Hi lime light power
The answer is that many see energy produced from, say, the wind to be unreliable: the wind doesn't always blow.
Same with solar: we get cloudy days.
You could also ask why haven't alternative technologies - like the Well's Turbine and Professor Salter's Duck (both wave power systems) - been deployed?
Answer. The petro-chemical/oil industry lobbies hard to prevent such systems from getting any serious consideration at government level. Everything is stacked against alternative tech'. And most government's 'green credentials' are entirely spurious.
If you would care to investigate a new concept in vertical axis wind turbine design (all my own work) you can download a pdf - that explains my ideas with text and diagrams - from the link below. I would be most interested to hear any views/input you may have on the subject.
My best regards