Power From Environmental Gradients
There are many settings where having electrical energy is helpful but not practical. Some sensors and actuators require relatively low levels of power but are inappropriate for battery power and connecting to a power grid is cost prohibitive. When the power needs are modest, such as nighttime decor lighting or intermittent RF transmission, thermoelectric generation can be the solution --- generating power where it is needed. Temperature gradients as low as a few degrees can be successfully harvested for electrical energy.
The
theory
is well known, but the technology is only now becoming practical for energy harvest from low level heat streams as noted in the following video:
