Clarification: By saying half the energy is wasted, I only meant that it was available but unused. In other words, the device doesn’t take full advantage of what the wall is providing. It only uses 40-50% of the provided potential. I never meant to imply that the energy was dissipated as heat or dumped somewhere else. “Wasted” and “efficiency” felt like good words for that, but apparently I was wrong given the response in the comments. There’s some ambiguity there that I did not anticipate. Oops! In hindsight, I can see how this could be misleading.