For more than a century, electric power has been produced and distributed using alternating current technology. But the DC system, pioneered by Thomas Edison in the 1880s, could have particular benefits for buildings that use solar photovoltaics, according to Edison Revisited: Should we use DC circuits for lighting in commercial buildings?, published in the journal Energy Policy.
CMU researchers examined the economic feasibility of operating several lighting technologies and scenarios in a 48,000-square-foot building using either a central DC power supply or traditional AC grid electricity.
They found that using DC instead of AC for fluorescent lighting yields the same or slightly higher costs. But if LEDs are installed instead of fluorescent lamps, the CMU researchers found a savings of $24,000 per year using DC. If the LEDs are powered with solar PV power augmented with grid electricity, even bigger savings can be gained by using DC, according to the research.
And as the cost of LEDs decrease, the savings from transitioning to an LED-DC combination will improve, according to CMU researchers. By 2015, projections from the Department of Energy show use of LEDs in a 48,000-square-foot commercial building with traditional alternating current could see cost savings of $10,000 per year compared to fluorescent lamps. The researchers found that decreasing the capital and operating costs of using LEDs – especially when used with solar PV, a technology that produces DC electricity and usually requires an AC converter to feed it back to the grid – are key factors to make a dedicated DC strategy worth considering.
However, the research shows that current DC wiring still has higher installation charges than an AC system. Researchers also pointed out that further work is needed to better understand potential safety risks with DC distribution and to remove design, installation, permitting and regulatory barriers.
In February, power and automation technology group ABB won an order from ship owner Myklebusthaug Management to supply the first direct current power grid on board a ship, in an installation ABB says should reduce fuel consumption and emissions by up to 20 percent.