An article by Tamara Cohen:

"Our brains have 100 billion neurons. Each one performs billions of 'calculations' per second – roughly similar to a desktop computer. So the brain computer will need to be able to do a billion billion calculations which will require the output of a nuclear power station. Finding a way to power the supercomputer will be one of the researchers' major challenges."

SOURCE

http://www.dailymail.co.uk/sciencetech/article-2130124/Scientists-build-human-brain-Supercomputer-simulate-mind-exactly-help-fight-brain-diseases.html