I just had a quick Google and found a bunch of training videos on YouTube for Brazilian Jiu-Jitsu, so it does seem possible. Having done a number of martial arts myself I do understand that having a partner does make a massive difference but I've never come across a martial art that doesn't have solo training exercises to enable individuals to practice when alone. Even the martial arts that you wouldn't expect could work solo (like fencing) still have solo training exercises.