Also, I've been doing some research on antimatter.
For one, it's extremely difficult to contain, even in small amounts. This would mean that transporting large amounts in the time in this roleplay would obviously be easier, but it would be far for perfect, or completely safe.
Second, antimatter is like matter, except with an opposite charge. When one particle of matter collides, meets, or touches a particle of antimatter, they both annihilate each other in a burst of pure energy. Dark Matter, from my research on it, would only produce a small shower of "Familiar Particles." Theoretically, Dark Matter would be illogical to use as an alternate, better energy source than Antimatter, because it doesn't produce energy.
Third, antimatter can still be elements. All it antimatter is oppositely charged, which means you can create antihydrogen, or antigold, or antiiron. It's been done, today, in this century.
Fourth. There is not nearly as much antimatter as is thought here. While it can be very destructive, due to its... annihilation properties, it is extremely rare in this universe. While theories run rampant about whether or not there could be an entire universe that is the opposite of ours -all antimatter, and barely any matter- , antimatter is rare, and in low quantities. There are a recorded 28 antimatter particles in orbit around Earth, in part of a belt around the Earth, inside the gravitational fields that come out of the poles, and loop around to the opposite side. I believe it's called the Atlantic Anomaly, or somesuch, where the belt dips closest to Earth.
Antimatter is a source of large amounts of pure energy, with just a small amount of antimatter.
Dark energy is nothing, with no true science behind it. Who says that something completely fictional, with nothing proving it to be a viable source of energy, now or the future? There is several discussions about the option of antimatter for energy generation, but all Dark Matter does is explode in familiar particles when it comes into contact with another Dark matter particle. The only use I see for the Dark stuff is for easy storage. Grab 4 Dark Matter particles, toss it together in a chamber filled with antimatter, and the burst of particles should be enough to cause such a reaction as to create a burst of pure, plentiful energy.
We've got it wrong: Dark Energy here, and antimatter-generated energy over there, when they actually should be working together. Dark Matter to save space, since there appears to be half a dozen or more familiar particles in each particle, and antimatter because of the energy. DM is more space-efficient, and AM is more energy-efficient!