You have to be willing to spend an awful lot in that R&D phase before you see the benefits. When you look at the companies that have really won customers over in technology - say, Apple and Google - you find that they spend billions of dollars on R&D each year, often spending that much on a product before they ever make a dime back in profits.

Whatever my current beliefs are, on any topic, they're all open to being changed by the right facts and the right evidence.

On almost every environmental issue I care about, in fact, I've been wrong at one point or another. I used to think that climate change was no big deal, that most environmental problems were massive exaggerations, that oil reserves were effectively unlimited, and more.

Often we need to use policy to level the playing field, or to be sure that a technology is managed in a responsible way.

When it comes to trying to manage how our entire planet-wide market and all the people and businesses in it deal with nature and our natural resources - we first and foremost need to change the incentives.

Unfortunately, in the environment, I don't see as much willingness to invest heavily in R&D as I do in consumer technology. And that's a pity.

You have to be able to generate usable energy without greenhouse gas emissions and you have to be able to do it cheaply if you want people to choose that approach.