7. Solar Energy: Estimates of Energy Potential and Environmental Issues

The Sun energy falling on the Earth at the rate of about 100 PW/year is enough to support our energy needs about a few thousand times. If new technology could find a practical way of transformation and accumulation, we would have supply by energy our industry and personal consumption without any energy crisis. Although the heat of the Sun stirs up the atmosphere and causes wind and water circulations on the surface of the Earth, a considerable part can be used to generate electricity or used directly. The currently used photovoltaic cells are inefficient and expensive to substitute traditional fossil energy sources. Also the territorial claims are high and output power variable due to meteorological conditions. Despite the Sun giving approximately 1.4 kW per square meter to the Earth, we can use a small part such as about 100–200 W per square meter at the Earth’s surface, with higher values at the equator. Although current technology for electricity generation is still too costly for general use, there are many applications for relatively small amounts of electricity needed in remote sites such as navigation lights, road signs, computer networks, power supply, or recharging of consumer electronics. Another way is to use solar energy for domestic water heating. Many houses are equipped with solar panels that can substitute a part of heating energy produced by traditional heating systems on sunny days.