http://www.patricksaviation.com/videos/SUPERGT/3384/

For those not familiar with fighter aircraft, EPU (Electrical Power
Unit) provides hydraulic and electrical power in event of failure of
the engine. The EPU is powered by Hydrazine which decomposes into hot
gasses as it passes across a catalyst bed or engine bleed air (if
available). The hot air passes through a turbine which drive the
emergency hydraulic pump and generator through a gear box.