What is the cheapest type of device to power?

The cheapest type of device to power depends on various factors such as the energy source available, the energy efficiency of the device, and the cost of the energy source in a particular location. However, in general, devices that use manual power or passive energy sources tend to be the cheapest to power. Here are a few examples:

1. Manual-powered devices: Devices that rely on human power, such as hand-cranked flashlights or manual kitchen appliances, are typically inexpensive to power since they don't require any external energy sources. They are powered directly by the user's effort.
   
2. Solar-powered devices: Solar energy is a free and renewable energy source. Solar-powered devices, such as solar calculators, solar-powered lights, or solar chargers for electronic devices, can be cost-effective to power once the initial investment in the solar panels or equipment is made. The ongoing operational costs are minimal.
   
3. Wind-powered devices: Wind energy can be harnessed to generate electricity using small wind turbines. If you have a suitable location with consistent wind flow, wind-powered devices can be relatively inexpensive to power. However, initial installation costs and maintenance requirements should be considered.
   
4. Passive energy devices: These devices utilize natural or passive energy sources, such as gravity or temperature differentials, to operate without the need for external power. For example, passive solar heating systems or gravity-fed water systems can provide cost-effective energy solutions.
   

It's important to note that the cost-effectiveness of powering a device also depends on factors such as the initial investment in equipment, maintenance requirements, and the availability and cost of alternative energy sources in your specific location. Additionally, the energy efficiency of the device itself plays a significant role in determining the overall cost of powering it.  Talk to your local electrician if you have any questions