To distribute money more efficiently all you need to do is ensure that 'mining' (the process itself, not its results) has a net positive effect (involves expenditure on renewable goods and services) instead of a net negative one (energy waste). It's simple as that.
(quoting myself here...)
OK it's not quite as simple as that, because you have to factor in time horizons and the early adoption phase, in which coin production costs are marginal (thus not allowing for efficient distribution). With BTC the design was such that a great deal of coins were produced during the early phase for a very low cost (the first 1,000,000 BTC were mined for a cost of what it would take to mine less than 1 BTC today, roughly speaking).
More efficient distribution would thus require (aside from finding a way to make mining a net positive process) a shorter early adoption phase in which production costs are trivial, so that we could arrive at the point where mining produces tangible positive effects more quickly. However, the early adoption phase should still last long enough and be lucrative enough for the coin to gain popularity.