I lived in Michigan for many years which is as cold or colder than where you live. I personally think a engine block heater is a waste unless you live in extremes where overnight temps regularly drop under -20F in the winter. THe newer cynthetic oils perform well in cold temps, and I alos think the whole "cold start-up" concern is mostly nonsense. Oil bonds fairly well to metal, so even after sitting all night, there is still a film of oil on the contact surfaces. Oil pressure comes almost immediately since the oil pump is directly driven by the crankshaft.

I had a '91 Tercel that survived 12 Michigan winters and 120,000 miles with regular, cheap non-synthetic multiweight oil. It was outside all winter and as a teenager I abused the car heavily and rarely let it warm up before accelerating hard. When I sold the car the engine still never burned a drop of oil and I was even towing a 1000 lb trailer with it on occasion and also had a roof rack.

Modern engines are far more durable that people think.

To answer your question, block heaters are electric and plug into a standard 120VAC wall outlet. I believe some just try to heat up the oil in the oil pan. Others try to warm up the entire engine block.