I'm an engineer. As an engineer, when you think about optimizing something or fixing something, you think about the 80% case. Its nice to think of the tiny micro-optimizations that will gain you a percent here, a percent there, but for the most part, they're futile academic exercises. Applying the same logic to energy, I think the 80% problem is energy *harvesting* not conservation.
Note: harvesting not production. Why? The sun is the closes source of infinite energy (by todays consumption rates). Various nuclear reactions on the sun are going on and are expending the energy stored there (as a result of the big bang, or God, depending upon your choice in these matters) and blasting this energy out to us. The amount of energy that sun blasts out does not change irrespective of how much you or I use. It is available for harvesting and if you don't harvest it, its gone.
Note again: I lied. Energy coming from the sun is clearly not infinite. Its a finite resource. However, it is more, by several orders of magnitude (unverified, pulled-out-of-thin-air stat here folks!) than the energy that we consume as a planet.
Hence my conclusion: Conservation is not the 80% problem. Better harvesting is the 80% problem and that's what we should be focusing on.
Now this is clearly untrue for known finite energy production resources such as nuclear fuel, coal, natural gas and of course, oil. The known capacity of these resources is within the same order of magnitude as our current energy needs x several decades or centuries. Which is worrying given that as our society evolves, our energy needs will go up and thus the known period of time for which we can survive on these resources will go down.
There is another, non-trivial argument for conservation: Energy costs. *Because* we get energy from increasingly expensive finite resources, the cost of energy keeps going up. Right now, its bordering on the edge of becoming a non-trivial part of living expenses, I think sooner or later, it will become this. Some percentage of our living expenses will be the energy. Cities will be able to attract or repel people based on how much energy they can supply and how much it costs (this already happens for industry which requires a steady supply of clean electricity at relatively low costs). So for purely monetary reasons, I think conservation is fine - even necessary in order to keep our daily costs down.
However, for anything else, we're attacking the wrong problem. Lets focus on harvesting, not on conservation. Go after the 80%.