The most important groups of fuels are fossil fuels, bio-fuels, hydrogen and nuclear fuel (uranium). Of these fuels, only bio-fuels and hydrogen are strictly renewable, but in both cases, this really depends on the energy source used to produce it. We have traditionally been heavily dependent on fossil fuels (first coal, then oil and now natural gas) and more recently on nuclear power. In the future, we will need a more sustainable range of fuels for all potential uses. New technologies such as fuel cells may require a wider range of fuels (e.g. hydrogen) and widen the range of applications for which fuels may be used (e.g. methanol-fuelled fuel cells to power laptops). There are many controversial topics surrounding fuels, from carbon emissions and climate change through the potential for bio-fuel crops to compete with food crops to the whole debate around nuclear power generation. - 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