Guilt-free gadgets?

[I ran out of room to include this topic in my recent IET talk]

As late as the 1880’s a debate was raging about whether to distribute electricity to our homes by Direct Current (DC), where the current always flows in one direction as from a battery, or Alternating Current (AC), where the current reverses direction many times a second. The prolific American inventor Edison advocated DC, while European genius Tesla advocated AC.  It was called the War of the Currents (what is it with all these “war” analogies? Enough already!).
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