Direct Current Powers Building

July 29, 2015 By Linda Hardesty

Ft CollinsAdolfson & Peterson Construction is beginning Phase I of a project to redevelop the city of Fort Collins, Colorado’s municipal services complex. The first project is the erection of a new 3-story, 37,500-sq-foot Utilities Administration Building that will rely on Direct Current Power, as opposed to traditional Alternating Current. This will make the building unique as the first building in the US designed with a full DC distribution system, according to Bob Lachenmayer, chief operating officer of Pos-En, a Fort Collins company that is designing and installing the system.

Lachenmayer says the traditional ways of powering a building make it difficult to cost effectively integrate on-site generation and do not take advantage of improvements in resiliency, reliability and safety that are technologically available today. The system being designed for the Utilities Administration Building will have its primary loads run entirely off of a battery storage system that will allow the facility to take advantage of these system improvements.

The unique architecture of the system eliminates the need to have generation and load synchronized, which is inherent to the traditional grid system. The building is being designed around a battery system that will be charged from multiple sources, including the grid, allowing the building to leverage every energy source available.

The system will be automated to pick and choose when to use available energy resources. This will take advantage of low demand/low cost opportunities from the grid, and allow the building to use onsite resources, such as solar, whenever they are available. The use of battery storage also allows for the use of onsite and renewable energy even when the renewables are not available.

Surprisingly, the up-front cost of the system for the project came in about 5 percent lower than traditional AC costs. This was largely because the team was able to capture a number of cost savings associated with a DC system including eliminating the need for a backup generator. “Because the battery gives you a minimum of an hour of full load capacity, you no longer need a diesel generator backup system,” says Lachenmayer.

Additionally, the solar system does not require an inverter system, which is also a common failure point for traditional solar systems. Because all of the lighting is being distributed at 24 volts DC, which is Class 2 wiring, there is no longer a need for conduit. The cable trays that are used in place of conduit are much less expensive.

Once installed, operating costs may also be lower. In buildings today, the majority of the loads are native DC, including Variable Frequency Drives (VFDs) that feed many AC motors. Using DC distribution allows for the elimination of the conversion losses associated with powering these native DC devices.

When asked why similar systems are not more common, Lachenmayer says, “A number of factors have come together in just the last couple of years that have made this very compelling. Significant advances in technology, along with the lowering cost of renewable energy and the increasing cost of the utility makes this technology a no brainer.”

One significant technological advance is the science behind the life of the batteries, making them extremely cost effective. For example, initial tests on the battery system being installed on the project show it could last approximately 100 or more years before needing to be replaced. This is compared to a battery life of only 10 years less than a decade ago.

Construction on the new administration building is scheduled to wrap-up in the fall of 2016.

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