Dr. Stephen Frank,
Commercial Buildings Engineer at the National Renewable Energy Laboratory
Modern Use of Currents:
"Electricity touches just about everything in modern life. It's so important that the National Academy of Engineering selected electrification as the greatest engineering achievement of the 20th century! Today, same as during the past hundred years, alternating current (AC) forms the backbone of the electric grid: we use it big power stations, transmission lines, transformers, substations, distribution lines, distribution transformers, and finally in our homes. As Tesla knew, AC is uniquely suited for long-distance transmission because transformers let you easily change AC voltage level; this is why our electric grid still looks like something Tesla and his peers would recognize...
Direct current (DC) though has had something of a resurgence since Tesla and Edison's time. Since the invention of the transistor, an electronic component that lets us easily control DC, many of what we call "end use" devices have changed from AC to DC. Computers, tablets, cellular phones, TVs, stereos, modern (LED) light bulbs, and even modern large appliances all rely on DC for some or all of their functions. To use DC, all these devices convert AC from the grid to DC internally using a rectifier. New generation technologies, such as solar photovoltaics (PV) also generate DC electricity. All batteries are also DC. So we're at an interesting place now where the electric grid is AC, but most of what we use in the home or workplace is DC.
This state of affairs has led a bunch of people (both researchers and companies) to propose what are called "DC microgrids", where local DC electricity from generation like PV serves local DC loads. All this time after the war of the currents, we may actually be coming back around to Edison's idea of locally generated DC power, but this time for very different reasons."
Leadership in the War of Currents:
"From what I know Tesla mainly played the "good guy" card to Edison's fearmongering. When Edison claimed that AC was too dangerous, Tesla famously held demonstrations where he ran high frequency AC through his body to power light bulbs and similar things, just to prove it was safe. (Don't try that at home, though... Tesla knew exactly what he was doing with high frequencies but modern AC from the electric grid is NOT safe to touch.)
Tesla also worked really hard to figure out the practical details of AC, and invented the induction motor that could easily turn AC into rotating kinetic energy. All this technological innovation enabled Tesla to team up with George Westinghouse to produce an electrical system half the cost of Edison's for the 1893 World's Fair in Chicago. That sealed the fate of AC as the winner."
Future of Electricity Distribution:
"The war of the currents basically set the direction for the next 70 years of electrification, and beyond. Instead of many small, local, costly DC generators, the country integrated large, remote, AC generators with loads (people's homes and businesses) via long-distance transmission lines. Eventually, all this electrification grew into the North American power grid, which some have called the largest machine on the plant. Until the 1950's, there wasn't any good way to transmit DC electricity over long distances, and even today DC transmission remains a niche application. So basically all the grid infrastructure we have now stemmed from the early decision of investors to favor AC over DC."
Modern Role of Currents:
"The electric grid still relies heavily on AC. Transformers (which change AC voltage levels) don't work with DC, and without transformers, cost-effective long-distance electric power transmission is a lot more difficult. So the grid as we know it can't exist without AC electricity."
Many electric motors also rely on AC, specifically synchronous and induction motors. Loads that use induction motors---like many washers, dryers, and power tools---therefore also rely on AC. (However, those are actually older motor technologies. Instead of using AC directly, many modern motor drives actually use DC and what's called "pulse width modulation" (PWM) to create the rotating fields needed to drive the motors. Or, they use DC motors. For example, cordless drills, saws, etc., all use DC motors.)
Oddly, though, almost everything else we use is now DC, not AC. So again, as I mentioned above, we're at a weird place where nearly every load needs an AC/DC converter (rectifier) in order to connect to the grid. Since computers and related hardware use DC, new pure AC technologies are getting rare. So maybe DC distribution is coming back in the future."
"Electricity touches just about everything in modern life. It's so important that the National Academy of Engineering selected electrification as the greatest engineering achievement of the 20th century! Today, same as during the past hundred years, alternating current (AC) forms the backbone of the electric grid: we use it big power stations, transmission lines, transformers, substations, distribution lines, distribution transformers, and finally in our homes. As Tesla knew, AC is uniquely suited for long-distance transmission because transformers let you easily change AC voltage level; this is why our electric grid still looks like something Tesla and his peers would recognize...
Direct current (DC) though has had something of a resurgence since Tesla and Edison's time. Since the invention of the transistor, an electronic component that lets us easily control DC, many of what we call "end use" devices have changed from AC to DC. Computers, tablets, cellular phones, TVs, stereos, modern (LED) light bulbs, and even modern large appliances all rely on DC for some or all of their functions. To use DC, all these devices convert AC from the grid to DC internally using a rectifier. New generation technologies, such as solar photovoltaics (PV) also generate DC electricity. All batteries are also DC. So we're at an interesting place now where the electric grid is AC, but most of what we use in the home or workplace is DC.
This state of affairs has led a bunch of people (both researchers and companies) to propose what are called "DC microgrids", where local DC electricity from generation like PV serves local DC loads. All this time after the war of the currents, we may actually be coming back around to Edison's idea of locally generated DC power, but this time for very different reasons."
Leadership in the War of Currents:
"From what I know Tesla mainly played the "good guy" card to Edison's fearmongering. When Edison claimed that AC was too dangerous, Tesla famously held demonstrations where he ran high frequency AC through his body to power light bulbs and similar things, just to prove it was safe. (Don't try that at home, though... Tesla knew exactly what he was doing with high frequencies but modern AC from the electric grid is NOT safe to touch.)
Tesla also worked really hard to figure out the practical details of AC, and invented the induction motor that could easily turn AC into rotating kinetic energy. All this technological innovation enabled Tesla to team up with George Westinghouse to produce an electrical system half the cost of Edison's for the 1893 World's Fair in Chicago. That sealed the fate of AC as the winner."
Future of Electricity Distribution:
"The war of the currents basically set the direction for the next 70 years of electrification, and beyond. Instead of many small, local, costly DC generators, the country integrated large, remote, AC generators with loads (people's homes and businesses) via long-distance transmission lines. Eventually, all this electrification grew into the North American power grid, which some have called the largest machine on the plant. Until the 1950's, there wasn't any good way to transmit DC electricity over long distances, and even today DC transmission remains a niche application. So basically all the grid infrastructure we have now stemmed from the early decision of investors to favor AC over DC."
Modern Role of Currents:
"The electric grid still relies heavily on AC. Transformers (which change AC voltage levels) don't work with DC, and without transformers, cost-effective long-distance electric power transmission is a lot more difficult. So the grid as we know it can't exist without AC electricity."
Many electric motors also rely on AC, specifically synchronous and induction motors. Loads that use induction motors---like many washers, dryers, and power tools---therefore also rely on AC. (However, those are actually older motor technologies. Instead of using AC directly, many modern motor drives actually use DC and what's called "pulse width modulation" (PWM) to create the rotating fields needed to drive the motors. Or, they use DC motors. For example, cordless drills, saws, etc., all use DC motors.)
Oddly, though, almost everything else we use is now DC, not AC. So again, as I mentioned above, we're at a weird place where nearly every load needs an AC/DC converter (rectifier) in order to connect to the grid. Since computers and related hardware use DC, new pure AC technologies are getting rare. So maybe DC distribution is coming back in the future."