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

Electricity is fundamental to modern societies. It is the backbone to nearly all other technologies and we use it daily in lighting, appliances, communications and healthcare. Currently most electricity is generated in centralised, large-scale power stations fuelled by fossil fuels, uranium (nuclear power) or through renewable or alternative energy sources such as wind or hydro-electric power. It is becoming increasingly clear that we need to secure long-term, cost-effective and sustainable alternatives to fossil fuel power stations to cover both current demand, and future growth. There is an urgent need for open debate and consensus on the future of electricity generation as decisions are being made now that will still need to be in place in thirty years time, when the world might look radically different from how it does now. - Description added by: David Lockie

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