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.

Certain food-based biofuels like biodiesel have always been a bad idea. Others like corn ethanol have served a useful purpose and essentially are obsoleting themselves.

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 state of healthcare today is that we are busy in the practice of medicine vs. being in the science of medicine.

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

The right way to build a company is to experiment in lots of small ways, so that you have plenty of room to make mistakes and change strategies.

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.