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

Heating and cooling are typically extremely energy intensive technologies. In the United Kingdom the majority of heating in our homes and buildings is provided by burning natural gas. Renewable energy technologies such as solar heating, or heat pumps provide a sustainable low carbon alternative. Condensing boilers, and combined heat and power (CHP) also offer significant energy savings. In this circumstance energy that would have otherwise been wasted (which happens in traditional power plants) is instead used by the local community via a district heating scheme. Alternatively, a micro CHP system (such as a residential fuel cell, or Stirling engine) produces both electricity and heat to serve a local heat demand i.e. for a particular building. Energy efficiency technologies such as low carbon ventilation solutions can reduce the energy demands of buildings. - 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