The current turbulence on the market does not change the basically positive trends in solar energy if we can believe the latest sustainability study conducted by Sarasin. Nonetheless, change is afoot.

The unwavering predictability and scale of the tides in some parts of the world make them an attractive renewable energy source. Some estimates put the energy in the world's tides at as much as 1 million GWh per year, or about 5 per cent of the electricity generated worldwide, though only a fraction of this is likely to be exploited due to practical constraints.

One of the key problems with renewables is their intermittent availability. You can only generate energy from the wind when it is blowing, or from the sun when it's shining. Critics argue this is why we will never be able to rely on renewables for the majority of our electricity generation. But that criticism may soon be silenced.