The dimensional generator is able to generate energy from anything (nether, end portals etc.) that makes you be able to teleport to other dimensions in a radius of 5 blocks. If a nether portal is in its radius, it would generate 128 EU/t (medium voltage), if an end portal is nearby, it would generate 512 EU/t, but if a mob or player goes throught the portal, there would be a short boost of +128 EU/t.
recipe:
ey|ey|ey
a| |a
ey = eye of ender
a = air/nothing