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 state of the environment in which we live is of the highest importance – without it we cannot live, and if it is not functioning normally our lives become increasingly difficult. The number of people on the planet and the accelerating rate of individual resource consumption are having negative or disruptive effects on the environment. Global warming and climate change are now global challenges attracting much media attention. Resources such as drinkable water, food and non-polluted environments are all becoming more dependent on technology and competition is growing for these resources. Thus the decisions that we need to make on our journey to becoming 'low carbon' should always be taken with environmental impacts in mind. - 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