Solar chimney and heliostat are the devices to provide solar energy with low technology and low cost.The solar chimney is based on helio-aero-gravity concept.It consists of an air turbine-generator system placed in a chimney at the center of a transparent canopy collector open at the periphery in communication with the ambient air.Air heated under the transparent canopy rises into the chimney,where it hits the turbine and the generator produces the electricity.This way about 50 kW of power per km2 of land can be produced at a low cost.A similar chimney can be used for cleaning polluted air if placed in the polluted area by spraying water at the top of the chimney.A heliostat is a mirror reflecting sunlight on a predetermined target.A dual axis-tracking device keeps aligned either the mirror or the target with the Sun.The target contains a medium such as water or molten salt, which is heated and travels through a heat exchanger, produces steam and generate electricity through a team turbine.