Compared to other forms of electric heating, storage heaters are cheaper to run and they impose lower peak loads. The highest peak loads come from instantaneous electric heating, such as immersion water heaters, which create heavy loads for short durations, although instantaneous water heaters may use less electricity overall. High-efficiency ground source heat pumps are able to use up to 66% less electricity than storage heaters in heating by recovering heat from the ground, and are regarded as preferable even though they use electricity throughout the day. These are not to be confused with air conditioning (A/C) heat pumps which are now considered to be an environmental liability in some, (in particular hotter climate), countries.