Also (too late to edit my previous comment), this assumes fusion converts all of the deuterium mass to energy, but actually it's only the change in nuclear bind

Also (too late to edit my previous comment), this assumes fusion converts all of the deuterium mass to energy, but actually it's only the change in nuclear binding energy between D + T and n + He-4, which is 17.6 MeV per reaction, or 2.8e-12 Joules (note minus sign). So this assessment above seems to be off by about a factor of 10^24, or 1 trillion trillion. To get all the energy out of a deuteron, you need an anti-deuteron. This is dramatically less practical than thermonuclear fusion because we have no credible source of meaningful amounts of anti-matter fuel. The linked ucsd page is pretty solid.