Marine Current Turbines' SeaGen system quadruples the world tidal-turbine power record.
Technical advances jump-start electric cars, wind turbines, and solar power.
Will putting a price on carbon increase the use of renewables?
Clean energy depends on new infrastructure.
A leading economist explains why a carbon tax is the best strategy for cutting greenhouse gases and the use of fossil fuels.
Without a radically expanded and smarter electrical grid, wind and solar will remain niche power sources.