The resource energy must be distinguished between renewable and non-renewable energies. In the context of IWM the focus of attention is towards the renewable energies:

• solar
• biomass 
• wind
• water
• geothermal

Most  common  is  the  focus on  solar, biomass, and water, because here decentralised and simple operating devices are  available. It is also possible to direcly influence the availability and sustainable utilisation of these energies. 

Non-renewable energies require in general centralised systems or the devices are independent of any topics from IWM (sich as e.g. cars).