United Kingdom is the windiest country in Europe, so much so that we could power our country several times over. 
How Heat pumps work
Both Ground Source and Air Source Heat pumps work by absorbing energy from either the ground or the air.
Air Source heat pumps utilise a large fan to draw in outside air, this energy is then transferred through large heat exchange units, which work similar to a fridge, by displacing the cold air, through compression and evaporation, so that you are left with warm air.
This can then be transferred directly to pipes circulating water (Air to Water system) or through a combination of successive fans, spreading the air throughout the home (Air to Air system). Air Source heat pump efficiencies reduce substantially when temperatures fall below 40 C, therefore a supplementary back up heating system is generally required in places with colder, harsher climatic conditions.
Ground Source Heat pumps work by piping a mixture of water and antifreeze through coils buried 2 metres deep directly in the ground. As the water passes through the pipe work, the temperature slowly begins to rise, through the process of convection, due to the slightly higher temperature of the inherent topsoil, which is regarded as stored solar heat, (not to be confused with geothermal heat) which is heat derived directly from magma within the earth’s mantle. Ground Source heat pumps are generally more reliable, as the temperature of the topsoil, acting as a thermal storage body, tends to be relatively constant throughout the year, and thus maintains sufficient temperature differentials.