Why do transmission lines carry such high voltages?

Line Construction is a Big Ecological Footprint!

Consider the following hypothetical (and non-physical) situation in the town of Toasterville:

• Electricity is generated at the generating plant at 120 Volts and then delivered to the households over conductors.

• There are 10 households and each needs 1000 Watts (for their toasters)

• The electric company must therefore supply 10x1000 = 10,000 Watts.

• Power = P = I x V I = P/V I = 10000/120 = 83 amps would therefore flow as current through this 120 V distribution system.
  
  
  
  
• Ohms Law: V = I x R; but V also can be expressed as P/I therefore P/I = I x R or P =I²R

• So electrical power which is transmitted is dissipated as heat according to P = I²R (this is how your stove element works)

• Lets set R= 1: We now have heat dissipation = (83.3)*(83.3)(1) = 6944 watts. Heat dissipation is energy lost by the system. This loss is unavoidable!

  
  

• To deliver the 10,000 watts that the consumer needs requires that we generate 16,944 watts and hence have an overall efficiency of 10,000/16,944 = 59% which the consumer would pay for

How to solve the loss problem:

Current = Power/Voltage; If we increase V by a factor of 10, then I lowers by a factor of 10 (at constant power) and the power dissipated as heat lowers by a factor of 10².

Hence if we increase 120 Volts to 1200 Volts we have only 69.4 watts of energy loss and a 99% energy efficient delivery system This is why high voltage (typically 115-230 thousand Volts or kiloVolts) transmission lines are required to delivery electricity from central generating sources (e.g. a hydroelectric dam) to consumers/grids hundreds of miles away.

But you don't want 115 KV coming into your house:

In principle the distribution system is simple:

However, in practice its somewhat of a regulatory nightmare:




with most of the infrastructure being PRIVATELY Owned even through regulation is happening at the Federal level



The major regulatory framework was set up right after WW II:



and has remained unchanged. This has lead to the serious problem of Transmission Congestion which will just get worse in the future.



But we are NOT adding new transmission at the necessary pace: - 10,000 new miles since 2000 out of 275,000 miles prior to that quantifies as Jack Shit: