We've past all the long hanging fruit. Everything from here on forward is going to take more time, money, and people than. 100-200 years ago there were thousands of people at best with the education to push things forward. Often they were experts in several fields. Today we have hundreds of thousands of people pushing on these fields (of which people are only an expert in one or two things). All of the easy answers are gone.

This is compounded by the bar being really high and the regulation really thick. What counts as a great innovation in alternate energy today requires at least being competitive with existing technology, which has almost one hundred years of development by tens of thousands of engineers at thousands of companies. It is no wonder it takes longer. And you have to worry (rightly so) the environmental and safety aspects of things that wouldn't have mattered 150 years ago.

All of these things slow down progress and make it more expensive. One of the reason progress was cheap in computer science was because the field was young, but as it matures we will see a slow down in innovation. Only fools will continue to believe Moore's "law" has any truth looking 20 years into the future.