I don't really get the idea that we should force everyone to vote.
There are a lot of possible objections to the idea - it should be your right not to vote as much as it is your right to spoil your ballot, you don't really want uninformed people voting anyway.
If you really want 100% voter turnout, you're probably going about it the wrong way. I think what you really want is a statistically significant voter turnout.
That is, from the list of all eligible voters, choose 20,000 completely at random and require THEM to vote. The result is probably going to be the same, and if it's too close to be sure, then expand the vote.
I wonder what it would do to political involvement though... I wonder what that would do the campaign expenditures, where there aren't obvious groups to target.