From their press release on the
official site (additional images, articles, etc.):
Power Source
Every effort was made to ensure that the U.C. Berkeley exoskeleton is energetically autonomous and is field re-fuelable. A significant challenge in the design of the lower extremity exoskeleton was the development of a power supply and actuation system that would satisfy its power and energy requirements for a long mission. The Berkeley exoskeleton uses a state-of–the-art small hybrid power source, which delivers hydraulic power for locomotion and electrical power for the exoskeleton computer. Work on the exoskeleton project on-going, with the focus turning to the miniaturization of exoskeleton components, the development of a smaller, quieter and more powerful power source and a faster and more intelligent controller.
Yeah, it's a bit of doublespeak and hype, but it's obvious they're not blind to the power issues either. Anyways, the original question wasn't so much about the pragmatism of these in the near future, but how- when implimented- they will affect infantry philosophy.
Roughly, your options are:
Increase defense - adding armor
Increase offense - adding weapons
Increase survival - adding supplies
Increase speed - add nothing
Increase all - increase all to lesser degrees
Edit: If you want to guesstimate fuel weight... look at the image. From the articles, we're told that the machine weighs 100 lbs and the pack weighs 70 lbs (and, according to users, the whole rig feels like it's only 5 lbs once active). So, looking at the image, shave off the weight of the 70 lbs pack and guess how much the legs weigh... subtract from 100 and you've got- roughly- the power source weight.