i dont know that either how much electricty does bitcoin need if you want a PC miner you need 1 PC and video card it depends in video card that can mind bitcoin if you have more video card the bitcoin you have will increase and increase more the electricity you have use it to small it cannot affect in your work or in your house it has a website if you want to compute your own bill using the PC miner that you have and bitcoin salaries that you have earn everyday.