The first of these involves a trough which rotates in a single plane in order to follow the sun. The second and third types involve tracking two axis reflectors that focus the energy on a single point. The efficiency of CSP in converting heat to electricity is typically between 20% and 30% and the amount of energy generated is dependent on the solar intensity of the location. Much of the Sahara receives over 800W/m2 and a 150,000km2 installation of CSP, occupying around 3% of the Sahara, could provide the world’s current demand for energy of all kinds.