Every type of energy has its own storage issues, but perhaps the hardest challenge is to store electricity. As the proportion of electricity generated from renewable sources increases, the problem of storing it grows too. For example, a solar panel on a roof generates electricity during daylight hours, but we might need that electricity at night (for lights especially). So it is common to use solar panels (or any other intermittent renewable energy device) with batteries that can store a limited amount of electricity for use later on. Unfortunately this tends to work less well for high-demand appliances such as fridges, washing machines and kettles, because the sheer amount of electricity they need would require a really large bank of batteries. New technologies such as fuel cells may create ways to convert this electricity in to hydrogen during times of plenty and then back in to electricity when electricity is needed, but there are efficiency and cost barriers to this that still need to be overcome. - Description added by: David Lockie

The word 'offsetting' simply means 'compensating for'. 'Carbon offsetting' means compensating for carbon dioxide (CO2) that's being generated. We need to compensate for CO2 because of the threats posed by climate change.

Realistically, no-one can expect people to cut out absolutely everything they do that leads to CO2 emissions. We all can - and must - reduce the CO2 we're responsible for, but offsetting means we can compensate for the CO2 we can't avoid creating. Carbon offsetting schemes work by reducing CO2 that would otherwise be created, or by removing existing CO2 from the atmosphere.

And who benefits from the carbon offsetting? Who gets compensated? The answer is Planet Earth - and absolutely everyone and everything that lives on it. - Description added by: David Lockie

You can add your own description here to help people understand what 'energy' means

Renewable and alternative energy sources are set to play an increasingly important role in providing the electricity, heat, cooling and fuels that society needs. There is a wide range of energy sources such as solar (both photovoltaic and solar thermal), wind, bio-fuels and biomass, hydro-electric, geothermal and heat pumps. - Description added by: David Lockie