Startups allow technologists and scientists to take risks and change plans in a way that would be frowned upon in a big company. Having said that, big companies will play a key role in certain areas and in partnerships with little companies. Each has its strengths.

The first rule of venture capitalism is hands-on experience. You have to get your hands dirty.

As for companies invested in the space - I think its important to distinguish between a good investment and a material climate change technology - you can have the first without the second, even in the "clean tech" space.

Spreadsheets are fiction. Believing in what you're doing and what you're building is what's important.

Setting an aggressive enough carbon-reduction goal will result in an appropriate price for carbon and will help many a renewable technology. Consumer education will help. Most importantly, though, will be the continually declining cost trajectory of the real breakthrough in clean-technology costs driven by research and innovation. In the end, private capital is the real barometer of change.

In my view, it’s irreverence, foolish confidence and naivety combined with persistence, open mindedness and a continual ability to learn that created Facebook, Google, Yahoo, eBay, Microsoft, Apple, Juniper, AOL, Sun Microsystems and others.

If I collected all the diamonds in the world, I'd have no 'income' but I'd have a lot of 'assets'. Would my company be worth nothing because I have no income? A lot of Net companies are collecting assets. They have to be measured with a new set of metrics.