In most buildings, including our homes, we are surrounded by devices and equipment that internally operates on Direct Current (DC). We plug these devices into a typical Alternating Current (AC) outlet, and then convert AC to DC to operate the devices and equipment. This process of conversion is not 100 percent efficient, and wastes energy.
Many newly constructed buildings are deploying renewable energy sources such as solar which generate DC power. With the large number of DC powered devices in buildings, and with DC generation now utilized in many newer structures, we need to take a look at the use of distributed DC power in buildings and approaches to eliminate the conversion waste -- and thus maximize the use of DC power generated by renewables.
Yet, while we live in an “AC world,” we find nearly all of our equipment uses DC within the devices and, as previously mentioned, converting AC to DC or DC to AC results in conversion losses. While the efficiencies of power conversion are dependent on current and voltage, conversion equipment is typically “rated” from 90 to 95 percent can actually be much lower.
If there are multiple conversions, such as converting AC to DC, then converting DC back to AC, and finally converting AC to DC within the device, the inefficiency of conversion is multiplied. So at best we’re wasting 5-10 percent of energy in the conversion and much more with multiple conversions and less efficient conversion equipment.
AC and DC have been battling it out since the beginning. Thomas Edison (who once held the world record of 1,093 patents for inventions) developed the first commercial electric power transmission system which used direct current (DC). After he deployed around 190 power stations, a “war of currents” started.
Opposing the use of DC was the inventor of transformers and Alternating Current (AC), Nikola Tesla, and George Westinghouse, a proponent of AC power. Their basic argument was that DC power couldn’t be transmitted very far, only around a mile and a half, whereas AC current could be carried over hundreds of miles and was better suited for central power stations.
The “war of currents” got nasty at times but eventually AC power won out for power generation, transmission and distribution.
But now, DC is making a comeback.
Photo of electric current power supply provided by cheyennezj/Shutterstock
Next page: The growing DC infrastructure