Wind
Wind power, as an alternative to burning fossil fuels, is plentiful, renewable, widely distributed, clean and produces no greenhouse gas emissions during operation.
Water
For someone with a worthwhile resource, Hydropower is the most viable form of renewable energy being relatively cheap to install compared to the energy generated.
Solar
The sun is the power source of the planet and energy from the sun is at the heart of all renewable energy, whether Solar Thermal/PV, Wind, Biomass or Hydro.