In most cases, installation of a geothermal system is easy, especially when it's replacing another forced-air system. It can be installed in locations unsuitable for natural gas or propane furnaces - there is no combustion, and thus no need to vent exhaust gases.
In fact, geothermal components can be added to existing heating equipment for those wishing to have a dual-fuel system. A conventional furnace can be kept as a backup in extremely cold weather if additional heat is needed.
A standard 200-amp electrical service will have more than enough capacity to power a geothermal heat pump. Your contractor should contact Alliant Energy's Operating Department to determine proper distribution loading.
If you're replacing a forced-air system, a geo system can use the existing ductwork. If you currently have a boiler system with radiators, the conversion will be more complex.