Today is a big day in the history of electricity & electrification!
Two nationally incredible and one personally thrilling things happened #thisdayinhistory
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Two nationally incredible and one personally thrilling things happened #thisdayinhistory
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On Sept 4, 1882, Thomas Edison turned on Pearl Street Station in the Manhattan financial district, the first central generation station distributing electricity commercially in the United States.
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By 1882 Edison had already founded Menlo Park, and invented, among other things, the phonograph. He also improved on the automatic telegraph from knowledge gained from a 1973 trip to England.
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This trip (which of course happend in 1873 not 1973) is notable to the history of electricity because the English telegraph system was underground and Edison struggled with the inductive forces as a result.
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Moving electricity underground continues to be a challenge to this day for the domiant electricty technology, alternating current. Direct current systems do not have this issue
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I *think* this experience is what led to Edison's direct current approach to electricity. I have a vague memory of learning this in grad school, but will have to dig up my textbooks later today to confirm. Stay tuned on that front.
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Back to Pearl Street Station. The internet tells me this is what made Edison famous, the Wizard of Menlo Park (which for all my childhood I thought was in NY but is in fact in California).
While on the topic of geography, I'll note that Edison was born in Ohio! #GoBuckeyes
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While on the topic of geography, I'll note that Edison was born in Ohio! #GoBuckeyes
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Pearl Street was a direct current system. Edison's competitors, Tesla and Westinghouse, used an alternating current system. [Heads up, the 126th anniversary of Niagra Falls station is on January 12]
You can read or watch any number of books and movies on The Current War
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You can read or watch any number of books and movies on The Current War
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There's a great overview of these technologies and the "war" from @ENERGY here: energy.gov/articles/war-c…
The crux is the PR war was just noise to the real problem Edison faced: technoeconomics
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The crux is the PR war was just noise to the real problem Edison faced: technoeconomics
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You see, power is most efficiently sent at high voltage.
Power = voltage x current, but
losses=line resistance x current^2
So to reduce losses you need to lower the current. Transmitting the same amount of power requires higher voltage.
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Power = voltage x current, but
losses=line resistance x current^2
So to reduce losses you need to lower the current. Transmitting the same amount of power requires higher voltage.
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Edison was 60 years too early. The technology to transform DC systems to higher voltage wasn't invented until the 1940s.
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Tesla and Westinghouse benefitted from physics. AC is transformed to higher voltages by simply winding the wires in the right ratio. It's absolutley wild how electric and magnetic fields work this way. [These same properties are what lead to the undergrounding issue]
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Edison lost the current war, but DC is still around. After mercury arc valves (1940s) and thyristors (1970s) came about, DC was primarily used to move hydropower, because it was a lot of power over a long distance.
(Ironic, since the 1st big AC station was Niagara)
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(Ironic, since the 1st big AC station was Niagara)
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Now we have a third technology, transistors (IGBTs specifically) that make more flexible systems that can work a bit more like AC, easily tapping off power along the line.
Costs are coming down, too, as we learn and apply this technology.
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Costs are coming down, too, as we learn and apply this technology.
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DC could be the backbone of the future grid, through a #macrogrid that provides national balancing, relibaility and resilience, and even through medium and lower voltage distribution (e.g. a local DC microgrid)
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THAT WAS JUST THE FIRST NATIONALLY IMPORTANT THING!
Next up, a famous birthday.
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Next up, a famous birthday.
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On September 4, 1848 Lewis Latimer was born.
He was the son of enslaved people who escaped from Virginia.
He became an inventor, laywer, and colleague of Edison's.
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He was the son of enslaved people who escaped from Virginia.
He became an inventor, laywer, and colleague of Edison's.
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Latimer wrote the first book on incandecent lighting and patented techniques for improving the materials and manufacturing of carbon filaments.
(Oops, he was not a lawyer, he worked with lawyers. I think)
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(Oops, he was not a lawyer, he worked with lawyers. I think)
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Latimer married a woman from Providence, RI which is only relevant because I'm a proud Rhode Islander.
He worked with Alexander Graham Bell.
He patented improvements to toilets, elevators, and even invented the precursor to air conditioning!
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He worked with Alexander Graham Bell.
He patented improvements to toilets, elevators, and even invented the precursor to air conditioning!
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And now the personal fact:
On September 4, 2020 I defended my @CMU_EPP dissertation,
"HVDC: New Opportunities to Expand Transmission Capacity"
Flanking this on my shelf are two other dissertations that highly influenced my work, those of my mother & @ShaliniVajjhala
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On September 4, 2020 I defended my @CMU_EPP dissertation,
"HVDC: New Opportunities to Expand Transmission Capacity"
Flanking this on my shelf are two other dissertations that highly influenced my work, those of my mother & @ShaliniVajjhala
20/fin
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