I have avoided electric blankets. For sleeping I use 2 duvets and a hot water bottle. I like the feel of the weight of the duvets, and they provide a lot of insulation. The water bottle can be filled from any source. Normally I use an electric kettle, but I also have a gas cooker and, in a pinch, coal.

(I live in the UK. I gather Americans have a different attitude to kettles on account of their mains power being less.)