As I recall from a tour I went on of jet 30 years ago there are a large bank of flywheels which spin up over several minutes, these are then rapidly discharged to a bank of capacitors which are then used to power the experiment, I believe the duty cycle was 9 minutes. [1][2]

I believe some electric cars used capacitors to store regenerated electricity from breaking.

"More Ampères please Mister Woodbine." - Road to Welville

[1] - http://pia.sagepub.com/content/200/2/95.abstract

[2] - http://www.euro-fusionscipub.org/wp-content/uploads/2014/11/...