Here's a post that touches on the crunch issue for many alternative energy companies;
Do you want jam today or jam tomorrow?

The posting talks briefly about Renewable Energy Holdings.

So here's my take on the jam - viewed as what is cost effective and able to generate profits free of government intervention.

Jam today technologies - now until 2010

Waste (landfill) gas
Onshore wind
Solar thermal
Geothermal

Jam tomorrow technologies - post 2010

Biodiesel
Bioethanol
Biogas
Energy storage
Offshore wind

Jam the day after tomorrow technologies - post 2025

Fuel cells
Solar PV
Wave