in the commercial sector who already have started to use DC power agree with Patterson's assessment. "The adoption of DC power systems has picked up over the past two years," Wilberforce says. "This adoption has been facilitated by the availability of DC-powered equipment, including lights and ceiling grids." He says DC power grids also offer a safer and more efficient way of managing a building's lighting and power needs.
Jim Saber, vice president of business and technology development at the NextEnergy Center, a 45,000-square-foot innovation center and test bed for new advanced energy technologies, can attest to this. "For us, the significant benefits are simplicity and efficiency," Saber says. "We are seeing that it's easier to integrate new technologies into our center via our DC power system, particularly in respect to control technologies. With respect to our lighting systems, we are seeing approximately a 20 percent improvement within our laboratories on our DC power system."
PNC recently completed construction of a net-zero energy branch in Florida, Wilberforce says. "To design a building that is 50 percent more efficient than comparable buildings, we used innovative technologies and approaches, including a DC microgrid system. Since opening the branch in January, we have seen low energy consumption and experienced several net positive months."
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