There are people working on reversible computing hardware for that very reason. You still have to consume energy to output information, but that's relatively insignificant.
Kurzweil talks about it in The Singularity Is Near, when he examines just how far Moore's Law can go. If we can figure out reversible computing, the upper bound is quite a bit further out, since heat dissipation issues go away. Ask a reversible computer a yes-no question that takes enormous computation, and it will consume no more energy than a rock, until at last you have to pay for your one bit of output.
No, sorry. Aside from Kurzweil, I read an article a year or two ago about someone who'd made a bit of a breakthrough, figuring out how to break a large computation into a lot of smaller reversible chunks. But I don't have the link.
Kurzweil talks about it in The Singularity Is Near, when he examines just how far Moore's Law can go. If we can figure out reversible computing, the upper bound is quite a bit further out, since heat dissipation issues go away. Ask a reversible computer a yes-no question that takes enormous computation, and it will consume no more energy than a rock, until at last you have to pay for your one bit of output.