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Energy storage and management

Energy storage and management

Experts agree on advantages of direct current power in buildings

28 Aug 2018
Photo of buildings in New York City.
(Courtesy: iStock/giovanni1232)

Experts broadly agree that a widespread adoption of direct current (DC) power systems in commercial and residential buildings could offer significant advantages over alternating current (AC) systems, according to a new study. The finding could help change perceptions of DC among industry professionals, potentially resulting in safer, more reliable, more energy-efficient buildings.

Brock Glasgo at Carnegie Mellon University, US, and colleagues consulted 17 experts in a variety of industrial and academic fields to identify the advantages of a more widespread adoption of DC power systems while acknowledging their potential challenges.

Our society’s use of electricity is changing rapidly. While developments in renewable energy generation have seen sources for the power grid becoming more dispersed, increases in modern electrical components and devices in buildings have caused power consumption to grow steadily. In light of these changes, many scientists have encouraged increased adoption of DC power distribution in commercial and residential buildings.

According to Glasgo, the case for DC power has three key aspects. “Firstly, we now have semiconductor-based power electronics that function as DC-DC transformers and are nearly as efficient as modern AC-DC and DC-AC transformers,” he says. “Secondly, we’re seeing consistent growth in the installation of solar PV [photovoltaic] and other distributed generation sources that generate DC. And thirdly, a growing fraction of the electricity consumed in modern buildings is either consumed as DC or passes through a transient DC state on its way to being consumed.”

To some, these advantages prove that power systems that incorporate both AC and DC are becoming overly-complex and outdated. “Eliminating unnecessary DC-AC and AC-DC conversions by distributing DC power would not only simplify our building-level power supply but would also save energy,” says Glasgo.

Yet despite its technical and economic advantages, the widespread adoption of DC faces major barriers in other areas. Through their interviews, Glasgo’s team identified the two biggest obstacles as an unfamiliarity with DC among industry professionals, and the under-representation of DC devices and components in the market.

“The AC grid has been in place for over 120 years, and all of the physical components, the design, maintenance, construction, operation, and end users’ interactions with the electric transmission and distribution system are based on a long history and the physics of AC,” Glasgo says. “A transition to DC-powered buildings will depend on far more than the technical feasibility of the systems themselves.”

However, the experts generally remained hopeful that these challenges could be overcome; identifying areas which they believed should be prioritised to make a better case for widespread adoption.

“Our experts proposed training engineers and electricians on DC systems and identifying niche use cases where DC power distribution holds a clear advantage over AC and building pilot projects to help build the market for DC devices and components,” says Glasgo. “The professionals responsible for DC power systems and the markets needed to support them will need to undergo a major transformation before they [DC power systems] can be employed to more efficiently, safely, and reliably meet the demands of future buildings.”

Glasgo and colleagues reported the findings in Environmental Research Letters (ERL).

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