Basically, if there are no thermals, but a strong wind, is there a way to use that wind to gain altitude?
Yes, it's called ridge lift. From Wikipedia:
Ridge lift (or 'slope lift') is created when a wind strikes an obstacle, usually a mountain ridge or cliff, that is large and steep enough to deflect the wind upward.
If the wind is strong enough, the ridge lift provides enough upward force for gliders, hang gliders, paragliders and birds to stay airborne for long periods or travel great distances by 'slope soaring'.
If you happen to be in the San Diego area on a nice summer day. Go to the Torrey Pines glider port above Black's Beach in La Jolla and just north of the Scripps Institution of Oceanography. The onshore wind striking the bluff overlooking the beach is forced upwards and provides plenty of lift for hang gliders working their way back and forth.
You can see images of people doing that at the Torrey Pines Gliderport website or just Google "torrey pines gliding images" for additional images.