Every week someone at a conference will suggest, "What we need is a Moore's Law for energy." It comes right after someone else asks, "Where is the Google of greentech?"

I thus want to give a big thumbs up to Vivek Mehra, a partner at August Capital and co-founder of Cobalt Networks, for publicly and eloquently stating what some of us have less effectively mumbled for a while.

"There is no such thing as a Moore's Law in energy," he said to an audience at the Smart Grid Innovation Symposium sponsored by the Innovation Center of Denmark (which took place in Menlo Park, Calif.) "The time scales are just different," he added.

Technology will improve, he noted, but not with the same rigorous efficiency that we saw with computers. As a result, investors and entrepreneurs may have to wait a lot longer for a more modest payoff from their investments.

The problem ultimately boils down to the nature of matter and engineering. It turns out that silicon structures can be shrunk at a steady, consistent pace. Back in the 1960s, engineers could shrink the size of transistors by half every year. Now, it takes about two years, but that is being stretched toward two-and-a-half years. Shrinking transistors means that the electrons running through them have a shorter commute. A shorter commute means better performance. If you think about it, Moore's Law is really about urban planning for semiconductors. (here is a fuller article on the subject.) Back in 2003 at an Intel 35th anniversary celebration, I asked Dr. Moore why the observation named after him worked so well.

Well, we got kind of lucky, he said. He listed a bunch of other factors, but I was struck that luck was the first one listed.

Greentech is far different. Biofuel companies mostly revolve around chemistry, so the same silicon dynamics don't apply. Solar cells are semiconductors. However, shrinking their size only decreases the performance: a smaller solar cell has less surface area to capture sunlight.

And if you want to know why there isn't a Google of greentech, think about solar panels for a second. If Google had to come to your house, install large pieces of glass on the roof, and hand you a bill for $30,000 dollars before you conducted your first search, you'd switch to Yahoo.