Did you factor in the inefficiencies of the power distribution grid and the heating element of the kettle? I'd say the journalists are just repeating what they've been told by the scientists, and the scientists factored inefficiency in on a calculation similar to your first.
There may exist inefficiencies in the transfer of heat from the element to the water, but there is no such thing as an inefficient heating element. All of the power it uses will be converted to heat. Take a light bulb for example. When used to light a space, the inefficient part would be the energy that is lost to heat. The rest is converted to light, but as soon as that light hits an object, it's converted to heat. So even a light bulb is a perfectly efficient heating element.
With this in mind, you aren't saving any money on your electric bill by turning off lights when your furnace is on.
The internal heating element isn’t strictly speaking 100% efficient on AC as it’s producing a changing electric field etc. It’s just generally ignorable in practical terms.
Nope, I didn't factor in anything like that. Also kettle's don't actually heat every ml to 100C so there's some fudge in the other direction. I mostly was just getting nerdsniped.
