Forbes reported $15 million per day in power consumption for the entire Bitcoin network back in January but some people disagree with that estimate.

I think a fair estimate of Bitcoin power consumption is about $150,000 per day.

The current "hash rate" for the Bitcoin network is about 30 million GH/s.

Assuming everyone mining Bitcoin is using recent hardware (like this contraption being sold on Amazon that consumes 2W/GH/s) then the total power consumption is about 60,000 kW/h. At approximately 10 cents per kWh that's about $150,000 being spent on power per day.

Probably most mining isn't as efficient as 2W/GH/s and some mining is being done in countries with higher power prices but I think $150k/day is a good rough estimate of the power consumption of the network.