Resilient Power Hubs: Emergency Power That Pays Off
By: Gita Nandan, RA, a founding principal of thread collective llc
A prototype on-site energy generation system could provide reliable back-up power during utility failures and other
THREE YEARS AFTER Superstorm Sandy devastated the East Coast and left thousands without power for days or weeks, many affected areas are experiencing renewed interest in more secure and uninterruptible power supplies. In response, municipal leaders and building owners and developers, among others, are seeking innovative power solutions. Some new concepts offer promising answers to a serious and potentially life-threatening question: How to provide power to buildings when the larger electrical grid goes down, whether in long-term emergency situations or simple, day-to-day outages?
One of those techniques recently got the green light in New York City. Called the Resilient Power Hub (RPH), this innovative system connects solar photovoltaic (PV) collectors to a combined heat-and-power (CHP) plant and energy storage technology to maximize the amount of power available to a building or site during utility failures. The system shows potential for commercial applications at office, industrial and mixed-use buildings.
The Resilient Power Hub incorporates six primary elements to provide reliable back-up power. In grid-connected scenarios, the battery is discharged during times of peak demand on the energy system, reducing the building’s energy costs.
Prototype Projects Funded
In May 2015, the New York City Economic Development Corporation awarded a grant to build at least three RHPs, noting the system’s value as a low-carbon, resilient power option with a “building-based ‘microgrid’ technology.” The prototype projects will support three commercial facilities in as-yet-undisclosed New York City locations.
Leading the project are the energy technology and efficiency expert Bright Power Inc. and the architecture, design and landscape architecture firm thread collective. The two firms comprise one of 11 teams to win RISE : NYC grants, which underwrite innovative technological solutions for resiliency that show promise for broader commercial applications.
Even better, a Resilient Power Hub will pay for itself over time, providing an economic advantage to building owners and developers. Still, some may ask, what’s the advantage of a 150-kW RPH over a standard, 150-kW gas-fired backup generator? Benefits include the following:
- The hub is protected from the fluctuating, unpredictable costs of natural gas and, even more important, the vulnerability of the gas supply infrastructure (like that of the electrical grid) to interruptions during severe weather and other disasters.
- Solar collectors and storage technology provide a continuous, decentralized and low-carbon power source that will work even on cloudy days.
- The byproduct of hot water from the CHP system will deliver a secondary energy source as well as hot water and heating when needed.
- Critical building loads — such as elevators, pumps, lighting and telecommunication devices — all will be protected from utility grid disruptions.
A Building-specific Solution
Like backup generators, the RPH is a building-specific solution that provides on-site, decentralized power generation. While its system components are fairly standard, and implementation is similar across building types, the hub also involves architectural elements that may benefit building occupants. If the PV arrays are elevated above the roof planes, for example, the solar canopies will offer tenants cooling shade over outdoor terraces and green roofs. In fact, solar power and green roofs are highly compatible, contrary to popular wisdom: Shade plants can lower temperatures by as much as 30 degrees compared with a black roof, allowing the solar array to run efficiently. In addition, new thin-film PV technology can be seamlessly integrated with facades, glass assemblies and skylights.
Before a hub can be installed, the CHP, software management and battery systems must be housed within a conditioned space, requiring clearance, structural support and access to the building’s electrical system. New construction can easily accommodate these systems when planned early in the design phase. But most RPHs probably will be installed on existing buildings, either as standalone upgrades or as part of larger renovations.
The RPH, a building-based power plant, offers a decentralized energy-generation solution that can be installed in a variety of architectural configurations.
Because the hub’s goal is to guarantee operation during times of distress, its components should be protected from possible flooding, fire, severe wind and seismic events. It can be installed at grade, above the FEMA-approved design flood elevation, or adjacent to the roof bulkhead near the solar array. As part of the RISE : NYC grant, thread collective is exploring the cost and architectural impact of each type of configuration.
With greater business continuity, reduced utility costs from solar energy and protection against income loss, many commercial developers and owners recognize the potential benefits of the Resilient Power Hub. Payback scenarios range from two to eight years, based on today’s utility rates, according to Bright Power. Avoiding day-to-day power interruptions and financial problems while also preparing for the next severe storm or other resiliency challenge seems like a good bet for savvy building owners.