Energy. Creating a single anti-hydrogen atom requires an absurd amount of energy to first create a collision in a particle accelerator and then capture that anti-hydrogen before it eliminates against another atom.
Only about 0.01% of the energy used to operate the particle collider creates antimatter, the vast majority of which is impossible to capture. All in all, the efficiency of the entire process - if you were to measure it in the e^2=(pc)^2+(mc^2)^2 sense - is probably on the order of 1e-9 or worse.
Has there been research on more efficient ways to generate antiprotons? (By the way anti-hydrogen isn't how you would store it as anti-hydrogen can't be trapped.)
Only about 0.01% of the energy used to operate the particle collider creates antimatter, the vast majority of which is impossible to capture. All in all, the efficiency of the entire process - if you were to measure it in the e^2=(pc)^2+(mc^2)^2 sense - is probably on the order of 1e-9 or worse.