Burning fossil fuels increases the amount of CO2 in our atmosphere, with serious consequences such as ocean acidification and an increased greenhouse effect. Reducing CO2 emission is important, though it would still leave much CO2 still in the atmosphere. Actually we should look for ways to remove that from the air, one way to do so would be reforesting.
Science Daily has an article which describes that scientists of the University of Oregon has invented a new method to take CO2 from the atmosphere and to use it for the production of ultra-capacitors which could be used to store energy. One of the issues of solar and wind energy, is that supply and demand are not synchronous. In order to manage the discrepancies between production and consumption of energy, energy storage is essential. There is enough solar and wind power available to run the world.